methysticin and dihydrokavain

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

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