Context: Myrtus communis L. (Myrtaceae), myrtle, is an evergreen shrub with strong antibacterial, anti-inflammatory, antihyperglycemic and antioxidant activities. Also, it is used as a sedative-hypnotic plant in Iranian traditional medicine.
Objective: This study evaluates the effect of 80% ethanolic extract of M. communis leaves on sleep and anxiety in mice and rats.
Materials and methods: Male NMRI mice were subjected to open field, righting reflex, grip strength and pentylentetrazole-induced seizure tests. Male Wistar rats were used to evaluate the alterations in rapid eye movement (REM) and non-REM (NREM) sleep. They were treated with 25-400 mg/kg doses of the extract intraperitoneally.
Results: The applied doses (50-200 mg/kg) of M. communis extract increased vertical (ED50 = 40.2 ± 6.6 mg/kg) and vertical and horizontal activity (ED50 = 251 ± 55 mg/kg), while treatment with 200 and 400 mg/kg attenuated muscle tone significantly compared to vehicle treated animals (p < 0.001 for all) in a dose-independent manner. Also, a significant hypnotic and not anticonvulsant effect was observed when animals were treated with 200 mg/kg of the extract (p < 0.01). In this regard, electroencephalography results showed that REM sleep time was decreased (2.4 ± 0.5%), while total and NREM sleep times were increased significantly compared to the control group of mice (82.5 ± 7.6%).
Discussion and conclusion: The data show the anxiolytic and muscle relaxant effect of the extract without anticonvulsant activities. The anxiolytic, myorelaxant and hypnotic effects without effect on seizure threshold are in line with the effect of a alpha 2 GABA receptor agonist.
Keywords: Medicinal plants; hypnosis; muscle relaxation; myrtle.