Antioxidant Activity of the Fruit and Stem Bark of Tetrapleura tetraptera Taub (Mimosaceae)

The present investigation was carried out to evaluate the antioxidant activity of ethanol extracts of Tetrapleura tetraptera stem bark and fruit. 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and ferric reducing antioxidant property (FRAP) assay were carried out to determine the antioxidant activity of the extracts. The antioxidant activity of the extracts which was determined by DPPH increases with a corresponding increase in concentration. The percentage DPPH radical inhibition ability of the stem bark ranged from 28.74% to 85.26% while that of fruit ranged from -10.56% to 66.01%. The percentage antioxidant activity of the stem bark extract is almost at par with that of ascorbic acid while that of fruit extract is about 75%. But at 25 mg/ml, the fruit extract showed a pro-oxidant activity. The reductive ability of the stem bark extract ranged from 0.393 to 1.641 mg ascorbic acid equivalent per mL of extract (about two-fifth of the reference drug) while that of fruit extract ranged from 0.342 to 1.325 mg ascorbic acid equivalent/mL of extract (one-third that of reference drug). The efficacy of the fruit and stem bark extracts of T. tetraptera in some of its bioactivities may be attributed to its favourable antioxidant potential.