Abstract
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 (4), dihydromethysticin (5), kavain (6), 7,8-dihydrokavain (7), 5,6-dehydrokavain (8), 5,6-dehydromethysticin (9) and yangonin (10), 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 (1), 7,8-dihydro-5-hydroxy-kavain (2), 11,12-dimethoxydihydrokavain (3), and flavokavains A, B and C (19, 20, 21). 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.
Key words
High performance liquid chromatography (HPLC) - electrospray - mass spectrometry -
Piper methysticum
- Piperaceae - plant drug analysis
