Estimation of total phenolic content, cytotoxicity and in–vitro antioxidant activity of stem bark of Moringa oleifera

Abstract

To assess the phytochemical constituents, total phenolic content, cytotoxicity and in-vitro antioxidant activity of stem bark extracts of Moringa oleifera (M. oleifera) (Moringaceae). Brine shrimp lethality (BSL) bioassay was used to investigate the cytotoxic effects. DPPH and nitric oxide radical scavenging activity was used to demonstrate antioxidant activity. Phytochemical analysis revealed the presence of tannins, flavonoids, steroids and alkaloids. The LC50 values were obtained for extracts as 850 μg/mL for petroleum ether extract, 800 μg/mL for chloroform extract and 900 μg/mL for methanol extract. The total phenolic content of the methanolic extract was 50.72% w/w, equivalent to gallic acid. Petroleum ether, chloroform and methanolic extracts of M. oleifera and standard ascorbic acid were found to be scavenger of DPPH radical with an IC50 of 124.75, 112.08, 54.34 and 13.86 μg/mL, respectively. Methanolic extract was found to be good scavenger of DPPH radical. Petroleum ether, chloroform, ethyl acetate soluble fraction of methanolic extracts of M. oleifera and ascorbic acid were found to be scavenger of nitric oxide radical with an IC50 of 93.32, 65.12, 54.83 and 12.59 μg/mL, respectively. Ethyl acetate soluble fraction was found to be good scavenger of nitric oxide radical. It can be concluded that the crude extracts of M. oleifera is a potential source of natural antioxidants, and this justifies its uses in folkloric medicines.