title: Icariin enhances endothelial nitric-oxide synthase expression on human endothelial cells in vitro.
abstract: Icariin, a flavonoid isolated from Epimedii herba, is considered to be the major therapeutical constituent of E. herba. The aim of this study was to investigate the possible protective effects and to clarify the mechanism of icariin on endothelial cells in vitro. Incubation of human umbilical vein endothelial cells (HUVEC) derived EA. hy926 cells with icariin(0.1, 1, 10 micromol l(-1)) from 6 h to 72 h, then the production of NO was measured to evaluate the protective effects of icariin. RT-PCR was employed to confirm the mRNA expression of endothelial nitric oxide synthase (eNOS). Western blotting was used to evaluate the protein expression of eNOS. NO production was enhanced in a time- and concentration-dependent manner (P<0.05), which was well matched with the expression of eNOS mRNA (up to 2.4-fold) and protein (up to 2.5-fold) after long-term incubation with icariin in endothelial cells (P<0.05). Moreover, activated NF-kappaB was increased in EA. hy926 cells incubated with icariin for 24 h, in association with an increase in the expression of eNOS gene. In addition to its long-term effects on eNOS expression, icariin also enhanced the production of bioactive NO in the short-term (after a 5 min incubation, P<0.05). In concert with other effects, the protective effects of icariin on endothelial cells may contribute to the cardiovascular protective effects.
authors.affiliation: Department of Cardiology, the Affiliated Hospital of Zhejiang Traditional Chinese Medicine University, Hangzhou 310006, China.
authors.forename: Hai-Bin
authors.initials: HB
authors.lastname: Xu
authors.forename: Zhao-Quan
authors.initials: ZQ
authors.lastname: Huang
mesh_terms: D015153:Blotting, Western; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006801:Humans; D016328:NF-kappa B / Q000032:analysis; D009569:Nitric Oxide / Q000096:biosynthesis; D052250:Nitric Oxide Synthase Type III / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013481:Superoxides / Q000378:metabolism
chemical_list: D005419:Flavonoids; D016328:NF-kappa B; D012333:RNA, Messenger; D013481:Superoxides; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; C056599:icariin