Review Article Sulforaphane and Other Nutrigenomic Nrf2 ...downloads.hindawi.com/journals/omcl/2016/7857186.pdf · Can the Clinician s Expectation Be Matched by the Reality? ChristineA.Houghton,RobertG.Fassett,andJeffS.Coombes

Review ArticleSulforaphane and Other Nutrigenomic Nrf2 ActivatorsCan the Clinicianrsquos Expectation Be Matched by the Reality

Christine A Houghton Robert G Fassett and Jeff S Coombes

School of Human Movement and Nutrition Science The University of Queensland Brisbane Australia

Correspondence should be addressed to Jeff S Coombes jcoombesuqeduau

Received 13 October 2015 Accepted 6 December 2015

Academic Editor Ahmed Abdel Moneim

Copyright copy 2016 Christine A Houghton et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The recognition that food-derived nonnutrient molecules can modulate gene expression to influence intracellular molecularmechanisms has seen the emergence of the fields of nutrigenomics and nutrigenetics The aim of this review is to describe theproperties of nutrigenomic activators of transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2) comparing thepotential for sulforaphane and other phytochemicals to demonstrate clinical efficacy as complementarymedicines Broccoli-derivedsulforaphane emerges as a phytochemical with this capability with oral doses capable of favourably modifying genes associatedwith chemoprevention Compared with widely used phytochemical-based supplements like curcumin silymarin and resveratrolsulforaphane more potently activates Nrf2 to induce the expression of a battery of cytoprotective genes By virtue of its lipophilicnature and low molecular weight sulforaphane displays significantly higher bioavailability than the polyphenol-based dietarysupplements that also activate Nrf2 Nrf2 activation induces cytoprotective genes such as those playing key roles in cellular defensemechanisms including redox status and detoxification Both its high bioavailability and significant Nrf2 inducer capacity contributeto the therapeutic potential of sulforaphane-yielding supplements

1 Introduction

Whilst early 20th century nutrition science resolved issuesrelated to micronutrient deficiency states and the latter partfocused more on macronutrient excesses [1] the first decadeof the 21st century has already seen old paradigms challengedand new theories proposed The recognition that food-derived nonnutrient molecules can modulate intracellularmolecular mechanisms has seen the emergence of the fieldsof nutrigenomics and nutrigenetics disciplines derived fromthe interweaving of the sciences of nutrition biochemistrymolecular biology and genomics It has been estimated thatthere are more than 5000 different phytochemicals present infood [2] and our current knowledge is limited to a reasonableunderstanding of the function of just a few

Against this background sits the quest to identify biomol-ecules with significant nutrigenomic potential A growingbody of research highlights one such biomolecule sul-foraphane an isothiocyanate (ITC) derived from the crucifer-ous vegetable family and in particular from Brassica oleracea

[3] Although the plant kingdom is the source of thousandsof phytochemicals little is known about the way in whichfood-derived phytochemicals support the maintenance ofhuman health and especially those associated with cellulardefensemechanisms As the science of nutrigenomics evolvesand our understanding of the many interactions betweenphytochemicals and endogenous cytoprotective mechanismsgrows the significance of plant foods in human healthbecomes clearer

A critical review of the formulations of some availablesupplements reveals numerous flaws shedding doubt on theirpotential efficacy [4] There are few published clinical trialsusing phytochemicals as the intervention material and only asmall number of these withstand scientific scrutiny Howevereven when benefit for a compound has been demonstratedit is common for a commercial product to include theingredient at a dose manyfold lower than that shown to beefficacious in either clinical trials or as it was traditionallyemployed by cultures of the past As a further trap forthe unwary consumer or uninformed clinician supporting

Hindawi Publishing CorporationOxidative Medicine and Cellular LongevityVolume 2016 Article ID 7857186 17 pageshttpdxdoiorg10115520167857186

2 Oxidative Medicine and Cellular Longevity

commentary may include citations for in vitro and animalstudies giving the reader a false impression of the productrsquoslikely efficacy as a supplement for humans

Because it appears that many consumers have accepteda role for complementary medicines in their personal healthmanagement it is important to review the evidence onwhether plant-derived supplements can assist in modifyingvarious biochemical and physiological risk factors for diseaseThe aim of this review is to describe the properties ofnutrigenomic activators of Nrf2 focusing on the potentialfor sulforaphane and other activators of gene expression todemonstrate clinical efficacy as complementary medicines

2 Beyond Nutritional Deficienciesand Excesses

21 Nutrigenetics and Nutrigenomics The interlinked sci-ences of nutrigenetics and nutrigenomics provide the clin-ician with a more targeted opportunity to personalise apatientrsquos treatment programme [5] revealing those geneticpolymorphismswhichmay compromise individual biochem-ical function Even without access to sophisticated genomeprofiling a clinicianrsquos knowledge that potent food-derivedbiomolecules can interact with intracellular signaling path-ways provides another dimension to clinical managementand disease prevention processes

The realization that food-derived molecules are in con-stant conversation with complex intracellular control systemsvia signaling pathways has unveiled the role of food as somuch more than a source of micro- and macronutrients[6] What becomes immediately apparent in this modelis that no multinutrient supplement can substitute for theenormous diversity in phytochemicals present in a balancedhuman diet Also evident is that the health benefits of thepopular polyphenolic phytochemicals such as those foundin green tea grape seed red wine curcumin pomegranateand olives are unlikely to be due to direct-acting antioxidanteffects demonstrated by these molecules in numerous invitro studies [7 8] Polyphenols are typically large bulkymolecules which are poorly absorbed and poorly bioavailable[9] so that it is unlikely that the intracellular micromolarconcentrations necessary to scavenge free radicals can beachieved Polyphenols can also behave as either antioxidantsor prooxidants depending on the experimental conditions[10] In addition newer evidence suggests polyphenols andother phytochemicals may function hormetically wherebydose response is characterised by low dose stimulatoryresponse and high dose inhibition [11]

In a bioactive-specific approach a recent comprehensivereviewof phytochemicals indicated for cardiovascular diseasefocused on both preclinical and clinical beneficial effects offour commonly supplemented compounds [12] The reviewconcluded that there are few definitive trials in this area andin some studies the exact dose used is not clear However theauthors confirm the findings of others in that the use of a veryhigh dose is associated with the most protective effects for afew phytochemicals whereas the lowest dose turns out to bethe most effective for other compounds

As with vitamin ldquoantioxidantsrdquo the notion that ingestedpolyphenol supplements act as ldquoantioxidantsrdquo in humancells is called into question [7] Emerging evidence suggeststhat polyphenols or their metabolites exert their systemicintracellular effects not as direct ldquoantioxidantsrdquo per se but asmodulators of signaling pathways

22 Cruciferous Vegetables Harbor Nutrigenomic PotentialThe classification cruciferous vegetables (crucifers) includesspecies predominantly from Brassicaceae family and themore common members are cultivars not only of Brassicaoleracea genus including broccoli cabbage cauliflower Brus-selsrsquo sprout and kale but also of Raphanus genus whichincludes various types of radish Although these vegetablesare good sources of micronutrients their value to humanhealth would seem to be at least partly due to the nature ofthe phytochemicals they contain and in particular the glu-cosinolates [13] the enzymatic hydrolysis products of whichare capable of modifying gene expression [14] Althoughvegetables such as broccoli are not popular dietary choices[15] the unique health-promoting value of crucifers contin-ues to be reaffirmed [16] A recent review [17] investigatingthe effect of crucifers on total and cardiovascular mortalityfound that several prospective studies showed no associationfor total vegetable consumption but did show a significantinverse association for cruciferous vegetable consumptionThe potential benefits of green leafy vegetables in generaland cruciferous vegetables in particular are not limitedto their effects in cancer and cardiovascular disease In a27-year prospective cohort study on cognitive decline inageing women (119899 = 15080) those in the highest quintileof cruciferous vegetable intake declined more slowly thanthose in the lowest quintile with an evident linear doseresponse [18] Those in the highest quintile of green leafyvegetable intake also experienced slower cognitive declineThe association did not change when data for participantswith cardiovascular disease and diabetes were excluded

Most research on crucifers has focused on broccoliBrassica oleracea (both vegetable and sprouts) as a sourceof bioactive compounds with nutrigenomic potential Thelast two decades have seen accelerating interest in the roleof broccoli in human health following evidence that induc-tion of detoxification enzymes might be responsible for themajority of the observed health benefits of vegetables [19 20]After isolating broccoli-derived sulforaphane Zhangrsquos groupshowed that sulforaphane was a major and very potent PhaseII enzyme inducer The group of induced enzymes includesNAD(P)HNQO1 (quinone reductase) and the family ofglutathione-S-transferases (GSTs) both ofwhich are requiredfor the detoxification of steroids and the ubiquitous environ-mental toxin benzo(a)pyrene [21ndash23] Zhang et al concludedthat the induction of detoxification enzymes by sulforaphanemay significantly contribute to the anticarcinogenic action ofbroccoli The way that sulforaphane demonstrably increasedtarget enzymes is indicative of a nutrigenomic effect eventhough the precise mechanism to explain such gene expres-sionwas not known at the time It would be another two yearsbefore the mechanism to explain the effect of sulforaphanewould be elucidated [24]

Oxidative Medicine and Cellular Longevity 3

3 Influencing Signaling Pathways

31 Nrf2 as ldquoMaster Regulatorrdquo of Cell Defense Althoughsulforaphane interacts in a number of mammalian biochem-ical pathways its effect on the redox-sensitive transcriptionfactor Nrf2 (nuclear factor erythroid 2-related factor 2)appears to be responsible for its greatest clinical potentialwhen administered at practical oral doses [25] Referenceto Nrf2 first appeared in the scientific literature in 1994and has subsequently been the subject of over 5500 MED-LINE published papers [24] In the ensuing two decadesNrf2 has emerged as a key modulator of the cellrsquos primarydefense mechanism countering many harmful environmen-tal toxicants and carcinogens [26] Considerable researchhas focused on Nrf2rsquos role in preventing the activation ofcarcinogens to toxic metabolites especially by inductionof the Phase II detoxification enzyme NAD(P)Hquinonereductase (NQO1) [27]

The elucidation of the mechanism by which Nrf2 acts asa cytoplasmic ldquoswitchrdquo to activate a battery of cytoprotectivegenes arguably heralds a new paradigm in nutrition scienceIdentification of Nrf2 gave the first real clue that bioactivediet-derived compounds like sulforaphane had the potentialto coordinately influence large banks of function-specificgenes [28]

Nrf2 has been variously described as an activator ofcellular defense mechanisms [29] the master redox switch[30] and a guardian of health span and gatekeeper of specieslongevity [31] As a mediator for amplification of the mam-malian defense system against various stressors Nrf2 sits atthe interface between our prior understanding of oxidativestress and the endogenous mechanisms cells use to deal withitWhat has become clear is that although attempts to counteroxidative stress by ldquoantioxidantrdquo vitamin supplementationhave been disappointing [32] many phytochemicals havethe capacity to activate Nrf2 and thereby induce genes [33]which collectively regulate much of the cellrsquos endogenousdefense system enhancing its survival [34] This findingmay be clinically significant in that diseases known to beunderpinned by oxidative stress may prove to be moreresponsive to such amplification of cellular defenses via Nrf2activation compared to by the administration of direct-actingantioxidant supplements [35]

32 Sulforaphane an Inducer of Nrf2 Target Genes Notablyand perhaps surprisingly given its significant cytoprotectivepotential sulforaphane does not exhibit a direct antioxidanteffect instead it is weakly prooxidant [36] As further evi-dence to support the critical role of redox signaling in cellulardefense mechanisms the ability of sulforaphane to induceNQO1 and cell cycle arrest in prostate cancer cell lines wasshown to have been completely abrogated by pretreatmentwith the glutathione (GSH) precursor N-acetylcysteine [3738] This finding has implications for the regular ingestion ofreadily available supplements of N-acetylcysteine

Sulforaphane [1-isothiocyanato-(4R)-(methylsulfinyl)butane CH

3S(O)(CH

2)4-N=C=S] is a small (MW = 17729)

aliphatic lipophilic organosulfur molecule which is notpresent in cruciferous or other plants (Supplementary Data

Figure 1 in Supplementary Material available online athttpdxdoiorg10115520167857186) Instead plants ofBrassica genus contain a biologically inactive precursorcompound glucoraphanin (GRN) which is containedwithin a plant cell vacuole together with an enzymemyrosinase (MYR) which is separately compartmentalized[39] It is when the plant cell ruptures and the GRN andMYR come into contact that sulforaphane is enzymaticallyproduced [40] (Supplementary Data Figure 2) Comparedwith its stable GRN precursor the resulting sulforaphaneaglycone is relatively unstable [41] this has implicationsfor culinary applications of broccoli and other cruciferousvegetables Broccoli is not the only crucifer which yieldssulforaphane but it yields the highest amounts with its GRNcontent around 75 [42] of total glucosinolates Notablyglucosinolate-containing plants contain variable quantitiesof both precursor and enzyme [43] As a result the yield ofsulforaphane and other isothiocyanates can vary widely

Cutting chewing or otherwise disrupting the broccoliplant cell structure initiates the synthesis of sulforaphanewhich compared to its stable GRN precursor begins degrad-ing soon after synthesis [44] For consumers to take advan-tage of the cytoprotective benefits of broccoli and othercrucifers steps must be taken to conserve the integrity of thesulforaphane released

Sulforaphane belongs to one of nine identified classes ofchemical Nrf2 activator [45] Structurally varied the onlyproperty shared by all inducers is their ability to react withsulfhydryl (-SH) groups Nrf2 therefore is intimately tied tosulfur chemistry and provided dietary protein is adequate abalanced diet should furnish sufficient sulfur However thereare concerns that sulfur intake inmanymay bemarginal [46]with some researchers suggesting that deficiency of sulfuramino acids can compromise GSH synthesis to a greaterextent than for protein synthesis in both the presence andabsence of inflammatory stimuli [47]Whilst vegan diets mayprovide significant levels of phytochemicals [48] there maybe a need for vigilance regarding sulfur adequacy given thatthe sulfur-containing amino acids are least abundant in plantproteins and that vegans typically consume about half of thesulfur consumed by those consuming a mixed balanced diet[46]

