Antioxidant activity of methanol extract of the lotus leaf (Nelumbo nucifera Gertn.).

In this study, hydrogen peroxide (H2O2)-mediated Caco-2 cytotoxicity was employed to investigate the potential antioxidant activity of the methanol extract from the lotus leaf (Nelumbo nucifera Gertn.). A dose-dependent protective effect against reactive oxygen species (ROS)-induced cytotoxicity was observed when Caco-2 cells were treated with 10 mM H2O2 in combination with the methanol extract of the lotus leaf (0.1-0.3 mg/ml). However, no significant effect was found when co-treating Caco-2 cells with 10 mM H2O2 and alpha-tocopherol. In vitro assay revealed that the extract exhibited scavenging activities on free radicals and hydroxyl radicals, and metal binding ability as well as reducing power, which may explain in part the mechanism behind the extract's ability to protect cells from oxidative damage. In addition, the extract also exhibited concentration-dependent antioxidant activities against hemoglobin-induced linoleic acid peroxidation and Fenton reaction-mediated plasmid DNA oxidation.