5-6-dehydrokawain and methysticin

Topics: Calibration; Chromatography, High Pressure Liquid; Dietary Supplements; Kava; Lactones; Limit of Detection; Plant Roots; Pyrans; Pyrones

Metabolic pathways for kavalactone metabolism in humans and rats have been identified, but more detailed description of the enzyme kinetics involved is lacking. The disposition profiles of three of the six major kavalactones (kavain, methysticin and desmethoxyyangonin) and their respective metabolites (p-hydroxykavain, m,p-dihydroxykavain and p-hydroxy-5,6-dehydrokavain) were examined in the perfusate and bile of the isolated perfused rat liver. The metabolism of the kavalactones is first-order in nature with similar decay half-lives. p-Hydroxykavain and m,p-dihydroxykavain were the only metabolites detected in the perfusate. Kavalactone biliary excretion was negligible.

Topics: Animals; Bile; Half-Life; In Vitro Techniques; Liver; Male; Perfusion; Pyrans; Pyrones; Rats; Rats, Sprague-Dawley

The specific CYP enzymes involved in kavalactone (KLT) metabolism and their kinetics have not been fully examined. This study used rat liver microsomes (RLM) to determine kavain (KA), methysticin (MTS) and desmethoxyyangonin (DMY) enzyme kinetic parameters, to elucidate the major CYP450 isoforms involved in KLT metabolism and to examine gender differences in KLT metabolism. Formation of the major KLT metabolites was first-order, consistent with classic enzyme kinetics. In both male and female RLM, clotrimazole (CLO) was the most potent inhibitor of KA and MTS metabolism. This suggests CYP3A1/3A23 (females) and CYP3A2 (males) are the main isoenzymes involved in the metabolism of these KLTs in rats, while the roles of CYP1A2, -2 C6, -2 C9, -2E1 and -3A4 are limited. Desmethoxyyangonin metabolism was equally inhibited by cimetidine (CIM) and CLO in females, and CIM and nortriptyline in males. This implies that DMY metabolism involves CYP2C6 and CYP2C11 in males, and CPY2C12 in females. CYP3A1/3A23 may also be involved in females.

Topics: Animals; Aryl Hydrocarbon Hydroxylases; Cytochrome P-450 CYP3A; Female; Isoenzymes; Male; Membrane Proteins; Microsomes, Liver; Pyrans; Pyrones; Rats; Rats, Sprague-Dawley; Sex Factors

Nuclear factor-kappaB (NF-kappaB) is a transcription factor that plays an essential role in cancer development. The results of our recent chemopreventive study demonstrate that kava, a beverage in the South Pacific Islands, suppresses NF-kappaB activation in lung adenoma tissues, potentially a mechanism responsible for kava's chemopreventive activity. Methysticin is identified as a potent NF-kappaB inhibitor in kava with minimum toxicity. Other kava constituents, including four kavalactones of similar structures to methysticin, demonstrate minimum activities in inhibiting NF-kappaB.

Topics: Anticarcinogenic Agents; Antineoplastic Agents, Phytogenic; Cell Line, Tumor; Humans; Kava; NF-kappa B; Pyrans

Three novel, simple and reproducible high-performance liquid chromatography quantitative assays with UV detection were developed and validated for three major kavalactones--desmethoxyyangonin, methysticin and kavain--in rat liver microsomes using diazepam as an internal standard; liquid-liquid extraction was used for sample preparation and analysis was performed on a Shimadzu 10A high-performance liquid chromatography system. The analysis was carried out in reversed-phase mode with a Luna C(18) column (150 x 2.00 mm, 3 microm) at 40 degrees C. The limit of quantitation was 0.1 microg/mL using 0.25 mL of microsomal solution. The assays were linear over the range 0.1-10 microg/mL for desmethoxyyangonin, methysticin and kavain. Quality control samples exhibited good accuracy and precision with relative standard deviations lower than 15% and recoveries between 85 and 105%. The assays exhibited satisfactory performance with high sensitivity for quantifying desmethoxyyangonin, methysticin and kavain in rat liver microsomes and were successfully used to determine the three kavalactones and their microsomal metabolites.

