Characterization and identification of diarylheptanoids in ginger (Zingiber officinale Rosc.) using high-performance liquid chromatography/electrospray ionization mass spectrometry

In our continuing investigation of diarylheptanoids in Zingiberaceae plants using liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS/MS), 26 diarylheptanoids were identified from fresh ginger rhizome. Of the 26 compounds, 15 diarylheptanoids appear to be new compounds. In addition, the majority of these compounds (18) were acetylated, which is different from our investigation of diarylheptanoids from turmeric, another member of the Zingiberaceae, which did not possess any acetylated diarylheptanoids. In all, five distinct groups (homologous series) of diarylheptanoids were found in extracts from ginger rhizome. These groups were differentiated by structural differences on the heptane skeletons, whereas homologs within each group differed by substitution patterns on the aromatic rings. Diagnostic fragmentation behavior in (+)- and (-)ESI-MS/MS analyses for each group of homologs, as well as information regarding polarity obtained from retention time data, allowed us to classify compounds by group and identify them based on key structural features.