Distinctive carbohydrate profiles of black ginseng revealed by IM-MS combined with PMP labeling and multivariate data analysis

Despite the widely recognized importance of ginseng carbohydrates, their structural analysis is still challenging due to structural complexity. This study presents the first ion mobility-mass spectrometry (IM-MS) combined with 1-phenyl-3-methyl-5-pyrazolone (PMP) labeling and multivariate data analysis for profiling carbohydrates in the seven ginseng products. 11 carbohydrates were tentatively annotated, including 5 first found in ginseng, and three of them were solely detected in black ginseng (BG) samples, speculated as monosaccharides bearing various groups based on MS(2) analysis. Furthermore, 3D profiles of carbohydrates in IM-MS of the samples showed good discrimination between the varieties of ginseng which were classified into two groups utilizing carbohydrate contents by PLS-DA. The big difference between BG and the others may be ascribed to the repeated heating and steaming process for preparation of BG products. Our findings may provide insights into the differences in bioactivity of different ginseng varieties for future research and show a valuable methodology for discovering unknown carbohydrates.