Topics: Animals; Chromatography, High Pressure Liquid; Microsomes, Liver; Molecular Structure; Pyrans; Pyrones; Rats; Reproducibility of Results; Spectrophotometry, Ultraviolet

The chemical composition of kava (Piper methysticum) lactones and various phytochemicals obtained following the sonication of ground kava roots extracted in the solvents hexane, chloroform, acetone, ethanol, methanol and water, respectively, was analyzed. Eighteen kava lactones, cinnamic acid bornyl ester and 5,7-dimethoxy-flavanone, known to be present in kava roots, were identified, and seven compounds, including 2,5,8-trimethyl-1-naphthol, 5-methyl-1-phenylhexen-3-yn-5-ol, 8,11-octadecadienoic acid-methyl ester, 5,7-(OH)(2)-4'-one-6,8-dimethylflavanone, pinostrobin chalcone and 7-dimethoxyflavanone-5-hydroxy-4', were identified for the first time. Glutathione (26.3 mg/g) was found in the water extract. Dihydro-5,6-dehydrokavain (DDK) was present at a higher level than methysticin and desmethoxyyagonin, indicating that DDK is also a major constituent of kava roots. Acetone was the most effective solvent in terms of maximum yield and types of kava lactones isolated, followed by water and chloroform, whereas hexane, methanol, and ethanol were less effective as solvents. Total phenolic and antioxidant activity varied among the extracting solvents, with acetone and chloroform producing the highest effects, followed by water, while methanol, ethanol and hexane were less effective.

Topics: Antioxidants; Biphenyl Compounds; Chalcones; Chromatography, High Pressure Liquid; Free Radical Scavengers; Gas Chromatography-Mass Spectrometry; Glutathione; Kava; Lactones; Phenols; Picrates; Plant Extracts; Plant Roots; Pyrans; Pyrones; Solvents; Sonication

To examine the bioavailability of kavalactones in vitro and the possible differences in their bioavailability because of variations in either chemical structure or the method of extraction used.. Caco-2 cell monolayers were used to determine the potential bioavailability of kavalactones. Kavalactones were added to the apical layer and basolateral samples were taken over 150 min to examine the concentration diffusing across the cell monolayer. Kavalactone concentrations in these samples were determined by high pressure liquid chromatography.. Kavalactones were found to be potentially bioavailable as they all readily crossed the Caco-2 monolayers with apparent permeabilities (P(app)) increasing from 42 x 10(-6) cm/s and most exhibiting more than 70% crossing within 90 min. Not all differences in their bioavailability can be related to kavalactone structural differences as it appears that bioavailability may also be affected by co-extracted compounds. For example, the P(app) for kawain from ethanol extracts was higher than the values obtained for the same compound from water extracts or for the kavalactone alone.. While the extraction method used (ethanol or water) influences the total (but not the relative) concentrations of kavalactones, it does not markedly affect their bioavailability. Hence, any differences between an ethanolic or an aqueous extract in terms of the propensity of kava to cause liver damage is not because of differing kavalactone bioavailabilities.

Topics: Biological Availability; Biological Transport; Caco-2 Cells; Cell Membrane Permeability; Chromatography, High Pressure Liquid; Humans; Kava; Kinetics; Lactones; Models, Biological; Molecular Structure; Plant Extracts; Pyrans; Pyrones; Rhizome

In recent years, Kava kava (Piper methysticum, Forst. f., Piperaceae), a folkloric beverage and popular herbal remedy, has been implicated in a number of liver failure cases. Many hypotheses as to the mechanism of its hepatotoxicity, for example interactions with other co-ingested medication, have been postulated. This present study investigated whether pharmacokinetic interactions between kava constituents and alcohol via alcohol dehydrogenase (ADH) inhibition by individual kavalactones might explain its claimed hepatotoxic effects. Four kavalactones, (+/-)-kavain, methysticin, yangonin and desmethoxyyangonin, fail to inhibit ADH in vitro at 1, 10 or 100 microM concentrations.

Topics: Alcohol Dehydrogenase; Alcohol Drinking; Chemical and Drug Induced Liver Injury; Herb-Drug Interactions; Kava; Lactones; Plant Extracts; Pyrans; Pyrazoles; Pyrones; Spectrophotometry

A simultaneous HPLC separation of the enantiomers of kavain, dihydrokavain, methysticin and dihydromethysticin, as well as the achiral dienolides yangonin and desmethoxyyangonin was carried out on a ChiraSpher NT column. For quantitative determinations, calibration curves with correlation coefficients between 0.9982 and 0.9996 were established for the genuine kavapyrones. Detection limits between 0.25 microg and 0.5 microg per injection were measured at 240 nm. The defined scopes of work corresponded with the different kavapyrone amounts, depending on growth factors of distinct plant locations. The precision of the method was verified by analysing a phytopharmacon with a nominal value of 40 mg kavapyrones per tablet. The evaluation revealed 39.62 mg per tablet by the sum of single calculated kavapyrones. Relative standard deviations between 1.06% and 2.39% were found for the compounds under investigation. The accuracy of the method was proved by a recovery of 99.7%. To simplify the determination of the total kavapyrone amount, response factors and correlation factors for (+)-dihydrokavain, (+)-methysticin, (+)-dihydromethysticin, yangonin and desmethoxyyangonin were calculated relative to (+)-kavain.

Topics: Anti-Anxiety Agents; Chromatography, High Pressure Liquid; Pyrans; Pyrones; Reproducibility of Results; Sensitivity and Specificity; Stereoisomerism