Mutagenicity and preclinical safety assessment of the aqueous extract of Clinacanthus nutans leaves

Context: Clinacanthus nutans (CN) is used traditionally for treating various illnesses. Robust safety data to support its use is lacking. Objective: To evaluate the adverse effects of aqueous extract of CN leaves (AECNL). Materials and methods: The oral toxicity of the AECNL was tested following Organisation for Economic Co-operation and Development (OECD) guidelines. Mutagenicity (Ames test) of AECNL was evaluated using TA98 and TA100 Salmonella typhimurium strains. Results: No mortality or morbidity was found in the animals upon single and repeated dose administration. However, significant body weight loss was observed at 2000mg/kg during sub-chronic (90 d) exposure. In addition, increased eosinophil at 500mg/kg and decreased serum alkaline phosphatase levels at 2000mg/kg were observed in male rats. Variations in glucose and lipid profiles in treated groups were also observed compared to control. Ames test revealed no evidence of mutagenic or carcinogenic effects at 500g/well of AECNL. Conclusion: The median lethal dose (LD50) of the AECNL is >5000mg/kg and the no-observed-adverse-effect level is identified to be greater than 2000mg/kg/day in 90-d study.