Abstract: AIM: To study theProtective effects and mechanism of onychin against vascular endothelial cell damage induced by oxidative stress.METHODS: Cultured human umbilical vein endothelial cells(ECV304)and incubated them for 30 min with either vehicle(DMSO),genistein or different concentrations of onychin(0.1,0.3,1,3,and 10μmol·L^-1)before being damaged with 2 mmol·L-1 H₂O₂.Cell viability was measured by the MTT assay andlDH assay,and cell morphologic changes were determined under microscope.Meanwhile,and the western blot was used to measure the expression ofPhospho-ERK,P90RSK,andPhospho-p38 of endothelial cells.RESULTS: Different doses of onychin obviously inhibited cell viability and increasedlDH release(P<0.01).Onychin(0.3,1,and 3μmol·L^-1)improved the cellProliferation with the growth rate from 73.4 % to 82.9 %,90.1 % and 95.2 %,respectively.Onychin also attenuated the release of lDH(H₂O₂-induced)and inhibited H₂O₂-inducedPhosphorylation ofP38MAPK(P<0.01).Onychin showed no effect onPhosphorylation of ERK andP90RSK.CONCLUSION: OnychinPrevents H₂O₂-induced endothelial cell injury by inhibiting thePhosphorylation ofP38 MAPK.

Key words: pharmacology, onychin, endothelial cells, hydrogenPeroxide, p38 MAPK, ERK