Quality control and immunological activity of lentinan samples produced in China

Structural Dynamics, Gut Microbiota Modulation, and Immunological Impacts of Shiitake Mushroom β-Glucan during In Vitro Intestinal Fermentation

This study investigated the structure-function relationship of shiitake β-glucan (SBG) through simulated digestion and colonic fermentation. SBG, composed of β-(1 → 3)-linked glucan backbones with β-(1 → 6)-linked side chains, exhibited notable resistance to enzymatic and acidic degradation in the upper gastrointestinal tract. During in vitro colonic fermentation, 59% of carbohydrates were consumed within 48 h, with a significant pH reduction and a 1.5-fold increase in short-chain fatty acid production. Microbiome analysis demonstrated that SBG enhanced Bacteroides and Lactobacillus populations, while suppressing Escherichia-Shigella. Within the first 12 h, SBG maintained a rigid triple-helix structure, with a slight decrease in branching from 48.02 to 44.26%. After 24 h, the triple helix unwound, and extensive depolymerization of the backbone occurred by 48 h. Immunomodulatory activity was preserved early in fermentation but decreased as the triple-helix structure broke down. These findings emphasize the critical role of molecular rigidity and conformational integrity in β-glucan's functionality for food and therapeutic applications.

Lentinan enhances microbiota-derived isoursodeoxycholic acid levels to alleviate hepatic ischemia-reperfusion injury in mice

Hepatic ischemia-reperfusion injury (HIRI) is an essential clinical concern caused by liver transplantation, resection, trauma, and shock that must be addressed immediately. Although the mechanisms underlying HIRI are well-documented, effective prevention and treatment strategies are still lacking. Inflammation is a central mechanism of HIRI, with macrophages playing a crucial role in initiating and amplifying the inflammatory response. Numerous plant polysaccharides exhibit substantial anti-inflammatory and hepatoprotective properties. However, the function of Lentinan (LNT) in HIRI has not been fully explored. Thus, this study aims to investigate the preventive potential of LNT in HIRI. Here, we reveal that oral administration of LNT considerably reduces hepatic inflammation and improves liver pathology in mice with HIRI by modulating gut microbiota. Specifically, LNT considerably increased microbiota-derived isoursodeoxycholic acid (IsoUDCA). Further experiments showed that IsoUDCA alleviates hepatic injury by suppressing macrophage inflammation. Mechanistically, IsoUDCA directly binds to and activates the neuron-derived clone 77 (Nur77) transcription factor, inhibiting the NF-κB signaling pathway in macrophages. Our findings shed light on the significant role of the LNT-microbiota-IsoUDCA-Nur77 axis in attenuating macrophage inflammation during HIRI, offering novel insights into potential therapeutic targets and avenues for preventing HIRI.

Polydatin Alleviates Cyclophosphamide-Induced Mouse Immunosuppression by Promoting Splenic Lymphocyte Proliferation and Thymic T Cell Development and Differentiation

Immunosuppression increases disease risk, and the natural compound polydatin (PD) has been reported to modulate immune-related disorders. In cyclophosphamide-induced immunosuppressed mice, PD was evaluated for its immunomodulatory effects. Immune organ indices were measured, while H&E staining and ELISA assessed spleen pathology and serum cytokine levels. The proliferation of splenic lymphocytes, both total and subpopulation, was determined using concanavalin A or lipopolysaccharide stimulation, with flow cytometry analyzing peripheral blood and splenic lymphocytes, thymic T cell subtypes, cell cycling, and bromodeoxyuridine incorporation. Western blotting was used to assess Ki67, PCNA expression, and MAPK activation. PD significantly alleviated cyclophosphamide-induced reductions in spleen and thymus indices, improved the organization of red and white pulp in the spleen, and restored TNF-α and IFN-γ levels. It reversed cyclophosphamide-induced cell cycle arrest, characterized by increased PCNA and decreased Ki67, and corrected the diminished numbers of B and T cells and the reduced CD4+/CD8+ ratio in the thymus. In vitro, PD directly promoted splenic lymphocyte proliferation and cell cycling via MAPK activation. Overall, our findings demonstrated that PD alleviated mouse immunosuppression by activating splenic lymphocyte proliferation and re-organizing thymic T cell development and differentiation.

