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Objective To investigate the toxicity of aqueous extract of Guibourtia tessmannii (Harms) J. Leonard ( G. tessmannii ) and evaluate its safety. Methods NMRI mice were used to determine the acute toxicity of G. tessmannii . Increasing concentrations of the plant extracts were administered intraperitoneally or by force-feeding. General behavior and death were monitored and recorded daily for 7 days. In order to determine the sub-acute toxicity of the extract, several doses were administered by oral gavage daily for 28 days in adult Wistar rats. Different parameters were assessed including body weight, food and water intake, biochemical parameters and several vital organ weights. Results LD 50 of 328.78 mg/kg was obtained by i.p. route and more than 5 000 mg/kg was obtained in acute toxicity by oral route. In sub-acute toxicity, no significant alteration was observed in body weight or vital organs, food and water intake, and biochemical parameters. Conclusions The results showed that the aqueous extract of G. tessmannii has low toxicity intraperitoneally and no sub-acute toxicity via oral intake.

In sub-Saharan Africa, traditional medicine is widely used in rural and urban areas also. This is essentially due to the prohibitive cost of pharmaceutical-based medicine and the low incomes of a major part of the population. In addition, the efficacies of many of these traditional and plant-based medicines are proven, but the fact remains that certain plants used in traditional medicine have toxic effects. It is in this perspective that we investigated by bibliographic literature on the toxicity of plants used in traditional medicine. It is crucial to gain knowledge on these plant-based medicines prepared and prescribed by practitioners, particularly in terms of toxicity, composition, specific efficacy of disease and to advise practitioners of this alternative medicine on the protection and security of patients.

Ethnopharmacological relevance The use of medicinal plants in Gabon contributes widely to the primary health care of the people of this area of Central Africa. This paper investigates the pharmacological properties of Dichrostachys cinerea, the plant barks are traditionally used by Gabonese and Ivorian populations to treat bronchial asthma, rheumatism, and other various diseases. Although D. cinerea barks have been reported to be used by population to facilitate childbirth, to the best of our knowledge no scientific evidence has been published. Aim of study In the present study, we investigated the pharmacological properties of D. cinerea methanolic extract, on isolated uterine smooth muscle and compared its effects to those of oxytocin, which is used by obstetricians to facilitate childbirth. We also explored the possible mechanism pathways of the in vitro uterine contraction induced by D. cinerea. Materials and methods The effects of different concentrations (3.2 µg/ml, 16 µg/ml, 80 µg/ml, 400 µg/ml, and 2 mg/ml) of the methanolic extract of D. cinerea on isolated strips of the uteri of pregnant rats were studied. These effects were compared to those of oxytocin (8.4×10–5 µg/ml, 8.4×10–4 µg/ml, 8.4×10–3 µg/ml, 8.4×10–2 µg/ml). The EC (50) and E (max) was determined graphically and statistically analysed using one-way ANOVA and Dunnett post hoc test. Results Cumulative concentrations of D. cinerea have caused rise in the contractile force of the uterine fragments that were isolated from the pregnant rats, as seen with oxytocin concentrations. We observed contractions amplitude of 30.41 mN (12%) at 80 µg/ml and amplitude of 39.68 mN (14.17%) at 400 µg/ml for D. cinerea. In parallel, oxytocin concentration of 8.4×10–3 µg/ml induced contractions of 45.82 mN with the highest concentration (8.4×10–2 µg/ml) that induced contractions of 55.82 mN. Conclusions Our results revealed that D. cinerea increased the contractile force and the frequency of muscle contractions. These findings support the use of D. cinerea to facilitate childbirth, as it has been used in traditional medicine.