In Vitro Evaluation of Free Radical Scavenging and Antioxidant Activities of Averrhoa bilimbi Fruit Extracts

The phytochemicals are biologically active compounds and have therapeutic potential for free radical associated disorders. Free radicals are implicated in the development of various chronic and degenerative diseases including diabetes mellitus, coronary heart disease, arthritis, cancer, ageing etc. The present study evaluates the antioxidant potential of different solvent fractions of Averrhoa bilimbi Linn. (Oxalidaceae) fruits. Antioxidant activity was assessed by various in vitro methods such as 1, 1-Diphenyl-2-Picrylhydrazyl (DPPH) radical scavenging assay, superoxide radical scavenging assay, nitric oxide radical scavenging assay, total reducing power and total antioxidant activity. Total phenolic and flavonoid contents of different solvent fractions (petroleum ether, ethyl acetate, butanol and water) were also determined and expressed in gallic acid and quercetin equivalents respectively. The results of the study show that the ethyl acetate fraction (ABE) of the lyophilized aqueous extract of Averrhoa bilimbi fruits has superior antioxidant properties than the other fractions. IC50values of the ethyl acetate fraction for superoxide radical scavenging and nitric oxide radical scavenging activities were 72 and 61.5 µg/ml, respectively. Total phenolic content (31.26 ± 1.16 mg%) and flavonoid content (6.15 ± 0.23 mg%) of ABE was significantly higher than other fractions. The results of the present study indicate that Averrhoa bilimbi fruits are a rich source of natural antioxidants and might be utilized as a functional food/nutraceutical.