EVALUATION OF HYDROXYL RADICAL-SCAVENGING PROPERTY OF PURPUROGALLIN USING HIGH-PRESSURE LIQUID-CHROMATOGRAPHY

Purpurogallin (PPG) has been used as an additive to edible and non-edi ble oils or fats to retard oxidation. Its antioxidant mechanism is not known. We investigated the ability of PPG to scavenge exogenously gen erated hydroxyl radicals (.OH) using a sensitive high pressure liquid chromatographic (HPLC) method. .OH was generated by photolysis of H2O2 (1.25-10 mu moles) with UV light and was trapped with salicylic acid (500 nmoles). Salicylic acid is hydroxylated to produce .OH adduct pro ducts 2,3- and 2,5-dihydroxybenzoic acid (DHBA). H2O2 produced concent ration-dependent .OH as estimated by generation of 2,3- and 2,5-DHBA. PPG (100, 200, 300, 400, 500 and 600 nmoles) produced concentration-de pendent decreases in .OH adduct products (approximately 70% inhibition with 600 nmoles of PPG). It did not affect the peak of standard 2,3- and 2,5-DHBA indicating that the decrease in the adduct product genera ted by H2O2 is due to scavenging of .OH. These results indicate that p hotolysis of H2O2 by UV light produces .OH and that PPG scavenges .OH.