Saponins and phenolics of Yucca schidigera Roezl: Chemistryand bioactivity

Sonia Piacente1,*, Cosimo Pizza1 & Wieslaw Oleszek21Dipartimento di Scienze Farmaceutiche, Universita degli Studi di Salerno, via Ponte Don Melillo, 84084,Fisciano (Salerno), Italy; 2Department of Biochemistry, Institute of Soil Science and Plant Cultivation, ul.Czartoryskich 8, 24100, Pulawy, Poland; *Author for correspondence (Tel: +39-089-962616; Fax: +39-089-962828; E-mail: piacente@unisa.it)

Key words: animal nutrition, antioxidant activity, anti-yeast activity, foaming agent, furostanol saponins,NO production inhibition, platelet aggregation inhibition, resveratrol, spirostanol saponins, yuccaols A–E

Abstract

Yucca schidigera (Agavaceae) is one of the major commercial source of steroidal saponins. Two products ofyucca are available on the market. These include dried and finely powdered logs (yucca powder) ormechanically pressed and thermally condensed juice (yucca extract). These products possess the GRASlabel which allows their use as foaming agent in soft drink (root beer), pharmaceutical, cosmetic, food, andfeeding-stuffs industries. The main application of yucca products is in animal nutrition, in particular as afeed additive to reduce ammonia and fecal odors in animal excreta. The positive effects of dietary sup-plementation with yucca products on the growth rates, feed efficiency, and health of livestock seem to bedue not only to the saponin constituents but also to other constituents. These observations prompted us toinvestigate the phenolic constituents of Y. schidigera. This study led to the isolation of resveratrol, trans-3,3¢,5,5¢-tetrahydroxy-4¢-methoxystilbene, the sprirobiflavonoid larixinol along with novel phenolic deriv-atives with very unusual spirostructures, named yuccaols A–E and yuccaone A. Taking into account themultifunctional activities of resveratrol and the novelty of yuccaols A–E, structurally related to resveratrol,a program aimed to evaluate for yucca phenolics some of the activities exerted by resveratrol has beencarried out. This review describes the chemistry of yucca saponins and phenolics, summarizes the biologicalactivities of yucca products and constituents and gives an account on the actual and potential applicationsof yucca products.

Introduction

Yucca schidigera, known as yucca, is a plantbelonging to the Agavaceae family, native to theSouth-Western United States and Mexico. Indiansrecognized Yucca as one of the nicest desertplants, ‘a tree of life’ with health promotingactivity. Its extracts have been used for centuries infolk medicine to treat a wide variety of inflam-matory disorders, especially headaches, gonor-rhea, arthritis, and rheumatism (Cheeke, 1998).

Two products obtained from the trunk ofY. schidigera are available on the market: yucca

powder which is dried and finely powdered logsand yucca extract which is obtained by subjectingthe powdered material to mechanical squeezing ina press, producing a juice which is concentrated byevaporation. These products possess GRAS label(Generally Recognized As Safe) given by FDAwhich allows their human dietary use.

An important application of yucca extract is asfoaming agent in soft drink, pharmaceutical, cos-metic, food, and feeding-stuff industries. Thefoaming activity of Yucca extract is due to the veryhigh saponin content (about 10% of dried mate-rial) (Oleszek et al., 2001a). Y. schidigera is one of

Phytochemistry Reviews (2005) 4: 177–190 � Springer 2005DOI 10.1007/s11101-005-1234-5

the two major commercial sources of saponins, theother one being Quillaia saponaria (Cheeke, 2000).The main application of yucca products is in ani-mal nutrition, in particular as a feed additive toreduce ammonia and fecal odors in animal excreta(Cheeke, 2000). Dietary supplementation withyucca products is reported to produce positiveeffects on the growth rates (Mader and Brumm,1987; Anthony et al., 1994; Cline et al., 1996), feedefficiency (Mader and Brumm, 1987) and health oflivestock (Anthony et al., 1994; Balog et al., 1994).These effects have been historically attributed tothe saponin constituents but investigations per-formed on rat metabolism to determine if thebiological effects of yucca were due exclusively toits saponin fraction or also to non-saponin com-pounds, indicated that the active constituents arepresent in both fractions (Duffy et al., 2001).

Taking into account these results we haveundertaken a systematic investigation of the phe-nolic fraction of yucca which led to the isolationof resveratrol, trans-3,3¢,5,5¢-tetrahydroxy-4¢-meth-oxystilbene, the spirobiflavonoid larixinol alongwith novel phenolic derivatives with very unusualspirostructures, named yuccaols A–E and yuccaoneA (Oleszek et al, 2001b; Piacente et al. 2002, 2004).

Resveratrol is the natural phytoalexin found inconsiderable amounts in the skin of grapes(Calderon et al., 1993; Jeandet et al., 1995), mul-berries and peanuts (Langcake and Price, 1976)and in some medicinal plants (Jayatilake et al.,1993; Kimura et al., 1995; Orsini et al., 1997). Inthe last 15 years this compound has received a lotof attention because of its biological activities, asantimutagenic (Uenobe et al., 1997), antiviral(Docherty et al., 1999), antiinflammatory (Tsaiet al., 1999) and cancer preventing (Jang et al.,1997; Surh et al., 1999). In particular, it is believedthat because of its antioxidant properties, resve-ratrol is responsible for the reduced risk of car-diovascular disease associated with a moderateconsumption of red wine (Siemann and Creasy,1992; Pendurthi et al., 1999). The multifunctionalactivities of resveratrol together with the noveltyof yuccaols A–E (Oleszek et al., 2001b; Piacenteet al. 2004), structurally related to resveratrol,prompted us to carry out a program aimed toevaluate for yucca phenolics some of the activitiesexerted by resveratrol (Olas et al., 2002, 2003;Czeczot et al., 2003; Marzocco et al., 2004; Pia-cente et al. 2004).

