为研究多次蒸晒西洋参中皂苷成分变化及其在组织中的空间分布特征，采用超高效液相色谱四极杆飞行时间串联质谱仪(ultra performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry，UPLC-Q-TOF-MS/MS)对西洋参提取液进行检测和鉴定。采用基质辅助激光解吸电离质谱成像(matrix-assisted laser desorption/ionization mass spectrometry imaging，MALDI-MSI)对西洋参中原型皂苷及其代谢产物的空间分布和时空变化进行可视化分析。UPLC结果显示从 0～9 次蒸制西洋参中共鉴定出 90 种主要人参皂苷，在西洋参的反复蒸晒过程中，极性人参皂苷转化成低极性或非极性人参皂苷，原型皂苷含量减少，稀有皂苷含量增加，主要为人参皂苷 20(S/R)-Rg3、20(S/R)-Rh2、Rk1、Rg5、Rs5、Rs4 等。MALDI-MSI组织分布结果表明生西洋参中皂苷主要分布于表皮及韧皮部，蒸晒过程导致皂苷成分发生转化，木质部和髓质中的分布增加。该研究为西洋参蒸制引起的生物活性和药理作用的变化提供了基础信息，为扩大西洋参的药用范围提供了参考。
Identification and visual analysis of ginsenosides in multi-steamed roots of Panax quinquefolium based on UPLC-Q-TOF-MS/MS and MALDI-MSI
This study aims to investigate the component variations and spatial distribution of ginsenosides in Panax quinquefolium roots during repeated steaming and drying.Ultra performance liquid chromatography quadrupole time-of-flight tandem mass spectrome-try(UPLC-Q-TOF-MS/MS)was employed to identify the ginsenosides in the root extract.Matrix-assisted laser desorption/ionization mass spectrometry imaging(MALDI-MSI)was employed to visualize the spatial distribution and spatiotemporal changes of prototype ginsenosides and metabolites in P.quinquefolium roots.The UPLC results showed that 90 ginsenosides were identified during the steaming process of the roots,and polar ginsenosides were converted into low polar or non-polar ginsenosides.The content of prototype ginsenosides decreased,while that of rare ginsenosides increased,which included 20(S/R)-ginsenoside Rg3,20(S/R)-ginsenoside Rh2,and ginsenosides Rk1,Rg5,Rs5,and Rs4.MALDI-MSI results showed that ginsenosides were mainly distributed in the epider-mis and phloem.As the steaming times increased,ginsenosides were transported to the xylem and medulla.This study provides funda-mental information for revealing the changes of biological activity and pharmacological effect of P.quinquefolium roots that are caused by repeated steaming and drying and gives a reference for expanding the application scope of this herbal medicine.
Panax quinquefoliumrepeated steaming and dryingginsenosideUPLC-Q-TOF-MS/MSMALDI-MSI
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