Abstract: The purpose of this study was to assess the antioxidant and antitumor activities of Portulaca oleracea L. seed oil (PSO) in vitro and its application to delay rancidity of horse oil. We determined the reducing power of PSO and its scavenging effects on hydroxyl radicals (·OH) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and assessed its stability during horse oil storage with its addition. The results showed that PSO had remarkable, dose-dependent antioxidant activity, and could effectively prevent lipid oxidation in horse oil. We treated cervical cancer HeLa cells, human esophageal carcinoma Eca-109 cells and human breast adenocarcinoma MCF-7 cells with PSO using non-neoplastic monkey kidney Vero cells as control. The results indicated that PSO significantly inhibited tumor cell proliferation in a time-and dosedependent manner. Our findings suggest that PSO can be a substitute for synthetic antioxidants in food preservation and may be potentially useful as a food or cosmetic ingredient.

Key words: Portulaca oleracea L. seed oil (PSO), antioxidant, anti-proliferation, preservation