Critical review of the criterion of polysaccharide purity

Natural polysaccharides attract scientists and industries' interest with diverse applications in biomaterials, immune regulation, gut microbiota regulation, food additives, and more. Nevertheless, the absence of standardized purity criteria created significant challenges in characterizing polysaccharides, leading to varied and complicated structures, and impeding progress in research and development. Consequently, it is essential to obtain samples that adhere to high-level and unified purity standards for effective polysaccharide research. Herein we review current methods for assessing polysaccharide purity, emphasizing a commonly neglected impurity: mixtures of polysaccharides with similar molecular sizes. Such a mixture, previously regarded as a single sample, can present a much more complex and ambiguous chemical structure. To address this challenge, we propose enhancing the purity criteria to identify these mixtures. Briefly, the molecular size changes are monitored following hydrolysis with diagnostic enzymes which are identified through methylation and monosaccharide analysis. A pure polymer will exhibit a complete shift in its HPGPC peak, while a polymer mixture will display residual peaks. Establishing standardized criteria for assessing polysaccharide quality represents a significant milestone in the industrialization of these important biomolecules. By enabling accurate, consistent, reliable characterization, this advancement lays the groundwork for broader polysaccharide applications in pharmaceuticals, food, materials, and beyond.

Phellinus igniarius polysaccharides induced mitochondrial apoptosis of hepatic carcinoma by enhancing reactive oxygen species-mediated AKT/p53 signalling pathways

Phellinus igniarius (PI) has various kinds of biological activities, such as antitumour activities, and polysaccharides are one of its main components. In this study, polysaccharides from PI (PIP) were prepared, purified, analysed for their structure and investigated for their antitumour activity and mechanism in vitro. PIP consists of 12138 kDa of carbohydrates containing 90.5 ± 1.6% neutral carbohydrates. PIP consists of glucose, galactose, mannose, xylose, D-fructose, L-guluronic acid, glucosamine hydrochloride, rhamnose, arabinose and D-mannoturonic acid. PIP can significantly inhibit HepG2 cell proliferation, induce cell apoptosis and also inhibited migration and invasion in a concentration-dependent manner. PIP increased reactive oxygen species (ROS), increased the expression of p53, and induced cytochrome c release into the cytoplasm to activate caspase-3. PIP is a promising potential candidate for the therapeutic treatment of hepatic carcinoma via the ROS-mediated mitochondrial apoptosis pathway.

Lentinan progress in inflammatory diseases and tumor diseases

Shiitake mushrooms are a fungal food that has been recorded in Chinese medicine to nourish the blood and qi. Lentinan (lLNT) is an active substance extracted from shiitake mushrooms with powerful antioxidant, anti-inflammatory, anti-tumor functions. Inflammatory diseases and cancers are the leading causes of death worldwide, posing a serious threat to human life and health and posing enormous challenges to global health systems. There is still a lack of effective treatments for inflammatory diseases and cancer. LNT has been approved as an adjunct to chemotherapy in China and Japan. Studies have shown that LNT plays an important role in the treatment of inflammatory diseases as well as oncological diseases. Moreover, clinical experiments have confirmed that LNT combined with chemotherapy drugs has a significant effect in improving the prognosis of patients, enhancing their immune function and reducing the side effects of chemotherapy in lung cancer, colorectal cancer and gastric cancer. However, the relevant mechanism of action of the LNT signaling pathway in inflammatory diseases and cancer. Therefore, this article reviews the mechanism and clinical research of LNT in inflammatory diseases and tumor diseases in recent years.

Structural characterization and immunomodulatory effect of a starch-like Grifola frondosa polysaccharides on cyclophosphamide-induced immunosuppression in mice

In this study, a pure Grifola frondosa polysaccharide (GFP-1) was extracted and purified from Grifola frondosa. By HPLC, GC-MS, FT-IR, and NMR analysis, GFP-1 was determined to be a starch-like polysaccharide with an average molecular weight of 3370 kDa. It included three monosaccharides, i.e., glucose, galactose, and mannose. The backbone of GFP-1 consisted of →4)-α-Glcp-(1→ and →4,6)-α-Glcp-(1 → . The side branches were composed of →6)-α-Galp-(1→, α-Glcp-(1→, and a small amount of α-Manp-(1 → . By using a cyclophosphamide (CTX)-induced immunosuppressed mice model, we evaluated the immunomodulatory activity of GFP-1. The results showed that GFP-1 increased the thymic and spleen indices, promoted the level of IgG and IgA in serum, and activated the mitogen-activated protein kinase (MAPK) pathway in CTX-induced mice. Also, GFP-1 significantly promoted the mRNA expression of intestinal barrier factors and protected intestinal structural integrity in immunosuppressed mice. In conclusion, the data presented here suggested that GFP-1 might be a potential immune-enhancing supplement.

