kavain and dihydrokavain

Kava, the rhizomes and roots of Piper methysticum Forst, is a popular edible medicinal herb traditionally used to prepare beverages for anxiety reduction. Since the German kava ban has been lifted by the court, the quality evaluation is particularly important for its application, especially the flavokawains which were believed to be responsible for hepatotoxicity. Now, by employing two different standard references and four different methods to calculate the relative correction factors, eight different quantitative analyses of multicomponents by single-marker methods have been developed for the simultaneous determination of eight major kavalactones and flavokawains in kava. The low standard method difference on quantitative measurement of the compounds among the external standard method and ours confirmed the reliability of the mentioned methods. A radar plot clearly illustrated that the contents of dihydrokavain and kavain were higher, whereas flavokawains A and B were lower in different kava samples. Only one of eight samples did not detect flavokawains that may be related to hepatotoxicity. In summary, by using different agents as an internal standard reference, the developed methods were believed as a powerful analytical tool not only for the qualitative and quantitative of kava constituents but also for the other multicomponents when authentic standard substances were unavailable.

Topics: Chalcone; Chromatography, High Pressure Liquid; Dietary Supplements; Kava; Lactones; Phytotherapy; Plant Extracts; Plant Roots; Plants, Medicinal; Pyrones

Kava is regaining its popularity with detailed characterizations warranted. We developed an ultraperformance liquid chromatography high-resolution tandem mass spectrometry (UPLC-MS/MS) method for major kavalactones (kavain, dihydrokavain, methysticin, dihydromethysticin and desmethoxyyangonin) with excellent selectivity and specificity. The method has been validated for different matrices following the Food and Drug Administration guidance of analytical procedures and methods validation. The scope of this method has been demonstrated by quantifying these kavalactones in two kava products, characterizing their tissue distribution and pharmacokinetics in mice, and detecting their presence in human urines and plasmas upon kava intake. As expected, the abundances of these kavalactones differed significantly in kava products. All of them exhibited a large volume of distribution with extensive tissue affinity and adequate mean residence time (MRT) in mice. This method also successfully quantified these kavalactones in human body fluids upon kava consumption at the recommended human dose. This UPLC-MS/MS method therefore can be used to characterize kava products and its pharmacokinetics in animals and in humans.

Topics: Animals; Humans; Kava; Lactones; Male; Mice; Mice, Inbred C57BL; Pyrones; Radioisotope Dilution Technique; Tandem Mass Spectrometry; Tissue Distribution; Urinalysis

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

Topics: Chromatography, Supercritical Fluid; Kava; Lactones; Molecular Structure; Plant Roots; Pyrans; Pyrones

There is a substantial unmet need for new classes of drugs that block TNF-alpha-mediated inflammation, and particularly for small molecule agents that can be taken orally. We have screened a library of natural products against an assay measuring TNF-alpha secretion in lipopolysaccharide-stimulated THP-1 cells, seeking compounds capable of interfering with the TNF-alpha-inducing transcription factor lipopolysaccharide-induced TNF-alpha factor. Among the active compounds were several produced by the kava plant (Piper mysticum), extracts of which have previously been linked to a range of therapeutic effects. When tested in vivo, a representative of these compounds, kavain, was found to render mice immune to lethal doses of lipopolysaccharide. Kavain displays promising pharmaceutical properties, including good solubility and high cell permeability, but pharmacokinetic experiments in mice showed relatively rapid clearance. A small set of kavain analogs was synthesized, resulting in compounds of similar or greater potency in vitro compared with kavain. Interestingly, a ring-opened analog of kavain inhibited TNF-alpha secretion in the cell-based assay and suppressed lipopolysaccharide-induced TNF-alpha factor expression in the same cells, whereas the other compounds inhibited TNF-alpha secretion without affecting lipopolysaccharide-induced TNF-alpha factor levels, indicating a potential divergence in mechanism of action.

Topics: Animals; Anti-Inflammatory Agents; Cell Line, Tumor; Humans; Kava; Lipopolysaccharides; Mice; Plant Extracts; Pyrones; Tumor Necrosis Factor-alpha

An efficient catalytic asymmetric hetero-Diels-Alder reaction of Brassard's diene with aliphatic aldehydes was reported. The catalyst, which was generated from (R)-BINOL, Ti(i-PrO)4, and 4-picolyl chloride hydrochloride, promoted the reaction smoothly to afford the corresponding alpha,beta-unsaturated delta-lactone derivatives in moderate-to-good yields (46-79%) with high enantioselectivities (up to 88% ee). Natural products (R)-(+)-kavain (70% ee, >99% ee after single recrystallization) and (S)-(+)-dihydrokavain (84% ee) were also prepared in one step by using this methodology.

