Crocin, the digentiobiosyl ester of crocetin, was investigated for its cytoprotective effect on hydrogen peroxide-induced injury in bovine aortic endothelial cells (BAECs). The morphology of BAECs was observed by inverted phase contrast and electron microscopy. The MTT assay was used to measure cell viability. Cell apoptosis was evaluated by DNA argarose gel electrophoresis. The cells treated with H(2)O(2) (200 microM) showed apoptotic changes as revealed by cell shrinkage, condensation of nuclei, membrane blebbing and formation of apoptotic body. A concentration-dependent inhibition of cell injury was seen in cultures treated with crocin at dosages ranging from 1 to 10 microM. Furthermore, in the H(2)O(2)-treated group, agarose gel electrophoresis displayed a "DNA ladder". Whereas in the 10 microM crocin-pretreated group, cells remained intact and no "DNA ladder" was observed in agarose gel electrophoresis. Only very little DNA debris appeared on DNA-fragmentation analysis in the 1 muM crocin-pretreated group. Our data demonstrated that crocin has preventive effects on the cell apoptosis induced by H(2)O(2), which may contribute to its utilisation for cardiovascular diseases (e.g., atherosclerosis and hypertension).