title: Artemisia copa aqueous extract as vasorelaxant and hypotensive agent.
abstract: BACKGROUND
  Artemisia copa Phil. (Asteraceae) is a medicinal plant commonly used in traditional medicine in Argentina.
  
  
  OBJECTIVE
  The vasorelaxant and hypotensive activities of the aqueous extract of Artemisia copa have been investigated.
  
  
  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 (0.1-300mg/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.
  
  
  RESULTS
  Artemisia copa had a relaxant effect in endothelium-intact aortic rings that had been pre-contracted with 10(-7)M phenylephrine (Emax=96.7±1.3%, EC50=1.1mg/ml), 10(-5)M 5-hydroxytriptamine (Emax=96.7±3.5%, EC50=1.5mg/ml) and 80mM KCl (Emax=97.9± 4.4%, EC50=1.6mg/ml). In denuded aortic rings contracted by phenylephrine, a similar pattern was observed (Emax=92.7±6.5%, EC50=1.8mg/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 (Emax: 86% of inhibition for 3mg/ml and 52% de-inhibition for 1mg/ml). This pre-treatment also induced a significant attenuation of the norepinephrine-induced contraction in a concentration-dependent manner (Emax: 72.7% of inhibition for 3mg/ml and 27% de inhibition for 1mg/ml) in a Ca(2+) free medium. Upon analyzing the composition of the extract, the presence of p-coumaric acid, isovitexin, luteolin and chrysoeriol were found. Luteolin (CE50: 1.5μg/ml), chrysoeriol (CE50: 13.2μg/ml) and p-coumaric acid (CE50: 95.2μg/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.
  
  
  CONCLUSIONS
  The aqueous extract of Artemisia copa proved to have vasorelaxing and hypotensive effects through the inhibition of Ca(2+) 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.
authors.affiliation: Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, C1113AAD Buenos Aires, Argentina. sgorza@ffyb.uba.ar
authors.forename: Susana
authors.initials: S
authors.lastname: Gorzalczany
authors.forename: Valeria
authors.initials: V
authors.lastname: Moscatelli
authors.forename: Graciela
authors.initials: G
authors.lastname: Ferraro
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000032:analysis / Q000494:pharmacology / Q000627:therapeutic use*; D001013:Aorta, Thoracic / Q000187:drug effects / Q000502:physiology; D001118:Argentina; D019306:Artemisia; D001794:Blood Pressure / Q000187:drug effects; D006973:Hypertension / Q000188:drug therapy / Q000503:physiopathology; D066298:In Vitro Techniques; D008297:Male; D008519:Medicine, Traditional; D008517:Phytotherapy; D010936:Plant Extracts / Q000032:analysis / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D011918:Rats, Inbred SHR; D017207:Rats, Sprague-Dawley; D014665:Vasodilator Agents / Q000032:analysis / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D000959:Antihypertensive Agents; D010936:Plant Extracts; D014665:Vasodilator Agents