Ginsenoside Rb1 blocks homocysteine-induced endothelial dysfunction in porcine coronary arteries

OBJECTIVE: Homocysteine (Hcy) is an independent risk factor for atherosclerosis. This study investigates the effects of ginsenoside Rb1, a major constituent of ginseng, on Hcy-induced endothelial dysfunction and molecular changes in porcine coronary arteries. METHODS: The coronary arteries were harvested from pig hearts and cut into 5-mm ring segments, which were then divided into six groups, including control, Hcy alone (50 microM), low-dose (1 microM) or high-dose (10 microM) Rb1 alone, and Hcy plus low-dose or high-dose Rb1. After 24-hour incubation, the rings were analyzed for vasomotor function in response to thromboxane A2 analog U46619, bradykinin, and sodium nitroprusside (SNP), respectively. In addition, superoxide anion was assessed by lucigenin-enhanced chemiluminescence analysis. Endothelial nitric oxide synthase (eNOS) was studied using real-time polymerase chain reaction and Western blot. RESULTS: Endothelium-dependent relaxation (bradykinin) was significantly reduced in rings treated with Hcy alone as compared with the control (49.80% vs 71.77%, n = 8, P < .05), whereas neither high-dose nor low-dose Rb1 alone affected the endothelium-dependent relaxation. The low-dose Rb1-Hcy combined group had a partially improved endothelium-dependent relaxation (54.44%), whereas the high-dose Rb1-Hcy combined group showed a complete recovery of endothelium-dependent relaxation (72.89%). There was no substantial difference in maximal contraction induced by U46619 or endothelium-independent relaxation by SNP among all groups (P > .05). Furthermore, superoxide anion was markedly increased by 137% in the Hcy-treated group as compared with the control, but there were no statistically significant changes from the control in all other groups (P > .05). Lastly, eNOS mRNA and protein levels were substantially reduced in the Hcy-treated group, but not in the Rb1-Hcy combined groups. CONCLUSIONS: This is the first study to show that ginsenoside Rb1 can effectively block Hcy-induced endothelial dysfunction and superoxide anion production as well as eNOS downregulation in porcine coronary arteries. This study suggests that ginseng and its active constituents may have potential clinical applications in controlling Hcy-associated vascular injuries. CLINICAL RELEVANCE: Homocysteine (Hcy) is an independent risk factor for atherosclerosis and other vascular lesions. It causes endothelial dysfunction and oxidative stress. Ginseng compounds have effects of vasorelaxation and antioxidation. The purpose of this study was to determine the effect of ginsenoside Rb1, a major constituent of ginseng, on Hcy-induced endothelial dysfunction and molecular changes in porcine coronary arteries. Our results showed that ginsenoside Rb1 can effectively block Hcy-induced dysfunction of endothelium-dependent vasorelaxation as well as superoxide anion production and eNOS downregulation. This study suggests that ginseng compounds may have potential clinical applications in controlling Hcy-associated vascular diseases and other vascular lesions.