33 Broccoli Sprout versus Broccoli Vegetable Much of theclinically relevant Brassica research relates to broccoli sprouts[49] rather than to the mature vegetable with most ofthe early work in this field done by a group at the JohnsHopkins University beginning in the early 1990s The groupfound that 3-day-old sprouts of cultivars of certain cruciferscontained 10ndash100 times higher concentration of GRN thanthe corresponding mature plants [49] With a focus on iden-tifying plants with cancer chemopreventive properties theyfound that the sprouts were highly effective in reducing theincidence multiplicity and rate of development of mammarytumors in dimethylbenz(a)anthracene-treated rats Broccolisprouts also had the added advantage of containing mostlythe methylsulfinylalkyl glucosinolate (75 of the total) andvery little of the indole glucosinolate found in the matureplant which is a potential tumor promoter [50] Their


TT

TT T

TT

T TT

G

G

GG

G

G G GA

AA A

AA A

A AA A

AA AA A

AA

AA

A AA

TT

TT

T T T

T T T

TT

TG G

GG

GG

GG

CCCC

CC

CC

CG

C

CC

C

C C

C C

HS

Actin filament

Small MAF

ARE

Geneexpression

Phase II enzymes and othercytoprotective compounds

HS

SS

KEAP-1

KEAP-1

Weak prooxidant stressor

Nrf2

Nrf2

Nrf2 Nucleus

Cytoplasm

Figure 1 The mechanism by which Nrf2 activation increases the expression of genes with an Antioxidant Response Element (ARE) in theirpromoter regions Human Keap-1 contains 27 cysteine residues providing sulfhydryl groups (-SH) which act as sensors of ARE inducersincluding oxidative stress [69] SmallMaf protein is essential for Nrf2 function [170] Figure adapted fromKensler et al 2003 with permission[51]

realization was that small quantities of broccoli sprouts mayprotect against cancer as effectively as much larger quantitiesof the vegetable stimulated subsequent research

34 How Nrf2 Activators Influence Gene ExpressionAlthough the complexity of Nrf2 pathways has not yetbeen fully elucidated the principal elements are depicted inFigure 1 [51] Essentially Nrf2 is sequestered in the cytoplasmby the actin-bound cytosolic repressor Keap-1 (Kelch-likeECH-associated protein 1) a cysteine-rich protein whichalso acts as a sensor of variations in cytoplasmic redox statusWhen the appropriate signal is detected by cysteine thiolswithin Keap-1 its ability to bind and retain the transcriptionfactor Nrf2 in the cytoplasm is lost Keap-1 typically respondsto an electrophilic or oxidative stress signal [51]

Thus released Nrf2 translocates to the nucleus whereit aligns with a short nucleotide base sequence in the pro-moter region of its target genes this sequence is commonlyknown as the Antioxidant Response Element (ARE) or theElectrophilic Response Element (EpRE) with the latter beingconsidered a more correct descriptor although the termsare used interchangeably [52] To bind Nrf2 dimerizes withother basic leucine zipper (bZIP) proteins such as small Mafproteins (MafG) to form a transactivation complex that bindsto AREs [53]

When an electrophilic or oxidative stressor challenges thecell Keap-1 senses the disturbance to its cytoplasmic redoxequilibrium After release from Keap-1 Nrf2 levels rapidlyrise in the nucleus upregulating a battery of cytoprotective

genes each containing at least one ARE Of significance isthe effect of Nrf2 on induction of the rate-limiting enzymefor (GSH) synthesis 120574-glutamyl-cysteine synthetase therebyelevating tissue GSH levels [54]

For the Nrf2-Keap-1 pathway to such a play a key role incytoprotection its activity must be capable of being regulatedin tandem with the ever-changing cellular environmentUnder basal nonstressed conditions Nrf2 is continuouslydegraded via the ubiquitin-proteasome pathway [55] Witha half-life of around 20 minutes [56] Nrf2 is maintained at alow cellular level [57] Exposure to stressors inactivates Keap-1 by direct modification of cysteine thiol residues thereafterreleasing Nrf2 in a derepression-type stress response [58]

The clinical significance of this mechanism is apparentwhen considering the hepatotoxic effects of acetaminophena drug responsible for considerable drug-induced liver injury[59] Excessive doses of this common analgesicantipyreticdrug rapidly deplete intracellular GSH reserves However thecell activates an adaptive response whereby Keap-1 senses theacetaminophen metabolite N-acetyl-p-benzoquinone imine(NAPQI) subsequently activating Nrf2 [60] GSH is syn-thesised rapidly along with a battery of other Nrf2 targetgenesThis mechanismmay not be adequate to increase GSHlevels in an acute care setting given that translation timesfor protein synthesis of various Nrf2 target genes can takehours A study investigating the effect on gene expressionof cytoprotective heme oxygenase-1 (HO-1) in neurons aftersubarachnoid haemorrhage showed thatNrf2 levels increasedsim4-fold at 12 hours peaking at gt45-fold at 24 hours with


HO-1 levels increased to gt3-fold at 12 hours and peaking atgt45-fold at 24 hours [61]

35 Phase II Enzymes and the Detoxification MechanismsThemechanisms that cells use to detoxify potentially harmfulcompounds often carcinogens [62 63] can involve a PhaseI component associated with monoamine oxidases of theCytochromeP450 family and aPhase II componentwhere theintermediate compound produced by Phase I is metabolisedin a way that permits ready excretion A compound whichactivates Phase I and Phase II enzymes is known as abifunctional inducer however if it activates only PhaseII enzymes it is a monofunctional inducer [64] Phase IIenzymes are induced by Nrf2 and as such are integral to thisdiscussion For safe and efficient detoxification a toxin willideally undergo a relatively slow Phase I reaction followedby a more rapid Phase II this tends to prevent accumulationof the Phase I metabolite which can be more toxic than itsprecursor [65]

Therefore for an optimal cellular detoxification envi-ronment Phase II reactions should be at a rate which pre-vents intermediate products of Phase I from accumulatingAliphatic sulforaphane acts as a monofunctional inducerwhereas the indole ITCs from mature broccoli are bifunc-tional inducers derived from the glucosinolate glucobras-sicin [49] Of clinical significance is the finding that PhaseII enzymes have a relatively long half-life so that upregulatedexpression of these proteins can remain for several days Ina study using human adult retinal pigment epithelial cells(ARPE-19) NAD(P)Hquinone reductase remained active formore than 5 days [66]

4 Inducers of Nrf2 Target Genes

Nrf2 can be activated by a variety of inducers not all of whichare obtained orally For example the prooxidant signalsgenerated by the reactive oxygen species released duringexercise [67] or from inhaled environmental chemicals [68]are capable of upregulating the cellular endogenous defensesprovided exposure is sufficiently modest that it does notoverwhelm the cellrsquos defenses

41 Diet-Derived Nrf2 Inducers Although a number ofphytochemicals have been investigated in relation to theirNrf2 inducer ability the mechanistic studies to explain thenature of the induction are limited A review paper focusedon molecular mechanisms of phytochemicals in chemopre-vention suggested that only three plant-derived moleculessulforaphane carnosol and quercetin have been mechanis-tically investigated in this regard and only sulforaphane hasbeen studied for its roles in multiple mechanisms [69] Giventhe more extensive literature on sulforaphane we hereafterconsider its potential as a supplement of clinical significanceand where the data exist comparing its potential with that ofpopular and widely available phytochemical supplements

42 Sulforaphane In Vitro Effects Sulforaphane is a potentNrf2 inducer with consequent induction of cellular defenses

[70] The effect is rapid in cell culture with activation by sul-foraphane occurring within 30 minutes in human bronchialepithelial BEAS-2B cells [71] Using microarray analysis toinvestigate the effect of sulforaphane in the wild-type murineliver Hu et al showed that expression levels of 1725 geneswere increased after 3-hour exposure and 3396 genes werechanged after 12 hours [33] Comparing expression patternsat different time points they also showed that maximalchange occurred 12 hours after a single administration ofsulforaphane based on fold changes greater than 2-foldThe identified Nrf2 target genes can be classified broadly asthose coding for a range of cytoprotective proteins includingantioxidants (enzyme and nonenzyme) drug-metabolisingenzymes drug-efflux pumps heat shock proteins NADPHregenerative enzymes growth factors and growth factorreceptors heavy metal binding proteins and various nuclearreceptors including PPAR-120574 as well as for Nrf2 itself [33]

Vitamin Drsquos protective effects on human cells are wellrecognized [72] it may be nutritionally significant that thevitamin D receptor (VDR) is Nrf2 target gene inducible bysulforaphane [73] in turn Vitamin D can increase Nrf2expression [74] To further illustrate this diversity Nrf2target genes include those coding for 120573-defensin-2 (HBD-2)an antimicrobial peptide associated with innate immunityprotecting the intestinal mucosa against bacterial invasionHBD-2 can be induced by sulforaphane [73] and was shownin a cell culture study using human Caco-2 cells to besignificantly induced 16-fold at 24 hours and 2-fold at 48hours by sulforaphane concentrations ofgt5 120583MThese resultsmay have relevance in disorders of the intestinal epitheliumbut systemically an intracellular concentration of 5120583M isprobably higher than what can be readily achieved by dietor even via practical doses of available oral sulforaphane-yielding supplements

The downstream enzyme products of Nrf2 target genesare efficient and versatileThey include thosewhich constitutethe glutathione and thioredoxin systems the major cellularreducing systems in the body [75] Several reasons explaintheir efficiency and versatility [76] (1) they are not consumedstoichiometrically as are direct-acting antioxidants such asascorbate and tocopherols (2) their duration of action is longwith half-lives measured in days so their induction need notbe continuous (3) they restore the endogenously produceddirect-acting antioxidants like coenzyme Q10 and the toco-pherols by returning them to the reduced state (in particularvia NQO1 because both coenzyme Q10 and tocopherols arequinones)Major products ofNrf2 target genes and their rolesin cytoprotection are listed in Supplementary Data Table 1

5 Quinone Reductase (NQO1)a Tool to Evaluate Inducer Capacity

Initially considered as an Nrf2-activated Phase II enzymeassociated with detoxification pathways the function ofNQO1 is now considered to bemuch broader [77] NQO1 hasbeen described as a ldquoquintessential cytoprotective enzymerdquoand is coded by what is considered ldquoone of the mostconsistently and robustly inducible genes within its classrdquo


[77] Furthermore its activity declines with age whilst upreg-ulation of its activity by Nrf2 induction is described as anavenue for maintaining cellular defenses with advancing age[31] Furthermore animal studies show significant decline inNrf2 activity between youth and old age [78ndash80] Humansgenetically deficient in NQO1 are more susceptible to thecarcinogenicity of benzene exposure [81] NQO1 is highlyactive in pulmonary tissues [82] as well as in epithelial andendothelial cells in general [25] suggesting that it could actdefensively against compounds absorbed via the airways gutand bloodstream NQO1 activity is used as a rapid screeningprocedure and a biomarker of the anticarcinogenic activity ofphytochemicals [45 83] The assay [20] uses cells defectivein Phase I function to provide the means for selectivelydistinguishing monofunctional inducers that elevate Phase IIenzymes [84]

51 CD Values as a Comparative Marker The term ldquoCDvaluerdquo describes the concentration required to double NQO1activity in murine hepatoma cells [85] A CD value is alsouseful for comparing the potential in vivo nutrigenomiceffects of an ingestible bioactive compoundTheCDvalue hasalso been used [19 83] to classify Brassica spp according totheir relative ldquoanticancer potentialrdquo When several cruciferswere compared for their Nrf2 inducer effect [86] ITCs of cab-bage kale and turnips exhibited less NQO1 inducer capacitythan broccoli-derived sulforaphane Sulforaphane returnedsim33000 units NQO1 inducer activityg fresh weight forbroccoli cabbage returned sim11000 units and kale returnedsim10000 units with turnip returning sim2000 units This prop-erty may partly explain why broccoli is researched moreextensively than other Brassica spp

52 Clinical Significance of CD Value In data from studiescomparing CD values of well-known phytochemicals sul-foraphane showed the highest potency with a concentrationas low as 02 120583M required to double the activity of NQO1 [1985]The comparative CDvalues of other phytochemicals havebeen documented by others [87ndash90] with lower micromolarconcentrations representing those with the higher induceractivity (Figure 2)

CD values are available for phytochemicals used incommon oral supplements [83 87ndash89 91] sulforaphane(02 120583M) andrographolides (143) quercetin (250) 120573-car-otene (72 120583M) lutein (120583M) resveratrol (21 120583M) indole-3-carbinol from mature broccoli vegetable (50120583M) chloro-phyll (250 120583M) 120572-cryptoxanthin (18mM) and zeaxanthin(22mM) An earlier study conducted in a different labora-tory [91] had shown curcumin (27 120583M) silymarin (36 120583M)tamoxifen (59 120583M) genistein (162 120583M) epigallocatechin-3-gallate (EGCG) (gt50 120583M) and ascorbic acid (gt50120583M) Thecomparative NQO1 inducer activity of these phytochemicalsis sulforaphane gt andrographolides gt quercetin gt curcumingt silymarin gt tamoxifen gt beta-carotene gt genistein gt luteingt resveratrol gt I-3-C gt chlorophyll gt 120572-cryptoxanthin gtzeaxanthin

Notably the CD value of sulforaphane is 135-fold greaterthan that of curcumin 18-fold greater than silymarin and105-fold greater than resveratrol all phytochemicals which

000

500

1000

1500

2000

2500

3000

Phytochemicalpharmaceutical

Sulfo

raph

ane

And

rogr

apho

lides

Curc

umin

Sily

mar

in

Tam

oxife

n

120573-C

arot

ene

Gen

este

in

Lute

in

Resv

erat

rol

CD value (120583M)

