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Functional Components Onion and Their Relation of Cancer and
Chronic Disease Prevention
Bhimu PatilPart-I
Phytochemicals• Naturally occurring biologically active components • Found in plant
Phytonutrient• Plant chemical with known nutrient properties• Consumed as part of a usual diet
Biologically active or Protect against DiseaseHealth Canada, 1998
Bioactive Compounds“Extranutritional” constituents that typically are naturally occurring in small quantities in plant products and lipid rich foods.
Kitts, 1994 Can J. Physiol Pharmacology 1994
Nutraceutical• Product isolated or purified from foods • Sold in medicinal forms - pill, powder, capsule
Functional Food• A conventional food• Consumed as part of a usual diet• Provide health benefit beyond basic nutrition
Biologically active or Protect against DiseaseHealth Canada, 1998
Fundamental Trends Driving Market
Aging Demographics
Emphasis on preventative measures to control health care costs
Increased interest, acceptance and utilization of “alternative” treatments
Expanding body of scientific evidence
Increasing Marketing and advertising activities
Claims of Food Harms vs Benefits in Media
IFIC, Food for Thought III, Feb, 2000
0
20
40
60
Benefits Harms
1995
1997
1999
Chemopreventive agents
• Micronutrients
–vitamins, beta carotene, molybdenum, calcium
• Phytochemicals
• Synthetics
–vitamin derivatives
–piroxicam
–tamoxifen
Phytochemicals
• Organosulfides
• Isothiocynates
• Indoles
• Dithiolthiones
• Polyphenols• Flavonoids• Tannins• Folic acid
Contd.
Phytochemicals
• Carotenoids
• Indole
• Saponins
• Coumarins• Dietary Fiber• Isoflavones• Protease
inhibitors
Cancer Producing Compounds
Blocking Agents
Cells Attacked By Cancer Producing Compounds
Suppressing Agents
Cancer Wattenburg, 1993
Chemopreventive agents
• Blocking agents
– Flavonoids
– Indoles
– Isothiocynates
– Diallyl sulfides
– D-limonene
Chemopreventive agents• Suppressing agents
–D-limonene, Diallyl sulfides, vitamin D, vitamin A and retinoids, monoterpenes, carotenoids, polyphenols, protease inhibitors, selenium and calcium
Anticarcinogenic mechanisms
• Antioxidant effects
• Increased activity of enzymes that detoxify carcinogens
• Effect on cell differentiation
• Blocked formation of nitrosamines
• Altered estrogen metabolism
• Decreased cell proliferation
• Maintenance of normal DNA repair
• Angiogenesis
Initiation
Promotion
Phase I enzymes
Oxidative damageFree radicals
Quercetin, Lycopene, Lutein, Zeaxanthin and Beta carotene
Procarcinogens
CarcinogensElectrophiles
DNA Damage
Phase II enzymesGlutathione S-transferaseLimonoidsFlavonoids ?
Tumor
What is Quercetin?
• Flavonoid
• Vacuoles of a plant cell
• Synthesized during bulb and leaf development
Background
• Flavonoids-non nutrient
• 1936-Szent-Gyorgyi, called flavonoids as vitamin P.
• 1950 disproved the theory
• Late seventies-mutagenecity of quercetin
• Recent research-anticarcinogenic
FLAVONOIDS
• Flavonols
• Flavonones
• Flavones
• Anthocyanidins-cyanidin
• Catechins-epigallocatechin
• Biflavans-proanthocynidin
O
OH
O R2
R1
HO
HO
Structure of flavonoids
X
7
6
5
3
2
4
8
6151
41
31
21
Flavonols: X=OH; Quercetin: R1=OH, R2=H; Kaempferol; R1=H, R2=H; Myrcetin: R1=OH, R2=OH.
