Fragmentation investigation of seven arylnaphthalide lignans using liquid chromatography/tandem quadrupole time-of-flight mass spectrometry

RATIONALE: The combination of fragmentation patterns in positive and negative ion modes could be helpful in understanding the structural features of these arylnaphthalide lignans. METHODS: Fragmentation patterns of seven arylnaphthalide lignans were investigated using liquid chromatography/ tandem time-of-flight mass spectrometry, and their fragmentation pathways were comprehensively characterized. RESULTS: In the positive ion mode, the cleavage of the C-1'-C-7' bond was the most characteristic fragmentation pattern of the lignans with both 2'-hydroxy and 4',5'-methylenedioxy groups on the B ring. Arylnaphthalide lignans containing a methylenedioxy group on the B ring could lose C2H2O2 easily. The characteristic mass losses of 58 Da (C2H2O2) could indicate the presence of a methylenedioxy group on the B ring. In the negative ion mode, the type of substituents at C-7 could affect the cleavage pattern of the lactone ring. CONCLUSIONS: In search for new compounds, and also in quality control, there is a need to have reliable methodology for the analysis of arylnaphthalide lignans. These results should be useful in the analysis of natural products with similar substructures from Chinese herbs in the future. Copyright (C) 2012 John Wiley & Sons, Ltd.