CD value (120583M)

Que

rcet

inlowast

Figure 2CDvalues of popular phytochemicals used as supplementsand a commonly prescribed pharmaceutical CD values refer to theconcentration of a compound required to double the activity of thePhase II detoxification enzyme quinone reductase [83 87ndash89 91]

are extensively promoted for their claimed health-promotingproperties It may be useful for relevant oral supplements tobe evaluated in relation to the CD value of their primaryingredient(s) given that an Internet search will readilyreveal many self-select and clinician-recommended supple-ments claiming to ldquoenhance detoxificationrdquo and ldquopromotelongevityrdquo even though supporting evidence is not apparentMany such supplements claiming to target ldquodetoxrdquo are basedon ingredients such as chlorophyll and vitamin C both ofwhich have comparatively low NQO1 inducer capacity

53 Comparing Effects of Indole Glucosinolates Indole-3-carbinol (I-3-C) the ITC found in mature broccoli vegetable(but not significantly in the sprout) required gt50 120583M todouble NQO1 activity [83] In vivo I-3-C must be dimer-ized in the acidic environment of the stomach to 331015840-diindolymethane (DIM) to be active [92] This has certainclinical implications as synthetic molecules of both I-3-C andDIM are available as supplements With significantly lowerinducer capacity than sulforaphane [91] it bears mentionthat DIM is also a bifunctional inducer of the detoxificationpathway thus limiting its cytoprotective potential Earlyresearch on broccoli sprouts suggested potential limitationsto the use of indole glucosinolates such as I-3-C as chemo-protectors in humans [49] Not only are they weak inducersof Phase II enzymes but also as bifunctional inducers theysimultaneously activate Phase I enzymesThey may also haveestrogen receptor binding activity adding to their potentialas tumor promoters [49]

Interestingly DIM is sometimes recommended clinicallyfor patients with compromised estrogen metabolism thetheory being that DIM inhibits CYP1B Inhibition of CYP1B1


shifts estrogen metabolism towards 4-hydroxyestrone ametabolite which can contribute to carcinogenesis [93] Notall data agree a 2007 cell culture study analyzed geneexpression using microarray profiling and quantitative realtime-polymerase chain reaction in MCF7 breast cancer cellstreated simultaneously with estradiol and DIM [94] CYP1B1was upregulated with a fold change of 393 plusmn 025 Suchfindings would tend to suggest that DIM may not protectagainst the metabolism of estrogen to the 4-hydroxymetabo-lites Such conflicting data indicate that clinical trials arerequired to establish the in vivo effects of such an interventionwhen using a clinically relevant dose of a readily availablesupplement

To illustrate the differences in potency between sul-foraphane and I-3-C in a study using a prostate cell line itwas found that both compounds inhibited the proliferationof the prostate cancer cells in a dose-dependent mannerbut the inhibitory concentration of sulforaphane requiredwas just 10 that of I-3-C [95] There may also be safetyissues which require caution in the recommendation of I-3-C supplements available at many times the quantity of I-3-Cachievable from broccoli vegetable consumption AlthoughI-3-C administered one week after the last dose of thecarcinogen has been shown in rats to result in a latencydelay of mammary tumor formation it did not alter tumorincidence or multiplicity among survivors [96] Any researchshowing a preventive benefit of this compound must beconsidered against the risk that it may promote liver andcolon cancer [96]

54 Other Modes of Activating Nrf2 Although our focus isto compare the inducer capacity of phytochemicals Nrf2 inhuman cells is activated by a range of stressors not all ofwhich are chemical in nature The diverse nature of Nrf2activators is highlighted in the three examples which followWe use several examples of pharmaceuticals with pleiotropicNrf2-inducing effects Furthermore we illustrate that whenpharmaceutical Nrf2 activation occurs at supraphysiologicallevels the outcome may be unexpected indicating that thesignificantly lower inducer capacity of diet-derived Nrf2activators may represent a hormetic effect [97]

541 Mechanical Effects The mechanical effects of bloodflow in regions where arteries are exposed to high shearstress are protected from inflammation and atherosclerosisBy contrast low-shear regions are susceptible and this effecthas been shown to be due to the effect of Nrf2 in reducingactivation of the endothelium at atherosusceptible sites [98]

542 Pharmaceutical Drugs The pharmaceutical tamoxifencommonly prescribed to women following treatment forbreast cancer is an NQO1 inducer but its CD value is 30-fold lower than that for sulforaphane [99] Nrf2 induceractivity may play some role in this drugrsquos therapeutic profilein addition to its primary role as a selective estrogen receptormodulator (SERM) [99] These comparative data may beclinically significant when considering the potential value ofa drug or supplement with cytoprotective potential A num-ber of other pharmaceuticals pleiotropically activate Nrf2

The redox-modulating activity of the frequently prescribedstatins and ACE inhibitors has been attributed to their Nrf2inducer ability [100] Similarly gold salts once the mainstayof treatment for rheumatoid arthritis are Nrf2 inducers[101] Indomethacin now seldom used in reducing thesymptoms of inflammatory joint diseases has Nrf2-inducingproperties illustrating that nonsteroidal anti-inflammatorydrugs (NSAIDs) exhibit properties other than their anti-inflammatory effects [102]

A relatively new pharmaceutical Bardoxolone Methyl(BARD) was shown to enhance estimated glomerular fil-tration rate (eGFR) in patients with chronic kidney diseasea disease characterised by significant oxidative stress [103ndash105] BARD is a synthetic analogue of oleanolic acid a triter-penoid found extensively in edible plants [106] with broadercytoprotective properties attributed to Nrf2 induction [107]The Phase 3 BEACON Trial [108] was halted in October2012 following adverse events including 57 deaths out of2185 participants in the BARD arm [105] In comparing theinducer activity of BARD with that of SFN a 2005 studycomparing a range of triterpenoids showed that BARD was230-foldmore potent than SFN as a NQO1 inducer [109]Theadverse effects demonstrated by the synthetic triterpenoidanalogue in the BEACON trial may be representative of ahormetic response at the upper end of a bifunctional doseresponse By contrast phytochemicals at the doses providedby foods are typically nontoxic [97]

543 Exercise Exercise is associated with an increased fluxof glucose and oxygen through the mitochondria a processwhich increases levels of ROS such as superoxide An essen-tial role for exercise-induced ROS formation in activatingtranscription factors and coactivators has been proposed[110] Ristow et al demonstrated that typical exercise-relatedchanges in gene expressionwere almost completely abrogatedby daily ingestion of supplements of vitaminsC andE at dosesof 1000mg and 400 IU respectively

A review highlighted 23 studies showing that antioxidantsupplementation interferes with exercise training-inducedadaptations [111] An emerging theme [112] supports theview that because Nrf2 is activated by a mild prooxidantsignal high doses of antioxidant supplements may bluntsignals required to activate endogenous defenses [113 114]Ristowrsquos assertion that antioxidant supplementation blocksmany of the beneficial effects of exercise is supported by suchevidence

55 Other Actions of NQO1 Which Can Be Influencedby Sulforaphane NQO1 exhibits broad substrate specificityextending well outside its better known role as a Phase IIinducer its other roles as described in the following sectionmay contribute to its cytoprotective capacity Its actionsinclude the following (1) it can protect against benzene-derived quinones such as benzo(a)pyrene a carcinogen foundcommonly in petrochemical exhaust gases and in barbecuedmeats [115] (2) NQO1 can reduce catechol estrogen quinonesto catechol estrogens a process associated with loweringbreast cancer risk due to elevated estrogen metabolites [116](3) NQO1 can scavenge superoxide albeit at a lower order of


magnitude than does superoxide dismutase (SOD) [117] (4)NQO1 stabilises p53 the tumor suppressor gene [77] and (5)NQO1 restores oxidized coenzyme Q10 (ubiquinone) and thetocopherols to their reduced forms [77]

Several NQO1 polymorphisms exist and these have beenassociated with risk of carcinogenesis The C609T genevariant is one of very few common single nucleotide poly-morphisms known to almost completely eliminate enzy-matic activity consequently NQO1 is attracting consider-able research attention given its multiple effects in cellulardefenses [118]

56 Other Mechanisms Animal Studies Although a largevolume of the published sulforaphane research is associ-ated with its Nrf2 inducer potential some studies pointto other mechanisms A recent study used broccoli sproutjuice as the intervention material in stroke-prone spon-taneously hypertensive rats to investigate possible effectson renal damage [119] After 4 weeks the animals wereshown to have been largely protected against renal damageMechanistically the effect was shown to be independent ofsystemic blood pressure but to parallel stimulation of theAMPKSIRT1PGC1aPPARaUCP2 axis Whether this canbe replicated in humans at practical doses has not yet beeninvestigated

6 The Issue of Bioavailability

61 Comparative Effects of Popular Phytochemical Supple-ments Aside from wide variation in Nrf2 inducer capacitya second barrier to clinical efficacy is bioavailability Whenbioavailability is low cell culture studies may significantlyoverestimate the intracellular concentration that ingestion ofsuch a compound can achieve being unlikely to demonstratethe expected clinical benefit indicated by the in vitro work[120 121] In considering the potential clinical efficacy of aphytochemical the active compound andor any of its activemetabolites must reach the cells of the target organ(s) inappropriate concentration Oral bioavailability of polyphe-nols is typically lt10 ranging between 2 and 20 [122]with many closer to 1 cooking and processing significantlyreduce polyphenol content [123] By comparison a pharma-cokinetic animal study showed that sulforaphane was rapidlyabsorbed with its absolute bioavailability 82 [124]

Many phytochemical-containing supplements containpolyphenolic molecules such as curcumin (turmeric) cate-chins (green tea) resveratrol (grapes) ellagic acid (berriesand pomegranate) and hydroxytyrosol and oleuropein(olives) Much of the evidence used to promote these supple-ments is from either in vitro or animal studies with limitedclinical evidence to support the assertions Supplements ofthese phytochemicals frequently bear an ldquoantioxidantrdquo claimeven though the amount of polyphenol reaching the circula-tion or target cells is seldom adequate to alter redox status [7125] gene expression studies have helped in quantifying likelysystemic responses Preclinical cell culture or animal studiesmay involve very high doses of an isolated polyphenol Suchdoses are seldom clinically practical considering average

80

267 4 1 073

Sulfo

raph

ane

And

rogr

apho

lides

Que

rcet

in

Curc

umin

Sily

mar

in

Comparative bioavailability of common phytochemicals

0102030405060708090100

Bioa

vaila

bilit

y (

)

Figure 3 Comparative bioavailability of phytochemicals commonlyused in supplements [90 124 127ndash129 153]

dietary intake of mixed polyphenols in food is approximately1 gram per day of poorly bioavailable compounds [126]

Curcumin resveratrol and silybin are examples of pop-ular polyphenol supplements for which preclinical findingscannot be readily extrapolated to the clinical environmentFigure 3 compares the bioavailability of several polyphenolswith that of sulforaphane (native curcumin at sim1 [127]resveratrol lt1 [128] and silybin sim073 [129]) In each casethe systemic bioavailability compares the plasma concentra-tion of an oral dose to an intravenous dose and is expressedas a percentage where 119865 is bioavailability [90]

119865oral=

(AUCoralDoseoral)

(AUCivDoseiv)

times 100 (1)

Thehigh intracellular concentrations of polyphenols requiredto replicate in vitro findings are difficult to achieve in humanswith practical oral doses

There is some evidence to suggest that the activity ofsome polyphenols may instead reside in their metabolites[130] so that small quantities absorbed intracellularly act assignaling molecules and may act synergistically with otherbiomolecules [131] It is likely that any direct antioxidanteffects occur only within the lumen of the gut [10 132] andnot systemically

Quercetin naturally found in onions watercress tea andother plants is a popular oral supplement typically promotedas an ldquoantioxidantrdquo or ldquoanti-inflammatoryrdquo agent Somestudies suggest that quercetin may have anticancer potential[133] but other studies describe potential for risk [134] giventhat quercetin may exhibit prooxidant effects especially in aGSH-depleted cellular environment [135]

Specifically quercetin can exert an inhibitory effect onthe metabolism of catechols via the catechol-O-methyl-transferase enzyme (COMT) [136] This may have impli-cations in estrogen-related disorders where inappropriatelymetabolised estrogens can form DNA adducts [93] Whetheroral doses of quercetin have these effects in humans isnot known but the issue has been flagged as ldquoconcerningrdquo


since readily available quercetin supplements represent up to100 times the quantity typically available in a Western diet[137]

62 Curcumin Curcumin is regarded as having in vitro anti-inflammatory activity by virtue of its ability to inhibit thetranscription factor NF-120581B [138] In a study investigatinginflammation in human tenocytes high concentrations of 5ndash20120583M were required to inhibit IL-1120573-induced inflammation[139] However very high oral doses in humans (up to8 g) yielded curcumin peak intracellular levels of only 05ndash20 120583M clearly not attaining a concentration of the sameorder commonly recommended supplemental doses of upto 180mg were undetectable in plasma [140 141] Laboratoryfindings demonstrating an impressive and diverse array ofcytoprotective effects for curcumin may not generally applyto practical oral doses in humans [142]

By contrast there is evidence for an effect in gastrointesti-nal tissue where transport occurs across a single enterocytemembrane [143 144] Patients with colorectal cancer wereadministered doses up to 36 g curcumin daily [145] M

1G

a marker of DNA damage decreased 38 in the colorectaltissue showing that a dose of 36 grams daily achievespharmacologically efficacious levels in colonocytes but withnegligible distribution outside the gut confirming its poorsystemic bioavailability

