DPPH radical is a stable lipophilic free radical which has been generally used for estimating antioxidant activity of food and medicine materials (Li, Shi, Wang, Wang, & Le, 2007). Fig. 3C and D depicted the DPPH radical scavenging effect of KOG (C) and Vc (D).
Scavenging activity of DPPH radical increased with the increasing of concentrations of KOG and Vc.
Moreover, as shown in Fig. 3C, 50%inhibition concentrations (IC50) of KOG was 3.816 mg/mL. DPPH is one of the compounds that possessed a proton free radical with acharacteristic absorption, which decreases significantly on exposure to proton radical sacvengers.
Further it is well accepted that the DPPH free radical scavenging by antioxidants is due to their hydrogen-donating ability.
In the present study, Vc showed a relatively high inhibitory effect compared to KOG at low concentration,which may be attributable to its strong hydrogen-donating ability.