Platelet derived growth factor (PDGF)-BB is one of the most potent vascular smooth muscle cell (VSMC) proliferative factors, and abnormal VSMC proliferation by PDGF-BB plays an important role in the development and progression of atherosclerosis. The aim of this study was to assess the effect of YP 12, a newly synthesized obovatol derivative, on the proliferation of PDGF-BB-stimulated rat aortic VSMCs. The anti-proliferative effects of YP 12 on rat aortic VSMCs were examined by direct cell counting and by using [3H] thymidine incorporation assays. It was found that YP 12 potently inhibited the growth of VSMCs. The pre-incubation of YP 12 (1-4 μM)significantly inhibited the proliferation and DNA synthesis of 25 ng/ml PDGF-BB-stimulated rat aortic VSMCs in a concentration-dependent manner. In accordance with these findings, YP 12 revealed blocking of the PDGF-BB-inducible progression through G0/G1 to S phase of the cell cycle in synchronized cells. Whereas, YP 12 did not show any cytotoxicity in rat aortic VSMCs in this experimental condition by WST-1 assay. These results also show that YP 12may have potential as an anti-proliferative agent for the treatment of restenosis and atherosclerosis.

Atherosclerosis, a disease of the large arteries, is the primary cause of heart disease and stroke. The abnormal proliferation of vascular smooth muscle cells (VSMCs) in arterial walls is an important pathogenetic factor of vascular disorders like atherosclerosis and restenosis after angioplasty. In the current study, the possible anti-proliferative effect of vitexin originated from Acer palmatum was investigated in rat aortic VSMCs. Vitexin was found to potently inhibit 5% fetal bovine serum (FBS)-induced growth of VSMCs. Pre-treatment with vitexin (5-50 μg/ml) in VSMCs for 24 h resulted in a significant decrease in cell number, i.e., the inhibition rates were 5.4±7.1, 52.5±8.4, and 78.9±5.2% with vitexin treatments of 5, 20, and 50 μg/ml, respectively. In addition, trteatment with vitexin resulted in significant and dose-dependent inhibition of 5% FBS-induced DNA synthesis. Vitexin did not show any cytotoxicity in rat aortic VSMCs under this experimental condition. These results indicate the potential for development of vitexin as an anti-proliferative agent for treatment of angioplasty restenosis and atherosclerosis.