When considering both CD value and bioavailabilitynative curcumin with bioavailability of sim1 would appearto be less clinically relevant than sulforaphane which showsboth high inducer activity and high bioavailability Evenenhanced forms of curcumin with sim7-fold higher bioavail-ability still exhibit comparatively low bioavailability [146]Investigating physiologically achievable doses of curcuminLao et al administered from 500 to 12000mg of a curcuminpowder no curcumin was detected in any of 74 participantstaking up to 8000mg low serum levels in the ngmL rangewere detected only for doses gt8000mg with doses below4000mg barely detected [147] Similarly curcumin was notdetected in normal liver or colorectal liver metastases inpatients receiving 36 gd for 1 week [145] Howells et alconclude that in vitro studies with curcumin in the high10 120583molL range or below might have human physiologicalrelevance but that its role as a chemopreventive agent may lieprimarily within the gastrointestinal tract [141]

63 Resveratrol Resveratrol achieved international acclaimafter studies inmice and lower organisms indicated that it wasresponsible for a longevity effect [148] Only mice injectedwith resveratrol from birth lived longer those that startedat middle age had no longevity benefit [149] The benefitappeared due to enhanced expression of survival genes anumber of which are also expressed during caloric restriction[150]

The longevity effect has never been tested in humans soan appropriate dose is not known nor even if a longevitybenefit is likely [151 152] Although well absorbed resveratroldisplays low bioavailability at least 70 of an oral 25mgdose in human subjects was shown to appear as resver-atrol metabolites in plasma with most of the oral dose

subsequently recovered in the urine [128] Like curcuminresveratrol is readily absorbed by enterocytescolonocytes[153] showing potential benefit to intestinal tissues A dailyresveratrol dose of 3000mg administered to overweight orobese men with nonalcoholic fatty liver disease (NAFLD)over 8 weeks did not significantly improve any of the featuresof NAFLD over placebo [154]

A review of 3650 publications on resveratrol concludedthat the evidence is not sufficiently strong to justify a recom-mendation for resveratrol to humans beyond the dose whichcan be obtained from dietary sources which is estimated tobe sim4mg daily for adults [155]

64 Silymarin Silymarin the major flavonoid complex inSilybum marianum has a long history of traditional usein liver disorders [156] Silymarin supplements claiming totarget human liver detoxification mechanisms are readilyavailable Silibinin the most bioactive of the complex isinsoluble in water and not lipophilic with low bioavailabilityof 073 in rats [129] Its CDvalue ranks next below curcuminand third after sulforaphane Where optimising Phase IIdetoxification is the desired outcome there may be valuein considering both CD values and bioavailability Suchevidence sheds considerable doubt on the likely efficacyof many such phytochemicals at doses typically found incommercially available supplements Nevertheless publishedtrials show that silymarin exhibits hepatoprotective proper-ties in humans indicating that other mechanisms may beresponsible [156 157]

65 Sulforaphane Sulforaphanersquos lipophilic nature and lowmolecular weight readily enable passive diffusion into cells[124] It is rapidly absorbed peaking in plasma as early as 1hour after ingestion [158] Predictably dose-dependent phar-macokinetics in rats reveals that bioavailability decreaseswithincreasing dose [124] The doses corresponded to sim05mg10mg and 50mgkg of pure sulforaphane which is relativelyhigh for humans who typically consume Brassica vegetableand not pure sulforaphane It is unlikely that humans throughdiet would ingest such high quantities of SFN By calculationMYR-active whole broccoli sprout supplement yielding 1SFN could deliver 10mg SFN per gram of powder cor-responding to sim12 grams of fresh broccoli sprouts (driedpowder retains sim8 moisture) Administering 50mgkg ofsulforaphane to a 70 kg human at the upper end of theanimal dose range represents an intake of 350mg or 35-foldthe quantity that a human might reasonably ingest dietaryfresh sprouts Clearly these quantities are not a practicalmeans of providing a broccoli sprout supplement for humanuse

66 Dose Considerations in Humans An indication of whatmight be practically achievable with supplementation is illus-trated by several human studies Ye et al showed that after asingle 200120583mol oral dose of sulforaphane both sulforaphaneand its metabolites were detected in plasma and erythrocytesin just 15 minutes peaking in all four subjects at sim200 120583Mafter 1 hour and declining with first-order kinetics with amean half-life of 177plusmn013 hours [159] To investigate effects


in systemic tissue Cornblatt et al showed that one hour aftera single 200120583mol oral dose of sulforaphane administeredto 8 women metabolites were detected in resected left andright breast tissue at concentrations of 145 plusmn 112 and 200 plusmn195 pmolmg tissue respectively This proof-of-principlestudy observed a significant induction of NQO1 enzymaticactivity in the same tissue [158] In another example adose escalation placebo-controlled study investigated PhaseII gene expression in human airways mucosa showing that a200-gram broccoli sprout homogenate delivering 102 120583mol ofsulforaphane increased NQO1 mRNA expression by almost200 [160]

Given that oral doses appear to be capable of increasingNQO1 we consider whether it may be possible that asulforaphane-yielding broccoli sprout powder might delivera plasma concentration of sim200 120583M By calculation a 1powder yields 564 120583mol sulforaphane per gram Ye et alshowed that a single 200120583mol dose resulted in a peak plasmaconcentration of sim20 120583M after 1 hour As Ye et al [159] hadshown that a 200120583mol oral dose had resulted in a plasmaconcentration of sim20 120583M and Riedl et al [160] had shownthat 102 120583mol had increased NQO1 mRNA expression bysim200 these orders of magnitude could be achievable with asulforaphane-yielding broccoli sprout powder Theoreticallyand by calculation an individual could consume around 2grams of a 1 sulforaphane-yielding broccoli sprout powderto achieve what Riedl et al achieved with 200-gram broccolihomogenate and 4 grams to achieve what Ye et al achievedwith a single 200 120583mol dose

7 Factors Governing Sulforaphane Yield

71 The Role of Myrosinase Glucosinolates as Brassica-derived precursor compounds are converted to their bioac-tive forms only under the action of MYR because GRN hasno inherent bioactivity Investigating the metabolic fate ofingested broccoli phytochemicals Shapiro et al showed thatMYR-inactivated broccoli resulted in 10ndash20 lower conver-sion to ITCs When the colonic microfloras were reducedrecovery of ITCs in a MYR-free environment was negligibleIt may be inferred that MYR is essential for sulforaphanesynthesis and that the colonic microflora may exhibit MYR-like activity

The colonic microfloras appear to be capable of lim-ited MYR activity with conversion to the bioactive ITCvarying from 1 to 40 of the dose [161] Several generaof human microflora such as Bifidobacterium Lactobacillusand Bacteroides have been reported to possess MYR-likeactivity [162] but with wide variability in their populationthe ability to hydrolyse glucosinolates cannot be reliablyestimated So unpredictable is this factor that a large clinicaltrial using MYR-inactive broccoli sprout extract could notachieve statistical significance [163] Many available broccolisprout supplements are MYR-inactive extracts which claimtheir clinical benefit is due to the alleged conversion tosulforaphane by the colonic microflora Neither consumersnor clinicians have any way of knowing if an individualharbors MYR-active microflora

72 The Nitrile Factor Among crucifers broccoli containssignificant amounts of epithiospecifier protein (ESP) a non-catalytic inhibitor of MYR activity [164] ESP produces inac-tive sulforaphane nitrile Under certain conditions the nitrilepathway is favoured with the hydrolysis product constitutingas much as 75 nitrile The colonic microfloras also supportnitrile formation thereby further limiting the potential ofMYR-inactive supplement [165] ESP deactivation can signif-icantly enhance sulforaphane yield illustrating that broccoliand broccoli sprout products cannot be meaningfully evalu-ated on the basis of their GRN content alone It is likely thatclinical trials using either fresh or powdered broccoli sproutsmay give conflicting results when the presence or absence ofnitrile has not been considered The presence of ESP meansthat assayedmeasurement of the sulforaphane yield is criticalin order to estimate the real efficacy of a broccoli sproutpowder intended for a supplement measurement only ofGRNandMYRdoes not allow for the effect of ESP on enzymeactivity

8 Clinical Implications

81 Cruciferous Vegetable Consumption The presence ofunquantified amounts of ESP in raw broccoli has clinicalimplications as a salad vegetable raw broccoli may not bean efficient means of obtaining the benefits conferred bysulforaphane Similarly cooking has been shown to destroythe enzyme in as little as 3 minutes of steaming [166]Five minutes of microwave cooking resulted in 74 lossof glucosinolates from broccoli florets with high-pressurecooking and boiling leading respectively to 33 and 55losses [83] Even consumers and clinicians conscious of theimportance of cruciferous vegetables in the diet may beunaware that open-air storage of broccoli as occurs duringtransport and in retail environments may lose 55 of itsglucosinolates after 3 days and storage in plastic bags at 22∘Cmay result in similar losses over 7 days [83]

Also of significance is the fact that broccoli cultivarsfor vegetable production are not selected on the basis oftheir sulforaphane yield It is possible that the cultivarsavailable to consumers are not good sources of cruciferousbioactives Until Food Law allows appropriate health claimsto be associated with cruciferous vegetables there is noincentive for growers to select higher yielding cultivars Inshort neither a clinician nor a consumer has the informationneeded to make an appropriate choice

82 Supplements Derived from Cruciferous Vegetables Sim-ilarly it is not generally known if a producer of broccolisprout powder as a supplement ingredient has deactivated theESP If two supplements contain high levels of GRN but onehas had the ESP deactivated the comparative sulforaphaneyield from these broccoli sprout powders may be markedlydifferent Ideally a sulforaphane-yielding supplement wouldbe characterised on the basis of the various determiningfactors the presence of quantifiable GRN and active MYRtogether with the inhibitory ESP

These concerns are reflected in a recent study whichcompared a commercially available supplement labelled as


containing 30mg ldquosulforaphane glucosinolaterdquo per dose witha quantity of fresh sprouts containing the same amount ofGRN [167] The study showed that consumption of MYR-devoid broccoli supplement when compared with broccolisprouts produced 7-fold lower plasma concentrations ofthe bioactive ITC metabolites in the subjects Clarke et alconcluded that these findings have implications for peoplewho consume the recommended dose of such MYR-inactivebroccoli supplement believing they are obtaining equivalentdoses of ITCsThis is significant in that the available broccolisprout supplements are dominated by the MYR-inactiveldquoextractsrdquo even though MYR-active whole broccoli sproutsupplements do exist

There is a further strong case for a whole food broccolisprout supplement on the grounds that although GRN isthe primary glucosinolate found in broccoli and broccolisprouts it is not the only one erucin and iberin comprisemost of the remaining 25 of the glucosinolate content ofbroccoli Recently it was found that erucin and sulforaphaneare interconvertible so that the clinical effects are likely to bedue to the combined effects of all the glucosinolate hydrolysisproducts [167]

9 Standardisation

To compound the difficulties associated with determiningthe clinical potential of a sulforaphane-yielding supplementvariations in nomenclature add to the problem The termldquosulforaphane glucosinolaterdquo which has recently appeared inthe scientific literature is now associated with and specifiedfor commercially available MYR-inactive extracts derivedfrom broccoli seed or sprout extracts [167 168] Sinceldquosulforaphane glucosinolaterdquo describes only the quantity ofldquoglucoraphaninrdquo this nomenclature could erroneously leadboth clinicians and consumers to believe that thematerial willdeliver sulforaphane when consumed

91 Commercial Assay Protocols Various methods todescribe a sulforaphane supplement are commonly used inindustry To evaluate and compare different broccoli sproutpowders intended as supplements or for use in clinical trialsassay methodologies must be standardised There are severalcommon practices for reporting the sulforaphane derivedfrom a broccoli sprout sample but because the assay protocolis almost never specified for a commercial product there isno way to reliably compare these values from one product toanother

92 Sulforaphane Potential Sulforaphane potential is a cal-culated value by measuring GRN and then assuming 100conversion to sulforaphane whether or not MYR hasbeen retained after processing Based on relative molecularweights the measured amount of GRN is multiplied by 0406to arrive at a sulforaphane potential No provision is made forthe presence or absence of eitherMYR or ESPWhere ESP hasnot been fully deactivated calculating sulforaphane potentialwill overestimate the amount of sulforaphane that could beproduced on ingestion Broccoli sprout powdered ingredientsor supplements which claim sulforaphane potential and for

which the ESP has not been deactivated may yield limitedsulforaphane

93 Sulforaphane Yield with Addition of Exogenous MYR Byadding enough exogenous MYR to ensure full conversion ofGRN to sulforaphane this method overcomes the possibilitythat the starting material may contain only GRN and maybe completely or partially MYR-inactive The assay resultsmay not specify that exogenous MYR was added so that thereader may incorrectly conclude that the material will yieldsulforaphane on ingestion

94 Sulforaphane Yield due to Endogenous MYR Thismethod more closely resembles the in vivo situation afteringestion of the supplement in that conversion to sul-foraphane is entirely dependent on the quantities of ESPand MYR retained after processing It may provide a lowersulforaphane value when compared with the other methodseven though it may be the method which most reliablyapproximates sulforaphanersquos metabolic fate in human phys-iology

The same supplement assayed by each of these proceduresis likely to produce quite different results and more impor-tantly only supplements which have retained MYR activityare likely to demonstrate in vivo effectsMethodswhich assesssulforaphanersquos inducer capacity in cell culture may more reli-ably evaluate the clinical potential of a supplement or enablecomparison of supplements PCR array and pathway analysisstudies provide gene expression data which is another closerstep to establishing the clinical effects of a supplement [169]

10 Conclusion

The evolving science of nutrigenomics is in many wayslegitimizing the important role of plant foods in humanhealth not just as sources of nutrients but as a huge libraryof phytochemicals capable of interacting with intracellularbiomolecules to influence gene expression Of the manythousands of phytochemicals in the food supply sulforaphaneexhibits properties whichmaymake it an ideal cytoprotectivebiomolecule deliverable in practical doses as a whole foodsupplement Commercial attempts to produce sulforaphane-releasing supplements have resulted mostly in forms withlittle or no bioactivity typically seed or sprout extractsThe ideal sulforaphane-releasing supplement retains both itsglucoraphanin precursor and its myrosinase enzyme in theform of a whole broccoli sprout ingredient with nothingbut water removed When compared with other phytochem-icals widely used in dietary supplements sulforaphane issignificantly more bioavailable than polyphenols such ascurcumin resveratrol and silymarin It is also significantlymore able to induce NQO1 a Phase II enzyme essential inthe metabolism of a number of exogenous toxins oxidizednutrients and endogenous metabolites Such comparativefindings call into question the clinical efficacy of many of thesupplements popular among consumers Alleged benefits ofsuch supplements appear to requiremuch higher intracellularconcentrations than can be achieved with reasonable oralintake


