Chromatographic analyses of gingerol compounds in ginger (zingiber officinale roscoe) extracted by liquid carbon dioxide

The gingerol compounds of freeze-dried ginger (Zingiber officinale Roscoe) were extracted by liquid carbon dioxide (600–700 p.s.i.), isolated by thin-layer chromatography and fractionated into individual gingerol compounds by preparative high-performance liquid chromatography. Two homologous series, 6-, 8-, 10-, 12-, 14-gingerols and methyl-6-, methyl-8-, methyl-10-, methyl-12-gingerols were identified by the combined results of (1) high-performance liquid chromatographic retention in analytical column; (2) molecular ion determination of isolated gingerol compounds by fast atom bombardment-mass spectrometry; (3) gas chromatography and gas chromatography-mass spectrometry analyses of aldehydes and ketones formed from the thermal degradation of the corresponding gingerol compounds. This is the first report of the presence in ginger of 14-gingerol and gingerols with methyl sidechains.