determined to the method reported by Gao et al. [14]. 1 mL of various
concentrations of sample solution were mixed with FeSO4
(1 mL, 9 mM), salicylic acid–ethanol (1 mL, 9 mM) and H2O2 (1 mL,
9 mM). The reaction mixtures were incubation at 37 ◦C for 0.5 h.
The absorbance at 510 nm was measured. Distilled water was used
as control and ascorbic acid (Vc) was served as positive control.
Finally, the hydroxyl radical scavenging activity was calculated
according to the following formula: hydroxyl radical scavenging
activity (%) = (A0 − A1 + A2)/A0 × 100, where A0 is the absorbance of
control group (water instead of JQPs), A1 is the absorbance of sample
in reactive system and A2 is the final absorbance of sample.