Isolation, purification, characterization, and immunomodulatory effects of polysaccharide from Auricularia auricula on RAW264.7 macrophages

A review of the fungal polysaccharides as natural biopolymers: Current applications and future perspective

As a unique natural resource, fungi are a sustainable source of lipids, polysaccharides, vitamins, proteins, and other nutrients. As a result, they have beneficial medicinal and nutritional properties. Polysaccharides are among the most significant bioactive components found in fungi. Increasing research has revealed that fungal polysaccharides (FPS) contain a variety of bioactivities, including antitumor, antioxidant, immunomodulatory, anti-inflammatory, hepatoprotective, cardioprotective, and anti-aging properties. However, the exact knowledge about FPS and their applications related to their future possibilities must be thoroughly examined to enhance a better understanding of this sustainable biopolymer source. Therefore, FPS' biological applications and their role in the food and feed industry, agriculture, and cosmetics applications were all discussed in this work. In addition, this review highlighted the mode of action of FPS on human diseases by regulating gut microbiota and discussed the mechanism of FPS as antioxidants in the living cell. The structure-activity connections of FPS were also highlighted and explored. Moreover, future perspectives were listed to pave the way for future studies of FPS applications. Hence, this study can be a scientific foundation for future FPS research and industrial applications.

Effects of Auricularia auricula-judae (Bull.) Quél. polysaccharide acid hydrolysate on glucose metabolism in diabetic mice under oxidative stress

BACKGROUND

Oxidative stress can lead to uncontrolled glucose metabolism and, thus, diabetes. Auricularia auricula-judae (Bull.) Quél. polysaccharides possess biological activities, such as antioxidant and hypoglycemic effects, but their mechanism of their acid hydrolysates on oxidative stress-injured glucose metabolism disorders is unclear.

PURPOSE

Using diabetic mice, we investigated the effect of the acid hydrolysate of polysaccharides from Auricularia auricula-judae (Bull.) Quél. on improving diabetes.

STUDY DESIGN AND METHODS

The structural information of sample polysaccharides was measured by high performance gel permeation chromatography, nuclear magnetic resolution, and high performance liquid chromatography. The diabetic model was established by intraperitoneal injection of streptozotocin. For eight consecutive weeks, the mice were orally administered sample polysaccharides (100, 200, and 300 mg/kg b.w. per day) for intervention. The improvement effect of the samples on diabetes was explored by detecting the changes in biochemical indicators in mice, and the underlying mechanism was studied by transcriptomic and metabolomic analysis.

RESULTS

The results showed that acid hydrolysate of Auricularia auricula-judae (Bull.) Quél. polysaccharides consisted mainly of mannose, xylose, glucuronic acid, and glucose; its weight-averaged molecular weight was 6.3842 × 104 Dalton, its number average molecular weight was 2.9594 × 104 Dalton; and the molecule contained α-Glc(1→4)-, β-Glc(1→3)-, and β-Man(1→4)-linked glycosidic bonds. A total of 100 mg/kg b.w. per day sample was the best intervention concentration. After eight weeks of intervention, the sample polysaccharides significantly reduced dynamic blood glucose and serum lipids, enhanced antioxidant enzyme activities, promoted glucagon like peptide-1 and insulin secretion, improved insulin sensitivity and alleviated insulin resistance in diabetic mice. Transcriptomic and metabolomic analyses showed that sample polysaccharides was able to ameliorate disorders of glucose metabolism by modulating gene expression such as glucokinase; and modulate the state of oxidative stress in mice in vivo by regulating the glutathione metabolism pathway.

CONCLUSION

Acid hydrolysate of Auricularia auricula-judae (Bull.) Quél. polysaccharides improved glucose metabolism disorders by slowing down the oxidative stress injury in mice, thereby alleviating diabetes. This study provided a basis for determining the underlying mechanism of the antidiabetic effect of Auricularia auricula-judae (Bull.) Quél. polysaccharides, which would significantly improve the deep development and application of these materials in diabetes control.

