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NUTR 3330: Final Exam Questions With
Verified Answers
Phytochemicals - Answers✔Chemicals found in plants
Generally non-nutritive substances
Physiologically active components
Polyphenols - Answers✔Most numerous and ubiquitous groups of plant metabolites
Ubiquitous in all plant organs-- integral part of diet
Range from simple phenolic molecules to highly polymerized compounds
Traditionally considered anti-nutrients
Have antioxidant capacities
Common structural feature of plant polyphenols - Answers✔Aromatic ring with at least one
hydroxyl group
Plant polyphenols synthesized via: - Answers✔1. Shikimate Pathway
2. Acetate Pathway
T/F: Plant polyphenols contribute to the pigmentation of plants - Answers✔True
What influences the amount of polyphenols in plants? - Answers✔Light-- highest conc of
polyphenols in leaves and outer parts of plants, only trace amounts in subterranean parts
Genetic factors
Environmental Condition s
Germination
Variety
Processing and storage
Presence of polyphenols in food can... - Answers✔increase astringency and bitterness
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T/F: Oxidation during processing/storage can affect food characteristics - Answers✔True
Polyphenols function in food: Digestibility of Macronutrients - Answers✔Bind and precipitate
protein
Reduced absorption and increased nitrogen in the feces
Polyphenols function in food: Mineral Bioavailability - Answers✔Form complexes with metal
cations
Interfere with absorption (ie. iron and copper)
How could binding iron be a good thing? - Answers✔Iron is thought to be involved in lipid
peroxidation as well as interacts with H202; so stopping it would slow down the formation of
ROS
Type of polyphenols in food - Answers✔Phenoic Acids
Flavonoids
Flavonoids - Answers✔Labelled Vitamin P (p= pigment)
Enhance the function of vitamin C: improving absorption and protecting it from oxidation
Antioxidant effects
Subgroup of low molecular weight polyphonic substances
Ubiquitous, found in most plants
Where are flavonoids found in most plants? - Answers✔Concentrated in seeds, fruit skins or
peel, bark, flowers
Decreased concentrations towards central core
Only trace amounts found in plants below soil surface (exceptions, garlic and onions)
Basic flavonoid structure - Answers✔A ring-- arises from acetate pathway
B ring-- arises from shikimate pathway
C ring-- determines the major class of flavonoid
What are the 6 major subclasses of flavonoids? Where do they differ? - Answers✔They differ in
terms of variations of the C-ring
1. Flavones
2. Flavonols
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3. Flavanones
4. Flavanols
5. Anthocyanins
6. Isoflavones
Flavonoid Glycosides - Answers✔Typically attached/conjugated to a carbohydrate moiety in
food
Glycoside vs. Aglycone - Answers✔Glycoside-- bound to a sugar molecule
Aglycone--not bound to a sugar molecule
T/F Majority of flavonoids are glycosides - Answers✔True
Purpose of Flavonoid Glycosides - Answers✔Increases POLARITY
Necessary for storage in plant vacuoles
Usually bound to carbohydrates-- mostly glucose
Flavonoid Bioavailability - Answers✔Flavonoids are absorbed and reach magnitudes of
concentrations in our biological fluids
Absorbed in the intestines
Flavonoid Biological Effects- Antioxidant - Answers✔Direct free radical scavengers due to ring
and hydroxyl group
Interacts with chelate metals (IRON) to prevent lipid per oxidation
Induces antioxidant-related enzymes (GST)
Protect vitamin E from oxidation; regenerates oxidized vitamin E
Flavonoid Biological Effects- Hormonal/Anti-hormonal - Answers✔Primarily estrogenic and
anti-estrogenic
Relation to hormone dependent cancers (breast, prostate)
Flavonoid Biological Effects- Anti-proliferative - Answers✔Inhibits cellular transformation and
proliferation
Inhibits growth of cancer cells (in vitro)
Interacts with enzymes associated with DNA
-- Topoisomerase iI
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