Cassia siamea Lam (Fabaceae), widely used in tropical countries for its nutritional and pharmacological properties, has been toxicologically evaluated. Oral administration of aqueous (CSE4) and ethanol (CSE3) Cassia siamea stem bark extracts did not show mortality up to 3000 mg/kg in albinos Wistar rats. LD 50 of petroleum ether (CSE1) and dichloromethane (CSE2) extracts were estimated at 1300 and 1275 mg/kg respectively. None of the extracts has cytotoxicity activity on KB and Vero cell lines. There were no differences in body weight and macroscopic examinations. Haematocrit, creatinine, alkaline phosphatase (ALP), alanine amino transferase (ALT) and Asparatate Amino Transferase (AST) parameters did not show difference of levels. Contrariwise, a significant increase in animal weight and blood glucose were observed in animals treated group. This increase can be explained by the presence of polysaccharides and phytosterols (stigmasterol, beta-sitosterol) in this plant. The lyophilised aqueous extract keeps its analgesic property for over two years.
Key words: Cassia siamea, stem bark extracts, cytoxicity, subchronic toxicity, pharmacological stability, analgesic activity.