Relaxant action mechanism of berberine identified as the active principle of Argemone ochroleuca Sweet in guinea-pig tracheal smooth muscle

• Published in: Journal of pharmacy and pharmacology Vol. 60; no. 2; pp. 229 - 236
• Main Authors: Sánchez-Mendoza, María Elena, Castillo-Henkel, Carlos, Navarrete, Andrés
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-02-2008
• Subjects: Animals; Argemone; Argemone - chemistry; Berberine - administration & dosage; Berberine - pharmacology; Dose-Response Relationship, Drug; Guinea Pigs; Male; Medicine, Traditional; Mexico; Muscarinic Antagonists - administration & dosage; Muscarinic Antagonists - pharmacology; Muscle Relaxation - drug effects; Muscle, Smooth - drug effects; Muscle, Smooth - metabolism; Papaveraceae; Plant Components, Aerial; Plant Extracts - administration & dosage; Plant Extracts - pharmacology; Receptors, Muscarinic - drug effects; Receptors, Muscarinic - metabolism; Trachea - drug effects; Trachea - metabolism; Mexico
• DOI: 10.1211/jpp.60.2.0012
• EISSN: 2042-7158
• ISSN: 0022-3573

In this study we investigated the relaxant effect of the aerial parts of Argemone ochroleuca (Papaveraceae), which is used in Mexican traditional medicine for the treatment of various respiratory diseases such as cough, bronchitis and asthma. The alkaloid berberine was identified as one of the active relaxant principles (EC50 = 118.50 ± 3.91 μM) in the dichloromethane extract of A. ochroleuca (EC50 = 78.03 ± 2.15 μg mL−1 with 95.12 ± 3.56% of relaxation). Berberine concentration‐dependently relaxed the carbachol‐induced precontractions but not histamine‐ or KCl‐induced precontraction. The relaxant effect of berberine was unaffected by the presence of propranolol (3 μM), glibenclamide (10 μM) or ODQ (10 μM). However, 2′, 5′‐dideoxyadenosine (10 μM) blocked the log concentration‐response curves of berberine. On the other hand, berberine produced a leftward shift of the log concentration‐response curves of isoproterenol, forskolin and nitroprusside. Additionally, berberine produced a parallel rightward shift of the concentration‐response curve of carbachol in a competitive manner with a pA2 of 3.87 ± 0.045. The above results suggest that the relaxant effect of berberine on tracheal muscle is due to its antagonistic effect on muscarinic acetylcholine receptors.