Atomic force microscopy based conformation and immunological activity of Lentinan injections

The purpose of this study was to investigate the morphological characteristics of different brands of lentinan injections produced in China using atomic force microscopy (AFM) and their relationship to immunological activity. Based on AFM imaging, chain height could be used as characterizing the conformation of lentinan, and the heights of 95 % confidence interval for triple, double and single helix were 1.746 ± 0.039 nm, 1.564 ± 0.037 nm and 1.243 ± 0.031 nm, respectively, which were calculated using self-developed MATLAB protocol. AFM characters and their immunological activity of different lentinan injection were compared. In detail, two parameters, triple helix ratio 51.3 % and adhesion force 800 pN, of Jinling (JL) lentinan injection are much higher than samples of other four manufacturers. In addition, immunological activity of JL lentinan injection is also significantly higher than Yineng's. High performance size exclusion chromatography (HPSEC) profiles of different lentinans were also compared, and the data were in accordance with those from AFM. Molecular weight accumulation curves could be used for evaluation of quality consistence of different batches of lentinan from same manufacturer and/or different manufacturers. The results showed that quality consistence of lentinan from different manufactures is poor, which should be greatly improved.

Design and development of novel magnetic Lentinan/PVA nanocomposite for removal of diazinon, malathion, and diclofenac contaminants

Increasing population growth and rapid expansion of the industrialization of the world society have caused severe environmental pollution to the planet. This study was carried out in order to investigate the synthesis of biopolymeric texture nano adsorbent based on the Lentinan (LENT), Poly Vinyl Alcohol (PVA) and Iron Oxide nanoparticles for the removal of environmental pollutants. The spherical structural morphology of Fe₃O₄@LENT/PVA nanocomposite has been determined by FE-SEM analyses. According to the obtained results from FTIR analyses, all absorption bands of the Fe₃O₄, LENT, and PVA, had been existed in nanocomposite and approved the successful formation of it. From EDS analysis, it has been revealed that 57.21 wt% Fe, 17.56 wt% C and 25.23 wt% O. Also, the XRD pattern of the nanocomposite, approved the presence of polymeric and magnetic parts with card no. JCPDS, 01-075-0033. The BET analysis has defined specific surface area (47 m²/g) and total pore volume (0.15 cm³/g). Moreover, high heterogeneity and structural stability of the fabricated Fe₃O₄@LENT/PVA nanocomposite have been proven by TGA. Besides, VSM analysis measured great magnetic property of the nanocomposite (48 emu/g). Also, the Fe₃O₄@LENT/PVA nanocomposite potential for effective removal of malathion (MA), Diazinon (DA), and Diclofenac (DF) from watery solution has studied by an experiment based on the efficacy of adsorbent dosage, pH, and temperature. The adsorption kinetics of three pollutants had investigated using pseudo-first-order (PFO), pseudo-second-order (PSO) and intra-particle diffusion (IPD) velocity equations, the results showed that the kinetics followed PSO velocity equations. Also, the Langmuir, Freundlich, Dubbin-Radushkevich (D-R) and Temkin isotherm models had investigated, and the adsorption isotherm was adopted from the Langmuir model. The results demonstrated that in the presence of Fe₃O₄@LENT/PVA nanocomposite, at the optimal conditions (contact time = 180 min, pH = 5, nanocomposite dosage = 0.20 g/L and temperature of 298 K) the maximum adsorption capacity of MA, DF, and DA were 101.57, 153.28, and 102.75 mg/g, respectively. The antibacterial features of the Fe₃O₄@LENT/PVA nanocomposite, had evaluated by Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria, but the result did not show any antibacterial activity.

