Abstract
Background and Objective: Albizia lebbeck is famous plant for its medicinal use in hyperactive gut and airways disorders. The objective of this study was therefore to provide a scientific rationale for the medicinal utility of Albezia lebbeck in diarrhea, gut spasm and bronchospasm, with the possible mode of action explored. Materials and Methods: The hydro-alcoholic extract of the pericarp of Albezia lebbeck (Al.Pericarp) was tested using in-vivo and in-vitro assays. Results: Albezia Pericarp, at 100 and 300 mg kg(-1) showed 40 and 80% protection of castor oil-induced diarrhea in mice, whereas loperamide (10 mg kg(-1)) showed complete protection. In isolated rabbit jejunum, Albezia. Pericarp completely inhibited spontaneous, carbachol (CCh; 1 mu M) and low K+(25 mM)-induced contractions but had only a weak effect against high K+ (80 mM). When tested for bronchodilatory activity in anesthetized rats, Albezia. Pericarp (3-30 mg kg(-1)) inhibited the CCh-induced bronchospasm in a dose-dependent manner, similar to aminophylline. In isolated guinea-pig tracheal preparations, Al.Pericarp selectively inhibited contractions induced by CCh and low K+. The inhibitory effect of Al.Pericarp against low K+ was reversed in the presence of tetraethylammonium (TEA), a non-specific blocker of K+-channels,whereas no significant inhibition was observed in the presence of glibenclamide (Gb) or 4-aminopyridine (4-AP), which are ATP-dependent and voltage-dependent K+ channel blockers, respectively.The plantextract (0.03 and 0.01 mg mL(-1)) also potentiated isoprenaline-inhibitory concentration-response curves (CRCs) by a shift to the left, in both jejunum and trachea, showing phosphodiesterase inhibition, similar to papaverine. Conclusion: These results indicated that the crude extract of Albizia lebbeck Pericarp possesses anti diarrheal, antispasmodic and bronchodilatory activities, mediated possibly through dual pathways, namely activation of a non-specific type of K+-channels and inhibition of phosphodiesterase enzyme. Thus, this study offered a sound basis for Albizia lebbeck to be developed for hyperactive gut and airways disorders.