Antioxidant Activity and Protective Effect Against Plasmid DNA Strand Scission of Leaf, Bark, and Heartwood Extracts from Acacia catechu

The antioxidant activity of methanol extract/fractions of leaf, bark, and heartwood of Acacia catechu was evaluated by various antioxidant assays, including free radical, superoxide and hydroxyl radical, reducing power, metal ion chelation, as well as hydroxyl radical induced DNA strand scission. The leaf, bark, and heartwood powder was extracted in methanol and the lyophilized methanol extract was fractionated with different solvents in the order of increasing polarity. The results indicate that ethyl acetate fraction of heartwood has the highest antioxidant capacities, presenting lower EC50 values particularly in free radical scavenging activity, including DPPH radicals (4.76 +/- 0.14 mu g/mL), superoxide anions (26.21 +/- 0.79 mu g/mL), and hydroxyl radicals (33.69 +/- 1.42 mu g/mL), in direct assay systems. Reducing power was also highest in ethyl acetate fraction of heartwood (EC50 of 79.05 +/- 1.02 mu g/mL). As for the chelating power on ferrous ions, leaf extract was more effective than bark and heartwood extracts. Furthermore, the ethyl acetate and acetone fractions of heartwood significantly protected pBR322 supercoiled plasmid DNA against strand scission induced by hydroxyl radicals in a Fenton's reaction mixture.