ANTIOXIDATIVE ACTIVITY OF MONOACYLATED ANTHOCYANINS ISOLATED FROM MUSCAT-BAILEY-A GRAPE

The antioxidative activity of four anthocyanins isolated from the Musc at Bailey A grape, which has a malvidin nucleus, was evaluated accordi ng to the amount of malonaldehyde formed by the autoxidation of linole ic acid in Trizma buffer (pH 7.4). Thiobarbituric acid derivatives of malonaldehyde were quantitatively analyzed by a spectrophotometer (at 535 nm). Malonaldehyde (20 nmol/mg of linoleic acid) was regularly det ected after a 16-h inculation period without antioxidants. Malvidin 3- O-(6-O-p-coumaroylglucosido)-5-glucoside showed only 2.6 nmol/mg of li noleic acid malonaldehyde production. p-Coumaric acid attached to malv idin 3-glucoside and malvidin 3,5-diglucoside was found to play an imp ortant role in preventing malonaldehyde production from linoleic acid. The antioxidative activity of an acylated anthocyanin was compared wi th other chemicals. Malvidin 3-O-(6-O-p-coumaroylglucosido)-5-glucosid e proved to be 2 times more effective than commercially available anti oxidants such as (+)-catechin and alpha-tocopherol. From the results, ii was found that the monoacylated anthocyanins from the pericarps of grapes can be used as powerful antioxidants as well as for colorants.