Toxicological studies of the stem bark extract of Khaya grandifoliola in rats

Abstract

Khaya grandifoliola (Welw) CDC (Meliaceae) is a tropical medicinal plant widely used in Africa for the management of malaria. In this study, toxicological evaluation of the aqueous extract of the stem bark of the plant has been evaluated with a view to ascertaining some of its possible toxic effects in the rats. Healthy rats of both sexes weighing between 62 g - 69 g body weight were used for this study. A group of rats were administered with graded doses (100, 200 and 500 mg/kg body weight, o.p) of the extract daily for 21 days. At the end of the 7 days, 21 days treatment periods and 21 days post-treatment (Recovery) period, the different groups of animals were sacrificed and assessed for tissue damage by measuring the plasma, liver, heart and spleen activities of alanine amino transferase (ALT), aspartate amino transferase (AST), and alkaline phosphatase (ALP). The liver, kidney, heart and spleen were also subjected to histopathological assessment. The result showed that following 1 week of administration of the extract that there was significant (p < 0.05) in the activities of plasma AST, ALT, and a decrease in plasma ALP, liver AST and ALT when compared to control. However, following 21 post-treatment days, these changes in enzyme activities were not significantly different (p < 0.05) from control values. There were also no marked histopathological alterations in any of the organs for different treatment groups except for the 500 mg/kg body weight group that showed mild lesions in the liver, kidney and spleen. In conclusion, administration of the extract depressed the liver amino transferase activities in a dose-dependent manner, with concurrent increased patterns
of activity in the plasma. This indicates that K. grandifoliola extract could be toxic when administered chronically at high doses.

Keywords: ALP, AST, ALT, Heart, Histology, Kidney, Liver, Spleen.