Lentinan: An unexplored novel biomaterial in drug and gene delivery applications

Recently, lentinan (LNT) has been utilized for its diversified potential in research with an extended role from nutritional or medicinal applications to a novel biomaterial. LNT is a biocompatible, multifunctional polysaccharide employed as a pharmaceutical additive in engineering customized drug or gene carriers with an improved safety profile. Its triple helical structure containing hydrogen bonding offers more extraordinary binding sites for the attachments of dectin-1 receptors and polynucleotide sequences (poly(dA)). Hence, the diseases expressing dectin-1 receptors can be specifically targeted through so-designed LNT-engineered drug carriers. Gene delivery using poly(dA)-s-LNT complexes and composites has exhibited greater targetability and specificity. The achievement of such gene applications is assessed through the pH and redox potential of the extracellular cell membrane. The steric hindrance-acquiring behavior of LNT shows promise as a system stabilizer in drug carrier engineering. LNT shows viscoelastic gelling behavior temperature-dependently and therefore needs to explore more to meet topical disease applications. The immunomodulatory and vaccine adjuvant properties of LNT help in mitigating viral infections too. This review highlights the new role of LNT as a novel biomaterial, particularly in drug delivery and gene delivery applications. In addition, its importance in achieving various biomedical applications is also discussed.

Synthesis of bioactive (1→6)-β-glucose branched poly-amido-saccharides that stimulate and induce M1 polarization in macrophages

β-Glucans are of significant interest due to their potent antitumor and immunomodulatory activities. Nevertheless, the difficulty in purification, structural heterogenicity, and limited solubility impede the development of structure-property relationships and translation to therapeutic applications. Here, we report the synthesis of a new class of (1→6)-β-glucose-branched poly-amido-saccharides (PASs) as β-glucan mimetics by ring-opening polymerization of a gentiobiose-based disaccharide β-lactam and its copolymerization with a glucose-based β-lactam, followed by post-polymerization deprotection. The molecular weight (Mn) and frequency of branching (FB) of PASs is readily tuned by adjusting monomer-to-initiator ratio and mole fraction of gentiobiose-lactam in copolymerization. Branched PASs stimulate mouse macrophages, and enhance production of pro-inflammatory cytokines in a FB-, dose-, and Mn-dependent manner. The stimulation proceeds via the activation of NF-κB/AP-1 pathway in a Dectin-1-dependent manner, similar to natural β-glucans. The lead PAS significantly polarizes primary human macrophages towards M1 phenotype compared to other β-glucans such as lentinan, laminarin, and curdlan.

Polysaccharides from Spores of Cordyceps cicadae Protect against Cyclophosphamide-Induced Immunosuppression and Oxidative Stress in Mice

This study investigated the purification, preliminary structure and in vivo immunomodulatory activities of polysaccharides from the spores of Cordyceps cicadae (CCSP). The crude CCSP was purified by diethylaminoethyl (DEAE)-cellulose and Sephadex G-100 chromatography, affording CCSP-1, CCSP-2 and CCSP-3 with molecular weights of 1.79 × 10⁶, 5.74 × 10⁴ and 7.93 × 10³ Da, respectively. CCSP-2 consisted of mannose and glucose, while CCSP-1 and CCSP-3 are composed of three and four monosaccharides with different molar ratios, respectively. CCSP-2 exhibited its ameliorative effects in cyclophosphamide-induced immunosuppressed mice through significantly increasing spleen and thymus indices, enhancing macrophage phagocytic activity, stimulating splenocyte proliferation, improving natural killer (NK) cytotoxicity, improving bone marrow suppression, regulating the secretion of cytokines and immunoglobulins, and modulating antioxidant enzyme system. These results indicate that CCSP-2 might be exploited as a promising natural immunomodulator.

Lentinan Impairs the Early Development of Zebrafish Embryos, Possibly by Disrupting Glucose and Lipid Metabolism

LNT is the major biologically active substance extracted from Lentinus edodes (L. edodes). Although functional and pharmacological studies have demonstrated that LNT has multiple benefits for animals and humans, the safety assessment is far from sufficient. To evaluate the potential safety risk, larval zebrafish were continuously exposed to varying concentrations of LNT for 120 h. The 96 h LC50 of LNT was determined to be 1228 μg/mL, and morphological defects including short body length, reduced eye and swim bladder sizes and yolk sac edema were observed. In addition, LNT exposure significantly reduced the blood flow velocity and locomotor activity of larval zebrafish. The biochemical parameters were also affected, showing reduced glucose, triglyceride and cholesterol levels in zebrafish larvae after being exposed to LNT. Correspondingly, the genes involved in glucose and lipid metabolism were disrupted. In conclusion, the present study demonstrates the adverse potential of high concentrations of LNT on the development of zebrafish larvae in the early life stage.