The results obtained show that new opportu-nities could be explored which could increase thecommercial value of yucca.

Chemistry of yucca saponins

Yucca saponins are steroidal saponins possessingspirostanol (Figure 1) and furostanol (Figure 2)aglycones (Tanaka et al., 1996; Miyakoshi et al.,2000; Oleszek et al., 2001a). The main spirostanolaglycones are smilagenin and sarsapogenin whichare characterized by a cis junction between ring Aand B and a b-OH group at position 3 which isthe glycosidation site. These two aglycones differonly for stereochemistry at C-25, being sarsapo-genin the 25S isomer and smilagenin its 25Repimer. Generally the separation of a mixture ofC-25 epimeric saponins into each C-25 epimer isvery difficult, thus structures are often elucidatedas C-25 epimeric mixtures. Other aglyconesoccurring in Y. schidigera are markogenin whichdiffers from sarsapogenin only for the occurrenceof a further b-hydroxy group at C-2 and its C-25epimer samogenin. Gloriogenin and its 25S epimercharacterized by a keto group at C-12 are alsopresent. There are also aglycones characterized bya double bond between C-25 and C-27. Also in thiscase, we can find only one hydroxyl group at C-3,a further hydroxyl group at C-2 or a keto group atC-12. A further aglycone, known as convallamar-ogenin, characterized by a b-OH group at positionC-1 was also reported (Miyakoshi et al., 2000).Our study aimed to isolate and characterizethe main saponins of yucca trunk showed thatY. schidigera saponin mixture contain predomi-nantly spirostanol saponins but also furostanolsaponins, which make up 6–7% of the total sapo-nin mixture (Oleszek et al., 2001a). The furostaneaglycones of Y. schidigera saponins isolated untilnow are (25R)-3b,26-dihydroxy-5b-furost-20(22)-en-12-one and (25R)-5b-furostan-3b,22a,26-triol(Figure 2). Sugar chains of Y. schidigera saponinscontain two or three sugars. They have glucoseor galactose linked to the aglycone and this firstsugar links at position 2 another glucose. Only inone case, compound 24, there is galactose linkedat position 2 of the first sugar glucose. In thecase of trisaccharide chains, at position 3 of thefirst sugar we can find xylose or glucose(Figure 3).

178

Figure 1. Spirostane aglycones of Y. schidigera saponins.

179

Biological activities of Yucca products

A study of Japanese researchers showed that asaponin fractionofY. schidigera logs exhibitedpotentgrowth-inhibitory activity with MIC ranging from31.3 to 125 lg/ml against certain food-deterioratingyeasts (Candida albicans), film-forming yeasts(Debaryomyces hansenii, Pichia nakazawae,Zygosaccharomyces rouxii), dermatophytic yeasts(Candida famata, Hansenula anomala, Pichia carso-nii), and against brewer’s yeast (Saccharomycescerevisiae) (Miyakoshi et al., 2000). Some structure–activity relationships were deduced. Saponins havinga trisaccharide chain without any oxygen function-alities at C-2 and/or C-12 of the aglycone exhibitedpotentactivity,while saponinswith2b-OHor12-ketogroups showed veryweakor no activity. Low activitywas observed for saponins with a disaccharide chainand no activity was observed for the aglycones ob-tained after acid hydrolysis. It is known that thedeterioration of cooked foods is mainly caused byinfections with yeasts. Thus the extract of yucca andits saponin fraction are now on sale in Japan as an

anti-deteriorating agent for extending the shelf-life offood products containing cooked rice, beans, pickledvegetables, processed fish meat, and fermented sea-sonings.

The main use of Yucca extract is in animalnutrition to reduce ammonia concentration andfecal odors (Cheeke, 2000). Since Y. schidigeraextract has become commercially available, anumber of investigations into its effects on a widerange of animals have been carried out (Hussainet al., 1996; Hristov et al., 1999; Killeen et al.,1998a; Colina et al., 2001; Duffy et al., 2001;Flaoyen et al., 2002; Kaya et al., 2003). Thesestudies have shown that the extract has manybenefits on growth and performance of livestock(Mader and Brumm, 1987; Anthony et al., 1994;Balog et al., 1994; Cline et al., 1996) in particularit reduces gastrointestinal and fecal ammonia lev-els (Cheeke, 2000). Effects of Yucca extracts onnitrogen metabolism include reduction in serumurea and ammonia. Yucca extract componentsmay alter kidney function increasing the rate ofurea clearance, lowering blood urea and ammonia

Figure 2. Furostane saponins of Y. schidigera.

180

Figure 3. Saponins of Y. schidigera.

