Total antioxidant activity. Total antioxidant activity of plant extract and trolox. Effect of (a) T. chebula, T. belerica and E. officinalis extracts and (b) reference compound trolox on ABTS radical cation decolorization assay. The percentage of inhibition was plotted against concentration of sample. All data are expressed as mean ± S.D. (n = 6).