Neuropharmacological Activity of Pimenta Pseudocaryophyllus (Gomes) L.R. Landrum

Pimenta pseudocaryophyllus (Gomes) L.R. Landrum (Pp) is popularly used as a tranquilizer in the treatment of emotional tension in the city of Campos do Jordão, São Paulo, Brazil. The aim of this study was to evaluate behavioral changes induced by ethanol extract of the Pp leaves (PpEE), seeking to identify the most active fraction. PpEE was obtained by soaking the dried leaf powder in ethanol (95%;1:5). The hexane (HF), dichloromethane (DF), ethyl acetate (ACF) and aqueous (WF) fractions were prepared through PpEE Fractionation with solvents of different polarities. Swiss male mice (25–35g) were treated orally with PpEE 1g/kg; HF160mg/kg; DF260mg/kg; ACF420mg/kg, or WF 640mg/Kg in proportion to their respective yield. After 1hr of treatment, anxiolytic effect was evaluated in sleep induced by sodium pentobarbital (50mg/kg, i.p.), open field (OF) and elevated plus maze (EPM) models. Group treated with Diazepam (1 or 5mg/kg, i.p.) and vehicle 10 mL/Kg were used as a positive and negative control respectively. The PpEE increased sleep duration by 32% and reduced sleep latency by 20%. DF prolonged sleep time by 62%; increased the number of squares crossed and time spent at the center by 10,8% and 39% respectively in the OF. Number of entry and time spent on the open arm of EPM were also increased by 31% and 42% respectively. These results suggest the presence of compounds with anxiolytic activity in the DF.

Keywords: Pimenta pseudocaryophyllus, Anxiolytic effect, Medicinal plant, Elevated plus maze