Anti-oxidative activities of the various extracts of stem bark, root and leaves of Ziziphus mucronata (Rhamnaceae) in vitro

Abstract

The present study was conducted to examine the anti-oxidative activities of extracts from different parts of Ziziphus mucronata. Stem bark, root and leaf samples were sequentially extracted with solvents of increasing polarity and tested for in vitro anti-oxidative activity using various models. Our results indicated that all the extracts had potent electron donating and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activities. However, the ethanolic extracts exhibited a significantly (p<0.05) more potent DPPH radical scavenging activity than other extracts and possessed lower IC50 values than ascorbic acid and trolox. The organic extracts of all the parts demonstrated hydroxyl radical scavenging activities but the ethyl acetate extracts of the stem bark and root as well as the ethanolic extract of the leaves displayed more powerful anti-OH* activity than trolox. All aqueous extracts were found to possess pro-oxidative activities in the hydroxyl radical scavenging method. Nitric oxide (NO) scavenging activities were observed in all the extracts tested except the aqueous extract of the roots that was found to be pro-oxidative at higher concentrations. Furthermore, dose dependent NO scavenging activities were observed in the ethanolic extract of the stem bark and ethyl acetate extracts of the root and leaves as well as the aqueous extract of the leaves. Data from this study suggest that the different parts of Z. mucronata, especially the ethanolic extracts possessed potent anti-oxidative activities that warrant further studies to identify the active key principles. Key words: Anti-oxidative, free radicals, extracts, leaves, root, stem bark, Ziziphusmucronata.