Antioxidant Capacity Evaluation of Extracts

FRAP assay was determined according to Ferreira et al. (2023) [36 (link)]. In a microplate, aliquots of 35 µL of each extract (Section 3.6) were mixed with 265 µL of the FRAP reagent: acetate buffer (0.3 M), TPTZ solution (10 mM), and FeCl₃ (20 mM). The microplate was incubated (37 °C, 30 min), light-protected, and the absorbance was measured in a microplate reader at 595 nm (Synergy HT GENS5, BioTek Instruments, Inc., Winooski, VT, USA). A calibration curve with ferrous sulphate (y = 0.002x + 0.080, R² = 0.999, 25–500 mg/L) was used for quantification. Results were expressed as g of FSE/100 g of sample in fw and dw.
DPPH^●-SA assay was determined according to Ferreira et al. (2023) [36 (link)]. In a microplate, aliquots of 30 µL of each extract (Section 3.6) were mixed with 270 µL of fresh DPPH^● solution in ethanol (6 × 10⁻² mM). Absorbance (525 nm) was measured in a microplate reader (Synergy HT GENS5, BioTek Instruments, Inc., Winooski, VT, USA) every 2 min until reaction endpoint at 20 min to assess the kinetics of the reaction. A Trolox calibration curve was obtained (y = −0.007x + 0.540, R² = 0.999, 5.62–175.34 mg/L) and results presented in g of TE/100 g of sample in fw and dw.