The structural characterization and anticancer activity of a polysaccharide from Coriolus versicolor

Coriolus versicolor is a traditional Chinese medicine and is widely applied as a functional food. In this study, a homogeneous polysaccharide, YZP-1a, was isolated from C. versicolor and its structure and anticancer activity were investigated.

In Vitro Immunomodulation of the Polysaccharides from Yam (Dioscorea opposita Thunb.) in Response to a Selenylation of Lower Extent

The immunomodulation of chemically selenylated polysaccharides has been attracting more attention recently, but the corresponding performance of the yam polysaccharides (YPS) with lower selenylation extent remains, thus far, unsolved. In this study, the YPS was selenylated with Na₂SeO₃ under acidic conditions generated by HNO₃ to reach two lower selenylation extents, yielding two selenylated YPSs, namely SeYPS-1 and SeYPS-2 with selenium contents of 715 and 1545 mg/kg, respectively. The results indicated that YPS, SeYPS-1, and SeYPS-2 all had in vitro immuno-modulation when using RAW 264.7 macrophages and murine splenocytes as cell models. In detail, the three polysaccharide samples at dose levels of 5–160 μg/mL showed insignificant cytotoxicity to the macrophages and splenocytes with cell exposure times of 12–24 h, because of the measured values of cell viability larger than 100%. However, Na₂SeO₃ at dose levels of 1.3–3.25 μg/mL mostly caused obvious cytotoxic effects on the cells, resulting in reduced cell viability values or cell death, efficiently. The results demonstrated that, compared with YPS, both SeYPS-1 and SeYPS-2 at a lower dose level (5 μg/mL) were more active at promoting phagocytosis activity, increasing the CD4⁺/CD8⁺ ratio of the T-lymphocyte sub-population in the murine splenocyte, improving cytokine secretion, including interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α in the macrophages, or increasing interferon-γ secretion, but suppressing IL-4 production in the splenocytes. Consistently, SeYPS-2 has more potential than SeYPS-1 at exerting these assessed bioactivities in the cells. Thus, we conclude that a chemical modification of YPS using trace element Se at a lower selenylation extent could bring about higher immunomodulatory activity towards macrophages and splenocytes, while selenylation extent of YPS is a critical factor used to govern the assessed activity changes of YPS.

Effects of Lycium barbarum Polysaccharides on Immunity and the Gut Microbiota in Cyclophosphamide-Induced Immunosuppressed Mice

The mechanism of immunoregulation by Lycium barbarum polysaccharides (LBPs) was assessed by studying the effect of LBP on the immunity and the gut microbiota. LBP isolated and purified in this study was composed of nine monosaccharides, with an Mw 1,207 kDa. LBP showed immunomodulatory activity in cyclophosphamide (Cy)-treated mice by restoring the damaged immune organs and adjusting the T lymphocyte subsets. We also found that LBP increased the diversity of the gut microbiota and the relative abundances of bacteria, such as Rickenellaceae, Prevotellaceae, Bifidobacteriaceae, and so on, which were positively associated with immune traits. In addition, Caco2 cells model was used to explore the intestinal absorption of LBP. Results showed that LBP was hardly absorbed in the intestine, which suggesting that most LBP may interact with gut microbiota. These findings suggest that the immune response induced by LBP is associated with the regulation of the gut microbiota.

Macrofungi as a Nutraceutical Source: Promising Bioactive Compounds and Market Value

Macrofungi production and economic value have been increasing globally. The demand for macrofungi has expanded rapidly owing to their popularity among consumers, pleasant taste, and unique flavors. The presence of high quality proteins, polysaccharides, unsaturated fatty acids, minerals, triterpene sterols, and secondary metabolites makes macrofungi an important commodity. Macrofungi are well known for their ability to protect from or cure various health problems, such as immunodeficiency, cancer, inflammation, hypertension, hyperlipidemia, hypercholesterolemia, and obesity. Many studies have demonstrated their medicinal properties, supported by both in vivo and in vitro experimental studies, as well as clinical trials. Numerous bioactive compounds isolated from mushrooms, such as polysaccharides, proteins, fats, phenolic compounds, and vitamins, possess strong bioactivities. Consequently, they can be considered as an important source of nutraceuticals. Numerous edible mushrooms have been studied for their bioactivities, but only a few species have made it to the market. Many species remain to be explored. The converging trends and popularity of eastern herbal medicines, natural/organic food product preference, gut-healthy products, and positive outlook towards sports nutrition are supporting the growth in the medicinal mushroom market. The consumption of medicinal mushrooms as functional food or dietary supplement is expected to markedly increase in the future. The global medicinal mushroom market size is projected to increase by USD 13.88 billion from 2018 to 2022. The global market values of promising bioactive compounds, such as lentinan and lovastatin, are also expected to rise. With such a market growth, mushroom nutraceuticals hold to be very promising in the years to come.

