2.7.4. DPPH radical scavenging activity
The DPPH radical scavenging activity was assayed according to
the reported method [15]. 2.0 mL sample solutions of various concentrations
were mixed with DPPH (2.5 mL of 100 M in methanol).
The mixtures were allowed to equilibrate for 30 min at room temperature
before measuring the absorbance at 517 nm. In this study,
the distilled water was used as control and ascorbic acid (Vc) was
served as positive control. The DPPH radical scavenging activity
was calculated by the equation as below: DPPH 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.