Abstract

The methanolic extract of Rhynchosia pseudo-cajan Cambess. was dissolved in distilled water and partitioned with n-hexane, chloroform, ethyl acetate and n-butanol sequentially. The antioxidant potential of all these fractions and remaining aqueous fraction was evaluated by four methods: 1,1-Diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, total antioxidant activity, Ferric Reducing Antioxidant Power (FRAP) assay and ferric thiocyanate assay along with determination of their total phenolics. All the fractions showed noteworthy antioxidant potential. The results revealed that ethyl acetate soluble fraction showed highest value of % inhibition of DPPH (92.45% ± 0.98) at concentration of 125 µg/ml. The IC₅₀ of this fraction was 22.75 ± 0.27 µg/ml, relative to butylated hydroxytoluene (BHT), having IC₅₀ of 12.1 ± 0.92 μg/ml. It also showed highest total antioxidant activity, that is, 1.946 ± 0.22 and total phenolic contents (129.49 ± 1.2 mg of gallic acid equivalents) as compared to other fractions. However, the crude methanolic extract displayed highest FRAP value (639.66 ± 1.9 µg of trolox equivalents) as well as highest value of inhibition of lipid peroxidation (54.48% ± 1.18) as compared to the studied fractions.

Key words: Rhynchosia pseudo-cajan Cambess., DPPH assay, total antioxidant activity, FRAP value, total phenolics, inhibition of lipid peroxidation (%).