Shade-dried flowers of Sarcostemma brevistigma Wight Syn (SBF) belonging to Asclepiadaceaeyielded a rare flavonol glycoside viz., Quercetin 5a prenyl, 3-O-glucosyl, 7-O-(4c-p-coumaroyl)neohesperidoside which were characterized based on chemical and spectral (including 2D NMR)studies. The ethyl acetate fraction of alcoholic concentrate (test sample) of flowers of this plant(SBF) was evaluated for its hepatoprotective and inhibition of lipid peroxidation activities toinvestigate the scientific basis of the traditional uses. The oral administration in varying dosesviz., 125 and 250 mg/kg of aqueous suspension of SBF to rats for 7 days produced significant (P <0.01) hepatoprotective effect comparable to that of standard drug silymarin. The SBF affordedgood hepatoprotection against CCl4 induced elevation levels of serum marker enzymes, serumbilirubin and liver weight. The free radical scavenging effects of SBF and flavonol glycoside (SA)were assigned by Fe2+/ascorbate induction method (in vitro), which revealed the inhibition oflipid peroxidation. The SBF and SA showed prominent anti-lipid peroxidation activity (IC50 about~ 180 mg/ml and 11.0 mg/ml respectively), which was comparable to standard drug curcumin(IC50 about ~ 8.25 mg/ml). Thus the hepatoprotective activity of SB could be correlated to the freeradical scavenging property of the flavonol glycoside.