lecture 27: polyphenols Flashcards
polyphenols
plant secondary metabolites
flavonoids
plant polyphenols with a basic chemical structure of 15C
flavanols
catechin, epicatechin
procyanidins
polymers/oligomers of flavanols
not degraded through gastric transit, found in intestine
conc in GI tract can be maintained or increased when consumed on a daily basis
local effects at GI tract
catechin, epicatechin
absorbed, but absorption and metabolism influenced by stereochemical configuration
(-)-epicatechin best absorbed
after absorption, transformed into several methylated, sulfated, etc metabolites
polyphenol inhibition of fat absorption
flavanols and procyanidins in tea inhibit TG absorption
tea polyphenols inhibit activity of pancreatic lipase (TG to FA)
polyphenol regulation of BP
flavon-3-ols decrease BP, protect against cardiovascular disease
(-)-epicatechin mimics effects of cocoa admin, improves flow-mediated dilation and increasing plasma NO metabolites
decrease NOX or increase eNOS
polyphenols and antioxidant effects
decreased oxidative stress, action of flavanols and procyanidins on cellular components > decreased level of tissue oxidants
if the concentration of flavonoids do not reach concentrations within the body to be effective metal chelators or free radical scavengers, how can they have antioxidant actions?
they must be effective modulators of specific protein targets
ex. flavanols inhibit NOX
2 measures of oxidative stress
GSH and MDA
glutathione (GSH)
antioxidant, preventing damage caused by ROS by serving as electron donor
oxidized to yield dimeric form GSSG
ratio of GSH:GSSG is indicator of oxidative stress
malondialdehyde (MDA)
results from lipid perodixation of PUFAs
degree estimated by MDA
Chronic blockade of NO synthesis by L-NAME-mediated NOS
