Antioxidant effects of aqueous extracts from dried calyx of Hibiscus sabdariffa Linn. (Roselle) in vitro using rat low-density lipoprotein (LDL).

The present study quantitatively investigated the antioxidant effects of the aqueous extracts from dried calyx of Hibiscus sabdariffa LINN. (roselle) in vitro using rat low-density lipoprotein (LDL). Formations of the conjugated dienes and thiobarbituric acid reactive substances (TBARs) were monitored as markers of the early and later stages of the oxidation of LDL, respectively. Thus, we demonstrated that the dried calyx extracts of roselle exhibits strong antioxidant activity in Cu(2+)-mediated oxidation of LDL (p<0.05) in vitro. The inhibitory effect of the extracts on LDL oxidation was dose-dependent at concentrations ranging from 0.1 to 5 mg/ml. Moreover, 5 mg/ml of roselle inhibited TBARs-formation with greater potency than 100 microM of vitamin E. In conclusion, this study provides a quantitative insight into the potent antioxidant effect of roselle in vitro.