181

concentrations (Wallace et al., 1994; Hristov et al.,1999). Reduction in serum urea concentration incattle may have some practical implications. Milkproduction and conception rates of dairy cattlecan be adversely affected by high blood urea levels.Thus the assumption of Yucca extract can result inan improvement of milk production and concep-tion rates (Hussain and Cheeke, 1995; Cheeke,2000). Despite the data on the positive effects ofdietary supplementation with yucca, the mecha-nism of action of Y. schidigera products remainsunclear and the compounds responsible for thebiological activity have not been conclusivelyidentified. The effects of Y. schidigera have beenhistorically attributed to its saponin constituentsbut experiments performed on rat metabolism toevaluate the effects of dietary supplementationwith the butanol extractable fraction (saponinfraction) and non-butanol extractable fraction(non-saponin fraction) of Y. schidigera extract ona number of serum, excretory, and hepatic vari-ables with particular regard to measurementsrelating to nitrogen metabolism, showed that bothfractions displayed effects, indicating that the ac-tive constituents are present in both fractions(Duffy et al., 2001). Regarding the mode of actionof Y. schidigera extract, several mechanisms havebeen proposed but none has been conclusivelyproven. Firstly, Y. schidigera extract was thoughtto be a potent in vitro inhibitor of the enzymeurease (Asplund, 1991) and its in vivo propertieswere attributed to inhibition of gastrointestinalurease (Anthony et al., 1994; Balog et al., 1994)but further studies have questioned this hypothesis(Killeen et al., 1994, 1998b). Other proposedmechanisms of action include modulation ofmicrobial populations in vivo (Peestok, 1979), di-rect binding to ammonia (Headon et al., 1991),inhibition of selected gut microorganisms (Hussainand Cheeke, 1995; Killeen et al., 1998b), in par-ticular rumen protozoa (Wallace et al., 1994).Saponins seem to be involved in the reduction ofruminal ammonia when Yucca extract is admin-istered to ruminants. The major source of ruminalammonia is proteolysis of bacterial proteins due toingestion of ruminal bacteria by protozoa (Wal-lace et al., 1994; Cheeke, 2000). Saponins haveantiprotozoal activity due to their ability to com-plex with cholesterol of protozoal cell membranescausing cell lysis and death. Thus reduction ofruminal ammonia has been attributed to the

antiprotozoal activity exerted by saponins (Wal-lace et al. 1994; Makkar et al., 1998). Antiproto-zoal activity against ruminal protozoa raises thequestion of whether saponins would be effectiveagainst protozoal diseases that afflict humans,livestock, and poultry. Those protozoal diseases inwhich part of the life cycle occurs in the gastro-intestinal tract would be expected to be responsiveto antiprotozoal activity of saponins (Cheeke,2000). An example is the disease giardiasis, causedby the protozoan Giardia lamblia, also known asGiardia duodenalis. G. lamblia is one of the mostcommon intestinal pathogens of humans (Adam,1991) and livestock (Olson et al., 1997) and iswidely recognized as a principal cause of water-borne disease in North America and Europe.Giardiosis is contracted when infective cysts areingested with waters, food or from contaminatedsurroundings. The trophozoites excysts within theduodenum multiply and cause histological andenzymatic changes in the small intestine (Buretet al., 1990). These changes in intestinal mor-phology and function have been related to diar-rhea and malabsorption in humans (Farthing,1994) and livestock (O’Handley et al., 1999). Inlivestock, Giardia-mediated diarrhea and malab-sorption reduce growth rate, feed efficiency andthe profitability of livestock production (Olsonet al., 1995). Because of the suspected zoonoticpotential of G. lamblia, and its negative impact onlivestock production, there is great interest inidentifying chemicals able to control G. lamblia. Abutanol extract of Y. schidigera powder resulted tobe effective for killing G. lamblia tropozoitesin vitro. Oral administration of butanol extract togerbils reduced but did not eliminate trophozoitepopulations in the small intestine. Including yuccapowder in diets for gerbils or lambs did not affectthe course of experimentally induced giardiosis,but reduced the excretion of cysts (McAllisteret al., 2001).

Saponins form insoluble complexes with cho-lesterol, other sterols and bile acids. It is generallybelieved that the principal action of saponins onblood cholesterol is by sequestration of cholesteroland bile acids in the intestine, preventing theirabsorption. Another possibility could be thatincreased rate of exfoliation of intestinal cellscaused by the membranolytic action of saponinscould result in an increased loss of cell membranecholesterol contained in the exfoliated cells

182

(Cheeke, 1999). Cholesterol lowering properties ofsaponins in humans are of obvious interest. BeingY. schidigera along with Q. saponaria the world-wide two major commercial sources of saponins,a study to evaluate the hypocholesterolemicproperties of a preparation based on Y. schidigeraand Quillaia saponaria saponins in human bloodhas been performed. The results of this study showthat this preparation reduced significantly totalcholesterol and LDL levels in blood plasma ofhypercholesterolemic patients without significantchanges in HDL levels (Kim et al., 2003).

Chemistry of yucca phenolics

The effects of Y. schidigera products seem to bedue not only to their saponin content but also toother constituents. Considering that, we haveperformed an investigation aimed to define thephenolic profile of Y. schidigera bark. It is note-worthy that phenolics occur in the external part ofthe trunk, not inside.

