Table 3: Antioxidant activities of the extracts of O. stamineus leaves obtained by supercritical CO2.

AssaysaIC50 valuesd of the samples in μg/mL
A1A2A3B1B2B3C1C2C3AA

ABTSbND1150NDND91.7*ND218ND1176.5**
DPPHc>200>200>20013642.8*16416856.1**1985.8**

Microtiter 96-well plate was used to assess the concentrations (12.5, 25, 50, 100, and 200 μg/mL) of test samples. Methanol was used as blank. ABTS or DPPH was used as negative control. Ascorbic acid (AA) was used as reference standard.
bAbsorbance for ABTS was measured at 734 nm.
cAbsorbance for DPPH was measured at 517 nm.
dUsing linear regression curves the median inhibitory concentrations (IC50) were calculated. The results are expressed as mean ± SD ( = 6); * < 0.05; ** < 0.01.