The Relation of Structure to Antioxidant Activity of Quercetin and Some of Its Derivatives II. Secondary (Metal‐Complexing) Activity

作者：Arieh Letan · 发表于：Journal of Food Science · 年份：1966 · DOI：10.1111/j.1365-2621.1966.tb00512.x · 被引用次数：46 · 研究领域：Free Radicals and Antioxidants、Computational Drug Discovery Methods、Phytochemicals and Antioxidant Activities

SUMMARY The secondary (metal‐complexing) activity of quercetin and some of its derivatives was studied with the conventional Warburg technique in an ascorbic acid system catalyzed with cupric ions. The 3‐hydroxy‐4‐keto group was the most powerful metalcomplexing group in the quercetin molecule; the 5‐hydroxy‐4‐keto group had some activity, but was considerably weaker. The 3′,4′‐o‐diphenolic group, important for the primary antioxidant activity, possessed virtually no metal‐deactivating properties. Methylation of the 4′‐ or 7‐hydroxyl (or, to a lesser degree, of the 3′‐hydroxyl) increased the complexing capacity of the 0‐methylated derivative of quercetin, while hydrogenation of the 2,3 double bond yielded an almost completely inactive compound (dihydroquercetin).