The antioxidant analysis was carried out using the ferric reducing antioxidant power assay (FRAP) according to [47 (link)]. Homogenized fresh leaf samples, 250 mg each, were resuspended with 60:40 (v/v) methanol/water solution and centrifuged at 14,000 rpm for 15 min at 4 °C. Then, acetate buffer containing 10 mM tripyridyltriazine (TPTZ) in 40 mM HCl, (1:1.6) and 12 mM·FeCl3 (1:16) was added to the extract (1:16 300 mM pH 3.6); After 1 h of incubation at 4 °C, the absorbance was measured at 593 nm with a spectrophotometer (UV-VIS Cary 100; Agilent Technologies, Palo Alto, CA, USA) using Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) as standard. The total antioxidant capacity was expressed as μmol Trolox equivalents per mg of fresh sample.
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