SUMMARY
Context: Reactive oxygen species (ROS) cause damage to cellular components. Antioxidant compounds scavenge or neutralize the ROS and thus have significant role in human health. Aims: The present study 70% methanol extracts of Nerium indicum leaf, stem and root were evaluated for in vitro total antioxidant, radical scavenging activity along with phenolic and flavonoid contents. Methods and Material: The extracts were examined for the scavenging activity of hydroxyl radical, nitric oxide, singlet oxygen, hypochlorous acid, superoxide, peroxynitrite, hydrogen peroxide. The extracts were also tested for their potential as an iron chelating agent, inhibition of lipid peroxidation and total reducing potential. Results: The present study indicates that the total antioxidant, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical and singlet oxygen scavenging potential is in the order of stem>root>leaf. The hydroxyl radical scavenging, hydrogen peroxide scavenging and hypochlorous acid scavenging activity is in the order leaf>stem>root, whereas superoxide scavenging and lipid peroxidation inhibition assay is root>leaf>stem. Miscellaneous results were obtained in the scavenging of other radicals by the extracts, viz., leaf>root>stem for peroxynitrite and iron chelation activity, root>stem>leaf for reducing power and stem>leaf>root for nitric oxide inhibition. The phenolic and flavonoid content is in the following order root>stem>leaf and leaf>stem>root respectively. Conclusions: The present study revealed that the leaf, stem and root extracts of N. indicum are effective free radical scavenger and might be used as a natural source of potent antioxidant.