Initial attempts to produce high-potency pharmaceuticalNrf2 inducers have so far been unsuccessful Given the preva-lence of diet-related disease and the evidence that many con-sumers have accepted a role for complementary medicinesin their personal healthmanagement appropriately validatedsulforaphane-releasing supplements may provide anotheravenue for supporting human health Such supplements willneed to demonstrate sufficient nutrigenomic potential thatthey can modify key biochemical and physiological riskfactors for disease

Conflict of Interests

Christine A Houghton is the managing director of Cell-Logic Pty Ltd a company thatmanufactures a broccoli sproutingredient Robert G Fassett and Jeff S Coombes declare thatthey have no conflict of interests regarding the publication ofthis paper

References

[1] R L Swank ldquoA prospective discussion of past internationalnutrition catastrophesmdashindications for the futurerdquo Nutritionvol 13 no 4 pp 344ndash348 1997

[2] R H Liu ldquoHealth-promoting components of fruits and vegeta-bles in the dietrdquo Advances in Nutrition vol 4 no 3 pp 384Sndash392S 2013

[3] D James S Devaraj P Bellur S Lakkanna J Vicini andS Boddupalli ldquoNovel concepts of broccoli sulforaphanes anddisease induction of phase II antioxidant and detoxifica-tion enzymes by enhanced-glucoraphanin broccolirdquo NutritionReviews vol 70 no 11 pp 654ndash665 2012

[4] M Nicoletti ldquoNutraceuticals and botanicals overview and per-spectivesrdquo International Journal of Food Sciences and Nutritionvol 63 supplement 1 pp 2ndash6 2012

[5] H-G Joost M J Gibney K D Cashman et al ldquoPersonalisednutrition status and perspectivesrdquo British Journal of Nutritionvol 98 no 1 pp 26ndash31 2007

[6] A M Ares M J Nozal and J Bernal ldquoExtraction chemicalcharacterization and biological activity determination of broc-coli health promoting compoundsrdquo Journal of ChromatographyA vol 1313 pp 78ndash95 2013

[7] D E Stevenson and R D Hurst ldquoPolyphenolic phyto-chemicalsmdashjust antioxidants or much morerdquo Cellular andMolecular Life Sciences vol 64 no 22 pp 2900ndash2916 2007

[8] H Sies ldquoPolyphenols and health update and perspectivesrdquoArchives of Biochemistry and Biophysics vol 501 no 1 pp 2ndash52010

[9] C Manach G Williamson C Morand A Scalbert and CRemesy ldquoBioavailability and bioefficacy of polyphenols inhumans I Review of 97 bioavailability studiesrdquo The AmericanJournal of Clinical Nutrition vol 81 no 1 supplement pp 230Sndash242S 2005

[10] B Halliwell ldquoAre polyphenols antioxidants or pro-oxidantsWhat do we learn from cell culture and in vivo studiesrdquoArchives of Biochemistry and Biophysics vol 476 no 2 pp 107ndash112 2008

[11] E J Calabrese ldquoHormesis why it is important to toxicology andtoxicologistsrdquo Environmental Toxicology and Chemistry vol 27no 7 pp 1451ndash1474 2008

[12] B Pagliaro C Santolamazza F Simonelli and S RubattuldquoPhytochemical compounds and protection from cardiovascu-lar diseases a state of the artrdquo BioMed Research Internationalvol 2015 Article ID 918069 17 pages 2015

[13] I Herr andMW Buchler ldquoDietary constituents of broccoli andother cruciferous vegetables implications for prevention andtherapy of cancerrdquo Cancer Treatment Reviews vol 36 no 5 pp377ndash383 2010

[14] T W Kensler P A Egner A S Agyeman et al ldquoKeap1-Nrf2signaling a target for cancer prevention by sulforaphanerdquoTopicsin Current Chemistry vol 329 pp 163ndash178 2013

[15] D Boivin S Lamy S Lord-Dufour et al ldquoAntiproliferativeand antioxidant activities of common vegetables a comparativestudyrdquo Food Chemistry vol 112 no 2 pp 374ndash380 2009

[16] J V Higdon B Delage D E Williams and R H DashwoodldquoCruciferous vegetables and human cancer risk epidemiologicevidence andmechanistic basisrdquo Pharmacological Research vol55 no 3 pp 224ndash236 2007

[17] X Zhang X-O Shu Y-B Xiang et al ldquoCruciferous vegetableconsumption is associated with a reduced risk of total andcardiovascular disease mortalityrdquo American Journal of ClinicalNutrition vol 94 no 1 pp 240ndash246 2011

[18] J H Kang A Ascherio and F Grodstein ldquoFruit and vegetableconsumption and cognitive decline in aging womenrdquo Annals ofNeurology vol 57 no 5 pp 713ndash720 2005

[19] Y Zhang P Talalay C-G Cho and G H Posner ldquoA majorinducer of anticarcinogenic protective enzymes from broc-coli Isolation and elucidation of structurerdquo Proceedings of theNational Academy of Sciences of the United States of Americavol 89 no 6 pp 2399ndash2403 1992

[20] H J Prochaska A B Santamaria and P Talalay ldquoRapid detec-tion of inducers of enzymes that protect against carcinogensrdquoProceedings of the National Academy of Sciences of the UnitedStates of America vol 89 no 6 pp 2394ndash2398 1992

[21] K Singletary and C MacDonald ldquoInhibition ofbenzo[a]pyrene- and 16-dinitropyrene-DNA adduct formationin human mammary epithelial cells bydibenzoylmethane andsulforaphanerdquo Cancer Letters vol 155 no 1 pp 47ndash54 2000

[22] E L Cavalieri and E G Rogan ldquoDepurinating estrogen-DNAadducts in the etiology and prevention of breast and otherhuman cancersrdquo Future Oncology vol 6 no 1 pp 75ndash91 2010

[23] D J Madureira F T Weiss P Van Midwoud D E HelblingS J Sturla and K Schirmer ldquoSystems toxicology approach tounderstand the kinetics of benzo(a)pyrene uptake biotrans-formation and DNA adduct formation in a liver cell modelrdquoChemical Research in Toxicology vol 27 no 3 pp 443ndash4532014

[24] P Moi K Chan I Asunis A Cao and Y W Kan ldquoIsolation ofNF-E2-related factor 2 (Nrf2) a NF-E2-like basic leucine zippertranscriptional activator that binds to the tandem NF-E2AP1repeat of the 120573-globin locus control regionrdquo Proceedings of theNational Academy of Sciences of the United States of Americavol 91 no 21 pp 9926ndash9930 1994

[25] J-M Lee J Li D A Johnson et al ldquoNrf2 a multi-organprotectorrdquo The FASEB Journal vol 19 no 9 pp 1061ndash10662005

[26] N F Villeneuve A Lau and D D Zhang ldquoRegulation of theNrf2-keap1 antioxidant response by the ubiquitin proteasomesystem an insight into cullin-ring ubiquitin ligasesrdquo Antioxi-dants amp Redox Signaling vol 13 no 11 pp 1699ndash1712 2010

[27] M Cuendet C P Oteham R C Moon and J M PezzutoldquoQuinone reductase induction as a biomarker for cancer


chemopreventionrdquo Journal of Natural Products vol 69 no 3pp 460ndash463 2006

[28] A K Jaiswal ldquoNrf2 signaling in coordinated activation ofantioxidant gene expressionrdquoFree Radical Biology andMedicinevol 36 no 10 pp 1199ndash1207 2004

[29] J-M Lee and J A Johnson ldquoAn important role of Nrf2-ARE pathway in the cellular defense mechanismrdquo Journal ofBiochemistry and Molecular Biology vol 37 no 2 pp 139ndash1432004

[30] Y-J Surh J K Kundu and H-K Na ldquoNrf2 as a master redoxswitch in turning on the cellular signaling involved in theinduction of cytoprotective genes by some chemopreventivephytochemicalsrdquo Planta Medica vol 74 no 13 pp 1526ndash15392008

[31] K N Lewis J Mele J D Hayes and R Buffenstein ldquoNrf2a guardian of healthspan and gatekeeper of species longevityrdquoIntegrative and Comparative Biology vol 50 no 5 pp 829ndash8432010

[32] CHart R CohenMNorwood and J Stebbing ldquoThe emergingharm of antioxidants in carcinogenesisrdquo Future Oncology vol 8no 5 pp 535ndash548 2012

[33] R Hu C Xu G Shen et al ldquoGene expression profiles inducedby cancer chemopreventive isothiocyanate sulforaphane in theliver of C57BL6J mice and C57BL6JNrf2 (--) micerdquo CancerLetters vol 243 no 2 pp 170ndash192 2006

[34] M-K Kwak N Wakabayashi K Itoh H Motohashi MYamamoto and T W Kensler ldquoModulation of gene expressionby cancer chemopreventive dithiolethiones through the Keap1-Nrf2 pathway identification of novel gene clusters for cellsurvivalrdquo The Journal of Biological Chemistry vol 278 no 10pp 8135ndash8145 2003

[35] A Rahal A Kumar V Singh et al ldquoOxidative stress prooxi-dants and antioxidants the interplayrdquo BioMed Research Inter-national vol 2014 Article ID 761264 19 pages 2014

[36] L Valgimigli and R Iori ldquoAntioxidant and pro-oxidant capaci-ties of ITCsrdquo Environmental andMolecularMutagenesis vol 50no 3 pp 222ndash237 2009

[37] J D Brooks V G Paton and G Vidanes ldquoPotent inductionof phase 2 enzymes in human prostate cells by sulforaphanerdquoCancer Epidemiology Biomarkers and Prevention vol 10 no 9pp 949ndash954 2001

[38] S-D Cho G Li H Hu et al ldquoInvolvement of c-Jun N-terminalkinase in G2M arrest and caspase-mediated apoptosis inducedby sulforaphane in DU145 prostate cancer cellsrdquo Nutrition andCancer vol 52 no 2 pp 213ndash224 2005

[39] A F Abdull Razis and N M Noor ldquoSulforaphane is supe-rior to glucoraphanin in modulating carcinogen-metabolisingenzymes in Hep G2 cellsrdquo Asian Pacific Journal of CancerPrevention vol 14 no 7 pp 4235ndash4238 2013

[40] M G Botti M G Taylor and N P Botting ldquoStudies onthe mechanism of myrosinasemdashinvestigation of the effect ofglycosyl acceptors on enzyme activityrdquo Journal of BiologicalChemistry vol 270 no 35 pp 20530ndash20535 1995

[41] H Wu H Liang Q Yuan T Wang and X Yan ldquoPreparationand stability investigation of the inclusion complex of sul-foraphane with hydroxypropyl-120573-cyclodextrinrdquo CarbohydratePolymers vol 82 no 3 pp 613ndash617 2010

[42] J D Clarke K Riedl D Bella S J Schwartz J F Stevensand E Ho ldquoComparison of isothiocyanate metabolite levelsand histone deacetylase activity in human subjects consumingbroccoli sprouts or broccoli supplementrdquo Journal of Agriculturaland Food Chemistry vol 59 no 20 pp 10955ndash10963 2011

[43] G R De Nicola M Bagatta E Pagnotta et al ldquoComparison ofbioactive phytochemical content and release of isothiocyanatesin selected brassica sproutsrdquo Food Chemistry vol 141 no 1 pp297ndash303 2013

[44] Y Jin M Wang R T Rosen and C-T Ho ldquoThermal degra-dation of sulforaphane in aqueous solutionrdquo Journal of Agricul-tural and Food Chemistry vol 47 no 8 pp 3121ndash3123 1999

[45] A T Dinkova-Kostova J W Fahey and P Talalay ldquoChemicalstructures of inducers of nicotinamide quinone oxidoreductase1 (NQO1)rdquoMethods in Enzymology vol 382 pp 423ndash448 2004

[46] M E Nimni B Han and F Cordoba ldquoAre we getting enoughsulfur in our dietrdquo Nutrition and Metabolism vol 4 article 242007

[47] R F Grimble and G K Grimble ldquoImmunonutrition roleof sulfur amino acids related amino acids and polyaminesrdquoNutrition vol 14 no 7-8 pp 605ndash610 1998

[48] I F F Benzie and S Wachtel-Galor ldquoVegetarian diets andpublic health biomarker and redox connectionsrdquo Antioxidantsamp Redox Signaling vol 13 no 10 pp 1575ndash1591 2010

[49] J W Fahey Y Zhang and P Talalay ldquoBroccoli sprouts anexceptionally rich source of inducers of enzymes that protectagainst chemical carcinogensrdquo Proceedings of the NationalAcademy of Sciences of the United States of America vol 94 no19 pp 10367ndash10372 1997

[50] R H Dashwood ldquoIndole-3-carbinol anticarcinogen or tumorpromoter in brassica vegetablesrdquo Chemico-Biological Interac-tions vol 110 no 1-2 pp 1ndash5 1998

[51] T W Kensler G-S Qian J-G Chen and J D GroopmanldquoTranslational strategies for cancer prevention in liverrdquo NatureReviews Cancer vol 3 no 5 pp 321ndash329 2003

[52] T M Buetler E P Gallagher C Wang D L Stahl J DHayes and D L Eaton ldquoInduction of phase I and phaseII drug-metabolizing enzyme mRNA protein and activityby BHA ethoxyquin and oltiprazrdquo Toxicology and AppliedPharmacology vol 135 no 1 pp 45ndash57 1995

[53] X Wang D J Tomso B N Chorley et al ldquoIdentificationof polymorphic antioxidant response elements in the humangenomerdquo Human Molecular Genetics vol 16 no 10 pp 1188ndash1200 2007