Flavones: X=H; Luteolin:R1=OH, R2=H; Apigenin: R1=H, R2=H
A
B
C
Biosynthesis of QuercetinPentose phosphate pathway Glycolysis
Shikimic acid pathway
Dihydroquercetin
Quercetin
Malonic acid pathway
Malonyl CoA 4 Coumaryl CoA
O
OH
O
HO
HO
OOH
OHOH
A
B
CA
B
Chalcone synthase
4 Coumaryl -Co A Malonyl-Co A
Chalcone isomerase
Naringenin Chalcone Flavonone (naringenin)
Case Control and Cohort Studies of All Types of Cancer (Contd.)
Steinmetz and Potter, 1996, JADA 96:1027-1039
Fruit No. of studiesInverse Positive
RawVegetables
33 2
Crucifers 38 8
Alliums 27 4
Legumes 14 16
GreenVegetables
61 13
Biological Effects of Quercetin
• In vitro– Mutagen– Genotoxic– DNA strand Scission
• In vivo– Anticarcinogenic
Contd.
Quercetin Superoxide DNA Strand BreakageCu, Fe
In vitro
In vivo
In Salmonella
In mammalian Cells
Superoxide DismutaseCatalase
Glutothione Peroxidase
Defend against:SuperoxideHydrogen Peroxide
Free radicals
Incubation
Components of Quercetin
• Glucosides
–Quercetin 3, 4' diglucoside
–Quercetin 4' monoglucoside
–Present in vacuoles
• Free quercetin (Aglycone)
–Oil glands and waxy layers
Optimum Hydrolysis
Sample Conditions Quercetin(mg/kg dry wt)
Cranberry 1.2 M HCl/0.5 hr 1485Onion 1.2 M HCl/2 hr 5076Lettuce 2.0 M HCl/2 hr 319Celery 2.0 M HCl/4hr <10
Hydrolysis of flavonols
Quercetin Glycosides Glycosidase
Mouth
Gut
Stomach
Fecalase
Quercetin (Aglycone)
Vegetable Quercetin Kaempferol
Onion 347 <2
Turniptops
7.3 48
Leek <1 30
Kale 110 211
Broccoli 30 72Hertog et al., (1992)
mg/kg fresh edible part
Vegetable Quercetin Kaempferol
Endive <1.3 46
Lettuce 14 <2
Frenchbeans
39 <12
Tomato 8 <2
Broad bean 20 <2Hertog et al., (1992)
mg/kg fresh edible part
Beverages Quercetin Myricetin
Red wine 4.1 7.5
Red Chainti1990
16 8.0
White wine <0.5 1.0
Grape juice 4.9 <0.5
Apple Juice 2.5 <0.5Hertog et al., (1992)
mg/L
Beverages Quercetin Myricetin
Tomato juice 13 <0.5
Lemon Juice 7.4 <0.5
Orange Juice 3.4 <0.5
Grapefruit Juice 4.9 <0.5
Beer (Heineken) <0.5 <0.5Hertog et al., (1992)
mg/L
Flavonol and flavone contents of common vegetables and fruits
Flavonol andflavone
Fruits andVegetables
High>50 mg/kg)
Broccoli, endive,kale, french beans,celery, onions,cranberries
Hollman et al (1996)
Flavonoland flavone
Fruits and Vegetables
Low<10 mg/kg
Cabbage, spinach,carrots, peas,mushrooms, peaches,strawberries, orangejuice, white wine, brewedcoffee
Medium<50 mg/kg
Lettuce, broad beans, redpepper, tomato, apples,grapes, cherries, tomatojuice, red wine, teabeverages
Flavone and Flavonol intake Quer
intake (mg/g)
Flavonol and flavone intake (mg/day)
Veg & fruits (%)
Red wine (%)
Tea (%)
Finland 6 6 100 0 0 USA 11 13 80 0 20 Siberia 10 12 98 2 0 Greece 21 16 97 3 0 Italy 13 27 54 46 0 Netherlands 30 33 36 0 64 Croatia 30 49 82 18 0 Japan 31 64 10 0 90
Hertog et al (1995)
Diet and Quercetin
Daily Intake of Flavonoids
1 g (USA)
2.5 g (Other countries)
