Electrospray high performance liquid chromatography-mass spectrometry in phytochemical analysis of kava (Piper methysticum) extract.

HPLC coupled with electrospray (ES) MS was used to study a chloroform extract from kava roots ( PIPER METHYSTICUM). A total of thirteen kavalactones and flavokavains were identified. Seven major kavalactones, methysticin, dihydromethysticin, kavain, 7,8-dihydrokavain, 5,6-dehydrokavain, 5,6-dehydromethysticin and yangonin, were easily recognized in the extract by their [M + H] (+) or [M + Na] (+) ions, UV spectra, and retention times, compared with those of standard compounds. Six minor constituents were isolated as our own reference compounds. These constituents were identified by their [M + H] (+) or [M + Na] (+) ions, UV spectra and NMR data as 11 -hydroxy-12-methoxydihydrokavain, 7,8-dihydro-5-hydroxy-kavain, 11,12-dimethoxydihydrokavain, and flavokavains A, B and C. HPLC-ES-MS appears to be a suitable technique for identification of kavalactones and kavachalcones in the kava extract. The method also provides direct guidance for identification of other trace constituents from kava extracts.