The Antioxidant Activity of Vegetable Extracts I. Flavone Aglycones ^a

Abstract

SUMMARY Hot‐water extracts of several plant tissues showed the following descending order of antioxidant activity, both as cover solutions of meats and in artificial systems: green onion tops, green pepper seeds, green peppers, celery, potato peels, green onions, and tomato peel. The over‐all antioxidant activity of extracts was not changed by hydrolysis of flavone glycosides, indicating that the naturally occurring glycosides possessed the same activity as the aglycones. The antioxidant activities of several known aglycones were compared and related to structural characteristics. Quereetin derivatives were the principal flavones of the extracts studied. Quereetin isolated from hydrolyzed extracts accounted for a large portion, hut not all, of the antioxidant activity of the extracts. Because of their effectiveness in heme‐catalyzed systems, the most significant role of the extracts as antioxidants is apparently their ability to break the chain reaction in lipid oxidation.