To evaluate the neuropharmacological properties of Costus speciosus (C. speciosus) rhizome using different experimental mouse models. Methods: The anxiolytic effect was investigated by hole-board test, elevated plus maze and light/dark test, while central nervous system (CNS) depressant effect was evaluated by thiopental sodium-induced sleep test. Finally, antidepressant effect was evaluated by forced swimming test and tail suspension test. Results: In both elevated plus maze and hole board test, 400 mg/kg C. speciosus showed more significant CNS depressant effect than 1 mg/kg diazepam. Both 200 mg/kg and 400 mg/kg C. speciosus extract produced a significant dose-dependent decrease in onset of sleep. In forced swimming test, C. speciosus rhizome showed a decrease in duration of immobility in a dose-dependent manner. Imipramine (10 mg/kg) and C. speciosus extract at 400 mg/kg dose exhibited a significant reduction in duration of immobility in tail suspension test which provided additional evidence of antidepressant effect of C. speciosus rhizome. Conclusions: Our study indicates that C. speciosus rhizome possesses CNS depressant, anxiolytic and antidepressant-like activities. Further studies are warranted determine the exact phytoconstituents and mechanism of action responsible for the neuropharmacological effect.

Objective: To analyze in-vitro antimicrobial activities of some ethno-pharmacologically significant medicinal plants (methanol extract) against the pathogenic microorganisms (Escherichia coli, Salmonella spp., Bacillus cereus, Staphylococcus aureus, Aspergillus niger and Candida albicans). Methods: The disc diffusion method was applied for antibacterial test and the poisoned food technique was applied for antifungal test. Results: The methanol extract of Terminalia chebula (bark), Phyllanthus acidus (fruits), Sarcochlamys pulcherrima (leaves) and Abelmoschus esculentus (fruits) had significant in vitro antibacterial activity angainst the entire test samples in comparison to standard drug ciprofloxacin. Most of the plant extracts showed low activity against Gram negative bacteria while potential activity against Gram positive bacteria. The antifungal activities of methanol extracts of these plants and standard drug griseofulvin were determined against two pathogenic fungi, and Polygonum lapathifolium (leaves) and Cinnamomum tamala (leaves) showed maximum activity, while Erioglossum rubiginosum (leaves) showed no antifungal activity. Conclusions: Further chemical and pharmacological investigations are required to identify and isolate chemical constituents responsible for these potential bioactivities and thus to determine their full spectrum of efficacy.