Investigation of the phenolic fraction ofY. schidigera bark resulted in the isolation of thestilbenic derivatives trans-3,3¢,5,5¢-tetrahydroxy-4¢-methoxystilbene and trans-3,4¢,5,-trihydroxy-stilbene well known as resveratrol, along withlarixinol, a spirobiflavonoid previously isolatedfrom Larix gmelini which is made up of two C15

units of flavonoid origin (Shen et al., 1986). Fur-thermore, the novel yuccaols A–E (Oleszek et al.,2001b; Piacente et al., 2004) and yuccaone A wereisolated (Piacente et al., 2002) (Figure 4). Yucca-ols A–E are characterized by unusual spiro struc-tures made up of a C15 unit, probably derived froma flavonoid skeleton, and a stilbenic portion linkedvia a c-lactone ring. They differ for the stilbenicportion which is resveratrol in yuccaols A and Band trans-3,3¢,5,5¢-tetrahydroxy-4¢-methoxystil-bene in yuccaols C, D, E; for the stilbenic positioninvolved in the linkage with the C15 unit which isposition 2 of the dioxygenated ring in yuccaols A–D and position 2 of the trioxygenated ring inyuccaol E; for the stereochemistry at C-3. To ourknowledge, yuccaols A–E represent the uniqueexample in nature of spirostructures including C15

and C14 units condensed to form a c-lactonering. They probably derive from the attachmentof the stilbenic derivative to the carbocationic

intermediate in the oxidative flavanone–flavanolconversion and subsequent rearrangement of theintermediate. The different stereochemistry ofyuccaols at C-3 is in good agreement with theinvolvement of the C-3 carbocationic intermediatein the proposed biogenetic pathway (Figure 5).Yuccaone A is a novel phenolic constituentbased on a spirobenzopyran-4-cyclopentan-3-onesystem.

Biological activities of yucca phenolics

The multifunctional activities of resveratroltogether with the novelty of yuccaols A–E, struc-turally related to resveratrol, prompted us to carryout a program aimed to evaluate for yuccaphenolics some of the activities exerted by resve-ratrol.

First of all the antioxidant activity of theMeOH extract, its phenolic fraction and the singlephenolic constituents of Y. schidigera bark wasassayed also with a view to the potential use ofY. schidigera, which already possesses GRAS label,as an antioxidant in food stuffs. The antioxidantactivity was evaluated by radical scavengingactivity in the Trolox Equivalent AntioxidantCapacity (TEAC) assay and in the coupled oxi-dation of b-carotene and linoleic acid (Piacenteet al., 2004).

The TEAC assay (Pietta et al., 1998; Re et al.,1999) measures the relative ability of antioxidantsubstances to scavenge the radical cation2,2¢-azinobis-(3-ethylbenzothiozoline-6-sulfonate)(ABTS+) as compared to a standard amount ofthe synthetic antioxidant Trolox (6-hydroxy-2,5,7,8-tetramethylcroman-2-carboxylic acid), awater soluble vitamin E analogue. The activity ofthe tested samples was expressed as TEAC values;TEAC value is defined as the concentration ofstandard Trolox with the same antioxidantcapacity as a 1 mM concentration of the antioxi-dant investigated sample. All the tested samplesexhibited good free radical scavenging activity(Table 1). The phenolic extract showed the highestactivity, which was also higher than that ofquercetin, the reference antioxidant compound.Trans-3,3¢,5,5¢-tetrahydroxy-4¢-methoxystilbenewas more active than resveratrol; this was in goodagreement with the higher activity exhibited byyuccaols C–E, which possess as stilbenic portion,

183

trans-3,3¢,5,5¢-tetrahydroxy-4¢-methoxystilbene.Membrane lipids are rich in unsaturated fattyacids, that are susceptible to oxidative processes,linoleic acid being especially the target of lipidperoxidation (Pratt, 1992; Igile et al., 1994). Theantioxidative effect of the MeOH extract ofY. schidigera, its phenolic fraction and the isolatedcompounds on the autooxidation of linoleic acidwas also determined. The values of antioxidantactivity (AA) measured at t=60 and 120 min,employing bleaching of b-carotene as a model

system are reported in Table 1. The data show thatall the tested samples, except trans-3,3¢,5,5¢-tetra-hydroxy-4¢-methoxystilbene, exhibited significantactivity in this test. In particular, all the yuccaolsshowed activity higher than that of the standardphenolic antioxidant 2,6-di-tert-butyl-4-methoxy-phenol (BHT) (at t=120 min).

Many in vitro studies have shown that resve-ratrol possesses antiplatelet activity which com-prises the decreased reactivity and function ofplatelets and the diminished platelet activation

Figure 4. Phenolics of Y. schidigera bark.

184

Figure 5. Biogenetic pathway hypothesized for yuccaols A–E.

185

induced by agonists (Zbikowska et al., 1999; Olaset al., 2001). On the basis of these reports, the ef-fects of trans-3,3¢,5,5¢-tetrahydroxy-4¢-methoxy-stilbene, yuccaols A and C on platelet aggregationinduced by thrombin and ADP have beenevaluated (Olas et al., 2002). Pretreatment ofplatelets with resveratrol or other tested phenolics(1–25 lg/ml) slightly reduced platelet aggregationstimulated by 5 lM ADP or 10 lM ADP. Thecomparison of the inhibitory effects of testedcompounds in thrombin-induced platelet aggre-gation revealed that phenolics showed evenstronger antiplatelet activity than resveratrol.These compounds also had an inhibitory effect onthe thrombin-induced enzymatic platelet lipidperoxidation determined as the level of thiobarbi-turic acid active substances.

