Pharmacological Effects of an Aqueous Extract of Picralima Nitida (Stapf) (Apocynaceae) of the Cardiovascular System and the Intestine of Mammals

Picralima nitida, aplant of African pharmacopoeia is used in the treatment of diseases such as malaria, typhoid fever and anemia. To promote this herb, we undertook to study its effect on the cardiovascular system and the smooth duodenal muscle.The study of this extract on the electrocardiogram of rabbits at doses of between 2.7×10-3 g/kg and 3.4×10-2 g/kg bw, showed that Pn causes an increase of the durations of PR and ST spaces respectively of 0.11 ±0.01 (p<0.001) and 0.14±0 sec (p<0.001) and a decrease in heart rate significantly (p <0.001).In the presence of propranolol (5.6×10-7-5.6×10-4 g/kg), Pn (3.9×10-2 g/kg) causes a decrease of the P-wave and the heart rate, an increase in the amplitude of the T-wave and the duration of the ST space. The amplitude of the QRS complex decreases before rising to high doses of propranolol.On the isolated heartof rat, the extract induced the positive chronotropic and inotropic effects for concentrations between 10-10 mg/ml and 10-6 mg/ml. Indeed, the extract causes an increase of the cardiacrate and amplitude respectively of 108.67±4.67% (p<0.05) and 219.6±5.43% (p<0.001).On the smooth muscle of duodenum of rabbit, Pn decreases the amplitude of the contractions depending of the concentration with a maximum effect (p<0.001) at 4×10-4 g/ml.In the presence of propranolol (4.10-10g/ml), the negative inotropic effects of Pn at 4×10-4g/ml were reduced by 52%.The results of this study show that this extract contains adrenomimetics substances inhibited by propranolol.