期刊
PLANTA MEDICA
卷 70, 期 8, 页码 718-722出版社
GEORG THIEME VERLAG KG
DOI: 10.1055/s-2004-827201
关键词
Selaginella tamariscina; amentoflavone; vasorelaxation; nitric oxide; cGMP
In the courses of in vitro screening for the vasorelaxant effect of the various extracts from medicinal plants, an ethyl acetate-soluble extract of Selaginella tamariscina was found to exhibit distinctive vasorelaxant activity. Further purifications of the extract as guided by in vitro vasorelaxant assay afforded an active biflavonoid, amentoflavone. Amentoflavone induced concentration-dependent relaxation of the phenylephrine-precontracted aorta, which disappeared by 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]-oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) inhibited the relaxation induced by amentoflavone. Amentoflavone-induced relaxations were also. markedly attenuated by addition of tetraethylammonium (TEA) or verapamil. However, the relaxant effect of amentoflavone was not blocked by pretreatment with indomethacin, glibenclamide, atropine, or propranolol. Incubation of endothelium-intact aortic rings with amentoflavone increased the production of cGMP, but this effect was blocked by endothelium-denudation or pretreatment with L-NAME or ODQ. These results suggest that amentoflavone relaxes vascular smooth muscle via endothelium-dependent nitric oxide-cGMP signaling, with possible involvement of non-specific K+ and Ca2+ channels.
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