An investigation on the antioxidant and antiproliferative activities of Scenedesmus obliquus RDS01, a freshwater unicellular alga was carried out. The methanolic extract from the dried sample of Scenedesmus obliquus RDS01 was prepared and examined for its phenolic compounds. The sample exhibited noticeable scavenging effects in DPPH free radical scavenging assay. It has also been evaluated the anti-proliferative effect of methanolic extract of Scenedesmus obliquus RDS01 on human cervical adenocarcinoma cell line (HeLa cells) proliferation using the MTT assay. The HeLa cell proliferation was inhibited upto 50% by the algal extract after 72 h of incubation. The phenolic constituent appears to be responsible (at least in part) for the observed antioxidant activity of the algal extract. The greater antioxidant activity of the algal extract reflected the greater phenolic content of the Scenedesmus obliquus RDS01. The results suggest that the Scenedesmus obliquus RDS01 could be a potential source of natural antioxidant
