Evaluation of phenolic contents, free radical scavenging activity and functional group analysis of the leaf extract of a medicinal plant in Niger Delta region

Funtumia africana leaves have been used by the people of Niger Delta region of Nigeria to treat diabetes. This study aims to evaluate the polyphenolic contents, antioxidant, and free radical scavenging activities of the leaf crude extract and fractions. The crude aqueous methanolic leaf extract of F. africana was extracted by liquid-liquid partitioning into n-hexane, dichloromethane, ethyl acetate and n-butanol fractions. The free radical scavenging activity of the fractions was measured in vitro by using the ferric-reducing antioxidant power (FRAP), 2, 2-diphenyl-1-picryl dihydrazyl (DPPH), and nitric oxide (NO) assays. Phytochemical screening showed the presence of tannins, saponins, alkaloids, terpenoids, steroids, reducing sugars, cardiac glycosides and flavonoids in the extract and polar fractions. The highest total phenolics, total flavonoids and total antioxidant capacity were found to be 1331.18±41.56 mg GAE/g, 833.96±19.14 mg QUE/g and 83.74±1.88 mgAAE/g respectively in the butanol fraction. The n-hexane and butanol fractions demonstrated strong DPPH scavenging activity with IC50 values of 0.06±0.57 and 0.06±0.5 μg/ml, respectively. The DCM fraction showed the highest NO scavenging activity with IC50 value of 0.741±0.07 mg/ml, while hexane fraction has negligible effect. The butanolic fraction has the highest ferric reducing antioxidant activity with value of 48.46±0.15 mg AAE/g of sample