4-oxy flavonoids (170 mg)
Quercetin- 50 mg
Flavones
Flavonols
After ingesting 225 g fried onions
0
50
100
150
200
250
300
0 2 4 24 48
Time (hour)
Plasma Quercetin
(ng/ml)
McAnis et al., (1998)
After ingesting 225 g fried onions
1.5
1.55
1.6
1.65
1.7
1.75
1.8
0 2 4 24 48
Time (hour)
Antioxidant activity
mmol/ trolox equivalents)
McAnis et al., (1998)
0
1
2
3
4
5
Flavonoids
Trol
ox e
quiv
alen
t an
tioxi
dant
ac
tivity
Quercetin Rutin Catechin LuteolinApigenin Naringenin Hesperetin Kaempferol
Cathrine et al (1997)
Antioxidant Activity
Flavonol and flavone intake and coronary heart disease
0
0.2
0.4
0.6
0.8
1
1.2
0-19 19.1-29.9 >29.9
Flavonol and flavone intake (mg/day)
Re
lati
ve
Ris
k
Crude
Adjusted (age,dietand risk factors)
Hertog et al (1993)
Factors influencing quercetin content
• Cultivars- sweet vs. fall storage
• Production systems
• Developmental stages
• Scale age
• Postharvest gamma irradiation
Changes bioactive compound levels from plant to human?
Genetic selection /production practices
Food
matr
ix /
oth
er
meal
com
pon
en
ts
Processing/culinary practices
Ind
ivid
ual ch
ara
cteristics
Plant content
Bioavailable content
IngestionIngestion
AbsorptionAbsorption
Factors influencing micronutrient contents in plants
Carotenoids Vitamin C Phenoliccompounds
Variety *** *** ***
Light * ** **
Fertilization **(less N)
**(less N)
Maturity stage
*** * *
Amiot-Carlin MJ 2003 Quality of plant-derived products. Forum Nutr 56:318-321
Vitamins T° Light Oxidative agents
Acids Alkali
Carotenoids
K
B9
C
Very sensitive
sensitive
Factors degrading vitamins during processing
Factors influencing quercetin content
• Cultivars- sweet vs. fall storage
• Production systems
• Developmental stages
• Scale age
• Postharvest gamma irradiation
Sweet Onion Cultivars
050
100150200250300350
Cutlivars
To
tal Q
uer
ceti
n (
mg
/kg
)
Patil et al., 1995. J. Amer. Soc. Hort 120(6):909-913
Sweet Onion Genotypic Variation - Total Quercetin
0
50
100
150
200
250
Genotypes
Qu
erce
tin
(m
g/k
g f
resh
wt)
Patil et al., 1995. J. Amer. Soc. Hort 120(6):909-913
Sweet Onion Genotypic Variation- Free Quercetin
0
2
4
6
8
10
12
14
2035
6G
2035
2G
2035
5G
2035
4G
2027
5G
2027
7G
2027
0G
2036
6G
2035
7G
2027
2G
2030
3G
2029
1G
2027
4G
2028
8G
2027
6G
2028
0G
2029
0G
2030
1G
2025
3G
2033
0G
2026
3G
2031
6G
2033
8G
2025
1G
2030
5G
2025
9G
2024
9G
2025
7G
Genotypes
Fre
e Q
ue
rce
tin
(m
g/k
g f
res
h
wt)
Patil et al., 1995. J. Amer. Soc. Hort 120(6):909-913
Comparison of quercetin
Authors mg/kg fresh wt
Hertog et al., 1993 544
Hermann et al., 1976 104-1060
Bilyk et al., 1986 15-62
Patil et al., 1995 54-202 ( sweet onion)500 (fall onions)
Price et al., 1997 89-1778
Variation of Quercetin: BiotechnologyTomato
Cultivar Conc. (ppm)
Roma 11
Cherry 15
Allsa Craig (Hp/Hp) 12
Allsa Craig (hp/hp) 220
Dr. James Giovannoni’s lab
Factors influencing quercetin content
