Abstract: ObjectiveTo study the antagonistic effect of tea pigment on vascular endothelial cells impaired by homocysteine.MethodsVascular endothelial cells were cultured and treated with a concentrated homocysteine and tea pigment for 48 hours.The cultured cells were examined by methyl-thizolyl-tetrazolium colorime tricassay.Meanwhile nitric oxide (NO),nitric oxide synthase,endothelin-1(ET-1),supero xide dismutase,glutathione peroxidase(GSH-Px)and malondial-hyde(MDA)contents in the culture medium were measured.ResultsHomocysteine had aninhibitory effect on the prolife-ration of vascular endothelial cells.The tea pigment could diminish harmful effects induced by homocy steine.NO content in culture mediumin middle and high dose tea pigment groups was significantly higher than that of homocysteine group.ET-1 content was significantly lower.Meanwhile MDA content in middle and high dose tea pigment groups was significantly lower than that of homocysteine group.The activities of GSH-Px and SOD were significantly higher than that of homocysteine group.ConclusionTea pigment can protect vascular endo the lial cells against impairment of homocysteine.The mechanism may relate to its antioxidation and regulation of cell factors.