Evaluation of Sedative and Hypnotic Effects and Acute Toxicity of Paeonia daurica subsp. macrophylla (Albov) D.Y.Hong Root Extracts in Mice

Background and objectives: Paeonia daurica ssp. macrophylla (PD) (Paeoniaceae) is a perennial plant, growing in Iran. In Persian medicine, another species, Paeonia officinalis "Oode-saleeb" has been used especially for treating epilepsy and brain disorders. This study aimed to evaluate the sedative and hypnotic activity and the acute toxicity of P. daurica root extracts in mice. Methods: Sedative and hypnotic effects of the aqueous extract, total hydro alcoholic 80% extract, and its fractions, hexane, chloroform, and methanol were examined by the righting reflex method. Plant samples (50, 100, and 200 mg/kg) and vehicle (10 mL/kg) were injected intraperitoneally (i.p.) 30 minutes before sodium thiopental injection (40 mg/kg, i.p.) in groups of seven mice. The time taken before losing the righting reflex and the time taken to regain the righting reflex were recorded as the onset of sleep and sleep duration, respectively. Results: The findings of the study indicated that, with the exception of the chloroform fraction and the total hydroalcoholic extract administered at the dose of 50 mg/kg, all the samples demonstrated a reduction in sleep onset time produced by sodium thiopental. Furthermore, chloroform (200 mg/kg) was the most effective sample on sleep duration compared to diazepam (3 mg/kg) (p<0.001). Conclusion: Results of this study demonstrated that Paeonia daurica root can be used as a sedative and hypnotic complementary drug.