On the basis of these results, the comparativeeffects of resveratrol,trans-3,3¢,5,5¢-tetrahydroxy-4¢-methoxystilbene, and yuccaols A and C onoxidative stress in resting blood platelets andblood platelets activated by different agonists(thrombin or thrombin receptor activating pep-tide, TRAP) have been evaluated (Olas et al.,2003). Phenolics, tested at a concentration range of1–25 lg/ml, reduced to different degrees the levelof reactive oxygen species measured by the lumi-nol-dependent chemiluminescence and changed

the production of O2) measured by the reduction

of cytochrome c in resting blood platelets. Theyalso inhibited the generation of free radicals inblood platelets activated by thrombin (p<0.05) orthrombin receptor activating peptide (p<0.05).Comparative studies using in vitro tests showed thatall the phenolics from Yucca bark exerted an anti-oxidant effect on different ROS produced in restingblood platelets and blood platelets activated bythrombin or TRAP. Trans-3,3¢,5,5¢-tetrahydroxy-4¢-methoxystilbene showed the highest ability, alsohigher than that of resveratrol, to inhibit the pro-duction of O2

) and chemiluminescence. This com-pound showed also a stronger antiplatelet actionthan resveratrol. Thus this compound may be apromising candidate for future evaluations of itspharmacological activity associated with antiplat-elet action. Blood platelet activation plays a crucialrole in hemostasis and pathomechanisms of sev-eral arterial disorders, including artherosclerosis,strokes, and myocardial infarction (Kroll andSchafer, 1995; Levy-Toledano, 1999). Blood plate-lets also participate in tumor progression, allergicinflammation, and non-allergic responses (Block-mans et al., 1995; Kroll and Schafer, 1995; Levy-Toledano, 1999). Phenolics ofY. schidigera bark, inparticular trans-3,3¢,5,5¢-tetrahydroxy-4¢-methoxy-stilbene, reduce the deleterious effects of oxidative

Table 1. Antioxidant activities of MeOH extract, phenolic fraction and single phenolic constituents in the TEAC and autooxida-tion assays.a

TEAC assay (mM)±SDb) Autooxidation assay

t=60 min t=120 min

MeOH extract 1.787 ± 0.02 34.3 55.7

Phenolic fraction 3.301 ± 0.01 26.4 45.7

Resveratrol 1.896 ± 0.09 24.9 45.9

Trans-3,3¢,5,5¢-tetrahydroxy-4¢-methoxystilbene 2.252 ± 0.12 3.1 2.9

Yuccaol A 0.960 ± 0.04 52.6 72.1

Yuccaol B 1.093 ± 0.08 76.3 72.1

Yuccaol C 1.598 ± 0.01 59.5 71.7

Yuccaol D 1.422 ± 0.02 66.4 66.2

Yuccaol E 1.852 ± 0.13 74.3 79.3

Yuccaone A 1.037 ± 0.04 40.6 43.4

Larixinol 1.788 ± 0.01 24.4 51.0

Quercetin 2.600 ± 0.02

BHTc 71.8 61.2

aFor protocols used, see Piacente et al. (2004).bn = 3.cBHT, 2,6-di-tert-butyl- 4-methoxyphenol, standard control substance.

186

stress on blood platelets and, with other antioxidantin diet, may exhibit stronger protective activityagainst oxidative stress in blood platelet in vivo(Olas et al., 2003).

The above results show the potential use ofY. schidigera as a source of antioxidant principles.This is interesting if we consider that Y. schidigeraproducts possess GRAS label which allows appli-cation of its extract and powder in pharmaceutical,cosmetic, food and feeding-stuff industries (Wal-lace et al., 1994; Tanaka et al., 1996).

Resveratrol was found strongly to inhibitnitrogen oxide generation in activated macro-phages and to reduce the expression of theinducible isoform of nitrogen oxide synthase(iNOS) (Tsai et al., 1999). NO produced by iNOSis a key mediator in inflammatory processes and itsproduction is a crucial step in both the immuno-responsive cells activation and in the mechanism ofNO-mediated cytotoxicity (Nathan, 1997). Thusthe effects of yuccaols A–C on NO productionhave been examined, incubating macrophages with

different concentrations of yuccaols A–C 1 h be-fore stimulation with Escherichia coli lipopolysac-charide (LPS) (Marzocco et al., 2004). As shownin Figure 6 yuccaol C, added 1 h before LPSinduction, inhibited significantly and in a dose-related manner NO release, yuccaol A had a sig-nificant effect on NO release only at the highestconcentration of 100 lM, no significant activitywas observed for yuccaol B. To determine if theinhibitory effect of yuccaol C was related to amodulation of iNOS induction, iNOS expressionby Western blot analysis was evaluated. A signif-icant and concentration-related inhibition of iNOSexpression could be observed (Figure 7). Deletionand mutational analyses have demonstrated thatthe transcription factor NF-jB is involved in theactivation of iNOS by LPS (Ruetten and Thi-emermann, 1997). To examine whether yuccaol Cselectively inhibited activation of NF-jB, analysisof NF-jB binding activity by gel mobility shiftassay was performed. Under control conditionsactivation of J774.A1 cells with LPS resulted in a

Figure 6. Effect of yuccaol C (0.01–10 lM) on NO release by LPS-stimulated J774.A1 macrophages.

Figure 7. Concentration-dependent effect of yuccaol C (0.01–10 lM) on LPS-induced iNOS expression in J774.A1 macrophages.Representative blot of iNOS expression.

