Use of liquid chromatography–electrospray ionization tandem mass spectrometry to identify diarylheptanoids in turmeric (Curcuma longa L.) rhizome

LC–ESI-MS/MS coupled to DAD analysis was used as an on-line tool for identification of diarylheptanoids in fresh turmeric rhizome extracts. Based on their mass spectra, from both negative and positive mode LC–ESI-MS/MS analysis, and supported by their DAD spectra, 19 diarylheptanoids were identified. Among these 19 compounds, curcumin, demethoxycurcumin, and bisdemethoxycurcumin were identified by comparing their chromatographic and spectral data with those of authentic standard compounds. The other diarylheptanoid compounds were identified or tentatively identified based on comparison to the three curcuminoids and each other. Twelve of the identified diarylheptanoids have not been previously reported from turmeric and six of these are new compounds.