Immunomodulatory activity of puerarin in RAW264.7 macrophages and cyclophosphamide-induced immunosuppression mice

CONTEXT

Puerarin, a natural isoflavone extracted from Radix puerariae, is famous for treating various cardiovascular and cerebrovascular diseases. However, little is known about its direct immunomodulatory activity.

OBJECTIVE

This study was designed to investigate the in vitro and in vivo immunomodulatory effects of Radix puerariae by using the murine monocyte-macrophage cell line RAW264.7 and immunosuppressed cyclophosphamide-induced mice.

METHODS

MTT and neutral red phagocytosis assays were conducted to evaluate the in vitro immunomodulatory activities of puerarin on cell viability and phagocytosis by measuring the proliferation, phagocytic, nitric oxide (NO) ability, and TNF-α production ability of stimulated and lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Immunosuppressed cyclophosphamide-induced mice were used to evaluate the in vivo immunomodulatory activities of puerarin by measuring IL-4 and IFN-γ, the serum half hemolysis value, spleen and thymus index, and proliferation assay for splenic lymphocytes.

RESULTS AND DISCUSSION

Results showed that puerarin improves immunomodulatory activity by increasing cell proliferation, cell phagocytosis, and NO secretion in RAW264.7 macrophages and reduces the abnormal immunologic activity by decreasing cell phagocytosis and NO secretion in LPS-stimulated RAW264.7 macrophages. In addition, puerarin enhanced the immunologic activity of cyclophosphamide-induced immunosuppression mice by increasing the secretion of NO, IFN-γ, and IL-4, the serum half hemolysis value (HC₅₀), the spleen and thymus index, and proliferation for splenic lymphocytes.

CONCLUSION

Puerarin exhibited an upregulated immunomodulatory effect on RAW264.7 macrophages and immunosuppression mice. In addition, puerarin had a downregulated immunomodulatory effect on RAW264.7 macrophages. The results suggest that puerarin could be a promising immunomodulator to assist in the treatment of tumors.

Immunostimulatory Effects of Polysaccharides from Spirulina platensis In Vivo and Vitro and Their Activation Mechanism on RAW246.7 Macrophages

In this study, Spirulina platensis (S.p.) polysaccharide (PSP) was obtained by ultrasonic-microwave-assisted extraction (UMAE) and purified by an aqueous two-phase system (ATPS). Two different methods were applied to purified Spirulina platensis (S.p.) polysaccharide (PSP), respectively, due to PSP as a complex multi-component system. Three polysaccharide fractions (PSP-1, PSP-2, and PSP-3) with different acidic groups were obtained after PSP was fractionated by the diethyl aminoethyl (DEAE)-52 cellulose chromatography, and two polysaccharide fractions (PSP-L and PSP-H) with different molecular weight were obtained by ultrafiltration centrifugation. The chemoprotective effects of PSP in cyclophosphamide (Cy) treated mice were investigated. The results showed that PSP could significantly increase spleen and thymus index, peripheral white blood cells (PWBC), and peripheral blood lymphocytes (PBL). The in vivo immunostimulatory assays demonstrated that PSP could in dose-dependent increase of TNF-α, IL-10, and IFN-γ production in sera. The in vitro immunostimulatory assays showed that PSP and its fractions (PSPs) could evidently enhance the proliferation of splenocytes and RAW 264.7 cells and increase the productions of nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin 6 (IL-6). PSPs could also enhance phagocytic activity of RAW 264.7 cells. The acidic polysaccharide fractions of PSP-2, PSP-3, and PSP-L with small molecular weight had the higher immunostimulatory activity. Signaling pathway research results indicated that PSP-L activated RAW264.7 cells through MAPKs, NF-κB signaling pathways via TLR4 receptor.