Inhibition of lipid peroxidation and structure-activity-related studies of the dietary constituents anthocyanins, anthocyanidins, and catechins.
The antioxidant activities of a series of commonly consumed and biogenetically related plant phenolics, namely, anthocyanidins, anthocyanins, and catechins, in a liposomal model system have been investigated. The antioxidant efficacies of the compounds were evaluated on their abilities to inhibit the fluorescence intensity decay of an extrinsic probe, 3-[p-(6-phenyl)-1,3,5-hexatrienyl]phenylpropionic acid, caused by free radicals generated during metal ion-induced peroxidation. Distinct structure-activity relationships were revealed for the antioxidant abilities of these structurally related compounds. Whereas antioxidant activity increased with an increasing number of hydroxyl substituents present on the B-ring for anthocyanidins, the converse was observed for catechins. However, substitution by methoxyl groups diminished the antioxidant activity of the anthocyanidins. Substitution at position 3 of ring C played a major role in determining the antioxidant activity of these classes of compounds. The anthocyanidins, which possess a hydroxyl group at position 3, demonstrated potent antioxidant activities. For the cyanidins, an increasing number of glycosyl units at position 3 resulted in decreased antioxidant activity. Similarly, the substitution of a galloyl group at position 3 of the flavonoid moiety resulted in significantly decreased antioxidant activity for the catechins. Among catechins, cis-trans isomerism, epimerization, and racemization did not play a role in overall antioxidant activity. The antioxidant activities of test compounds (at 40 microM concentrations) were compared to the commercial antioxidants tert-butylhydroquinone, butylated hydroxytoluene, butylated hydroxyanisole, and vitamin E (all at 10 microM concentrations).
Seeram
Navindra P
NP
Bioactive Natural Products and Phytoceuticals, Department of Horticulture and National Food Safety and Toxicology Center, Michigan State University, East Lansing, Michigan 48824, USA.
Nair
Muraleedharan G
MG
D000872:Anthocyanins / Q000737:chemistry / Q000494:pharmacology*; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D002392:Catechin / Q000737:chemistry / Q000494:pharmacology*; D004032:Diet; D005296:Ferrous Compounds / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects*; D015394:Molecular Structure; D013329:Structure-Activity Relationship; D014810:Vitamin E / Q000494:pharmacology
D000872:Anthocyanins; D000975:Antioxidants; D005296:Ferrous Compounds; D014810:Vitamin E; D002392:Catechin