Uterine contractile effects of the aqueous and ethanol leaf extracts of Newbouldia Laevis (Bignoniaceae) in vitro

Based on traditional reports, the aqueous and ethanol extracts of the leaves of N. laevis were tested on isolated uterine preparations of non-pregnant rats. The effects of increasing cumulative concentrations of the extracts on the amplitude and frequency of spontaneously contracting uterine tissues were tested. Direct effects of the extracts and acetylcholine on uterine smooth muscle were also tested in organ baths containing aerated physiological salt solution maintained at 37°. The EC₅₀ and Emax were determined and analyzed using one way ANOVA with Dunnett''s post hoc test. The extract significantly increased the frequency (P<0.05) of spontaneous contractions without significantly affecting the amplitude. The extracts and acetylcholine were observed to directly stimulate uterine contractions, however there were significant differences (P<0.05) in their EC₅₀ and Emax. In conclusion, the leaves of N. laevis increase the frequency of spontaneously contracting tissues and directly stimulate uterine contractions which may account for the use of the leaf extract traditionally.