Kalt antioxidant workshop - AISA-AHIF

175 Pages·2010·7 MB·English

Antioxidants in Fruits
and Vegetables
AO = antioxidant
AOC = antioxidant capacity
Fruit, Vegetables & Health
Fruit & vegetable consumption
reduces disease risk
HOW?
• Essential vitamins & minerals
• Fiber
• Phytochemicals
•Carotenoids
•Polyphenols
Antioxidants
•Tocopherols
•Ascorbate
•Isothiocyanates
Fruit & Vegetable Antioxidants
(cid:131)Certain cancers
(cid:131)Block et al.1992; Steinmetz & Potter 1996
(cid:131)Cardiovascular Disease
(cid:131)Hertog et al. 1993; Joshipura et al. 1999
(cid:131)Neurodegenerative disease
(cid:131)Kang JH et al. 2005
“...the protection provided against diseases by fruits and
vegetables has been attributed to the various antioxidants
contained in these foods.” (Ames et al., 1993)
Oxidative Stress
in Disease & Aging
• Accumulation of deleterious
changes to biological
molecules
• Change/damage to DNA,
lipids, protein
• Leading to disease & aging
• Due to Oxidative Stress
• Need for biomarkers of
oxidative damage linked to
disease
The Antioxidant ‘Arms Race’
(Antioxidant capacities per gram of fresh wt.)
Blueberry
Blackberry
Garlic
Kale
Strawberry
Spinach
Brussel Sprouts
Plum
Oxygen Radical
Alfalfa Sprouts Absorption Capacity
Broccoli Floret ORACROO (Fmol Trolox equiv. per gram)
0 5 10 15 20 25
Source: 1997 Research at the Jean Mayer USDA Human Nutrition Research Center on Aging, on the antioxidant characteristics
of various fruits and vegetables. Journal of Agricultural and Food Chemistry 44:701-705; 3426-3343
Antioxidant Research at AAFC
• Use existing tools to create an inventory
of AAFC antioxidant research*
• Survey antioxidant activity in vitro
– Cell-based and non cell-based assays
• Chemical profiling
– Correlate chemical composition with AOC
• Determine impact of production &
processing on AO compounds and AOC
• Animal and clinical studies
FAO’s AgroVoc
* http://www.fao.org/agrovoc
F&V AO Research
For each phytochemical AO consider…
• Genetic variation (within & among species)
• Tissue distribution (e.g. seeds, peels)
• Environmental factors (e.g. light, water, disease)
• Effect of maturity (e.g. green vs. ripe red fruit)
• Removal and degradation during processing &
storage (e.g. waste products, oxidation)
• Impact of complex food matrix
• Multiple forms (e.g. isomers, esters)
• Antioxidant capacity of in vivo metabolites
Polyphenolic Antioxidants
How well are polyphenol AO absorbed?
proanthocyanidin dimers
anthocyanidins
EGCG
EGC
EC
rutin
quercetin glucoside
naringin
hesperidin
genistin
daidzin
0 0.5 1 1.5 2 2.5
C max (uM)
Adapted from Manach et al. 2005 AJCN
& Williamson 2006 Experimental Biology
maximum plasma concentration
Serum Antioxidants
Source: Wikipedia
Antioxidant metabolite Solubility Human Serum (μM)
Ascorbic acid (vitamin C) Water 50 – 60
Glutathione Water 4
Lipoic acid Water 0.1 – 0.7
Uric acid Water 200 – 400
β-carotene: 0.5 – 1
Carotenes Lipid
retinol (vitamin A): 1 – 3
α-Tocopherol (vitamin E) Lipid 10 – 40
Ubiquinol (coenzyme Q) Lipid 5
versus transient serum polyphenol
Cmax of about 0.02 – 2.0 μM