• Cultivars- sweet vs. fall storage
• Production systems
• Developmental stages
• Scale age
• Postharvest gamma irradiation
Differences in location
• Griffin & Brand
–Soil: sandy loam
–400 m from Rio Grande River
• Starr County
–Soil: slightly heavier
–Two miles east of Rio Grande River, south of Rio Grande City
Growing location effect on quercetin
0
50
100
150
200
1607
B*
1613
B*
1627
B*
1631
B
1656
B
TG1015
Y*
Cultivars
Qu
erc
eti
n (
mg
/kg
fre
sh
w
t)
Griffin and Brand, McAllen, TX Starr County, TX
Patil et al., 1995. New Phytology 130(3):349-355
Factors influencing quercetin content
• Cultivars- sweet vs. fall storage
• Production systems
• Developmental stages
• Scale age
• Postharvest gamma irradiation
Quercetin content during
'TG1015Y' bulb development
0
20
40
60
80
100
9 March (0) 23 March(14)
1 April (24) 14 April(37)
21 April(44)
Date (Days after bulb development)
Qu
erc
eti
n (
mg
/kg
fre
sh
w
t)
Sandy loam clay
Patil and Pike 1995. J. Hort Sci. 70(4):643-640
Very earlylifting
Earlylifting
Latelifting
Very latelifting
Erect leaves
Fallen leaves
1 x Q 2 x Q
Common practiceCourtsey from Dr. Mogren
Lifting time – fresh onions
0% 50% 80% 100%0
20
40
60
80
100
120
140
160
180
200Q
ue
rce
tin g
luco
sid
e c
on
ten
t (m
g k
g-1 fw
)
Onions with fallen leaves at lifting
a
b
c
d
Mogren et al., 2006
Factors influencing quercetin content
• Cultivars- sweet vs. fall storage
• Production systems
• Developmental stages
• Scale age
• Postharvest gamma irradiation
Distribution among edible parts
050
100150200250300350400
Kadavan Red Bone TG1015Y TG502 Contessa
Different scales
Qu
erc
eti
n c
on
ten
t (m
g/k
g
fre
sh
wt)
1-2 rings 5-6 rings 7-10 rings
Patil and Pike 1995. J. Hort Sci. 70(4):643-640
Distribution among edible parts
0
100
200
300
400
500
600
700
Fresh Weight (mg/kg) Dry Weight (g/kg)
Different scales
Qu
erc
eti
n c
on
ten
t (m
g/k
g
fre
sh
wt)
1-2 rings 3-4 rings 5-6 rings 7-10 rings
Patil and Pike 1995. J. Hort Sci. 70(4):643-640
Factors influencing quercetin content
• Cultivars- sweet vs. fall storage
• Production systems
• Developmental stages
• Scale age
• Postharvest gamma irradiation
Effect of gamma irradiation
0
5
10
15
0.0 kGy 0.8 kGy 1.2 kGy
Treatments
Fre
e q
uer
cet
in
con
ten
t (m
g/k
g
fres
h w
t)
Patil et al., 1999. Subtropical Plant Science 51:15-21
Effect of gamma irradiation
0
50
100
150
200
250
0.0 kGy 0.8 kGy 1.2 kGy
Treatments
To
tal q
uer
ceti
n
con
ten
t (m
g/k
g f
resh
w
t)
Patil et al., 1999. Subtropical Plant Science 51:15-21
Effect of Processing
0
100
200
300
400
None Fried Boiled Microwaved
Cooking
Qu
erce
tin
(u
g/g
)
Crozier et al., 1997
Summary-Quercetin
• Sweet and fall storage onions differ significantly
• Within a group there are significant cultivar differences
• Influenced more by genotype than by environment
• Concentration gradient: outer scales greatest