Effects of the essential oil from leaves of Alpinia zerumbet on behavioral alterations in mice.

In phytotherapy, the essential oil from the leaves of Alpinia zerumbet (Alpinia speciosa K. Schum.) (EOAZ) is used for neuropsychiatric symptoms, such as depression, stress and anxiety, and chronic problems that are associated with reproductive hormone imbalances in women. The chemical composition of EOAZ was analyzed by GC/MS, and the EOAZ properties inducing behavioral alterations in mice were examined by behavioral observations (BO) and an elevated plus-maze task (EPM), widely used as a method for assessing anxiolytic-like behaviors. Five major compounds, p-cymene (28.0 +/- 5.0%), 1,8-cineole (17.9 +/- 4.2%), terpinen-4-ol (11.9 +/- 6.3%), limonene (6.3 +/- 2.2%), and camphor (5.2 +/- 2.1%) were identified by retention indices, mass spectra and comparison with standards. Inhalational administration of EOAZ (8.7 ppm) induced unique jumping behaviors in mice. To further investigate the behavioral regulatory mechanisms of EOAZ, we administered an intraperitoneal injection of either 10 mg/kg 5-HTP or 10 mg/kg fluoxetine prior to the EOAZ inhalations. By 5-HTP or fluoxetine pretreatments, the jumping frequencies were significantly decreased. In EPM, EOAZ (0.087 and 8.7 ppm) obviously showed the anxiolytic-like activity in mice.