Central nervous system effects of the essential oil of the leaves of Alpinia zerumbet in mice

Objectives Alpinia zerumbet, known in Brazil as colonia, is popularly used as a diuretic, antihypertensive, anti-ulcerogenic and sedative. Based on this, we have investigated the central effects of the essential oil isolated from A. zerumbet leaves. Methods Mice were treated once with 50 or 100 mg/kg of the essential oil, intraperitoneally, 30 min before being submitted to behavioural models of: locomotor activity (open-field), catalepsy, anxiety (elevated plus maze), depression (forced swimming test and tail suspension tests) as well as apomorphine-induced stereotypy. Key findings Results showed a dose-related decrease on locomotor activity and apomorphine-induced stereotypy. There was a decrease to the order of 55% of the grooming behaviour with both doses studied. The essential oil 100 mg/kg increased cataleptic activity (167%) and the immobility time in the forced swimming and tail suspension tests. Pretreatment with haloperidol (0.2 mg/kg, i.p.) alone also decreased locomotion, increased cataleptic activity and immobility time in the tail suspension test. No alterations in the elevated plus maze test were registered. Conclusions The essential oil of A. zerumbet leaves had depressant and possible antipsychotic activity, since it could reverse the stereotypy induced by apomorphine, presenting effects comparable with those obtained with haloperidol treatment.