Localization of constituents for determining the age and parts of ginseng through ultraperfomance liquid chromatography quadrupole/time of flight-mass spectrometry combined with desorption electrospray ionization mass spectrometry imaging

Ginseng has been used for prevention and treatment of disease for thousands of years in China and many other Asian countries. Phytochemical studies have indicated that ginsenosides, polysaccharides, alkaloids, and phenolic acids are the active constituents of ginseng. Main and branch roots of ginseng exhibit distinct bioactive behavior. Furthermore, the bioactive behavior of ginseng depends on its age. Traditional analysis is complex preparation and provides inadequate of chemical information of the original distribution of analytes. Therefore, in this study, ultraperformance liquid chromatography quadrupole/time of flight-mass spectrometry (UPLC-QTOF MS) and desorption electrospray ionization mass spectrometry imaging (DESI-MSI) combined with orthogonal partial least squares discriminant analysis were used to discriminate ginseng in different age and parts of ginseng, and profiled distribution of selected markers. The results indicated that UPLC-QTOF-MS and DESI-MSI could be used to determine the parts and age of ginseng. Fifteen variables including five of protopanaxatriol (PPT), four of protopanaxadiol (PPD), and six of other types were assumed as markers for different parts of ginseng. Moreover, four variables of PPT, four of PPD, and ten of other types were used to determine the age of ginseng samples. An analysis of localization of markers indicated that malonyl ginsenoside, including malonyl-ginsenoside Rb1, Rb2, Rc, and Rd was mainly distributed in the corks. Neutral ginsenoside Rg1, yesanchinoisde D, and chikusetsusaponin Iva were mainly distributed in the cork and phloem. Non-ginsenoside castanoside H, 20(S)-protopanaxatriol, unknown 2, saponin III and cistanoside C were distributed in all tissues. Ethyloleate, unknown 1 and monolinolein were distributed in the cork.