187

time-dependent increase in NF-jB expressionwhich peaked between 1 and 2 h and approachedbaseline values after 24 h. The induction of specificNF-jB binding activity by LPS was reduced sig-nificantly by yuccaol C (0.1–100 lM) added tocells 1 h before LPS challenge (Marzocco et al.,2004). Our results are strongly supported by otherstudies indicating the capability of resveratrol insuppressing nitric oxide synthase and down-regu-lating NF-jB activation in cultured macrophagesRAW 264.7 (Tsai et al., 1999). The above reporteddata are in good agreement with the anti-inflam-matory activity attributed to Y. schidigera in folkmedicine.

Conclusions

This review gives an account on the chemistry andbiological activities of Y. schidigera. In particular,it is the first report which summarizes the resultsgathered so far on the two metabolite classesoccurring in the polar fraction of Y. schidigeratrunk: saponins and phenolics. Biological activi-ties of Y. schidigera have been traditionallyattributed to its saponin constituents, thus moreattention has been given to the isolation andstructure elucidation of this class of compounds.More recently our investigations aimed to identifyother metabolites eventually co-responsible forthe biological activities of yucca products, led tothe isolation of very unusual stilbenic derivativesoccurring only in this plant. Their similarity tothe well-known resveratrol prompted us to carryout a program aimed to evaluate for yuccaphenolics some of the activities exerted by resve-ratrol. As a consequence of such efforts, inter-esting antioxidant-, platelet activation inhibiting-,iNOS expression-inhibiting activities have beenhighlighted. Thus the case of Y. schidigera indi-cate that even extensively studied plants may bethe source of exciting and unexpected discoveries,such as novel bioactivities of considerable prom-ise. The results obtained show that new oppor-tunities could be explored which could increasethe commercial value of yucca. In particular, thepossible application of Y. schidigera products,which already possess GRAS label, as food sup-plements with antioxidant properties has to beevaluated.

References

Adam RD (1991) The biology of Giardia spp Microbiol. Rev.55: 706–732.

Anthony NB, Balog JM, Staudinger FB, Wall CV, Walker RD& Huff WE (1994) Effect of urease inhibitor and ceiling fanson ascites in broilers. 1. Environmental variability andincidence of ascites. Poult. Sci. 73: 801–809.

Asplund RO (1991) Urease inhibition by extracts and extractfractions from species of the plant genus Yucca J. Anim. Sci.69:((Suppl. 1): 113.

Balog JM, Anthony NB, Wall CV, Walker RD, Rath NC &Huff WE (1994) Effect of urease inhibitor and ceiling fans onascites in broilers. 2. Blood variables, ascites scores and bodyand organ weights. Poult. Sci. 73: 810–816.

Blockmans D, Deckmyn H & Vermylen J (1995) Plateletactivation. Blood Rev. 9: 143.

Buret A, Gall DG & Olson ME (1990) Effects of murinegiardiasis on growth, intestinal morphology, and disaccha-ridase activity. J. Parasitol. 76: 403–409.

Calderon AA, Zapata JM, Munoz R, Pedreno MA & RosBarcelo A (1993) Resveratrol production as a part of thehypertensive-like response of grapevine cells to an elicitorfrom Trichoderma viride. New Phytol. 124: 455–463.

Cheeke PR (1998) Saponins: Surprising benefits of desertplants. In: The Linus Pauling Institute Newsletter (pp. 4–5).Oregon State University, Corvallis, OR.

Cheeke PR (2000) Actual and potential applications of Yuccaschidigera and Quillaja saponaria saponins in human andanimal nutrition. Proceedings of the Phytochemical Societyof Europe 45: 241–254.

Cline JL, Fischer BA, Trottier NL, Walker RD & Easter RA.(1996) Effect of feeding Micro-Aid on stillbirths, preweaningmortality, blood oxygen values of piglets and blood ureanitrogen in sows. J. Anim. Sci. 74(Suppl. 1): 189.

Colina JJ, Lewis AJ, Miller PS & Fischer RL (2001) Dietarymanipulation to reduce aerial ammonia concentrations innursery pig facilities. J. Anim. Sci. 79: 3096–3103.

Czeczot H, Podsiad M, Skrzycki M, Stochmal A & Oleszek W(2003) Evaluation of the mutagenic activity of phenolicsfrom the bark of Yucca schidigera Roezl. Acta Polon.Pharm. 60: 357–362.

Docherty JJ, Fu MM, Stiffler BS, Limperos RJ, Pokabla CM &De Lucia AL (1999) Resveratrol inhibition of herpes simplexvirus replication. Antiviral Res. 43: 145–155.

Duffy CF, Killeen GF, Connolly CA & Power RF (2001)Effects of dietary supplementation with Yucca schidigeraRoezl ex Ortgies and its saponin and non-saponin fractionson rat metabolism. J. Agric. Food Chem. 49: 3408–3413.

Farthing MJG (1994): Giardiasis as a disease, Giardia: FromMolecules to Disease. In: Thompson RCA, Reynoldson JA& Lymbery AJ (eds), Giardia: From Molecules to Disease(pp. 15–37). University Press, Cambridge, UK.

Flaoyen A, Wilkins AL & Sandvik M (2002) Ruminalmetabolism in sheep of saponins from Yucca schidigera.Veter. Res. Commun. 26: 159–169.

Headon DR, Buggle KA, Nelson AB & Killeen GF (1991):Glycofractions of the Yucca plant and their role in ammoniacontrol, Biotechnology in the Feed Industry. In: Lyons TP(eds), Biotechnology in the Feed Industry (pp. 95–108).Alltech Technical Publications, Nicholasville, KY.

