ABTS radical scavenging assay. The 2,20-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assay was done according to the method of Re et al. (1999). Five milliliters of ABTS solution (7 mM) was mixed with 88 ll of ammonium persulphate solution (140 mM) and then incubated in the dark at 25 C for 12–16 h, and then diluted with phosphate buffer (pH7.2) until the absorbance at 734 nm was 0.70 ±0.02. Aliquot (100 ll) of each sample was mixed with 3 ml of the prepared ABTS working solution and the change in absorbance was observed at 734 nm. The ABTS radical scavenging capacity of the sample was calculated by the following formula: