Effect of Mangifera indica L. extract (QF808) on protein and hepatic microsome peroxidation

The antioxidant activities of QF808, a steam bark extract of Mangifera indi ca L., were studied on hydroxyl-mediated oxidation of bovine serum albumin (BSA) and in a hepatic microsome system. The extract was effective in reduc ing the oxidation of BSA, since its half- maximal inhibition concentration (IC50) was 0.0049% w/v in the inhibition of carbonyl group formation and lo wer than 0.0025% w/v in the inhibition of sulfhydryl group loss. QF808 inhi bited lipid peroxidation which was initiated enzymatically by reduced nicot inamide adenine dinucleotide phosphate (NADPH), IC50 = 0.00075% w/v, or non -enzymatically by ascorbic acid, IC50 = 0.0126% w/v. The extract tested did not inhibit NADPH-dependent cytochrome P-450 reductase activity, since it had no effect on the oxidation rate of NADPH. These results suggest that QF 808 has an antioxidant activity, probably due to its ability to scavenge fr ee radicals involved in microsome lipid peroxidation. In addition, QF808 an tioxidant profile in vitro is probably similar to its principal polyphenoli c component, mangiferin, a glycosylated xanthone. Copyright (C) John Wiley & Sons, Ltd.