원광대학교 의과대학 산본병원 내과, 2 원광보건대학교 간호학과This study examined the neurotoxicity induced by lead acetate (LA) on cultured C6 glioma cells and the protective effects of Euphorbiae humifusae L. (EH) extract against LA-induced cytotoxicity. In this study, LA exhibited neurotoxicity in a dose-dependent manner compared to the control, and was determined to be highly-toxic according to the toxic criteria. The XTT50 value of LA was calculated at a concentration of 38.6 M after C6 glioma cells were incubated for 72 hours in the media containing 30∼50 M of LA, respectively. In addition, LA-induced neurotoxicity was suggested to correlate with the level of oxidative stress because vitamin E, an antioxidant, increased the cell viability damaged by LA-induced cytotoxicity. The EH extract effectively prevented cell injury from LA-induced cytotoxicity via its antioxidative effects, such as inhibitory ability of lipid peroxidation, superoxide dismutase-like activity and 1,1-diphenyl-2-picrylhydrazyl-radical scavenging activity. These antioxidative effects may result in components, such as polyphenol or flavonoids including gallic acid or quercetin. In conclusion, natural resources, such as EH extracts, may be a useful putative agent for the treatment of diseases associated with oxidative stress, such as lead neurotoxicity.