Topics: Aldehydes; Pyrones; Stereoisomerism

Root extracts from kava-kava (Piper methysticum G. Forst) are clinically used for the treatment of anxiety and restlessness. Due to reported cases of liver toxicity, kava-kava extracts were withdrawn from the market in several countries in 2002. Because the efflux transporter P-glycoprotein (P-gp) is involved in the absorption, distribution, and excretion of many drugs and often participates in drug-drug interactions, we studied the effect of a crude kava extract and the main kavalactones kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin on the P-gp-mediated efflux of calcein-acetoxymethylester in the P-gp-overexpressing cell line P388/dx and the corresponding cell line P388. The crude extract and the kavalactones showed a moderate to potent inhibitory activity with f2) (concentration needed to double baseline fluorescence) values of 170 microg/ml and 17 to 90 microM, respectively. The f2 value of yangonin could not be determined due to its higher lipophilicity. In conclusion, our results for the first time demonstrate P-gp-inhibitory activity of kava-kava and its components in vitro.

Topics: Animals; Anti-Anxiety Agents; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cell Line, Tumor; Dose-Response Relationship, Drug; Fluoresceins; Kava; Lactones; Leukemia P388; Mice; Plant Extracts; Plant Roots; Pyrones; Transfection

Inhibitors of cytochrome P450 3A4 (CYP3A4) were identified in crude extracts from the rhizomes of Piper methysticum G. Forst. (Kava-Kava) using bioassay-guided fractionation. After preliminary purification of an ethyl acetate extract with solid phase extraction, the eluate was further fractionated by means of HPLC and fractions were tested for inhibitory potency using cDNA expressed CYP3A4. Positive fractions were analysed with LC/MS using electrospray ionisation and kavapyrones could be identified as the main CYP3A4 inhibitory components of Piper methysticum.

Topics: Anisoles; Chromatography, High Pressure Liquid; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme Inhibitors; Kava; Lactones; Mass Spectrometry; Molecular Structure; Phytotherapy; Plant Extracts; Pyrans; Pyrones; Rhizome

Methanolic leaf and root extracts of the Hawaiian kava (Piper methysticum Forst.) cultivars, Mahakea, Nene, Purple Moi and PNG, were tested on binding affinities to CNS receptors including GABAA (GABA and benzodiazepine binding site), dopamine D2, opioid (mu and delta), serotonin (5-HT6 and 5-HT7) and histamine (H1 and H2). HPLC analysis was carried out in order to determine the amount of the main kavalactones kavain, 7,8-dihydrokavain, methysticin, 7,8-dihydromethysticin, yangonin and 5,6-demethoxyyangonin. The most potent binding inhibition was observed for leaf extracts to GABAA receptors (GABA binding site) with IC50 values of approximately 3 micrograms/ml, whereas root extracts were less active with IC50 values ranging from 5 micrograms/ml (Nene) to 87 micrograms/ml (Mahakea). Since the leaf extracts generally contained lower amounts of the kavalactones than the root extracts, there might exist additional substances responsible for these activities. Leaf extracts also inhibited binding to dopamine D2, opioid (mu and delta) and histamine (H1 and H2) receptors more potently than the corresponding root extracts with IC50 values ranging from 1 to 100 micrograms/ml vs. > or = 100 micrograms/l, respectively. Significant differences in the potential of binding inhibition were also observed between cultivars. Binding to serotonin (5-HT6 and 5-HT7) and benzodiazepine receptors was only weakly inhibited by both root and leaf extracts of all four cultivars. In conclusion, our investigation indicates that the GABAA, dopamine D2, opioid (mu and delta) and histamine (H1 and H2) receptors might be involved in the pharmacological action of kava extracts. Since the cultivars contained similar amounts of kavalactones, while their pharmacological activities differed markedly, other constituents may play a role in the observed activities. Additionally, leaves generally exhibited more potent binding inhibition than roots, therefore leaf of P. methysticum might be an interesting subject for further pharmacological studies.

Topics: Animals; Brain; Cattle; Cells, Cultured; Chromatography, High Pressure Liquid; Cricetinae; Dose-Response Relationship, Drug; Humans; In Vitro Techniques; Kava; Plant Extracts; Plant Leaves; Plant Roots; Plants, Medicinal; Pyrans; Pyrones; Rats; Rats, Inbred Strains; Rats, Wistar; Receptors, Dopamine D2; Receptors, GABA-A; Receptors, Histamine; Receptors, Opioid; Receptors, Serotonin; Semliki forest virus

The mode of action of the kava pyrones, kavain, dihydrokavain and dihydromethysticin on the specific binding of [3H]-batrachotoxinin-A 20-alpha-benzoate to epitope 2 of voltage-dependent Na+ channels was investigated by performing saturation experiments in the presence and absence of these kava pyrones. The tested compounds significantly decreased the apparent total number of binding sites (Bmax) for [3H]-batrachotoxinin-A 20-alpha-benzoate (control: 0.5 pmol/mg protein, kava pyrones: 0.2-0.27 pmol/mg protein) with little change in the equilibrium constants (KD) for [3H]-batrachotoxin-A 20-alpha-benzoate (control: 28.2 nM, kava pyrones: 24-31 nM). The results indicate for the kava pyrones a non-competitive inhibition of the specific [3H]-batrachotoxinin-A 20-alpha-benzoate binding to receptor site 2 of voltage-gated Na+ channels.

Topics: Animals; Batrachotoxins; Cerebral Cortex; Ion Channel Gating; Male; Protein Binding; Pyrones; Rats; Rats, Wistar; Sodium Channels; Synaptosomes; Tritium