PhD student, University of Ibadan
ABSTRACT Aim: The aim of this work is to evaluate the in‐vitro antioxidant activity as well as estimate the total phenolic and flavonoid content of methanolic extract and fractions of Cleome viscosa L. Study Design: Evaluation of the antioxidant capacity of Cleome viscosa L. Methodology: Antioxidant activity of the methanol extract (MCV) and derived hexane (HCV) and ethyl acetate (ECV) fractions of Cleome viscosa L. was performed by DPPH radical scavenging, Ferric reducing antioxidant power (FRAP) assay and phosphomolybdate assay. The total phenolic and total flavonoid contents were also estimated using Folin-Ciocalteu and colorimetric aluminum chloride methods respectively. Results: The ethyl acetate fraction showed the highest total phenolic content (77.33±4.21 mg of gallic acid equivalent/g of extract (r2=0.9646)) and total flavonoid content (71.677±8.125 mg of quercetin equivalent/g of extract (r2=0.9449)). In the DPPH radical scavenging test, the IC50 value of MCV, ECV and HCV was 0.91, 0.34 and 1.06 mg/mL, respectively also showing ethyl acetate fraction as the most active with activity comparable to that of standard ascorbic acid (AA) (IC50 0.034 mg/mL). The total antioxidant capacity was equally higher in ECV (384.70±7.37 mg of ascorbic acid equivalent/g of extract (r2=0.9843)) than in MCV and HCV which were 204.04±2.72 mg/g and 157.13±2.36 mg/g, respectively. The reducing activity on ferrous ion was ranked as ECV> MCV > HCV. Conclusion: The study showed that C. viscosa has good antioxidant property, with the active compounds, which may be phenolic and flavonoid most extractible in ethyl acetate.
Keywords: Cleome viscosa, antioxidants, free radical scavenging, total phenolic content, total flavonoid content