[54] K Itoh T Chiba S Takahashi et al ldquoAn Nrf2small Mafheterodimer mediates the induction of phase II detoxifyingenzyme genes through antioxidant response elementsrdquo Bio-chemical and Biophysical Research Communications vol 236no 2 pp 313ndash322 1997

[55] D Stewart E Killeen R Naquin S Alam and J Alam ldquoDegra-dation of transcription factorNrf2 via the ubiquitin-proteasomepathway and stabilization by cadmiumrdquoThe Journal of Biologi-cal Chemistry vol 278 no 4 pp 2396ndash2402 2003

[56] Y Katoh K Iida M-I Kang et al ldquoEvolutionary conservedN-terminal domain of Nrf2 is essential for the Keap1-mediateddegradation of the protein by proteasomerdquoArchives of Biochem-istry and Biophysics vol 433 no 2 pp 342ndash350 2005

[57] A Kobayashi M-I Kang H Okawa et al ldquoOxidative stresssensor Keap1 functions as an adaptor for Cul3-based E3 ligaseto regulate proteasomal degradation of Nrf2rdquo Molecular andCellular Biology vol 24 no 16 pp 7130ndash7139 2004

[58] K Taguchi H Motohashi and M Yamamoto ldquoMolecularmechanisms of the Keap1-Nrf2 pathway in stress response andcancer evolutionrdquoGenes to Cells vol 16 no 2 pp 123ndash140 2011

[59] J A Hinson D W Roberts and L P James ldquoMechanisms ofacetaminophen-induced liver necrosisrdquo Handbook of Experi-mental Pharmacology vol 196 pp 369ndash405 2010


[60] I M Copple C E Goldring R E Jenkins et al ldquoThehepatotoxic metabolite of acetaminophen directly activates thekeap1-Nrf2 cell defense systemrdquo Hepatology vol 48 no 4 pp1292ndash1301 2008

[61] G Chen Q Fang J Zhang D Zhou and Z Wang ldquoRole ofthe Nrf2-ARE pathway in early brain injury after experimentalsubarachnoid hemorrhagerdquo Journal of Neuroscience Researchvol 89 no 4 pp 515ndash523 2011

[62] N Juge R F Mithen and M Traka ldquoMolecular basis forchemoprevention by sulforaphane a comprehensive reviewrdquoCellular andMolecular Life Sciences vol 64 no 9 pp 1105ndash11272007

[63] D Liska M Lyon and D S Jones ldquoDetoxification and bio-transformational imbalancesrdquo Explore The Journal of Scienceand Healing vol 2 no 2 pp 122ndash140 2006

[64] N Laso S Mas M J Lafuente et al ldquoInduction of NAD(P)Hquinone oxidoreductase by vegetables widely consumed inCatalonia Spainrdquo Nutrition and Cancer vol 52 no 1 pp 49ndash58 2005

[65] P Talalay ldquoChemoprotection against cancer by induction ofPhase 2 enzymesrdquo BioFactors vol 12 no 1ndash4 pp 5ndash11 2000

[66] X Gao A T Dinkova-Kostova and P Talalay ldquoPowerfuland prolonged protection of human retinal pigment epithelialcells keratinocytes and mouse leukemia cells against oxidativedamage the indirect antioxidant effects of sulforaphanerdquo Pro-ceedings of the National Academy of Sciences of the United Statesof America vol 98 no 26 pp 15221ndash15226 2001

[67] M L Pall and S Levine ldquoNrf2 a master regulator of detox-ification and also antioxidant anti-inflammatory and othercytoprotective mechanisms is raised by health promotingfactorsrdquo Sheng Li Xue Bao vol 67 no 1 pp 1ndash18 2015

[68] P C Spiess D Kasahara A Habibovic et al ldquoAcrolein exposuresuppresses antigen-induced pulmonary inflammationrdquo Respi-ratory Research vol 14 article 107 2013

[69] A L Eggler K A Gay and A D Mesecar ldquoMolecular mech-anisms of natural products in chemoprevention induction ofcytoprotective enzymes by Nrf2rdquoMolecular Nutrition and FoodResearch vol 52 supplement 1 pp S84ndashS94 2008

[70] R K Thimmulappa K H Mai S Srisuma T W KenslerM Yamamoto and S Biswal ldquoIdentification of Nrf2-regulatedgenes induced by the chemopreventive agent sulforaphane byoligonucleotidemicroarrayrdquoCancer Research vol 62 no 18 pp5196ndash5203 2002

[71] Y-J Lee and S-H Lee ldquoSulforaphane induces antioxidativeand antiproliferative responses by generating reactive oxygenspecies in human bronchial epithelial BEAS-2B cellsrdquo Journalof Korean Medical Science vol 26 no 11 pp 1474ndash1482 2011

[72] M FHolick ldquoVitaminD evolutionary physiological andhealthperspectivesrdquo Current Drug Targets vol 12 no 1 pp 4ndash18 2011

[73] M Schwab V Reynders S Loitsch D Steinhilber O Schroderand J Stein ldquoThe dietary histone deacetylase inhibitor sul-foraphane induces human 120573-defensin-2 in intestinal epithelialcellsrdquo Immunology vol 125 no 2 pp 241ndash251 2008

[74] M J Berridge ldquoVitamin D cell signalling in health and diseaserdquoBiochemical and Biophysical Research Communications vol460 no 1 pp 53ndash71 2015

[75] X-L Chen and C Kunsch ldquoInduction of cytoprotective genesthrough Nrf2antioxidant response element pathway a newtherapeutic approach for the treatment of inflammatory dis-easesrdquo Current Pharmaceutical Design vol 10 no 8 pp 879ndash891 2004

[76] J W Fahey and P Talalay ldquoAntioxidant functions of sul-foraphane a potent inducer of phase II detoxication enzymesrdquoFood and Chemical Toxicology vol 37 no 9-10 pp 973ndash9791999

[77] A T Dinkova-Kostova and P Talalay ldquoNAD(P)Hquinoneacceptor oxidoreductase 1 (NQO1) a multifunctional antioxi-dant enzyme and exceptionally versatile cytoprotectorrdquoArchivesof Biochemistry and Biophysics vol 501 no 1 pp 116ndash123 2010

[78] G P Sykiotis I G Habeos A V Samuelson and D BohmannldquoThe role of the antioxidant and longevity-promoting Nrf2pathway in metabolic regulationrdquo Current Opinion in ClinicalNutrition and Metabolic Care vol 14 no 1 pp 41ndash48 2011

[79] J H Suh S V Shenvi B M Dixon et al ldquoDecline in tran-scriptional activity of Nrf2 causes age-related loss of glutathionesynthesis which is reversible with lipoic acidrdquo Proceedings of theNational Academy of Sciences of theUnited States of America vol101 no 10 pp 3381ndash3386 2004

[80] M M Rahman G P Sykiotis M Nishimura R Bodmerand D Bohmann ldquoDeclining signal dependence of Nrf2-MafS-regulated gene expression correlates with aging phenotypesrdquoAging Cell vol 12 no 4 pp 554ndash562 2013

[81] A T Dinkova-Kostova and P Talalay ldquoPersuasive evidence thatquinone reductase type 1 (DT diaphorase) protects cells againstthe toxicity of electrophiles and reactive forms of oxygenrdquo FreeRadical Biology andMedicine vol 29 no 3-4 pp 231ndash240 2000

[82] M M Iba and R J Caccavale ldquoGenotoxic bioactivation ofconstituents of a diesel exhaust particle extract by the humanlungrdquo Environmental and Molecular Mutagenesis vol 54 no 3pp 158ndash171 2013

[83] E H Jeffery and K E Stewart ldquoUpregulation of quinonereductase by glucosinolate hydrolysis products from dietarybroccolirdquoMethods in Enzymology vol 382 pp 457ndash469 2004

[84] R P Robertson ldquoAIRarg and AIRgluc as predictors of insulinsecretory reserverdquo Transplantation Proceedings vol 36 no 4pp 1040ndash1041 2004

[85] J W Fahey K K Stephenson A T Dinkova-Kostova P AEgner TW Kensler and P Talalay ldquoChlorophyll chlorophyllinand related tetrapyrroles are significant inducers of mammalianphase 2 cytoprotective genesrdquo Carcinogenesis vol 26 no 7 pp1247ndash1255 2005

[86] T A Shapiro J W Fahey K L Wade K K Stephenson and PTalalay ldquoHuman metabolism and excretion of cancer chemo-protective glucosinolates and isothiocyanates of cruciferousvegetablesrdquo Cancer Epidemiology Biomarkers and Preventionvol 7 no 12 pp 1091ndash1100 1998

[87] J W Fahey and T W Kensler ldquoRole of dietary supple-mentsnutraceuticals in chemoprevention through induction ofcytoprotective enzymesrdquo Chemical Research in Toxicology vol20 no 4 pp 572ndash576 2007

[88] Y Yuan L Ji L Luo et al ldquoQuinone reductase (QR) inducersfrom Andrographis paniculata and identification of moleculartarget of andrographoliderdquo Fitoterapia vol 83 no 8 pp 1506ndash1513 2012

[89] J Yang and R H Liu ldquoInduction of phase II enzyme quinonereductase in murine hepatoma cells in vitro by grape extractsand selected phytochemicalsrdquo Food Chemistry vol 114 no 3pp 898ndash904 2009

[90] L Ye T Wang L Tang et al ldquoPoor oral bioavailabilityof a promising anticancer agent andrographolide is due toextensive metabolism and efflux by P-glycoproteinrdquo Journal ofPharmaceutical Sciences vol 100 no 11 pp 5007ndash5017 2011


[91] C Gerhauser K Klimo E Heiss et al ldquoMechanism-based invitro screening of potential cancer chemopreventive agentsrdquoMutation ResearchmdashFundamental and Molecular Mechanismsof Mutagenesis vol 523-524 pp 163ndash172 2003

[92] H L Bradlow and M A Zeligs ldquoDiindolylmethane (DIM)spontaneously forms from indole-3-carbinol (I3C) during cellculture experimentsrdquo In Vivo vol 24 no 4 pp 387ndash391 2010

[93] E Cavalieri D Chakravarti J Guttenplan et al ldquoCatecholestrogen quinones as initiators of breast and other human can-cers implications for biomarkers of susceptibility and cancerpreventionrdquo Biochimica et Biophysica Acta vol 1766 no 1 pp63ndash78 2006

[94] L Mulvey A Chandrasekaran K Liu et al ldquoInterplay of genesregulated by estrogen and diindolylmethane in breast cancercell linesrdquoMolecular Medicine vol 13 no 1-2 pp 69ndash78 2007

[95] H R Frydoonfar D R McGrath and A D Spigelman ldquoTheeffect of indole-3-carbinol and sulforaphane on a prostatecancer cell linerdquo ANZ Journal of Surgery vol 73 no 3 pp 154ndash156 2003

[96] G Stoner B Casto S Ralston B Roebuck C Pereira andG Bailey ldquoDevelopment of a multi-organ rat model for eval-uating chemopreventive agents efficacy of indole-3-carbinolrdquoCarcinogenesis vol 23 no 2 pp 265ndash272 2002

[97] T G Son S Camandola and M P Mattson ldquoHormetic dietaryphytochemicalsrdquo NeuroMolecular Medicine vol 10 no 4 pp236ndash246 2008

[98] M Zakkar K Van der Heiden L A Luong et al ldquoActivationof Nrf2 in endothelial cells protects arteries from exhibiting aproinflammatory staterdquo Arteriosclerosis Thrombosis and Vas-cular Biology vol 29 no 11 pp 1851ndash1857 2009

[99] N Krishnamurthy Y Hu S Siedlak Y Q Doughman MWatanabe and M M Montano ldquoInduction of quinone reduc-tase by tamoxifen orDPNprotects againstmammary tumorige-nesisrdquoThe FASEB Journal vol 26 no 10 pp 3993ndash4002 2012

[100] L L Stoll M L McCormick G M Denning and N LWeintraub ldquoAntioxidant effects of statinsrdquo Drugs of Today vol40 no 12 pp 975ndash989 2004

[101] N-H Kim M-K Oh H J Park and I-S Kim ldquoAura-nofin a gold(I)-containing antirheumatic compound acti-vates Keap1Nrf2 signaling via Rac1iNOS signal and mitogen-activated protein kinase activationrdquo Journal of PharmacologicalSciences vol 113 no 3 pp 246ndash254 2010

[102] M Aburaya K-I Tanaka T Hoshino et al ldquoHeme oxygenase-1 protects gastric mucosal cells against non-steroidal anti-inflammatory drugsrdquo The Journal of Biological Chemistry vol281 no 44 pp 33422ndash33432 2006

[103] P E Pergola P Raskin R D Toto et al ldquoBardoxolone methyland kidney function in CKD with type 2 diabetesrdquo The NewEngland Journal of Medicine vol 365 no 4 pp 327ndash336 2011

[104] M B Sporn K T Liby M M Yore L Fu J M Lopchuk andG W Gribble ldquoNew synthetic triterpenoids potent agents forprevention and treatment of tissue injury caused by inflamma-tory and oxidative stressrdquo Journal of Natural Products vol 74no 3 pp 537ndash545 2011

[105] C Zoja A Benigni and G Remuzzi ldquoThe Nrf2 pathway in theprogression of renal diseaserdquo Nephrology Dialysis Transplanta-tion vol 29 supplement 1 pp i19ndashi24 2014

[106] J Liu ldquoOleanolic acid and ursolic acid research perspectivesrdquoJournal of Ethnopharmacology vol 100 no 1-2 pp 92ndash94 2005

[107] Q Q Wu Y Wang M Senitko et al ldquoBardoxolone methyl(BARD) ameliorates ischemic AKI and increases expression of

protective genes Nrf2 PPAR120574 and HO-1rdquo American Journalof PhysiologymdashRenal Physiology vol 300 no 5 pp 1180ndash11922011

[108] D de Zeeuw T Akizawa R Agarwal et al ldquoRationale andtrial design of bardoxolone methyl evaluation in patients withchronic kidney disease and type 2 diabetes the occurrence ofrenal events (BEACON)rdquo American Journal of Nephrology vol37 no 3 pp 212ndash222 2013

[109] A T Dinkova-Kostova K T Liby K K Stephenson etal ldquoExtremely potent triterpenoid inducers of the phase 2response correlations of protection against oxidant and inflam-matory stressrdquo Proceedings of the National Academy of Sciencesof the United States of America vol 102 no 12 pp 4584ndash45892005

[110] M Ristow K Zarse A Oberbach et al ldquoAntioxidants preventhealth-promoting effects of physical exercise in humansrdquo Pro-ceedings of the National Academy of Sciences of the United Statesof America vol 106 no 21 pp 8665ndash8670 2009

[111] T-T Peternelj and J S Coombes ldquoAntioxidant supplementationduring exercise training beneficial or detrimentalrdquo SportsMedicine vol 41 no 12 pp 1043ndash1069 2011

[112] Q Zhang J Pi C G Woods and M E Andersen ldquoA systemsbiology perspective on Nrf2-mediated antioxidant responserdquoToxicology and Applied Pharmacology vol 244 no 1 pp 84ndash972010

[113] V R Muthusamy S Kannan K Sadhaasivam et al ldquoAcuteexercise stress activates Nrf2ARE signaling and promotesantioxidant mechanisms in the myocardiumrdquo Free RadicalBiology and Medicine vol 52 no 2 pp 366ndash376 2012

[114] M J M Magbanua E L Richman E V Sosa et al ldquoPhysicalactivity and prostate gene expression in men with low-riskprostate cancerrdquo Cancer Causes and Control vol 25 no 4 pp515ndash523 2014

[115] L Wang X He G D Szklarz Y Bi Y Rojanasakul andQ Ma ldquoThe aryl hydrocarbon receptor interacts withnuclear factor erythroid 2-related factor 2 to mediateinduction of NAD(P)Hquinoneoxidoreductase 1 by 2378-tetrachlorodibenzo-p-dioxinrdquo Archives of Biochemistry andBiophysics vol 537 no 1 pp 31ndash38 2013

[116] S Singh D Chakravarti J A Edney et al ldquoRelative imbal-ances in the expression of estrogen-metabolizing enzymes inthe breast tissue of women with breast carcinomardquo OncologyReports vol 14 no 4 pp 1091ndash1096 2005

[117] D Siegel D L Gustafson D L Dehn et al ldquoNAD(P)Hquinoneoxidoreductase 1 role as a superoxide scavengerrdquo MolecularPharmacology vol 65 no 5 pp 1238ndash1247 2004

[118] B Lajin and A Alachkar ldquoThe NQO1 polymorphism C609T(Pro187Ser) and cancer susceptibility a comprehensive meta-analysisrdquo British Journal of Cancer vol 109 no 5 pp 1325ndash13372013

[119] S Rubattu S Di Castro M Cotugno et al ldquoProtective effects ofBrassica oleracea sprouts extract toward renal damage in high-salt-fed SHRSP role of AMPKPPAR120572UCP2 axisrdquo Journal ofHypertension vol 33 no 7 pp 1465ndash1479 2015

[120] H-J Cho J-E Kim D-D Kim and I-S Yoon ldquoIn vitro-in vivo extrapolation (IVIVE) for predicting human intestinalabsorption and first-pass elimination of drugs principles andapplicationsrdquo Drug Development and Industrial Pharmacy vol40 no 8 pp 989ndash998 2014

[121] H Lennernas ldquoModeling gastrointestinal drug absorptionrequires more in vivo biopharmaceutical data experience


from in vivo dissolution and permeability studies in humansrdquoCurrent Drug Metabolism vol 8 no 7 pp 645ndash657 2007

[122] M Hu ldquoCommentary bioavailability of flavonoids and poly-phenols call to armsrdquo Molecular Pharmaceutics vol 4 no 6pp 803ndash806 2007

[123] M DrsquoArchivio C Filesi R Varı B Scazzocchio and RMasellaldquoBioavailability of the polyphenols status and controversiesrdquoInternational Journal of Molecular Sciences vol 11 no 4 pp1321ndash1342 2010

[124] N Hanlon N Coldham A Gielbert et al ldquoAbsolute bioavail-ability and dose-dependent pharmacokinetic behaviour ofdietary doses of the chemopreventive isothiocyanate sul-foraphane in ratrdquo British Journal of Nutrition vol 99 no 3 pp559ndash564 2008

[125] S K Nicholson G A Tucker and J M Brameld ldquoEffectsof dietary polyphenols on gene expression in human vascularendothelial cellsrdquo Proceedings of the Nutrition Society vol 67no 1 pp 42ndash47 2008

[126] C Manach A Scalbert C Morand C Remesy and L JimenezldquoPolyphenols food sources and bioavailabilityrdquo American Jour-nal of Clinical Nutrition vol 79 no 5 pp 727ndash747 2004

[127] K-Y Yang L-C Lin T-Y Tseng S-C Wang and T-H TsaildquoOral bioavailability of curcumin in rat and the herbal analysisfrom Curcuma longa by LC-MSMSrdquo Journal of Chromatog-raphy B Analytical Technologies in the Biomedical and LifeSciences vol 853 no 1-2 pp 183ndash189 2007

[128] T Walle ldquoBioavailability of resveratrolrdquo Annals of the New YorkAcademy of Sciences vol 1215 no 1 pp 9ndash15 2011

[129] S Javed K Kohli and M Ali ldquoReassessing bioavailability ofsilymarinrdquo Alternative Medicine Review vol 16 no 3 pp 239ndash249 2011

[130] A Scalbert C Manach C Morand C Remesy and L JimenezldquoDietary polyphenols and the prevention of diseasesrdquo CriticalReviews in Food Science and Nutrition vol 45 no 4 pp 287ndash306 2005

[131] R H Liu ldquoPotential synergy of phytochemicals in cancerprevention mechanism of actionrdquo Journal of Nutrition vol 134no 12 supplement pp 3479Sndash3485S 2004

[132] J Kanner and T Lapidot ldquoThe stomach as a bioreactor dietarylipid peroxidation in the gastric fluid and the effects of plant-derived antioxidantsrdquo Free Radical Biology and Medicine vol31 no 11 pp 1388ndash1395 2001

[133] A J Vargas and R Burd ldquoHormesis and synergy pathways andmechanisms of quercetin in cancer prevention and manage-mentrdquo Nutrition Reviews vol 68 no 7 pp 418ndash428 2010

[134] G Galati S Teng M Y Moridani T S Chan and P JOrsquoBrien ldquoCancer chemoprevention and apoptosis mechanismsinduced by dietary polyphenolicsrdquo Drug Metabolism and DrugInteractions vol 17 no 1ndash4 pp 311ndash349 2000

[135] R Ferraresi L Troiano E Roat et al ldquoEssential requirementof reduced glutathione (GSH) for the anti-oxidant effect of theflavonoid quercetinrdquo Free Radical Research vol 39 no 11 pp1249ndash1258 2005

[136] M B M van Duursen J T Sanderson P C de Jong MKraaij and M van den Berg ldquoPhytochemicals inhibit catechol-O-methyltransferase activity in cytosolic fractions from healthyhuman mammary tissues implications for catechol estrogen-induced DNA damagerdquo Toxicological Sciences vol 81 no 2 pp316ndash324 2004

[137] L IMennen RWalker C Bennetau-Pelissero andA ScalbertldquoRisks and safety of polyphenol consumptionrdquo The American

Journal of Clinical Nutrition vol 81 supplement 1 pp 326Sndash329S 2005

[138] A Shehzad G Rehman and Y S Lee ldquoCurcumin in inflamma-tory diseasesrdquo BioFactors vol 39 no 1 pp 69ndash77 2013

[139] C Buhrmann A Mobasheri F Busch et al ldquoCurcuminmodulates nuclear factor 120581B (nf-120581B)-mediated inflammation inhuman tenocytes in vitro role of the phosphatidylinositol 3-kinaseAkt pathwayrdquo Journal of Biological Chemistry vol 286no 32 pp 28556ndash28566 2011

[140] R A Sharma S A Euden S L Platton et al ldquoPhase I clinicaltrial of oral curcumin biomarkers of systemic activity andcompliancerdquo Clinical Cancer Research vol 10 no 20 pp 6847ndash6854 2004

[141] L M Howells E P Moiseeva C P Neal et al ldquoPredicting thephysiological relevance of in vitro cancer preventive activities ofphytochemicalsrdquo Acta Pharmacologica Sinica vol 28 no 9 pp1274ndash1304 2007

[142] B B Aggarwal and K B Harikumar ldquoPotential therapeuticeffects of curcumin the anti-inflammatory agent against neu-rodegenerative cardiovascular pulmonary metabolic autoim-mune and neoplastic diseasesrdquo International Journal of Bio-chemistry and Cell Biology vol 41 no 1 pp 40ndash59 2009

[143] R Sareen N Jain and V Pandit ldquoCurcumin a boon to colonicdiseasesrdquo Current Drug Targets vol 14 no 10 pp 1210ndash12182013

[144] S K Yadav A K Sah R K Jha P Sah and D K ShahldquoTurmeric (curcumin) remedies gastroprotective actionrdquo Phar-macognosy Reviews vol 7 no 13 pp 42ndash46 2013

[145] G Garcea D J L Jones R Singh et al ldquoDetection of curcuminand its metabolites in hepatic tissue and portal blood of patientsfollowing oral administrationrdquoBritish Journal of Cancer vol 90no 5 pp 1011ndash1015 2004

[146] B Antony B Merina V S Iyer N Judy K Lennertz and SJoyal ldquoA pilot cross-over study to evaluate human oral bioavail-ability of BCM-95CG (Biocurcumax) a novel bioenhancedpreparation of curcuminrdquo Indian Journal of PharmaceuticalSciences vol 70 no 4 pp 445ndash449 2008

[147] C D Lao M T Ruffin IV D Normolle et al ldquoDose escalationof a curcuminoid formulationrdquo BMC Complementary andAlternative Medicine vol 6 article 10 2006

[148] J A Baur K J Pearson N L Price et al ldquoResveratrol improveshealth and survival of mice on a high-calorie dietrdquo Nature vol444 no 7117 pp 337ndash342 2006

[149] K J Pearson J A Baur K N Lewis et al ldquoResveratroldelays age-related deterioration and mimics transcriptionalaspects of dietary restriction without extending life spanrdquo CellMetabolism vol 8 no 2 pp 157ndash168 2008

[150] E Morselli M C Maiuri M Markaki et al ldquoCaloric restric-tion and resveratrol promote longevity through the Sirtuin-1-dependent induction of autophagyrdquoCell Death andDisease vol1 no 1 article e10 2010

[151] J M Smoliga J A Baur and H A Hausenblas ldquoResveratroland healthmdasha comprehensive review of human clinical trialsrdquoMolecular Nutrition and Food Research vol 55 no 8 pp 1129ndash1141 2011

[152] B Agarwal and J A Baur ldquoResveratrol and life extensionrdquoAnnals of the New York Academy of Sciences vol 1215 no 1 pp138ndash143 2011

[153] TWalle F HsiehMH DeLegge J E Oatis Jr andU KWalleldquoHigh absorption but very low bioavailability of oral resveratrolin humansrdquoDrugMetabolism andDisposition vol 32 no 12 pp1377ndash1382 2004


[154] V S Chachay G A Macdonald J H Martin et al ldquoResveratroldoes not benefit patients with nonalcoholic fatty liver diseaserdquoClinical Gastroenterology and Hepatology vol 12 no 12 pp2092ndash2103 2014

[155] O Vang N Ahmad C A Baile et al ldquoWhat is new for an oldmolecule systematic review and recommendations on the useof resveratrolrdquo PLoS ONE vol 6 no 6 Article ID e19881 2011

[156] S C Pradhan and C Girish ldquoHepatoprotective herbaldrug silymarin from experimental pharmacology to clinicalmedicinerdquo Indian Journal of Medical Research vol 124 no 5pp 491ndash504 2006

[157] L Abenavoli R Capasso NMilic and F Capasso ldquoMilk thistlein liver diseases past present futurerdquo Phytotherapy Researchvol 24 no 10 pp 1423ndash1432 2010

[158] B S Cornblatt L Ye A T Dinkova-Kostova et al ldquoPreclinicaland clinical evaluation of sulforaphane for chemoprevention inthe breastrdquo Carcinogenesis vol 28 no 7 pp 1485ndash1490 2007

[159] L Ye A T Dinkova-Kostova K L Wade Y Zhang TA Shapiro and P Talalay ldquoQuantitative determination ofdithiocarbamates in human plasma serum erythrocytes andurine pharmacokinetics of broccoli sprout isothiocyanates inhumansrdquoClinica Chimica Acta vol 316 no 1-2 pp 43ndash53 2002

[160] M A Riedl A Saxon andD Diaz-Sanchez ldquoOral sulforaphaneincreases Phase II antioxidant enzymes in the human upperairwayrdquo Clinical Immunology vol 130 no 3 pp 244ndash251 2009

[161] J W Fahey S L Wehage W D Holtzclaw et al ldquoProtectionof humans by plant glucosinolates efficiency of conversionof glucosinolates to isothiocyanates by the gastrointestinalmicroflorardquo Cancer Prevention Research vol 5 no 4 pp 603ndash611 2012

[162] Z Fuller P Louis A Mihajlovski V Rungapamestry BRatcliffe and A J Duncan ldquoInfluence of cabbage processingmethods and prebiotic manipulationof colonic microflora onglucosinolate breakdown in manrdquo British Journal of Nutritionvol 98 no 2 pp 364ndash372 2007

[163] T W Kensler J-G Chen P A Egner et al ldquoEffects of glucos-inolate-rich broccoli sprouts on urinary levels of aflatoxin-DNAadducts and phenanthrene tetraols in a randomized clinicaltrial in He Zuo Township Qidong Peoplersquos Republic of ChinardquoCancer Epidemiology Biomarkers and Prevention vol 14 no 11part 1 pp 2605ndash2613 2005

