Mechanisms underlying the antispasmodic and bronchodilatory properties of Terminalia bellerica fruit.

AIM OF THE STUDY The present investigation was carried out to provide the pharmacological basis for the medicinal use of Terminalia bellerica in hyperactive gastrointestinal and respiratory disorders. MATERIALS AND METHODS Crude extract of Terminalia bellerica fruit (Tb.Cr) was studied in in vitro and in vivo. RESULTS Tb.Cr caused relaxation of spontaneous contractions in isolated rabbit jejunum at 0.1-3.0mg/mL. Tb.Cr inhibited the carbachol (CCh, 1microM) and K(+) (80mM)-induced contractions in a pattern similar to that of dicyclomine, but different from nifedipine and atropine. Tb.Cr shifted the Ca(++) concentration-response curves to right, like nifedipine and dicyclomine. In guinea-pig ileum, Tb.Cr produced rightward parallel shift of acetylcholine-curves, followed by non-parallel shift at higher concentration with the suppression of maximum response, similar to dicyclomine, but different from nifedipine and atropine. Tb.Cr exhibited protective effect against castor oil-induced diarrhea and carbachol-mediated bronchoconstriction in rodents. In guinea-pig trachea, Tb.Cr relaxed the CCh-induced contractions, shifted CCh-curves to right and inhibited the contractions of K(+). Anticholinergic effect was distributed both in organic and aqueous fractions, while CCB was present in the aqueous fraction. CONCLUSIONS These results indicate that Terminalia bellerica fruit possess a combination of anticholinergic and Ca(++) antagonist effects, which explain its folkloric use in the colic, diarrhea and asthma.