Comparative Metabolomic Analysis Reveals Tissue- and Species-Specific Differences in the Abundance of Dammarane-Type Ginsenosides in Three Panax Species

The genus Panax contains traditional herbs that have been widely used in traditional medicine. The active constituents, collectively known as ginsenosides, are well characterized in the most representative species, P. notoginseng. However, the major bioactive chemical constituents of P. stipuleanatus together with P. vietnamensis are relatively less studied. In this study, an untargeted metabolomic analysis was performed in P. notoginseng, P. stipuleanatus, and P. vietnamensis using root and leaf organs. Further metabolomic differences in P. stipuleanatus were compared with those of the two most prevalent species. The analysis results revealed tissue-specific qualitative and quantitative metabolic differences in each species. Several differentially accumulated metabolites were enriched in the biosynthesis of secondary metabolites, including the biosynthesis of ginsenosides I. The ginsenosides Rb1, Rf, Rg1, Rh1, Rh8, and notoginsenosides E, M, and N had a higher abundance level in the roots of both P. notoginseng and P. vietnamensis. In P. stipuleanatus, the accumulation of potentially important ginsenosides is mainly found in the leaf. In particular, the dammarane-type ginsenosides Rb3, Rb1, Mx, and F2 as well as the notoginsenosides A, Fe, Fa, Fd, L, and N were identified to have a higher accumulation in the leaf. The strong positive correlation network of different ginsenosides probably enhanced secondary metabolism in each species. The comparative analysis revealed a significant differential accumulation of metabolites in the leaves of both species. The various compounds of dammarane-type ginsenoside, such as Rb1, Rg1, Rg6, Rh8, Rh10, Rh14, and majoroside F2, had a significantly higher concentration level in the leaves of P. stipuleanatus. In addition, several notoginsenoside compounds such as A, R1, Fe, Fd, and Ft1 showed a higher abundance in the leaf. These results show that the abundance level of major ginsenosides is significant in P. stipuleanatus and provides an important platform to improve the ginsenoside quality of Panax species.