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摘要
Ethnopharmacological relevance: Artemisia copa Phil. (Asteraceae) is a medicinal plant commonly used in traditional medicine in Argentina. %26lt;br%26gt;Aim of the study: The vasorelaxant and hypotensive activities of the aqueous extract of Artemisia copa have been investigated. %26lt;br%26gt;Materials and methods: The in vitro effect of the extract and isolated compounds from Artemisia copa was investigated using isolated rat aortic rings. The acute effect caused by the intravenous (i.v.) infusion (0.1-300 mg/kg) on blood pressure and heart rate was evaluated in spontaneous hypertensive rats. In addition, a phytochemical analysis of the extract was performed by HPLC. %26lt;br%26gt;Results: Artemisia copa had a relaxant effect in endothelium-intact aortic rings that had been pre-contracted with 10(-7) M phenylephrine (E-max=96.7 +/- 1.3%, EC50=1.1 mg/ml), 10(-5) M 5-hydroxytriptamine (E-max= 96.7 +/- 3.5%, EC50=1.5 mg/ml) and 80 mM KCl (E-max= 97.9 +/- 4.4%, EC50=1.6 mg/ml). In denuded aortic rings contracted by phenylephrine, a similar pattern was observed (E-max=92.7 +/- 6.5%, EC50=1.8 mg/ml). L-NAME, indomethacin, tetraethylammonium and glibenclamide were not able to block the relaxation induced by the extract Nevertheless, the pre-treatment with Artemisia copa attenuated the CaCl2-induced contraction in a concentration-dependent manner (E-max: 86% of inhibition for 3 mg/ml and 52% de-inhibition for 1 mg/ml). This pre-treatment also induced a significant attenuation of the norepinephrine-induced contraction in a concentration-dependent manner (E-max: 72.7% of inhibition for 3 mg/ml and 27% de inhibition for 1 mg/ml) in a Ca2+ free medium. Upon analyzing the composition of the extract, the presence of p-coumaric acid, isovitexin, luteolin and chrysoeriol were found. Luteolin (CE50: 1.5 mu g/ml), chrysoeriol (CE50: 13.2 mu g/ml) and p-coumaric acid (CE50: 95.2 mu g/ml), isolated from the aqueous extract, caused dilatation of thoracic aortic rings pre-contracted with phenylephrine. Artemisia copa administered i.v. also induced a decrease in the mean arterial pressure but did not affect the heart rate in hypertensive rats. %26lt;br%26gt;Conclusions: The aqueous extract of Artemisia copa proved to have vasorelaxing and hypotensive effects through the inhibition of Ca2+ influx via membranous calcium channels and intracellular stores. The presence of luteolin, chrysoeriol and p-coumaric acid found in this plant could be involved in this effect.
- 出版日期2013-6-21
