In vitro determination of the uterine stimulatory effect of the aqueous leaf extract of Ficus exasperata

Abstract

Ethnopharmacological relevance The leaves of Ficus exasperata Vahl (Moraceae) are used by traditional healers in Southern Nigeria to arrest pre-term contractions and are also used as an abortifacient in some parts of Africa. Aim of study An earlier study on the aqueous leaf extract of Ficus exasperata (AET) showed that the extract at lower concentrations inhibited oxytocin-induced uterine contractions and at higher concentrations, stimulated uterine contraction. This study thus aims to determine, the possible mechanisms by which AET stimulates uterine contraction in vitro. Materials and methods The contractile effect of AET (5.0 × 10 −2 to 100 × 10 −2 mg/ml) and oxytocin (which was used as a reference drug) were examined in the presence of the following antagonists: atropine (1.18 and 11.91 nM); indomethacin (1.42 and 14.25 nM); verapamil (2.03 and 20.35 nM); phentolamine (4.09 and 40.91 nM), or diphenhydramine (4.45 and 44.47 nM). The EC 50 and E max were determined and statistically analyzed using one-way ANOVA and Dunnett post hoc test. Results There was no significant difference in the EC 50 and E max of AET and oxytocin in the presence of atropine. Diphenhydramine and phentolamine significantly inhibited ( p < 0.01) the extract but both drugs had no effect on oxytocin. However, significant differences ( p < 0.01) were observed in the EC 50 and E max of AET and oxytocin in the presence of verapamil and indomethacin. Conclusions These results suggest that the stimulation of uterine contractility by AET may arise from the activation of histamine H 1- and/or α-adrenergic receptors, interference with calcium channels and/or stimulation of prostaglandin synthesis in utero.