Species belonging to the genus Panax are highly vulnerable to surrounding environmental conditions and frequently encounter continuous-cropping obstacle (CCO) issues when grown on a large scale. Ginsenosides, which constitute the chief active ingredients in the roots of these plants, function as important allelochemicals that promote CCO. Previous investigations tracked the fate of Panax notoginseng (PN, also called Sanqi ginseng) constituents in rhizosphere soil mainly through LC-based analysis and standard chromatographic isolation. The current research employs more powerful analytical strategies to uncover the transformed products (TPs) arising from ginsenosides in this soil environment. An approach integrating UPLC-MS² with molecular networking (MN) was implemented to mine for TPs generated in Sanqi rhizosphere soil following supplementation with ginsenosides. Detailed structural characterization of the resulting substances relied on extensive chromatographic purification combined with spectroscopic methods, informed by the MN data. The isolates were subsequently evaluated for their ability to suppress growth of four key probiotic and pathogenic fungi linked to PN, thereby clarifying their contribution to CCO. Through UPLC-MS² data processed via MN, researchers anticipated the formation of 20 nortriterpenoid dimers incorporating 11 varied moiety classes within the ginsenoside-amended Sanqi rhizosphere soil. Leveraging these insights, 16 nortriterpenoids were successfully purified and structurally determined, consisting of 13 dimers designated notoginsenoids T8−T20 and 3 monomers labeled T21−T23. These substances demonstrated clear growth-suppressing activity toward fungi obtained from Sanqi rhizosphere soil. For the first time, this work thoroughly maps both the structural variety and the biotransformation routes of ginsenosides within the plant rhizosphere, delivering novel understanding of allelopathic processes.
