2.15. Analytical Method for Antioxidative Enzyme Activities

For antioxidative enzyme activities, the extract was prepared from fresh plant tissue by homogenizing with ice-cold 0.5 M Tris–HCl (pH 6.8) buffer, according to the method of Abbasi et al. [25]. Centrifugation was conducted at 10,000 rpm (20 min at 4 °C). Supernatant was used for enzyme assays. A UV–vis spectrophotometer (Halo DR-20, UV-vis spectrophotometer, Dynamica Ltd., Melbourne, VC, Australia) was used for measuring absorption. Phenylalanine ammonia lyase (PAL) activity (EC 4.3.1.5) was quantified as described by Ref. [26]. Catalase (CAT; EC 1.11.1.6) was quantified by the method of Ref. [27], superoxide dismutase (SOD; EC 1.15.1.1) was assayed by the method of Ref. [28], peroxidase (POD; EC 1.11.1.7) was determined as mentioned by Ref. [29], and ascorbate peroxidase (APx; EC 1.11.1.11) was determined by the method of Ref. [30].