[164] N V Matusheski J A Juvik and E H Jeffery ldquoHeatingdecreases epithiospecifier protein activity and increases sul-foraphane formation in broccolirdquo Phytochemistry vol 65 no9 pp 1273ndash1281 2004

[165] D-L Cheng K Hashimoto and Y Uda ldquoIn vitro digestionof sinigrin and glucotropaeolin by single strains of Bifidobac-terium and identification of the digestive productsrdquo Food andChemical Toxicology vol 42 no 3 pp 351ndash357 2004

[166] C C Conaway S M Getahun L L Liebes et al ldquoDispositionof glucosinolates and sulforaphane in humans after ingestion ofsteamed and fresh broccolirdquo Nutrition and Cancer vol 38 no2 pp 168ndash178 2000

[167] J D Clarke A Hsu K Riedl et al ldquoBioavailability and inter-conversion of sulforaphane and erucin in human subjectsconsuming broccoli sprouts or broccoli supplement in a cross-over study designrdquo Pharmacological Research vol 64 no 5 pp456ndash463 2011

[168] C A Houghton R G Fassett and J S Coombes ldquoSul-foraphane translational research from laboratory bench toclinicrdquo Nutrition Reviews vol 71 no 11 pp 709ndash726 2013

[169] S Qin J Chen S Tanigawa and D-X Hou ldquoMicroarrayand pathway analysis highlight Nrf2ARE-mediated expressionprofiling by polyphenolic myricetinrdquo Molecular Nutrition andFood Research vol 57 no 3 pp 435ndash446 2013

[170] H Motohashi F Katsuoka J D Engel and M YamamotoldquoSmall Maf proteins serve as transcriptional cofactors for ker-atinocyte differentiation in the Keap1-Nrf2 regulatory pathwayrdquoProceedings of the National Academy of Sciences of the UnitedStates of America vol 101 no 17 pp 6379ndash6384 2004

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


MEDIATORSINFLAMMATION

of


Behavioural Neurology

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of



Computational and Mathematical Methods in Medicine

OphthalmologyJournal of


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Gastroenterology Research and Practice


Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom


commentary may include citations for in vitro and animalstudies giving the reader a false impression of the productrsquoslikely efficacy as a supplement for humans

Because it appears that many consumers have accepteda role for complementary medicines in their personal healthmanagement it is important to review the evidence onwhether plant-derived supplements can assist in modifyingvarious biochemical and physiological risk factors for diseaseThe aim of this review is to describe the properties ofnutrigenomic activators of Nrf2 focusing on the potentialfor sulforaphane and other activators of gene expression todemonstrate clinical efficacy as complementary medicines

2 Beyond Nutritional Deficienciesand Excesses

21 Nutrigenetics and Nutrigenomics The interlinked sci-ences of nutrigenetics and nutrigenomics provide the clin-ician with a more targeted opportunity to personalise apatientrsquos treatment programme [5] revealing those geneticpolymorphismswhichmay compromise individual biochem-ical function Even without access to sophisticated genomeprofiling a clinicianrsquos knowledge that potent food-derivedbiomolecules can interact with intracellular signaling path-ways provides another dimension to clinical managementand disease prevention processes

The realization that food-derived molecules are in con-stant conversation with complex intracellular control systemsvia signaling pathways has unveiled the role of food as somuch more than a source of micro- and macronutrients[6] What becomes immediately apparent in this modelis that no multinutrient supplement can substitute for theenormous diversity in phytochemicals present in a balancedhuman diet Also evident is that the health benefits of thepopular polyphenolic phytochemicals such as those foundin green tea grape seed red wine curcumin pomegranateand olives are unlikely to be due to direct-acting antioxidanteffects demonstrated by these molecules in numerous invitro studies [7 8] Polyphenols are typically large bulkymolecules which are poorly absorbed and poorly bioavailable[9] so that it is unlikely that the intracellular micromolarconcentrations necessary to scavenge free radicals can beachieved Polyphenols can also behave as either antioxidantsor prooxidants depending on the experimental conditions[10] In addition newer evidence suggests polyphenols andother phytochemicals may function hormetically wherebydose response is characterised by low dose stimulatoryresponse and high dose inhibition [11]

In a bioactive-specific approach a recent comprehensivereviewof phytochemicals indicated for cardiovascular diseasefocused on both preclinical and clinical beneficial effects offour commonly supplemented compounds [12] The reviewconcluded that there are few definitive trials in this area andin some studies the exact dose used is not clear However theauthors confirm the findings of others in that the use of a veryhigh dose is associated with the most protective effects for afew phytochemicals whereas the lowest dose turns out to bethe most effective for other compounds

As with vitamin ldquoantioxidantsrdquo the notion that ingestedpolyphenol supplements act as ldquoantioxidantsrdquo in humancells is called into question [7] Emerging evidence suggeststhat polyphenols or their metabolites exert their systemicintracellular effects not as direct ldquoantioxidantsrdquo per se but asmodulators of signaling pathways

22 Cruciferous Vegetables Harbor Nutrigenomic PotentialThe classification cruciferous vegetables (crucifers) includesspecies predominantly from Brassicaceae family and themore common members are cultivars not only of Brassicaoleracea genus including broccoli cabbage cauliflower Brus-selsrsquo sprout and kale but also of Raphanus genus whichincludes various types of radish Although these vegetablesare good sources of micronutrients their value to humanhealth would seem to be at least partly due to the nature ofthe phytochemicals they contain and in particular the glu-cosinolates [13] the enzymatic hydrolysis products of whichare capable of modifying gene expression [14] Althoughvegetables such as broccoli are not popular dietary choices[15] the unique health-promoting value of crucifers contin-ues to be reaffirmed [16] A recent review [17] investigatingthe effect of crucifers on total and cardiovascular mortalityfound that several prospective studies showed no associationfor total vegetable consumption but did show a significantinverse association for cruciferous vegetable consumptionThe potential benefits of green leafy vegetables in generaland cruciferous vegetables in particular are not limitedto their effects in cancer and cardiovascular disease In a27-year prospective cohort study on cognitive decline inageing women (119899 = 15080) those in the highest quintileof cruciferous vegetable intake declined more slowly thanthose in the lowest quintile with an evident linear doseresponse [18] Those in the highest quintile of green leafyvegetable intake also experienced slower cognitive declineThe association did not change when data for participantswith cardiovascular disease and diabetes were excluded

Most research on crucifers has focused on broccoliBrassica oleracea (both vegetable and sprouts) as a sourceof bioactive compounds with nutrigenomic potential Thelast two decades have seen accelerating interest in the roleof broccoli in human health following evidence that induc-tion of detoxification enzymes might be responsible for themajority of the observed health benefits of vegetables [19 20]After isolating broccoli-derived sulforaphane Zhangrsquos groupshowed that sulforaphane was a major and very potent PhaseII enzyme inducer The group of induced enzymes includesNAD(P)HNQO1 (quinone reductase) and the family ofglutathione-S-transferases (GSTs) both ofwhich are requiredfor the detoxification of steroids and the ubiquitous environ-mental toxin benzo(a)pyrene [21ndash23] Zhang et al concludedthat the induction of detoxification enzymes by sulforaphanemay significantly contribute to the anticarcinogenic action ofbroccoli The way that sulforaphane demonstrably increasedtarget enzymes is indicative of a nutrigenomic effect eventhough the precise mechanism to explain such gene expres-sionwas not known at the time It would be another two yearsbefore the mechanism to explain the effect of sulforaphanewould be elucidated [24]








3S(O)(CH

2)4-N=C=S] is a small (MW = 17729)







TT

TT T

TT

T TT

G

G

GG

G

G G GA

AA A

AA A

A AA A

AA AA A

AA

AA

A AA

TT

TT

T T T

T T T

TT

TG G

GG

GG

GG

CCCC

CC

CC

CG

C

CC

C

C C

C C

HS

Actin filament

Small MAF

ARE

Geneexpression


HS

SS

KEAP-1

KEAP-1


Nrf2

Nrf2

Nrf2 Nucleus

Cytoplasm




























000

500

1000

1500

2000

2500

3000


Sulfo

raph

ane

And

rogr

apho

lides

Curc

umin

Sily

mar

in

Tam

oxife

n

120573-C

arot

ene

Gen

este

in

Lute

in

Resv

erat

rol

CD value (120583M)

CD value (120583M)

Que

rcet

inlowast























80

267 4 1 073

Sulfo

raph

ane

And

rogr

apho

lides

Que

rcet

in

Curc

umin

Sily

mar

in


0102030405060708090100

Bioa

vaila

bilit

y (

)




119865oral=

(AUCoralDoseoral)

(AUCivDoseiv)

times 100 (1)









1G

























9 Standardisation








10 Conclusion






References

























































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of























3S(O)(CH

2)4-N=C=S] is a small (MW = 17729)







TT

TT T

TT

T TT

G

G

GG

G

G G GA

AA A

AA A

A AA A

AA AA A

AA

AA

A AA

TT

TT

T T T

T T T

TT

TG G

GG

GG

GG

CCCC

CC

CC

CG

C

CC

C

C C

C C

HS

Actin filament

Small MAF

ARE

Geneexpression


HS

SS

KEAP-1

KEAP-1


Nrf2

Nrf2

Nrf2 Nucleus

Cytoplasm




























000

500

1000

1500

2000

2500

3000


Sulfo

raph

ane

And

rogr

apho

lides

Curc

umin

Sily

mar

in

Tam

oxife

n

120573-C

arot

ene

Gen

este

in

Lute

in

Resv

erat

rol

CD value (120583M)

CD value (120583M)

Que

rcet

inlowast























80

267 4 1 073

Sulfo

raph

ane

And

rogr

apho

lides

Que

rcet

in

Curc

umin

Sily

mar

in


0102030405060708090100

Bioa

vaila

bilit

y (

)




119865oral=

(AUCoralDoseoral)

(AUCivDoseiv)

times 100 (1)









1G

























9 Standardisation








10 Conclusion






References

























































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















TT

TT T

TT

T TT

G

G

GG

G

G G GA

AA A

AA A

A AA A

AA AA A

AA

AA

A AA

TT

TT

T T T

T T T

TT

TG G

GG

GG

GG

CCCC

CC

CC

CG

C

CC

C

C C

C C

HS

Actin filament

Small MAF

ARE

Geneexpression


HS

SS

KEAP-1

KEAP-1


Nrf2

Nrf2

Nrf2 Nucleus

Cytoplasm




























000

500

1000

1500

2000

2500

3000


Sulfo

raph

ane

And

rogr

apho

lides

Curc

umin

Sily

mar

in

Tam

oxife

n

120573-C

arot

ene

Gen

este

in

Lute

in

Resv

erat

rol

CD value (120583M)

CD value (120583M)

Que

rcet

inlowast























80

267 4 1 073

Sulfo

raph

ane

And

rogr

apho

lides

Que

rcet

in

Curc

umin

Sily

mar

in


0102030405060708090100

Bioa

vaila

bilit

y (

)




119865oral=

(AUCoralDoseoral)

(AUCivDoseiv)

times 100 (1)









1G

























9 Standardisation








10 Conclusion






References

























































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of



































000

500

1000

1500

2000

2500

3000


Sulfo

raph

ane

And

rogr

apho

lides

Curc

umin

Sily

mar

in

Tam

oxife

n

120573-C

arot

ene

Gen

este

in

Lute

in

Resv

erat

rol

CD value (120583M)

CD value (120583M)

Que

rcet

inlowast























80

267 4 1 073

Sulfo

raph

ane

And

rogr

apho

lides

Que

rcet

in

Curc

umin

Sily

mar

in


0102030405060708090100

Bioa

vaila

bilit

y (

)




119865oral=

(AUCoralDoseoral)

(AUCivDoseiv)

times 100 (1)









1G

























9 Standardisation








10 Conclusion






References

























































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of






















000

500

1000

1500

2000

2500

3000


Sulfo

raph

ane

And

rogr

apho

lides

Curc

umin

Sily

mar

in

Tam

oxife

n

120573-C

arot

ene

Gen

este

in

Lute

in

Resv

erat

rol

CD value (120583M)

CD value (120583M)

Que

rcet

inlowast























80

267 4 1 073

Sulfo

raph

ane

And

rogr

apho

lides

Que

rcet

in

Curc

umin

Sily

mar

in


0102030405060708090100

Bioa

vaila

bilit

y (

)




119865oral=

(AUCoralDoseoral)

(AUCivDoseiv)

times 100 (1)









1G

























9 Standardisation








10 Conclusion






References

























































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of


































80

267 4 1 073

Sulfo

raph

ane

And

rogr

apho

lides

Que

rcet

in

Curc

umin

Sily

mar

in


0102030405060708090100

Bioa

vaila

bilit

y (

)




119865oral=

(AUCoralDoseoral)

(AUCivDoseiv)

times 100 (1)









1G

























9 Standardisation








10 Conclusion






References

























































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of























80

267 4 1 073

Sulfo

raph

ane

And

rogr

apho

lides

Que

rcet

in

Curc

umin

Sily

mar

in


0102030405060708090100

Bioa

vaila

bilit

y (

)




119865oral=

(AUCoralDoseoral)

(AUCivDoseiv)

times 100 (1)









1G

























9 Standardisation








10 Conclusion






References

























































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of




















1G

























9 Standardisation








10 Conclusion






References

























































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of































9 Standardisation








10 Conclusion






References

























































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of



















9 Standardisation








10 Conclusion






References

























































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of




















References

























































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of













































































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of











































































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of











































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of










































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of







































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of





















of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
















Documents

Review Article Sulforaphane and Other Nutrigenomic Nrf2 ...downloads.hindawi.com/journals/omcl/2016/7857186.pdf · Can the Clinician s Expectation Be Matched by the Reality? ChristineA.Houghton,RobertG.Fassett,andJeffS.Coombes