Abstract: AIM: To investigate the effects of onychin (Ony) on proliferation of cultured aortic smooth muscle cells. METHODS: Cell culture technique was used in vitro.The inhibited effect of Ony on the proliferation of SMC was observed by measuring MTT metabolism and cell counting.Flow cytometry was performed to track cell cycle progression.Western blots were performed to examine ERK1/2 phosphorylation. RESULTS: The metabolism of MTT by VSMC and cell number of onychin group are declined markedly.There were dose-dependent inhibited effects on VSMC in four different concentrations of Onychin.This inhibited effect reached plateau at 10 μmol·L ^-1.As compared with those of the control group, differences were significant (P <0.01).Flow cytometry analysis indicated that the G1-Phase fraction ratios of onychin group (85.1 %) were higher than that of 10 %NCS group (70.0 %) while its S-Phase fraction ratios (4.3 %) were lower than that of 10 %NCS group (16.4 %).Western blot results displayed that Ony inhibited the phospphorylation of ERK1/2 compared to control group. CONCLUSION: Onychin can inhibit the proliferation of VSMC through G1 phase cell cycle arrest.This effect may be related to influence on MAPK/ERK transduction by inhibiting the phosphorylation of ERK1/2.

Key words: pharmacology, onychin, aortic vascular smooth muscle cells, MAPK ERK