Acute oral toxicity, antinociceptive and antimicrobial activities of kava dried extracts and synthetic kavain.

Piper methysticum G. Forst, popularly known as kava, is a traditional medicinal plant widely used for the treatment of anxiety and insomnia. The aim of this study was to investigate new therapeutic applications of this plant. Nociceptive response induced by heat (hot-plate) was used as pain model. Susceptibility of different strains to kava ethanolic dried extracts was evaluated by broth microdilution method. Acute oral toxicity was performed according to Organisation for Economic Cooperation and Development (OECD) guideline. Administration of kava dried extracts and kavain inhibited the nociceptive response in the hot-plate model and did not affect the time mice spent in the rota-rod apparatus. The samples showed no significant antibacterial activity, however slight antifungal activity was verified. The extracts may be considered of low oral acute toxicity. Kava extracts exhibited promising antinociceptive activity in model of nociceptive pain, which should be deeper explored as a new therapeutic application of kava.