Evaluation of the toxic effect of aqueous extract of the bark of Morinda morindoides root in male Wistar rats

The toxic effect of the aqueous extract of the bark of the root of Morinda morindoides was studied in 24 sexually matured, male Wistar rats weighing between 150-200g. The rats were randomly divided into four groups (I-IV). Rats in groups I, II and III received 400 mg/kg, 800 mg/kg and I,600 mg/kg of 50mg/ml of the aqueous extract respectively once daily for 28 days while the control group (Group IV) was given distilled water (5ml/kg) once daily for 28 days after which the rats were euthanized. Following euthanasia, about 3 ml of blood was collected and was divided into 1.5ml each for haematology and serum chemistry. In addition, samples of the kidney, liver, heart, lungs and spleen were also harvested for histopathology. Haematological and serum biochemical values were expressed as mean ± standard error of mean and were analyzed using One-way Analysis of Variance (ANOVA) followed by Duncan’s multiple range test. Lesions observed in histopathology were scored as mild, moderate or severe. Results were considered statistically significant at 95% confidence interval (P<0.05). In this study, there was no significant difference in the haematological parameters, alanine aminotransferase and aspartate aminotransferase between the treated groups and the control. Histopathologically, the extract caused mild, diffuse degeneration of the liver, mild tubular nephrosis; mononuclear cellular infiltration in the heart and mild hypoplasia of the lymphoid nodules in the spleen of rats to which 1,600 mg/kg of the extract was administered. It was therefore concluded that aqueous extract of the root of Morinda morindoides may produce subchronic toxicity at the dosage of 1600mg/kg.Keywords: Toxicity, Haematology, Serum, Biochemistry, Histopathology, Morinda morindoides