In vitro Antioxidant potential of Sphaeranthus indicus and Abrus precatorius leaves extracts

Background: The purpose of this study was to evaluate the antioxidant potential of Sphaeranthus indicus and Abrus precatorius leaves. Methods: Both plant leaves powder was exhaustively extracted by soxhlet apparatus with various solvents of increasing order of polarity, petroleum ether followed by chloroform, methanol and water. The total phenol, tannins and flavonoids content were determined spectrophotometrically. Quantitative estimation of phenolic and flavonoid compounds in the extracts was estimated by using the Folin–Ciocalteu reagent and aluminum chloride colorimetric method respectively. The antioxidant potential of all these extracts was evaluated by reducing ability assay and DPPH radical scavenging assay with vitamin C as a standard. The antioxidant activity increased with dose dependence of extracts (from 20 to 200μg/ml). Results: The order for reducing power of extracts was recorded as vitamin C > methanol > water ≈ chloroform > petroleum ether and the same order was found in the DPPH assay having 50% inhibitory concentration (IC50) values. The results revealed that the methanolic extract exhibited the highest percent inhibition of the reducing ability and DPPH radical scavenging assay as compared to the other extracts of both plant. Moreover, methanolic extract showed concentration dependent significant scavenging of DPPH, especially with S. indicus [IC50 values 112.23±0.39 μg/ml] and A. precatorius [IC50 values 101.44±0.41μg/ml], while that of the standard was 13.45±0.37μg/ml (vitamin C). Methanolic extract showed phenolics, flavonoids and tannins contents were significantly higher than all the extracts investigated in both plant. Conclusions: A correlation between the antioxidant activity and the total phenolic contents of the extracts indicated that phenolic compounds were the dominant contributors to the antioxidant activity of the plant. The results suggest that methanolic leaves extract of S. indicus and A. precatorius are source of natural antioxidants and free radical scavenging capability.