Oxidative DNA damage preventive activity and antioxidant potential of Stevia rebaudiana (Bertoni) Bertoni, a natural sweetener

At 0.1 mg/mL, the ethyl acetate extract (EAE) of the crude 85% methanolic extract (CAE) of Stevia rebaudiana leaves exhibited preventive activity against DNA strand scission by (OH)-O-center dot generated in Fenton's reaction on pBluescript II SK (-) DNA. Its efficacy is better than that of quercetin. The radical scavenging capacity of CAE was evaluated by the DPPH test (IC50 = 47.66 +/- 1.04 mu g/mL). EAE was derived from CAE scavenged DPPH (IC50 = 9.26 +/- 0.04 mu g/mL), ABTS(+) (IC50 = 3.04 +/- 0.22 mu g/mL) and (OH)-O-center dot (IC50 = 3.08 +/- 0.19 mu g/mL). Additionally, inhibition of lipid peroxidation induced with 25 mM FeSO4 on rat liver homogenate as a lipid source was noted with CAE (IC50 = 2.1 +/- 1.07 mg/mL). The total polyphenols and total flavonoids of EAE were 0.86 mg gallic acid equivalents/mg and 0.83 mg of quercetin equivalents/mg, respectively. Flavonoids, isolated from EAE, were characterized as quercetin-3-O-arabinoside, quercitrin, apigenin, apigenin-4-O-glucoside, luteolin, and kaempferol-3-O-rhamnoside by LC-MS and NMR analysis. These results indicate that Stevia rebaudiana may be useful as a potential source of natural antioxidants.