Hristov AN, McAllistar TA, Van Herk FH, Cheng KJ,Newbold CJ & Cheeke PR (1999) Effect of Yucca schidigera

188

on ruminal fermentation and nutrient digestion in heifers.J. Anim. Sci. 77: 2554–2563.

Hussain I & Cheeke PR (1995) Effect of dietary Yuccaschidigera extract on rumen and blood profiles of steers fedconcentrate- or roughage-based diets. Anim. Feed Sci.Technol. 51: 231–242.

Hussain I, Ismail AM & Cheeke PR (1996) Effects of feedingYucca schidigera extract in diets varying in crude protein andurea contents on growth performance and cecum and bloodurea and ammonia concentrations of rabbits. Anim. FeedSci. Technol. 62: 121–129.

Igile OG, Oleszek W, Jurzysta M, Burda S, Fafunso M &Fasanmade AA (1994) Flavonoids from Vernonia amygda-lina and their antioxidant activities. J. Agric. Food Chem.42: 2445–2448.

Jang M, Udeani G, Slowing KV, Thomas C, Beecher CWW,Fong HHS, Farnsworth NR, Kinghorn AD, Mehta RG,Moon RC & Pezzuto JM (1997) Cancer chemopreventiveactivity of resveratrol, a natural product derived fromgrapes. Science 275: 218–220.

Jayatilake GS, Jayasuriya H, Lee ES, Koonchanok NM,Geahlen RL, Ashendel CL, McLaughlin JL & Chang CJ(1993) Kinase inhibitors from Polygonum cuspidatum. J. Nat.Prod. 56: 1805–1810.

Jeandet PR, Bessis M, Sbaghi M & Meunier PJ (1995)Production of the phytoalexin resveratrol by grapes as aresponse of grapevine cells to Botrytis attack under naturalconditions. Phytopathology 143: 135–139.

Kaya S, Erdogan Z & Erdogan S (2003) Effect of differentdietary levels of Yucca schidigera powder on the perfor-mance, blood parameters and egg yolk cholesterol of layingquails. J. Vet. Med. A 50: 14–17.

Killeen GF, Buggle KA, Hynes MJ, Walsh GA, Power RF &Headon DR (1994) Influence of Yucca schidigera prepara-tions on the activity of urease from Bacillus pasteurii. J. Sci.Food Agric. 65: 433–440.

Killeen GF, Connolly CR, Walsh GA, Duffy CE, Headon DR& Power RF (1998a) The effects of dietary supplementationwith Yucca schidigera extracts or fractions thereof onnitrogen metabolism and gastrointestinal fermentation pro-cesses in the rat. J. Sci. Food Agric. 76: 91–99.

Killeen GF, Madigan CA, Connolly CR, Walsh GA, Clark C,Hynes MJ, Timmins BF, James P, Headon DR & Power RF(1998b) Antimicrobial saponins of Yucca schidigera and theimplications of their in vitro properties for their in vivoimpact. J. Agric. Food Chem. 46: 3178–3186.

Kim SW, Park SK, Kang S, Kang HC, Oh HJ, Bae CY & BaeDH (2003) Hypocholesterolemic property of Yucca schidi-gera and Quillaia saponaria extracts in human body. Arch.Pharm. Res. 26: 1042–1046.

Kimura Y, Okuda H & Kubo M (1995) Effects of stilbenesisolated from medicinal plants on arachidonate metabolismand degranulation in human polymorphonuclear leukocytes.J. Ethnopharmacol. 45: 131–139.

Kroll MH & Schafer AJ (1995) The analysis of ligand–receptorinteraction in platelet activation. Immunopharmacology 29:31–65.

Langcake P & Price RJ (1976) The production of resveratrol byVitis vinifera and other members of the Vitaceae as a responseto infection and injury. Physiol. Plant. Pathol. 9: 77–86.

Levy-Toledano S (1999) Platelet signal transduction pathways:Could we organize them into a hierarchy Haemostasis 29:4–15.

Mader TL & Brumm MC (1987) Effect of feeding sarsaponin incattle and swine diets. J. Anim. Sci. 65: 9–15.

Makkar HPS, Sen S, Blummel M & Becker K (1998) Effect offractions containing saponins from Yucca schidigera, Quil-laia saponaria, and Acacia auriculoformis on rumen fermen-tation. J. Agric. Sci. 46: 4324–4328.

Marzocco S, Piacente S, Pizza C, Oleszek W, Stochmal A, PintoA, Sorrentino R & Autore G (2004) Inhibition of induciblenitric oxide synthase expression by yuccaol C from Yuccaschidigera Roezl. Life Sci. 75: 1491–1501.

McAllister TA, Annett CB, Cockwill CL, Olson ME &Wang Y(2001) Studies on the use of Yucca schidigera to controlgiardiosis. Vet. Parasitol. 97: 85–99.

Miyakoshi M, Tamura Y, Masuda H, Mizutani K, Tanaka O,Ikeda T, Ohtani K, Kasai R & Yamasaki K (2000) Antiyeaststeroidal saponins from Yucca schidigera (Mohave yucca), anew anti-food-deteriorating agent. J. Nat. Prod. 63: 332–338.

Nathan C (1997) Inducible nitric oxide synthase What differ-ence does it make? J. Clin. Invest. 100: 2417–2423.

