Fig. 4

Evaluation of antioxidant activity against ABTS and DPPH radical species, compared to the untreated control groups. a ABTS radical scavenging activity for each concentration of GO, AST, and GO-AST solution (GO; 10, 20, 50, and 100 µg mL⁻¹ and AST; 25, 50, 125, and 250 µg mL⁻¹). b ABTS radical scavenging activity according to the ratio of GO and AST. c Concentration-dependent antioxidant activity at the same ratio (GO and AST; 10, 20, and 50 µg mL⁻¹). d DPPH radical scavenging activity for each concentration of GO, AST, and GO-AST solution (GO; 10, 20, and 50 µg mL⁻¹ and AST; 25, 50, and 125 µg mL⁻¹). e DPPH radical scavenging activity according to the ratio of GO and AST. f Concentration-dependent antioxidant activity at the same ratio. GO and AST; 10, 20, and 50 µg mL.⁻¹ (*: p < 0.05)