Evaluation of the sleep modulating effects of methanolic extracts of Strychnos spinosa and Strychnos innocua fruits in mice

This study aimed to evaluate the sleep modulating properties of Strychnos spinosa and Strychnos innocua fruits in Swiss albino mice. The depressant effect of the extracts on the central nervous system was studied using a diazepam-induced sleep model in mice. The mice were divided into four groups of six mice each. The test groups received Strychnos spinosa and Strychnos innocua fruits extracts at the doses of 250, 500, and 1000 mg/kg body weight intraperitoneally. In contrast, the control group received distilled water at 10 ml/kg. Diazepam (Ranbaxy®, India) was used as a standard drug and administered 30 minutes after the initial treatment. The lethal doses (LD50) of the two extracts were estimated to be >5000 mg/kg. The results obtained from the onset of sleep of rats administered methanol extracts of Strychnos spinosa, and Strychnos innocua fruits showed that the extracts at 250, 500, and 1000 mg/kg, respectively, did not significantly (p >0.05) alter the onset of sleep when compared with the control. The onset of sleep in the groups treated with Strychnos spinosa fruit extracts indicated a dose-dependent decrease pattern. The study also revealed a prolonged duration of sleep in all the experimental groups treated with the two extracts compared to the control group. The treated groups of 250, 500 and 1000 mg/kg significantly (p <0.05) prolonged the duration of diazepam-induced sleep in a dose-dependent manner when compared to the control group. The group treated with 1000 mg/kg of Strychnos innocua fruit extract was significant (p <0.05) compared to the control group. In conclusion, the high LD50 observed in this study suggests that the two extracts are relatively safe and contain promising bioactive ingredients that cause sleep modulation in mice.