title: Vasorelaxant effect of stilbenes from rhizome extract of rhubarb (Rheum undulatum) on the contractility of rat aorta.
abstract: The vascular relaxant effect of the rhizome extract of Rheum undulatum was evaluated with isolated rat thoracic aorta preparations. The methanol extract of the rhizome induced a concentration-dependent relaxation of aortic preparations precontracted with 0.3 microm phenylephrine (EC50 value: 5.8 microg/mL). The activity-guided fractionation of the extract led to the isolation of seven hydroxystilbene components as active principles, i.e. piceatannol, resveratrol, desoxyrhapontigenin, rhapontigenin, piceid, rhaponticin and epsilon-viniferin. Of these, piceatannol, a tetrahydroxystilbene, exhibited the most potent vascular relaxant effect in rat aortic preparations (EC50 value 2.4 microm). The vasorelaxant effect of piceatannol on endothelium-intact aorta rings was diminished completely by the removal of functional endothelium or by pretreatment of the aortic tissues with N(G)-nitro-l-arginine methyl ester. These results suggest that piceatannol may be the major mediator responsible for the vasorelaxing properties of the rhizome extract of Rheum undulatum and the vasorelaxant effects of the piceatannol may be mediated via endothelium-dependent nitric oxide signaling pathway.
authors.affiliation: Korea Research Institute of Chemical Technology, Daejon, 305-343, Korea.
authors.forename: Mi Young
authors.initials: MY
authors.lastname: Yoo
authors.forename: Kwang-Seok
authors.initials: KS
authors.lastname: Oh
authors.forename: Jung Won
authors.initials: JW
authors.lastname: Lee
authors.forename: Ho Won
authors.initials: HW
authors.lastname: Seo
authors.forename: Gyu Hwan
authors.initials: GH
authors.lastname: Yon
authors.forename: Dae Young
authors.initials: DY
authors.lastname: Kwon
authors.forename: Young Sup
authors.initials: YS
authors.lastname: Kim
authors.forename: Shi Yong
authors.initials: SY
authors.lastname: Ryu
authors.forename: Byung Ho
authors.initials: BH
authors.lastname: Lee
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D010936:Plant Extracts / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D012250:Rheum / Q000737:chemistry*; D027343:Rhizome / Q000737:chemistry; D013267:Stilbenes / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D010936:Plant Extracts; D013267:Stilbenes; D014665:Vasodilator Agents