Estimation of total phenolics, total flavonoids and in vitro antioxidant activities of methanol extract of voacanga africana root bark and its fractions

Thesis Abstract

The in vitro antioxidant activities, total phenolic and flavonoid contents of the methanol extract of Voacanga africana root bark and the n-hexane, ethylacetate and n-butanol subfractions of the methanol extract were carried out in this study. The total phenol content was determined by using Folin-Ciocalteau assay while the total flavonoid content was determined by using the aluminium chloride colorimetric assay method. Total antioxidant activities of the methanol extract and subfractions of the plant were determined in vitro using three models 1,1 diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, phosphomolybdate method and ferric chloride reducing power. The results obtained showed that n-hexane fraction of the V.africana root bark had the highest total phenol – (116.61±95.13 mg GAE/g) followed by that of ethyl acetate fraction. The highest total flavonoid content was exhibited by n-hexane fraction (467.14±44.22 mg QE/g), followed by that of ethyl acetate fraction. Ethylacetate fraction had the highest (31.19±25.29) total antioxidant capacity (TAC). Methanol extract showed the highest DPPH radical scavenging activity (21.00±0.12), while n-hexane fraction showed the highest (43±11.27) ferric reducing antioxidant power (FRAP) followed by ethyl acetate (30.770±11.94). The antioxidant activities of methanol extracrt and the subfractions therefore, of Voacanga africana may be responsible for some of the health benefits attributed to the root of this plant.