Vasorelaxant effect of stilbenes from rhizome extract of rhubarb (Rheum undulatum) on the contractility of rat aorta.
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.
Yoo
Mi Young
MY
Korea Research Institute of Chemical Technology, Daejon, 305-343, Korea.
Oh
Kwang-Seok
KS
Lee
Jung Won
JW
Seo
Ho Won
HW
Yon
Gyu Hwan
GH
Kwon
Dae Young
DY
Kim
Young Sup
YS
Ryu
Shi Yong
SY
Lee
Byung Ho
BH
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*
D010936:Plant Extracts; D013267:Stilbenes; D014665:Vasodilator Agents