Medicinal Plant Research 2025, Vol.15, No.5, 197-205 http://hortherbpublisher.com/index.php/mpr 198 This study analyzed the research progress in the biosynthetic pathways of ginsenosides and polysaccharides in recent years, summarized the role of precursor metabolic pathways, key enzymes, regulatory factors, and multi-omics methods in revealing the biosynthetic network. Meanwhile, the latest progress in synthetic biology and metabolic engineering strategies for increasing the yield of metabolites was sorted out. By integrating basic research with potential applications, this study emphasizes the significant importance of biosynthesis research in the efficient utilization of ginseng resources, industrial development, and the modernization process of traditional medicines. 2 Biosynthetic Pathways of Ginsenosides in Ginseng 2.1 Precursors and primary metabolic pathways Biosynthesis of ginsenosides is triggered by the formation of isoprenoid precursors, isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP), via two distinct pathways: the cytosolic mevalonate (MVA) pathway and the plastidic methylerythritol phosphate (MEP) pathway. Both these pathways participate in the biosynthesis of ginsenosides in ginseng roots, while the MEP pathway is more active in leaves. Specifically, the IspD enzyme was identified as a candidate rate-limiting step of the MEP pathway, and its expression level was correlated with ginsenoside accumulation in different tissues (Xue et al., 2019; Yang et al., 2020). 2.2 Key rate-limiting enzymes and their regulation Key enzymes such as 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), squalene synthase (SS), squalene epoxidase (SE), and dammarenediol-II synthase (DS) are in charge of controlling the metabolic pathway toward ginsenoside biosynthesis. Environmental conditions, especially blue and red light, can strongly stimulate the expression of these genes, thereby the ginsenoside accumulation in leaves and roots (Di et al., 2023; Liu et al., 2023). Transcription factors (e.g., MYC2, GRAS) and microRNAs likewise control expression of these biosynthetic genes with developmental and environmental signals integrated (Eom and Hyun, 2025; Wang et al., 2025). 2.3 Cytochrome P450 enzymes and glycosyltransferases involved in triterpenoid saponin biosynthesis Cytochrome P450 monooxygenases (specifically the CYP716A family) introduce hydroxyl moieties onto the triterpene framework, and UDP-glycosyltransferases (UGTs) introduce sugar moieties, creating the structural diversity of ginsenosides. Some UGTs were recently identified and characterized, including UGT94 and UGT73 families, which are responsible for specific glycosylation reactions in both protopanaxadiol (PPD) type and protopanaxatriol (PPT) type ginsenosides (Hou et al., 2022; Zhang et al., 2022; Yuan et al., 2024; Yu et al., 2024). Synthetic biology advances have also enabled these pathways to be recreated in yeast to produce ginsenosides in high yields (Jiang et al., 2022; Li et al., 2022). 2.4 Tissue specificity and secondary metabolic regulation of ginsenoside biosynthesis Ginsenoside biosynthesis is strongly tissue-specific and developmentally regulated. Gene expression and ginsenoside accumulation vary among roots, leaves, and flowers, of which the most significant ginsenoside storage tissue are the roots (Xue et al., 2019; Di et al., 2023; Liu et al., 2023). Environmental factors (e.g., light quality) and hormone also control gene expression and metabolite accumulation. Transcription factors and microRNAs are also major regulators of the ginsenoside biosynthetic fine-tuning against developmental and environmental cues (Eom and Hyun, 2025; Wang et al., 2025) (Figure 1). 3 Biosynthetic Pathways of Ginseng Polysaccharides 3.1 Classification and structural characteristics of ginseng polysaccharides Ginseng polysaccharides are complex biological macromolecules composed of various monosaccharide units connected by glycosidic linkages. They are mainly classified into neutral and acidic polysaccharides, and their composition differs depending on the plant part (roots, leaves, flowers, berries) and cultivation conditions. Glucose is the predominant monosaccharide, with other sugars such as rhamnose, arabinose, galactose, galacturonic acid, and mannose present in varying proportions. Their structure, including branching patterns and uronic acid content, is directly linked to their biological activities like immunomodulation and antioxidant activities (Guo et al., 2020; Ji et al., 2020; Fang et al., 2022).
RkJQdWJsaXNoZXIy MjQ4ODYzNA==