title: Mechanisms of relaxant action of a crude hexane extract of Gnaphalium liebmannii in guinea pig tracheal smooth muscle.
abstract: We investigated the mechanisms of action of Gnaphalium liebmannii which is used as a folk medicine in México for treating various respiratory diseases such as gripe, fever, asthma, cough, cold, bronchitis, expectorating, and bronchial affections. The tension changes of guinea pig tracheal segments were isometrically recorder on a polygraph. Hexane extract of Gnaphalium liebmannii was the most active relaxant extract (IC(30)=54.23+/-19.79 microg/mL with 99.5+/-3.2 % of relaxation), followed by dichloromethane extract (IC(30)=120.22+/-5.27 microg/mL) and methanol extract (IC(30)=190.25+/-30.02 microg/mL). Hexane extract produced a parallel rightward shift of the concentration-response curve of carbachol in a competitive manner (pA(2)=-2.4), but did not modify the concentration-response curves for histamine. The relaxant effect of hexane extract of Gnaphalium liebmannii was unaffected by the presence of propranolol (3x10(-6)M) or glibenclamide (10 microM). However hexane extract produced a leftward shifts of the concentration-response curve of forskolin (10(-8) to 10(-3)M), nitroprusside (10(-10) to 10(-6)M), isoproterenol (3x10(-10) to 3x10(-5)M) and aminophylline (10(-11) to 10(-2)M). The above results suggest that Gnaphalium liebmannii induce relaxation of the tracheal muscle, probably via phosphodiesterase inhibition. The bronchodilator effect of Gnaphalium liebmannii might explain in part their traditional use as anti-asthmatic remedy.
authors.affiliation: Facultad de Química, Departamento de Farmacia, Universidad Nacional Autónoma de México, Ciudad Universitaria Coyoacán 04510, México DF, México.
authors.forename: María Elena
authors.initials: ME
authors.lastname: Sánchez-Mendoza
authors.forename: Gabriela
authors.initials: G
authors.lastname: Torres
authors.forename: Jesús
authors.initials: J
authors.lastname: Arrieta
authors.forename: Abigail
authors.initials: A
authors.lastname: Aguilar
authors.forename: Carlos
authors.initials: C
authors.lastname: Castillo-Henkel
authors.forename: Andrés
authors.initials: A
authors.lastname: Navarrete
mesh_terms: D000628:Aminophylline / Q000494:pharmacology; D000818:Animals; D001993:Bronchodilator Agents / Q000737:chemistry / Q000494:pharmacology*; D005576:Colforsin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D036622:Gnaphalium; D006168:Guinea Pigs; D006586:Hexanes / Q000737:chemistry*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D000432:Methanol / Q000737:chemistry; D008752:Methylene Chloride / Q000737:chemistry; D008800:Mexico; D009126:Muscle Relaxation / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009599:Nitroprusside / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology; D012997:Solvents / Q000737:chemistry*; D014132:Trachea / Q000187:drug effects*
chemical_list: D001993:Bronchodilator Agents; D006586:Hexanes; D010726:Phosphodiesterase Inhibitors; D010936:Plant Extracts; D012997:Solvents; D009599:Nitroprusside; D005576:Colforsin; D000628:Aminophylline; D008752:Methylene Chloride; D007545:Isoproterenol; D000432:Methanol