The Effect of Methylation Upon the Antioxidant and Chelation Capacity of Quercetin and Dihydroquercetin in a Lard Substratea,b,c

摘要

SUMMARYThe relative importance of the hydroxyl group positions of quercetin and the metal‐complexing sites of the molecule to antioxidant capacity in lard was investigated. The antioxidant action of quercetin seems to be a combination of reaction with free radicals and metal‐ion complexing; with the former being the more important. Selective methylation of the hydroxyl groups of the quercetin molecule generally decreased the antioxidant activity. Ultraviolet absorption spectra of quercetin and copper‐quercetin complexes suggest that quercetin will complex two moles of copper ion by intramolecular complexing and a third by intermolecular complexing. Copper‐quercetin complexes retain some antioxidant ability although it is much less than that of uncomplexed qu