Studies on antidiarrhoeal, antispasmodic and bronchodilator activities of Operculina turpethum Linn

BACKGROUND Traditionally, Operculina turpethum has been used in a wide range of ailments such as, gastrointestinal disturbances and asthma. It is found in China, South Asia, Pacific Islands, and Australia. This study was aimed to provide a possible pharmacological basis for the medicinal use of O. turpethum in gut and airways disorders. METHODS Castor oil-induced diarrhoeal mice model and isolated tissue preparations such as, rabbit jejunum and guinea-pig tracheal preparations were used to test the antidiarrhoeal, antispasmodic and bronchodilator effects and the possible mode of action(s) of the 70% aqueous-ethanolic extract of O. turpethum black variety (OTB). RESULTS In the castor oil-induced diarrhoea in mice, the crude extract of OTB caused a dose-dependent (300-1000 mg/kg) protection from diarrhoea, similar to that of loperamide. In isolated rabbit jejunum preparations, OTB produced a dose-dependent inhibition of spontaneous and high K+(80 mM)-induced contractions with resultant median effective concentrations (EC50 with 95% confidence interval) of 1.04 mg/ml (0.59-1.54) and 0.12 mg/ml (0.10-0.15; n = 4) respectively, thus showing more potency against K+. Pretreatment of the tissue with OTB (0.01 and 0.03 mg/ml) caused a rightward shift in the concentration response curves of Ca++, similar to that of verapamil. In isolated guinea-pig tracheal preparations, OTB caused inhibition of carbachol and high K+-induced constriction at similar concentrations with respective EC50 value of 0.66 mg/ml (0.53-0.82) and 0.59 mg/ml (0.45-0.62). Activity-directed fractionation revealed that the ethyl acetate fraction was more potent than the parent crude extract and hexane fraction. CONCLUSION These results suggest that the crude extract of O. turpethum possesses antidiarrhoeal, antispasmodic and bronchodilator activities, mediated possibly through the presence of Ca++ antagonist like constituent(s), though additional mechanism(s) cannot be ruled out. Thus, this study provides the evidence for the medicinal use of plant in diarrhoea and asthma.