Antioxidant capacity assay kit

The antioxidant activity of EMOS-1a was determined with an antioxidant capacity assay kit and the FRAP method (Beyotime Biotechnology Co., Ltd., Shanghai, China). A working solution was prepared by mixing a TPTZ dilution, TPTZ solution, and detection buffer at a ratio of 10:1:1 (v/v), and this FRAP working solution was then kept at 37 °C. Calibration solution, blank, or sample (5 μL) were added to 180 μL of working solution. Absorbance was measured at 593 nm after 3–5 min incubation at 37 °C. The FRAP values of the samples were calculated from a linear calibration curve and expressed as mmol FeSO₄ equivalents.

ABTS assay was carried out using an antioxidant capacity assay kit following the manufacturer’s protocol (Beyotime, Shanghai, China). About 10 µL of the VBV solution at different concentrations (0.125, 0.25, 0.5, 1, 2, and 4 mg/mL) was mixed with 200 µL of ABTS⁺ solution on a 96-well plate, incubated at room temperature in the dark for 10 min, and then measured at 734 nm. Additionally, vitamin C (0.25 mg/mL), aqueous solution, and ABTS⁺ solution were set as the positive control, negative control, and blank, respectively [47 (link),48 (link)]. The ABTS⁺ radical scavenging rate was calculated as follows: ((O.D. blank-O.D. sample)/O.D. blank) × 100%.