Transition metals like iron and copper, present inside the body system play a key role in the production of reactive oxygen radicals. These free radicals, causative agents of lipid peroxidation, not only damage proteins and DNA but also gradually changes the cellular membrane structure and ultimately leads to the loss of function and integrity. Uncontrolled lipid peroxidation results in various age related diseases, malignancy, infective diseases and injuries. Antioxidants and other phytochemical constituents present in the various plants are known to protect cells from such reactive oxygen species (ROS)-mediated damages. Here, we evaluated the effect of certain phytoconstituents present in the well-known medicinal plants on ROS scavenging using rat liver homogenate. The basal lipid peroxidation was found to be 0.1625±0.0095 ngMDA/min/mg protein, which got induced to 0.7938±0.0478 ngMDA/min/mg protein in the presence of Fe2+/ascorbate system. In this context, acteoside, berberine, catechin, 3´5-dihydroxyflavone7-o-ß-D-galacturonide-4-o-ß-D-glucopyranoside (a flavonoid glycoside from cumin), silibin and tetrahydrocurcumin decreased both basal and Fe2+/ascorbate induced lipid peroxidation as determined by thiobarbituric acid reaction. On the other hand, agnuside, andrographolide, picroside-I, negunoside, oleanolic acid, and glycerrihizin, showed enhancement in both basal and induced lipid peroxidation. Phytoconstituents which have decreased both basal and Fe2+/ascorbate induced lipid peroxidation may act as defensive against the deadly effects of ROS, causative agents of lipid peroxidation and other diseases either alone or in combination with diet/nutritional supplements.