Effect of Protein on the Antioxidant Activity of Phenolic Compounds in a Lecithin−Liposome Oxidation System

Abstract

The effect of bovine serum albumin (BSA) was investigated on the antioxidant activity of phenolic compounds, grape extracts, and red wines in a lecithin−liposome system oxidized at 37 °C with copper. In the absence of BSA, the phenolic compounds inhibited hydroperoxide formation in decreasing order: ferulic acid, epicatechin, catechin, rutin, malvidin, caffeic acid, quercetin, and propyl gallate. Hexanal formation was inhibited in the following decreasing order: ferulic acid, epicatechin, catechin, malvidin, caffeic acid, quercetin, rutin, and propyl gallate. Gallic acid and delphinidin promoted hydroperoxide and hexanal formation. In the presence of 20% BSA, liposome oxidation was much slower. Ferulic acid followed by malvidin and rutin were the most efficient in inhibiting lipid and protein oxidation. Two grape extracts and two red wines inhibited hydroperoxide and hexanal formation more efficiently without BSA. With BSA, the red wines were more active than the grape extracts in inhibiting lipid oxidation but were not different in inhibiting protein carbonyls. Keywords: Liposome oxidation; proteins; phenolic compounds; antioxidants; flavonoids; lecithin; liposome; hydroperoxides; hexanal; tryptophan; lysine; protein carbonyls; fluorescence