Phytochemical and Toxicological Studies of an Extract of the Seeds of Picralima Nitida (Stapf) (Apocynaceae) and Its Pharmacological Effects on the Blood Pressure of Rabbit

Abstract

The phytochemical screening of the seeds extracts of Picralima nitida has highlighted the presence of alkaloids and terpenes poly sterols in chloroform solutions, methanol and in the aqueous. Unlike chloroform and methanol solutions, the aqueous revealed the presence of saponins. An acute toxicity study in mice showed that the aqueous extract of Picralima nitida would be slightly toxic with a lethal dose (LD) 50 % of 9120.11 mg/kg of body weight (bw). This extract, in rabbits induced a dose-dependent hypotension for the doses between 3.10^-6 g / kg bw and 2.10^-5 g/kg bw with an effective dose 50% (ED50) equal to 4.07×10^-6 g/kg bw. In the presence of atropine (6.10^-9 g/kg), a competitive inhibitor of acetylcholine, the hypotensive effect of aqueous extract of Picralima nitida is reduced, confirming in this extract the presence of cholinomimetics substances of muscarinic type. The results therefore suggest the presence of cholinomimetics substances in the aqueous extract of Picralima nitida seed. These substances could be responsible for the hypotensive effect of this extract. The same extract did not induce diuresis in rats.