Pro-oxidant effect of petroleum ether and chloroform extracts towards superoxide anion generated by the non enzymatic system NBT/Riboflavine. Results were expressed as percentage of superoxide anion generation compared to the control. Values represent the mean ± SD of three separate experiments. The statistical significance of results was evaluated by the Student’s t-test. *P < 0.05, **P < 0.01, ***P < 0.001 means significant difference between control and treated sample.