Bronchodilator activity of Phymatodes scolopendria (Burm.) Ching and its bioactive constituent

• Published in: Journal of ethnopharmacology Vol. 102; no. 3; pp. 400 - 407
• Main Authors: Ramanitrahasimbola, D., Rakotondramanana, D.A., Rasoanaivo, P., Randriantsoa, A., Ratsimamanga, S., Palazzino, G., Galeffi, C., Nicoletti, M.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 01.12.2005; Elsevier
• Subjects: 1,2-Benzopyrone; Animals; Anti-asthmatic; asthma; Biological and medical sciences; Bronchodilator; Bronchodilator Agents - pharmacology; bronchodilators; Calcium Chloride - pharmacology; chemical constituents of plants; Coumarins - pharmacology; ethnobotany; Female; General pharmacology; Guinea Pigs; herbal medicines; Histamine Antagonists - pharmacology; Male; mechanism of action; Medical sciences; medicinal plants; medicinal properties; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Phymatodes scolopendria; plant extracts; Plant Extracts - analysis; Plant Extracts - pharmacology; Polypodiaceae; Polypodiaceae - chemistry; Potassium Chloride - pharmacology; Propranolol - pharmacology; Theophylline - pharmacology; Trachea - drug effects; Trachea - physiology; traditional medicine; Madagascar; 1,2-Benzopyrone; Anti-asthmatic; Phymatodes scolopendria; Bronchodilator; Lung disease; Respiratory disease; Pharmacognosy; Plant origin; Bronchus disease; Obstructive pulmonary disease; Asthma; Medicinal plant
• ISSN: 0378-8741; 1872-7573
• DOI: 10.1016/j.jep.2005.06.037

Phymatodes scolopendria (Burm.) Ching (Polypodiaceae) is widely used in the Eastern coast of Madagascar to treat respiratory disorders. Bioassay-guided fractionation using guinea pig trachea pre-contracted with histamine to monitor the activity led to the isolation of 1,2-benzopyrone (coumarin) as the main active constituent. Effectively, it induced a concentration-dependent relaxation of the histamine with a median effective concentration (EC 50) of 35.03 μg/ml, or carbachol (EC 50 = 33.41 μg/ml) pre-contracted guinea pig trachea, and also provoked 100% relaxation at 72.10 μg/ml. It was less active either on KCl pre-contracted trachea (EC 50 = 130.78 μg/ml) or endothelium denuded trachea (153.4 ± 22 μg/ml). It inhibited, in a non-competitive manner, the histamine and the external calcium spasm effect on the isolated trachea but it did not significantly modify the broncho-constrictive activity of KCl. When combined with theophylline, coumarin produced a significant additive relaxing effect on pre-contracted trachea. Furthermore, its bronchodilator effect was not blocked by propranolol. In vivo, pre-treated guinea pig with coumarin showed significant resistance to histamine inhalation, with an adequate dose protecting 50% of the tested animals (AD 50) of 75 mg/kg. These results indicate that the bronchodilator effect of coumarin is partly due to the endothelium-dependent tracheal relaxation, and may be mediated through a non-specific tracheal relaxation.