Acute toxicity study and parasympatholytic effect of burantashi ethanol extract on an isolated smooth muscle preparation

The acute toxicity and parasympatholytic effects of a powder made from the stem bark of Pausinystalia yohimbe, popularly called Burantashi was evaluated using carefully designed in vivo charcoal meal transit in rats and in vitro isolated tissue models. Results obtained revealed an acute toxicity value of about 1000mg/kg body weight. All doses of Burantashi ethanol extract (BEE) also elicited a significant (p< 0.05) relaxation effect on the smooth muscles of the rabbit jejunum. In the in vivo work, 100, 200 and 400mg/kg of BEE inhibited the movement of charcoal meal in the rat’s gastrointestinal tract by 8.61±0.89, 12.30±1.06 and 25.06±1.30% respectively and compared favorably with the effect of atropine (1mg/kg) which yielded a mean % inhibition of 34.27±4.15%. On isolated rabbit jejunum, BEE significantly inhibited rhythmic contractions at all final bath concentrations (FBC) administered. BEE also significantly blocked the contractile effect of acetylcholine but did not significantly affect that of propranolol (a non selective beta receptor blocker). The results obtained suggest that excessive and habitual consumption of burantashi could be deleterious to health, but mild to moderate use/consumption could be of medicinal value. The extract may contain substances with potent parasympatholytic properties which may be of value in the management of diseases associated with excess activity of the parasympathetic arm of the autonomic nervous system, and may yet serve as template for the development of more synthetic parasympatholytics of clinical significance.