Biopharmaceutical evaluation of kavain in Piper methysticum G. Forst dried extract: Equilibrium solubility and intestinal permeability in Caco-2 cell model.

ETHNOPHARMACOLOGICAL RELEVANCE: Piper methysticum G. Forst, popularly known as kava, is a traditional medicinal plant native from South Pacific islands and widely used to treat anxiety, depression and stress. The psychoactive properties are related to the kavalactones, mainly kavain. AIM OF THE STUDY: To evaluate the biopharmaceutical properties of synthetic kavain and when present in kava dried extracts by means of equilibrium solubility and intestinal permeability studies in the Caco-2 cell model. MATERIALS AND METHODS: The equilibrium solubility of kavain was performed using a shake flask incubator at 37 °C in different media at physiological pH range (1.2-6.8). The intestinal permeability of kavain evaluated in Caco-2 cells in the presence and absence of the P-glycoprotein inhibitor verapamil. Kavain concentrations were determined by reversed phase high performance liquid chromatography (HPLC). RESULTS: HPLC methods were developed and fully validated for kavain quantitation. Kavain demonstrated low solubility and the pH of the aqueous media did not affect its solubility. Kavain was found to be highly permeable and efflux of kavain mediated by P-glycoprotein was not significant during intestinal permeation. CONCLUSION: The results of biopharmaceutical studies provided useful information for predicting availability of kavain from the gastrointestinal tract and this compound was ranked as BCS Class II, exhibiting dissolution rate-limited absorption.

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.

Simultaneous quantitation of kavalactones in kava dry extracts: comparison of multi-standards and single standard validation approaches.

INTRODUCTION: Dried extracts of Piper methysticum G. Forst, also known as kava, has been widely used due to its anxiolytic and sedative properties. In order to assure the quality of these extracts, it is essential to accurately quantify kavalactones, known as the active principle. OBJECTIVES: To develop and validate an analytical method for the simultaneous quantification of six major kavalactones (kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin and demethoxyyangonin) in kava extracts, comparing multi-standards and single standard validation approaches. MATERIAL AND METHODS: Separation was performed using a C18 column, water/methanol/acetonitrile/2-propanol (66:07:09:18 v/v/v/v) and detection at 245 and 350 nm. A full method validation was performed, employing analytical standards for each compound. Commercial kava dried extracts were assayed and the results obtained using the method validated for six kavalactone standards were compared with those obtained when only kavain was used as standard. RESULTS: Baseline resolution for all kavalactones was obtained in short run time (15 min). Although the total kavalactone content varied between samples, a similar distribution profile was observed. When the method validated with all six analytical standards was compared to the calibration using only kavain standard, kavalactone contents were considerably different (from 7.57 to 36.53%). CONCLUSION: The obtained results demonstrate the importance of a validated method using individual kavalactone standards for the effective quality control of kava extracts. In a next step, the method needs to be adapted to also include flavokavin B (FKB), as an important authentication marker to distinguish between the accepted variety "noble Kava" and the toxic "two-day Kava".

Liquid chromatography-tandem mass spectrometry bioanalytical method for the determination of kavain in mice plasma: Application to a pharmacokinetic study.

A simple and fast bioanalytical method for the quantification of kavain in mice plasma was developed using liquid chromatography (LC)-tandem mass spectrometry (MS/MS). A full method validation was performed, according to regulatory guidelines, employing isotopically labeled kavain as the internal standard (racemic-kavain-d3). For the quantification, [M+H]+ was formed using an electrospray ionization (ESI) source in the positive ion mode and multiple reaction monitoring (MRM) was employed using a quadrupole-linear ion trap (4000 QTRAP®) instrument. The monitored MRM transitions were 231.0 â†’ 115.1 and 231.0 â†’ 152.8 for kavain; and 234.2 â†’ 199.2 for the internal standard. A linear response was obtained at the concentration range of 10 to 200 ng/mL with intra- and inter-day variations within the acceptable criteria for all quality control samples. After validation, the method was successfully applied for the quantification of kavain in mice plasma after oral administration of the kavain standard and Kava-kava extract. The plasma concentration over time results were applied for a pharmacokinetics study. The obtained pharmacokinetic parameters indicated a considerably higher bioavailability for kavain when Kava-kava extract was administered due to a pharmacokinetic synergism between the analyte and the other compounds present in the extract.