<i>In vitro</i> evaluation of antioxidant activity of <i>Anisopus mannii</i> N.E. Br.

Abstract

Anisopus mannii (Asclepiadaceae) –a plant widely used as an anti-diabetic agent in Northern Nigerian traditional medicine, was subjected to antioxidant evaluation. The crude methanol extract, n-butanol and ethyl acetate fractions were investigated for free radical scavenging activity of the 1, 1-diphenyl-2- picrylhydrazyl radical (DPPH), total phenolic contents and reducing power assay. The results of the DPPH free radical scavenging at 250 ìgml-1 indicated maximum antioxidant activity of 94.1, 94.3 and
88.7% for crude methanol extract, ethyl acetate and n-butanol fractions, respectively. The total phenolic content was higher in the ethyl acetate fraction (59.60 mg/g gallic acid equivalent GAE) than in the nbutanol
fraction (56.40 mg/g GAE) and crude methanol extract (53.20 mg/g GAE). The reducing power of n-butanol fraction was 0.112 nm higher than those of ethyl acetate fraction (0.110 nm) and crude methanol extract (0.106 nm). The antioxidant activities of the crude extract/fractions and the standards at maximum concentration of 250 ìgml-1 decreased in the order: ascorbic acid> ethyl acetate fraction> crude methanol extract> Gallic acid> n-butanol fraction, but there was no significant difference (p <
0.05) between them. The phytochemical screening revealed the presence of flavonoids, tannins and saponins. This suggests a potential utility of the plant as a source of phenolic antioxidants and may provide leads in the ongoing search for natural antioxidants from Nigerian medicinal plants to be used in treating diseases related to free radical reactions.