Toxicology of solvent extract and fractions of Alstonia boonei (DC.) Wild stem bark in Rats

Introduction: Toxic effects arising from the use of medicinal herbs have been frequently overshadowed by the therapeutic efficacy of phytomedicines. This study was carried out to assess the safety of extract and fractions of Alstonia boonei (de wild) stem bark, popularly used in the treatment of malaria especially in Africa. Methods: Rats were orally exposed to different doses (200 and 400 mg/kg body weight) of methanol extract (ME), n-hexane (HF), chloroform (CF), ethylacetate (EF) and aqueous fractions (AF) of A. boonei for 7 days. Furthermore, 10 mg/ kg body weight (bw) of chloroquine (CQN) was administered as standard drug for 7 days while, 5% tween 80 (TT) and distilled water (TW) were administered as control for 7 days. Group I (treatment group) was sacrificed after 7 days while group II (recovery group) was left for 21 days to recover and thereafter sacrificed. The effects of treatment and recovery were analyzed using serum biomarkers, hematological parameters and tissue histopathological evaluation. Results: There was reduction in hematological parameters after 7 days but recovered after 21 days. There was also increase in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP), after 7 days. Compared to TW and TT treated groups, histopathological scores of liver and kidney were critical for all groups at 400 mg/kg bw after 21 days. Conclusion: The animals did not fully recover after 21 days, suggesting that 400 mg/kg bw of extract and fractions of A. boonei were both hepatotoxic and nephrotoxic. Hence this plant should be used with cautious.