O’Handley RM, Cockwill C, McAllister TA, Jelinski M, MorckDW & Olson ME (1999) Duration of naturally acquiredgiardiosis and cryptosporidiosis in dairy calves and theirassociation with diarrhea. J. Am. Vet. Med. Assoc. 214: 391–396.

Olas B, Wachowicz B, Saluk-Juszczak J, Zielinski T, Kaca W &Buczynski A (2001) Antioxidant activity of resveratrol inendotoxin-stimulated blood platelets. Cell Biol. Toxicol. 17:117–125.

Olas B, Wachowicz B, Stochmal A & Oleszek W (2002) Anti-platelet effects of different phenolic compounds from Yuccaschidigera Roezl. Bark. Platelets 13: 167–173.

Olas B, Wachowicz B, Stochmal A & Oleszek W (2003)Inhibition of oxidative stress in blood platelets by differentphenolics from Yucca schidigera Roezl. Bark. Nutr. 19: 633–640.

Oleszek W, Sitek M, Stochmal A, Piacente S, Pizza C & CheekeP (2001a) Steroidal saponins of Yucca schidigera Roezl. J.Agric. Food Chem. 49: 4392–4396.

Oleszek W, Sitek M, Stochmal A, Piacente S, Pizza C & CheekeP (2001b) Resveratrol and other phenolics from the bark ofYucca schidigera Roezl. J. Agric. Food Chem. 49: 747–752.

Olson ME, McAllister TA, Deselliers L, Morck DW, ChengKJ, Buret AG & Ceri H (1995) Effects of giardiasis onproduction in a domestic ruminant (lamb) model. Am. J.Vet. Res. 56: 1470–1474.

Olson ME, Thorlakson CL, Deselliers L, Morck DW &McAllister TA (1997) Giardia and Cryptosporidium inCanadian farm animals. Vet. Parasitol. 68: 375–381.

Orsini F, Pellizzoni F, Verotta L, Aburjai T & Rogers CB(1997) Isolation, synthesis and antiplatelet aggregationactivity of resveratrol 3-O-b-D-glucopyranoside. J. Nat.Prod. 60: 1082–1087.

Peestok LA (1979) An investigation into the application ofYucca schidigera extracts to biological waste treatmentsMiami University, Oxford, OHM. Sc..

Pendurthi UR, Williams JT & Rao LV (1999) Resveratrol, apolyphenolic compound found in wine, inhibits tissue factorexpression in vascular cells: A possible mechanism for thecardiovascular benefits associated with moderate consump-tion of wine. Arterioscler. Thromb. Vasc. Biol. 19: 419–426.

Piacente S, Bifulco G, Pizza C, Stochmal A & Oleszek W (2002)A novel phenolic spiro derivative, yuccaone A, from Yuccaschidigera bark. Tetrahedron Lett. 43: 9133–9136.

189

Piacente S, Montoro P, Oleszek W & Pizza C (2004) Yuccaschidigera bark: Phenolic constituents and antioxidantactivity. J. Nat. Prod. 67: 882–885.

Pietta PG, Simonetti P & Mauri PL (1998) Antioxidant activityof selected medicinal plants. J. Agric. Food Chem. 46: 4487–4490.

Pratt DE (1992) Phenolic compounds in food and their effectson health. In: Huang MT & Lee CY (eds) Symp. Ser. 507,American Chemical Society Books Vol. II (54 p.) Washing-ton, DC.

Re R, Pellegrini N, Proteggente A, Pannala A, Yang M & Rice-Evans C (1999) Antioxidant activity applying an improvedABTS radical cation decolorization assay. Free Radic. Biol.Med. 26: 1231–1237.

Ruetten H & Thiemermann C (1997) Prevention of theexpression of inducible nitric oxide synthase and the down-regulation of the activation of NF-kB in macrophages byresveratrol. Br. J. Pharmacol. 126: 673–680.

Shen Z, Haslam E, Falshaw CP & Begley MJ (1986) Procyani-dins and polyphenols of Larix gmelini bark. Phytochemistry25: 2629–2635.

Siemann EH & Creasy LL (1992) Concentration of thephytoalexin resveratrol in wine. Am. J. Enol. Vitic. 43: 49–52.

Surh YJ, Hurh YJ, Kang JY, Lee E, Kong G & Lee SJ (1999)Resveratrol, an antioxidant present in red wine, inducesapoptosis in human promyelocytic leukemia (HL-60) cells.Cancer Lett. 140: 1–10.

Tanaka O, Tamura Y, Masuda H & Mizutani K (1996):Application of saponins in food and cosmetics: Saponins ofMohave yucca and Sapindus mukurossi, Saponins used inFood and Agricultural. In: Waller GR & Yamasaki K (eds),Saponins used in Food and Agricultural (pp. 1–11). PlenumPress, New York.

Tsai SH, Lin Shiau SH & Lin JK (1999) Suppression of nitricoxide synthase and the down-regulation of the activation ofNf-jB in macrophages by resveratrol. Br. J. Pharmacol 126:673–680.

Uenobe F, Nakamura S & Miyazawa M (1997) Antimutageniceffect of resveratrol against Trp-P-1. Mutat. Res. 373: 197–200.

Wallace RJ, Arthaud L & Newbold CJ (1994) Influence ofYucca schidigera extract on ruminal ammonia concentra-tions and ruminal microorganisms. Appl. Environ. Micro-biol. 60: 1762–1767.

Zbikowska HM, Olas B, Wachowicz B & Krajewski T (1999)Response of blood platelets to resveratrol. Platelets 10: 247–252.

190