Preliminary Evaluation of the Anti-Emetic Activity of Crude Methanol Extract and Fractions of Ocimum gratissimum

Background: There is a need for the development of safer, anti-emetic agents effective in several conditions such as in cancer chemotherapy where vomiting is a worrisome feature. Aim: The present study was carried out to evaluate the anti-emetic potential of crude methanol leaf extract and fractions of Ocimum gratissimum. Method: The anti-emetic activities of the fractions were carried out following the chick emetic model. Test samples and the negative control were administered at a single oral dose of 150 mg/kg to the respective groups (n = 5). Tween 80 (5%, 10 mL/kg) and chlorpromazine (i.p) served as negative and positive controls, respectively. The number of retches each animal produced was counted for 20 minutes and recorded. Anti-emetic activity was determined by calculating percentage reduction in number of retches relative to negative control. Results: The anti-emetic activity decreased in the following order; Chlorpromazine (98.76%) > butanol fraction (92.16%) > aqueous fraction (86.80%) > crude methanol fraction (65.15%) > N-hexane (63.09%) > and Ethyl-acetate fraction (5.98%). Butanol fraction elicited the highest activity among the tested fractions, while ethyl-acetate fraction produced the least activity. Conclusion: This study showed that the butanol extract has better anti-emetic properties than other fractions. Supplementary studies are required to isolate the active principles in butanol fraction of O. gratissimum responsible for the anti-emetic activity and also elucidate its mechanism of action.