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The metabolic profiles of Panax quinquefolius and its associated therapeutic values are critically affected by the repetitious steaming times. The times-dependent steaming effect of P. quinquefolius is not well-characterized and there is also no official guideline on its times of steaming. In this paper, a UPLC-Q-TOF-MS/MS method was developed for the qualitative profiling of multi-parametric metabolic changes of raw P. quinquefolius during the repetitious steaming process. Our method was successful in discriminating the differentially multi-steamed herbs. Meantime, the repetitious steaming-inducing chemical transformations in the preparation of black American ginseng (American ginseng that was subjected to 9 cycles of steaming treatment) were evaluated by this UPLC-Q-TOF-MS/MS based chemical profiling method. Under the optimized UPLC-Q-TOF-MS/MS conditions, 29 major ginsenosides were unambiguously identified and/or tentatively assigned in both raw and multi-steamed P. quinquefolius within 19 min, among them 18 ginsenosides were detected to be newly generated during the preparatory process of black American ginseng. The mechanisms involved were further deduced to be hydrolysis, dehydration, decarboxylation and addition reactions of the original ginsenosides in raw P. quinquefolius through analyzing mimic 9 cycles of steaming extracts of 14 pure reference ginsenosides. Our novel steaming times-dependent metabolic profiling approach represents the paradigm shift in the global quality control of multi-steamed P. quinquefolius products.

A high performance liquid chromatographyelectrospray tandem mass spectrometry (HPLC-ESI-MS/ MS n ) based chemical profiling method was developed to evaluate repetitious steaming-induced chemical transformations in black ginseng (BG and Korean white ginseng subjected to nine cycles of steam treatment). Under the optimized HPLC and ESI-MS/MS n conditions, more than 13 and 17 peaks were separated and detected in white ginseng (WG) and BG within 85 min, respectively. The components were identified by comparing the mass spectrum and/or matching the empirical molecular formula with that of known published compounds. In total, 17 major ginsenosides were identified in BG, 16 of which were determined to be newly generated during the BG preparatory process. The mechanisms involved were further deduced to be hydrolysis, dehydration, isomerization, and decarboxylation reactions of the original ginsenosides in WG by analyzing nine mimic cycles of steaming extracts of seven pure reference ginsenosides. A significant difference in chemical profiles between BGs developed from two batches of WG suggested that storage duration significantly influenced the quality consistency of not only the crude drug but also the BG derived from WG.

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