Aim: To determine the chemical and uterine contratile activity of extract of A. montanus using the Ugo basile organ bath model 4050.
Study Design: Five female Wistar non-pregnant rats weighing between 160-200 g were brought into oestrus by injecting 0.2 mg/kg of stilbesterol in ethanol intra-peritoneneally for 24 hours. The rats were sacrificed under chloroform anaeshesia. The uterine horns were identified and the two horns of the uterus cut out and transferred to a petri-dish containing physiological salt solution (PSS). 1.0-1.5 cm length was mounted in a 10 ml organ bath containing De-Jalon solution with the following chemical compositions NaCl, 154mM/L NaHCO3, 5.95 mM/L, D-Glucose, 2.78 mM/L KCl, 5.40 mM/L,CaCl2.2H2O, 5.44 mM/L. The tissue was aerated with air via an aerator and the temperature maintained at 37ºC with a pH of 7.4. The spontaneous contractions of the uterus were recorded by means of force displacement transducer connected to an amplifier and a multi-channel recorder and allowed to equilibrate for 30 minutes with periodic changing of the bath fluid every ten minutes under a resting tension of 750 mg.
The effect of the extract on the concentration response curves for oxytocin and acetylcholine was determined. Hence responses to different doses of oxytocin and acetylcholine alone and in the presence of the extract were also obtained. The effects of two positive controls (Salbutamol and atropine) were also determined.
The experiment was repeated five times and the mean and standard deviation of the results were calculated.
Place and Duration of Study: Department of Chemistry and Pharmacology, University of Benin, Benin City, between March 2016 to July 2017.
Methodology: A total of 980 g of the plant material was extracted with a soxhlet apparatus using 1.5 L of methanol (BDH, England) as solvent. The extract was concentrated in vacuo at 50ºC. The extract was stored in a refrigerator at 4ºC until needed for the experiment.
Female non-pregnant Wistar rats were pre-treated intra-peritoneally with 0.2 mg/kg of diethylstilbestrol 24 h prior to the actual experiment . The rats were sacrificed under chloroform anaesthesia. The abdomen was opened and the two horns of the uterus carefully isolated, freed of mesenteric fat and a 1 cm piece was mounted in a 10 mL organ bath containing De-Jalon physiological salt solution. The tissue was bubbled with air using an aerator and temperature was maintained at 37ºC, with a pH of 7.4. The spontaneous contraction of the uterus was recorded with 7003-B transducer connected to an Ugo Basile Data capsule device. The transducer was previously calibrated to establish a relationship between the force applied to the transducer and the gauge deflection (500 mg). The tissue was allowed to equilibrate for 30 minutes before the start of the experiment and placed under tension of 500 mg.
Results: From the phytochemical screening result, terpenoids was observed in larger amount than other phytochemicals. The presences of these bioactive constituents have been reported to have physiological effect in man .
The results also showed that various concentrations of oxytocin and acetylcholine produced a significant contraction of the rat uterus. Administration of the extract produced a significant (P = .05) dose-dependent reduction in oxytocin and acetylcholine induced contractions by the extract at concentration tested (Figs. 1-2). From the graphical plot, the percentage response to log dose of Acanthus montanus extracts supplemented with oxytocin exhibited anti-contractile effect of the uterus of rats at 30%: -2.699, 40%: -2.398 and 45%: -2.097 (Fig. 1), while for Acetylcholine induced contraction, the effect of anti contractile activity was observed at 25%: -0.699, 40%: -0.398, 45%:-0.097 and 45%: 0.301 (Fig. 2). This study revealed that extract at both doses produced significant inhibition of oxytocin and acetylcholine induced contractions of the uterine smooth muscle in non-pregnant rats.
Conclusion: The methanol extract of Acanthus montanus was found to possess anti-contractile activity on the uterine smooth muscles in non-pregnant rats, which corroborates the use of the plant extract in the treatment of spontaneous abortion.