Background: Various parts of Pandanus foetidus Roxb. are used as traditional medicines. However, scientific reports concerning the effect of this plant on central nervous system (CNS) depression and analgesia are unavailable. This study investigated the CNS depressant and antinociceptive effects of Pandanus foetidus leaf extracts in a rodent model. Methods: The sedative and anxiolytic activities of Pandanus foetidus extract (500 g) were tested using behavioural models of Swiss albino mice, and the analgesic activity was assessed by formalin-induced pain and tail immersion tests at 200 mg/kg body weight of the mice. The data were analysed by a one-way ANOVA, a repeated measure of ANOVA and a non-parametric test (Kruskal-Wallis test) using the SPSS software. Acute toxicity was tested using an established method. Results: Compared with the aqueous fraction, the methanol, petroleum ether and chloroform fractions of the extract exhibited a more significant (P < 0.001) reduction of locomotor activity in the mice in the open field, hole-cross, and elevated plus maze (EPM). The methanol fraction maximized the duration of sleeping time caused by the thiopental sodium induction. The extract produced a significant step-down in pain, as shown by the paw licking time in the early and late phases of the formalin test. In the tail immersion test, the chloroform fraction maximally reduced the heat-induced analgesia. The extract was found to be non toxic. Conclusion: The methanol, petroleum ether, and chloroform fractions of P. foetidus have strong CNS depressant and antinociceptive effects and thus merit further pharmaceutical studies.

OBJECTIVETo analyze in vivo neuro-pharmacological effects of Alpinia nigra as anxiety is a particular form of behavioral inhibition that occurs in response to novel environmental events.

METHODSIn present study, the extract of Alpinia nigra was evaluated for its central nervous system depressant effect using mice behavioral models, such as hole cross, open field and thiopental sodium induced sleeping time tests for its sedative properties and an elevated plus-maze test for its anxiolytic potential, respectively.

RESULTSIn anxiolytic study, the extract displayed increased percentage of entry into open arm at the dose of 400 and 200 mg/kg. The extract produced a significant (P<0.01) increase in sleeping duration and reduction of onset of sleep compared to sodium thiopental at both doses (200 and 400 mg/kg). The extract (200 and 400 mg/kg) also showed a dose-dependent suppression of motor activity and exploratory activity of the mice in both open field and hole cross test.

CONCLUSIONThis study demonstrates that the treated extract has significant central nervous system depressant effect. Further studies on active constituent of the extract can provide approaches for therapeutic intervention.