title: Effects of homocysteine and ginsenoside Rb1 on endothelial proliferation and superoxide anion production.
abstract: BACKGROUND
  Homocysteine (Hcy) is an independent risk factor for cardiovascular disease by its multiple effects on vascular cells and throbmosis factors, which may be involved in oxidative stress mechansims. Ginsenoside Rb1, a constituent of ginseng, bears various beneficial effects on the cardiovascular system. In the present study, we investigated the effect of Hcy on endothelial proliferation and a protective effect of ginsenoside Rb1 on the action of Hcy.
  
  
  METHODS
  We initially incubated a mouse lymph node endothelial cell line (SVEC4-10) with increasing concentrations of Hcy or for different time periods and then assessed cell proliferation by using [(3)H]-thymidine incorporation. We then incubated SVEC4-10 cells with Hcy (50 microM) for 24 h with or without Rb1 (10 microM) to examine its inhibitory effect on the proliferation. These experiments were repeated in human umbilical vein endothelial cells (HUVECs). To explore the underlying molecular mechanisms, we measured superoxide anion, a reactive oxygen species (ROS), by using dihydroethidium (DHE) staining.
  
  
  RESULTS
  SVEC4-10 cells treated with Hcy (50, 100, and 200 microM) for 24 h significantly reduced cell proliferation by 43%, 42%, and 40%, respectively, as compared with control cells (P < 0.01). SVEC4-10 cells treated with Hcy (50 microM) for 12 and 24 h showed a significant reduction of cell proliferation (P < 0.05). In HUVECs, Hcy (50 microM) significantly reduced cell proliferation by 55% as compared with control cells (P < 0.05). In the presence of Rb1, Hcy-induced inhibition of cell proliferation was effectively blocked in both SVEC4-10 and HUVECs. Furthermore, Hcy (50 microM) significantly increased superoxide anion production by 23% in SVEC4-10 as compared with control cells (P < 0.05). However, in the presence of Rb1, Hcy increased superoxide anion production by only 8%, showing that RB1 almost completely blocked the effect of Hcy.
  
  
  CONCLUSIONS
  Hcy significantly inhibits endothelial proliferation with increased production of superoxide anion, which is effectively blocked by ginsenoside Rb1. This study provides some new aspects of Hcy-induced endothelial dysfunction, and suggests a potential role of Rb1 to block Hcy action, which may have clinical applications.
authors.affiliation: Division of Vascular Surgery and Endovascular Therapy, Michael E. DeBakey Department of Surgery, Molecular Surgeon Research Center, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: Ryuji
authors.initials: R
authors.lastname: Ohashi
authors.forename: Shaoyu
authors.initials: S
authors.lastname: Yan
authors.forename: Hong
authors.initials: H
authors.lastname: Mu
authors.forename: Hong
authors.initials: H
authors.lastname: Chai
authors.forename: Qizhi
authors.initials: Q
authors.lastname: Yao
authors.forename: Peter H
authors.initials: PH
authors.lastname: Lin
authors.forename: Changyi
authors.initials: C
authors.lastname: Chen
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D036145:Ginsenosides / Q000494:pharmacology*; D006710:Homocysteine / Q000494:pharmacology*; D006801:Humans; D020138:Hyperhomocysteinemia / Q000188:drug therapy / Q000378:metabolism*; D008198:Lymph Nodes / Q000166:cytology; D051379:Mice; D018384:Oxidative Stress / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism*; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D036145:Ginsenosides; D006710:Homocysteine; D013481:Superoxides; C442759:ginsenoside Rb1