Broad spectrum antimutagenic activity of antioxidant active fraction of Punica granatum L. peel extracts

Over the past few decades, scientific research has indicated a credible basis for some of the traditional ethnomedicinal uses of pomegranate. This study aims to evaluate the broad spectrum antioxidant and antimutagenic activities of peel extracts of pomegranate. The sequentially extracted Punica granatum peel fractions were tested for their antioxidant activity by DPPH free radical scavenging, phospho-molybdenum, FRAP (Fe3+ reducing power) and CUPRAC (cupric ions (Cu2+) reducing ability) assays. The methanol fraction showed highest antioxidant activity by all the four in vitro assays comparable to ascorbic acid and butylated hydroxy toluene (BHT) followed by activity in ethanol, acetone, and ethyl acetate fractions. Based on the promising antioxidant activities, the methanol fraction was evaluated for antimutagenic activity by Ames Salmonella/microsome assay against sodium azide (NaN3), methyl methane sulphonate (MMS), 2-aminaluorene (2-AF) and benzo(a)pyrene (B(a)P) induced mutagenicity in Salmonella typhimurium (TA97a, TA98, TA100 and TA102) tester strains. The methanol fraction showed no sign of mutagenicity at tested concentration of 10-80 mu g/mL. This fraction showed antimutagenic activity against NaN3 and MMS with percent inhibition of mutagenicity ranging from 66.76% to 91.86% in a concentration-dependent manner. Similar trend of inhibition of mutagenicity (81.2-88.58%) against indirect mutagens (2-AF and B(a)P) was also recorded. Phytochemical analysis by H PLC, LC-MS and total phenolic content revealed high content of ellagitannins which might be responsible for promising antioxidant and antimutagenic activities of P.granatum peel extract. Further, contribution of bioactive compounds detected in this study is to be explored to understand the exact mechanism of action as well as their therapeutic efficacy. (C) 2010 Elsevier B.V. All rights reserved.