Class Notes (835,638)
Canada (509,305)
Nutrition (899)
NUTR 3330 (14)
Lecture

FLAVONOIDS.docx

4 Pages
238 Views
Unlock Document

Department
Nutrition
Course
NUTR 3330
Professor
Alison Duncan
Semester
Fall

Description
FLAVONOIDS WHAT ARE THEY - the stars of phytochemicals - when first discovered, called ‘Vitamin-P’, P = pigment. Vitamin concept later dismissed - subclass of polyphenols - sub-group of low molecular weight polyphenolic substances o star of plant polyphenols o most common group of polyphenols o research on possible nutritional role of polyphenols focused on flavonoids - ubiquitos; present in most plants o concentrated in seeds, fruit skin or peel, bark, flowers STRUCTURE - common structure of diphenylpropanes (C6-C3-C6) o 2 aromatic rings linked through 3 carbons - Basic flavonoid structure: A ring from acetate pathway B ring from Shikimate pathway  Both A & B rings have OH groups attached (→) C ring determines the major class of flavonoid FUNCTION - shown to enhance Vitamin C function – improves absorption and protects it from oxidation o beginning evidence supporting potent antioxidant effects CLASSIFICATION - over 5000 have been discovered - 6 major subclasses –based on C ring o (1) Flavones o (2) Flavonols o (3) Flavanones o (4) Flavanols o (5) anthocyanidins o isoflavones DISTRIBUTION IN PLANTS - same concept as polyphnols - mainly in leaves, flowers and outer parts of the plant (skin, peel) - decreased concentrations toward the central core - only trace amounts found in subterraneous parts of plant o some exceptions – onions, garlic FOOD SOURCES - widely distributed in foods and beverages of plant origin o fruit, vegetables, tea, cocoa, wine FLAVONOIDS FLAVONOID INTAKE - similar concepts to polyphenols - challenges in determining dietary intake relating to determination of flavonoid composition o Content variation – species & genetic variations, light, environmental conditions, germination, degree of ripeness, processing and storage  e.g. cherry tomatoes contain 6x more quercitin (flavonoid)/g fresh weight than normal size varieties – maybe because we eat more skin with cherry tomatoes as opposed to larger tomatoes o Analytical methodology  lack of standardization  information in the literature is often contradictory - determining intake – analytical studies not always correct - flavonols and flavones are the most measured FLAVONOID GLYCOSIDES - flavonoids typically attached/conjugated to carbohydrate moieties in food - Terminology... sugar molecule? o YES = flavonoid glycoside o NO = flavonoid aglycone - majority of flavonoids appear in plants as glycosides Purposes of flavonoid glycosylation - increase polarity - necessary for storage in plant vacuoles - most common sugar residue: o glucose o others include: arabinose, galactose, xylose, other less common carbohydrate substitutions BIOAVAILABILITY - initially thought to be negligible since bound to glycosides - not the case! - present in blood and urine - flavonoids are absorbed and reach concentrations of varying magnitudes in our biological fluids BIOLOGICAL EFFECTS 1. Antioxidant - direct free radical scavengers - protect vitamin E
More Less

Related notes for NUTR 3330

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit