Vasodilatory and anti-inflammatory effects of the aqueous extract of rhubarb via a NO-cGMP pathway |
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Authors: | Moon Mi Kyoung Kang Dae Gill Lee Jun Kyong Kim Jin Sook Lee Ho Sub |
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Affiliation: | Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk, 570-749, Republic of Korea. |
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Abstract: | While conducting an in vitro screen of various medicinal plant extracts, an aqueous extract of rhubarb (Rheum undulatum L, AR) was found to exhibit a distinct vasorelaxant activity. AR induced a concentration-dependent relaxation of the phenylephrine-precontracted aorta. This effect disappeared with the removal of functional endothelium. Pretreatment of the aortic tissues with N(G)-nitro-L-arginine methyl ester (L-NAME), methylene blue, or 1H-[1,2,4]-oxadiazole-[4,3-alpha]-quinoxalin-1-one (ODQ) inhibited the relaxation induced by AR. Incubation of human umbilical vein endothelial cells (HUVECs) with AR increased the production of cGMP in a dose-dependent manner, but this effect was blocked by pretreatment with L-NAME and ODQ, respectively. AR treatment attenuated TNF-alpha-induced NF-kappaB p65 translocation in HUVECs in a dose-dependent manner. In addition, AR suppressed the expression levels of adhesion molecules including ICAM-1 and VCAM-1 induced by TNF-alpha in HUVECs. TNF-alpha-induced MCP-1 expression was also attenuated by the addition of AR. This attenuation was blocked by pretreatment with either L-NAME or ODQ. AR treatment inhibited cellular adhesion of U937 cells onto HUVECs induced by TNF-alpha. Taken together, the present study suggests that AR dilates vascular smooth muscle and suppresses the vascular inflammatory process via endothelium-dependent NO/cGMP signaling. |
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Keywords: | Rheum undulatum (AR) Vasorelaxation NO/cGMP Adhesion |
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