Studies on the antioxidant and free radical-scavenging effect of sinapic acid: An in vivo and in vitro model

The aim of the present study was to evaluate the circulating antioxidants such as vitamin C, vitamin E and GSH in arsenic induced toxicity in rats and in vitro free radical scavenging assay. In this investigation, arsenic (5 mg/kg body weight (b.w) was administered orally for 30 days to induce toxicity. Sinapic acid was administered orally (40 mg/kg body weight) for 30 days with oral administration of arsenic. The toxic effect of arsenic was indicated by significantly decreased levels of non-enzymatic antioxidants like vitamin C, vitamin E and reduced glutathione. Treatment with sinapic acid exhibited a significant (P < 0.05) reversal of arsenic induced toxicity in rats. The free radical scavenging properties of sinapic acid at different concentrations (10-50uM) were investigated with various in vitro methods such as 2, 2-diphenyl-1picrylhydrazyl radical (DPPH), 2, 2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS), hydroxyl radical, superoxide anion scavenging activity and reducing power. Among the different concentrations, 50 μM of sinapic acid was more effective compared to other concentrations in all in vitro assays. Based on these findings, sinapic acid possesses potent in vivo and in vitro antioxidant activity and also effective free radical scavenger, augmenting its therapeutic value.