Acute and Sub-Acute Toxicity of Cola millenii Leaf and Stem Bark Extracts in Albino Rats

In the present study, the toxicity of monkey kola (Cola millenii) leaf and stem bark extracts were investigated in laboratory animals. The rats were orally administered with the plant extracts at gradual doses of 10 mg/kg, 100 mg/kg, 1,000 mg/kg, 2,500 mg/kg, 3,500 mg/kg and 5,000 mg/kg b.w. and were closely monitored for 24 h. In sub-acute toxicity, the animals were given 1,000 mg/kg b.w. and 2,500 mg/kg b.w. for 28 days. Thereafter, the effect of the extracts on the weight and haematological parameters of the rats were determined. The rats did not show any symptoms of toxicity throughout the experiment. In the sub-acute toxicity assay, starting from week two, the groups administered with 1,000 mg/kg and 2,500 mg/kg stem bark extract had significant (p ≤ 0.05) lower weight compared with the other groups. In the haematological assay, there were no significant differences (p ≥ 0.05) between the RBC and platelet counts as well as PCV, haemoglobin, urea, cholesterol, creatinine, LDL, HDL and AST level of all the groups given the extract in comparison with the control. Albeit, the level of white blood cells count, was higher in the treated groups compared with the control with concomitant significant (p ≤ 0.05) increase in the ALT and ALP levels of the animals treated with the extracts compared with the control. Results show that Cola millenii leaf and stem bark extracts are safe for oral use, although, at higher doses, stem bark extract may cause liver damage.