OH• scavenging assay OH• scavenging assay was performed according to the method of Wang, et al. (2008) with some modifications. 1 ml of different concentrations of the essential oil in methanol (0-5000 µg/ml) was mixed with a mixture of 1.5 ml of 1.5 mM FeSO4, 0.7 ml of 6 mM H2O2 and 0.3 ml of 20 mM sodium salicylate. The reaction mixture was incubated at 37C for 1 hr. The absorbance of the reaction mixture was measured at 562 nm against the blank, i.e. methanol. L-ascorbic acid was used as a positive control. The percentage of scavenging OH• radicals was calculated as follows