DPPH resulted in either transfer electron or hydrogen atom to DPPH and neutralized its free radical character. The IC50
could be determined by the changes in the absorbance at different concentrations of each plant extract (Table 2).
G. mangostana showed the best antioxidant activity and could inhibit 50% of free radicals at the concentration
of 6.13 μg/ml (r2 =0.9992). H. cordata (r2 = 0.9922), E. odoratum (r2 =0.9986) and S. alata (r2 = 0.9946) had
some antioxidant effects at the IC50 concentrations of 32.52, 67.55 and 112.46 μg/ml, respectively. The extracts of
B. lupulina, S. alata and A. paniculata showed no significant activity in IC50 values.