Acute and subchronic oral toxicity assessments of Combretum micranthum (Combretaceae) in Wistar rats

Background: Combretum micranthum (CM) (Combretaceae) is widely used in traditional medicine throughout West Africa for the treatment of diabetes, hypertension, inflammation, malaria and liver ailments. In our recent research we demonstrated that CM has nephroprotective potentials in diabetes mellitus, hypertension and renal disorders. However, to the best of our knowledge, no systematic study concerning its toxicity profile has been reported. Aim of the study: The study carried out to evaluates the potential toxicity of the hydroalcoholic extract from leaves of the CM, through the method of acute and sub-chronic oral administration in rats. Materials and methods: During the acute toxicity study, male and female rats were orally administrated with CM extract at single doses of 5000 mg/kg (n = 5/group/sex). Abnormal behaviour, toxic symptoms, weight, and death were observed for 14 consecutive days to assess the acute toxicity. For sub-chronic toxicity study, the extract was administered orally at doses of 500 and 1000 mg/kg (n = 5/group/sex) daily to Wistar rats for 28 days. The general behaviour and body weight of the rats was observed daily. A biochemical, haematological, macroscopical and histopathological examinations of several organs were conducted at the end of the treatment period. The CM extract was subjected to Fourier transform infrared spectrophotometric examination in order to detect the presence or absence of cyanide toxic compounds. Results: The absence of absorbance peaks between the 2220-2260 cm(-1) region of FT-IR spectrum of CM, indicating the absence of cyanide groups. This suggested that the CM extract may not contain toxic substances. During the acute toxicity test, no mortality or adverse effects were noted at the dose of 5000 mg/kg. In the subchronic study, the CM extract induced no mortality or treatment-related adverse effects with regard to body weight, general behaviour, relative organ weights, hematological, and biochemical parameters. Histopathological examination of vital organs showed normal architecture suggesting no morphological alterations. Conclusion: The present study revealed that oral administration of CM extract for 28 days, at dosage up to 1000 mg/kg did not induce toxicological damage in rats. From acute toxicity study, the median lethal dose (LD50) of the extract was estimated to be more than 5000 mg/kg.