Medicinal Plant Research 2025, Vol.15, No.1, 1-11 http://hortherbpublisher.com/index.php/mpr 2 impacts, potentially offering therapeutic benefits for diseases such as obesity, diabetes, and cancer (Chang et al., 2015; Sang et al., 2021). These interactions may have profound implications for developing novel therapeutic strategies aimed at enhancing immune health through dietary interventions. This study explores the interaction between Ganoderma lucidumpolysaccharides (GLPs) and gut microbiota, and their effects on immune health, particularly focusing on how GLPs regulate the composition and function of gut microbiota, identifying microbial metabolites involved in immune modulation, and assessing their overall impact on immune function. The study anticipates that GLPs will promote the growth of beneficial gut bacteria, improve gut barrier integrity, and modulate immune responses, thereby offering potential therapeutic strategies for immune-related diseases. This study attempts to provide new insights into the role of dietary polysaccharides in regulating the gut microbiota and supporting immune health, while also offering theoretical foundations and references for the development of disease interventions based on GLPs. 2 Chemical Composition and Biological Activities of Ganoderma lucidumPolysaccharides 2.1 Structural characteristics Ganoderma lucidum polysaccharides (GLPs) are composed of various monosaccharides, including glucose, galactose, and mannose. Their specific composition varies depending on the extraction method and the part of the G. lucidumused. For instance, GLP-1 and GLP-2 are purified fromG. lucidumvia gradient ethanol precipitation and anion-exchange chromatography, respectively (Li et al., 2019). Structural characterization has shown that GLP-1 is a D-galactoglucan containing →6)-β-D-glucose (Glcp)- and →6)-α-D-galactose (Galp)- residues, with a random linear conformation. In contrast, GLP-2 is a spherical β-D-glucan composed of →6)-β-D-Glcp and →3)-β-D-Glcp residues. The molecular weight of Ganoderma lucidumpolysaccharides (GLPs) ranges from several thousand to millions, which significantly affects their biological functions. GLPs exhibit various structural features, including both linear and branched conformations. For example, GLP-1, with a flexible random linear conformation, demonstrates superior immunomodulatory activity, effectively protecting the spleen and thymus, promoting hematopoiesis, and increasing serum IgA levels (Li et al., 2019). On the other hand, GLP-3, extracted from Ganoderma lucidum, is a spherical polysaccharide with immunomodulatory properties. Its main chain is composed of α-D-glucose, and research has shown that GLP-3 enhances immune regulation by activating specific signaling pathways, which is related to its tertiary helical structure (Gao et al., 2020). 2.2 Immunomodulatory effects Studies have found that Ganoderma lucidum polysaccharides (GLPs) can activate innate immune cells. For example, GLPs can regulate macrophage polarization through the MAPK/NF-κB signaling pathway, enhancing the expression of the M1 phenotype (pro-inflammatory) and inhibiting the M2 phenotype (anti-inflammatory), thereby suppressing tumor cell growth (Li et al., 2018; 2023). Additionally, GLPs can modulate the gut microbiota by inhibiting the TLR4/MyD88/NF-κB signaling pathway, improving intestinal barrier function, reducing the expression of inflammatory markers, and thus alleviating colonic inflammation and tumorigenesis (Guo et al., 2021). GLPs can modulate the production of various cytokines, which are signaling molecules that mediate and regulate immunity, inflammation, and hematopoiesis. For example, GLP treatment has been shown to downregulate pro-inflammatory cytokines such as IL-1β, iNOS, and COX-2, thereby reducing inflammation (Guo et al., 2021). And GLPs can enhance the production of anti-inflammatory cytokines, contributing to their overall immunomodulatory effects (Li et al., 2019). 2.3 Extraction and purification techniques Hot water extraction (HWE) is one of the most commonly used methods for extracting Ganoderma lucidum polysaccharides. This method involves boiling G. lucidummaterials in water to dissolve the polysaccharides. The extract is then concentrated and purified using techniques such as ethanol precipitation and ion-exchange chromatography (Zheng et al., 2022). This method is highly effective in yielding polysaccharides with significant
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