ESTIMATION OF TOTAL PHENOLICS, TOTAL FLAVONOIDS AND IN VITRO ANTIOXIDANT ACTIVITIES OF METHANOL EXTRACT OF VOACANGA AFRICANA ROOT BARK AND ITS FRACTIONS

ABSTRACT Phenolic and flavonoid contents in plants play a great role in scavenging free radicals in the body and act as antioxidants. Thus their determination is very vital. In vitro antioxidant activities, total phenolic and flavonoid contents of the methanol extract of Voacanga africana root bark and its fractions (n-hexane, ethyl acetate and n-butanol) were carried out in this study. The total phenolic content was determined by using the Folin-Ciocalteau assay while the the total flavonoid content was determined by the aluminium chloride colourimetric assay method. Total antioxidant activities of the methanol extract and fractions 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 result obtained showed that the n-hexane fraction of the plant exhibited the highest (116.607±95.13 mgGAE/g) total phenolic content (TPC) at all concentrations followed by the ethyl acetate fraction of the plants. The highest total flavonoid content across concentrations (300, 250, 200, 100, 50 and 25 µg/ml) was exhibited by n-hexane fraction (467.143±44.22 mg QE/g), followed by ethyl acetate fraction which also exhibited the highest (31.191±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). This variety of in vitro antioxidant activities of the extract and fractions of Voacanga africana root bark justifies its use in the treatment of vast disease conditions (teeth, fracture repairs, asthma, hernia and diabetes) for which it is applied in local medicine.