RESUMEN
The methanolic extract of Sida retusa Linn.(Malvaceae),Urena lobata Linn.(Malvaceae)and Triumfetta rhomboidea Jacq.(Teliaceae) roots were found to inhibit lipid peroxidation, scavenge hydroxyl and superoxide radicals in vitro. The quantity of S.retusa root extract required for 50% inhibition of lipid peroxidation, scavenging hydroxyl radical and superoxide radical was 1130.24 ug/ml respectively. IC 50 of root extract of U.lobata was 470.60 ug/ml, 1627.35ug/ml and 1109.24 ug/ml for superoxide radical scavenging, hydroxyl radical scavenging and lipid peroxidation respectively. T.rhomboidea root extract required for IC 50 was 336.65 ug/ml, 1346.03 ug/ml and 1004.22 ug/ml for superoxide scavenging, hydroxyl radical scavenging and lipid peroxidation respectively. The present investigation indicated that S. retusa, U.lobata and T.rhomboidea possessed significant antioxidant activity.