Investigation of anxiolytic and hypnotic effects of hydroalcoholic extracts of Lemon Verbena in mice

Benzodiazepines, which act via gama-aminobutyric acid (GABA) chloric channels are among the main drugs used for treatment of anxiety. Lemon Verbena is a herbal medicine, which contains compounds such as flavonoids, which similar to benzodiazepines have affinity to GABA receptors. Lemon verbena is used for treatment of anxiety and insomnia in folk medicine. In this study, we examined possible anti-anxiety and sedative effect of this plant.

Aqueous and alcoholic extracts of Lemon Verbena (1, 10 and 100 mg/kg), distilled water and diazepam (2 mg/kg) were injected intraperitoneally to groups of 7 to 8 mice. For investigating the anxiolytic effects, the animals were tested by elevated plus maze  (EPM) 45min thereafter. For evaluating hypnotic and sedative effects, we used ketamine induced sleeping time test and onset and duration of sleep were recorded.

Aqueous extract of Lemon Verbena (10 mg/kg) increased time spent in open arms and decreased time spent in closed arms compared to control group. Aqueous extract of Lemon Verbena (100 mg/kg) also reduced onset of sleep and increased sleep duration compared to control group. All doses of alcoholic extract reduced onset of sleep and increased sleep duration.

This study shows that lemone verbena possesses anti-anxiety and hypnotic activity in animal model.