Acute Toxicity and Sedative-hypnotic Effects of Ethanol Stem Bark Extract and Fractions of Milicia excelsa (Moraceae) in Mice

Aim: Milicia excelsa stem bark is used as sedative and for treating mental illnesses among the Hausa tribe of Northern Nigeria, but there is no scientific rationale for its use. Hence, this study investigated the oral acute toxicity and sedative potential of ethanol stem bark extract, n-hexane, ethylacetate, n-butanol and aqueous fractions of the stem bark extract in mice. The phytoconstituents in the extract and fractions were quantified. Methodology: The acute toxicity of the extract and fractions were investigated using OECD guidelines 425 of 2008. The sedative effects of the extract and fractions were investigated using pentobarbital-, and ketamine-induced sleep tests. Results and discussion: The results obtained showed that the acute toxicity of the extract and fractions were > 5000 mg/kg, suggesting that the extract and fractions may be safe. The extract, n-hexane, ethylacetate and aqueous fractions significantly (p<0.05) reduced sleep latencies, indicative of sedative effects, effective for sleep induction, while the extract and all the fractions significantly (p<0.05) prolonged the sleep durations, suggesting sedative effects, effective for sleep maintenance. Conclusion: This study therefore, concluded that the extract and fractions may be safe. The study further concluded that the sedative effect of the extract and fractions may be due to the abundance of flavonoids in the extract and fractions. Thus, providing scientific rationale for its ethnomedicinal use. However, further study may be warranted to isolate and characterize the sleep promoting bioactive principles as well as carry out GABA binding assay of the isolated compound(s) in ESB and its various fractions.