Structural characterization and immunomodulatory activity of a polysaccharide from Dioscotea opposita

The purified polysaccharides fraction, DOP-2, was prepared from Dioscorea opposita Thunb (D. opposita). This study combined in vitro and in vivo experiments to comprehensively investigate the index changes in RAW264.7 cells and immunocompromised mice under DOP-2 intervention, aiming to elucidate the potential mechanisms of immunomodulatory effects of DOP-2. DOP-2 (10 ∼ 500 μg/mL) significantly elevated the levels of NO, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) factors secreted by RAW264.7 cells, and restored the body weight of immunosuppressed mice and improve the degree of injury to the immune organ index, resulting in significant immunomodulatory effects. Notably, DOP-2 promoted the production of short-chain fatty acids (SCFAs) in immunosuppressed mice and modulated the composition of their gut microflora. These findings highlight the potential benefits of DOP-2 therapy in improving immune function and gut health, and will provide a theoretical basis for the application of D. opposita polysaccharides as an immunomodulatory adjuvant.

The function and application of edible fungal polysaccharides

Edible fungi, commonly known as mushrooms, are precious medicinal and edible homologous gifts from nature to us. Edible fungal polysaccharides (EFPs) are a variety of bioactive macromolecular which isolated from fruiting bodies, mycelia or fermentation broths of edible or medicinal fungus. Increasing researches have confirmed that EFPs possess multiple biological activities both in vitro and in vivo settings, including antioxidant, antiviral, anti-inflammatory, immunomodulatory, anti-tumor, hypoglycemic, hypolipidemic, and regulating intestinal flora activities. As a result, they have emerged as a prominent focus in the healthcare, pharmaceutical, and cosmetic industries. Fungal EFPs have safe, non-toxic, biodegradable, and biocompatible properties with low immunogenicity, bioadhesion ability, and antibacterial activities, presenting diverse potential applications in the food industries, cosmetic, biomedical, packaging, and new materials. Moreover, varying raw materials, extraction, purification, chemical modification methods, and culture conditions can result in variances in the structure and biological activities of EFPs. The purpose of this review is to provide comprehensively and systematically organized information on the structure, modification, biological activities, and potential applications of EFPs to support their therapeutic effects and health functions. This review provides new insights and a theoretical basis for prospective investigations and advancements in EFPs in fields such as medicine, food, and new materials.

Cold Alkali-Extractable Antioxidative Polysaccharide from Russula pseudocyanoxantha (Agaricomycetes), a Novel Mushroom, Stimulates Immune Responses in RAW264.7 Cells by Regulating the TLR/NF-κB Pathway

In our previous study, we have established Russula pseudocyanoxantha as a unique species, playing a crucial role in indigenous diets through ages. The research also brought attention to bioactive potential of polysaccharide fraction extracted from the unexplored food using hot water. However, residue of the conventional process still contains therapeutic biopolymers that could further be utilized for pharmacological purposes instead of being discarded. Therefore, the current study aims to valorize the solid remnants, contributing to a deeper understanding of the novel taxon. Subsequently, the leftover was treated with cold alkali, leading to the preparation of a high-yield fraction (RP-CAP). Chemical characterization through FT-IR, GC-MS, HPTLC, and spectroscopy demonstrated presence of several monomers in the carbohydrate backbone, predominantly composed of β-glucan. Furthermore, GPC chromatogram indicated presence of a homogeneous polymer with molecular weight of ~ 129.28 kDa. Subsequently, potent antioxidant activity was noted in terms of radical scavenging (O2·-, OH·, DPPH· and ABTS·+), chelating ability, reducing power and total antioxidant activity where EC50 values ranged from 472-3600 μg/mL. Strong immune-boosting effect was also evident, as the biopolymers stimulated murine macrophage cell proliferation, phagocytic activity, pseudopod formation, and NO as well as ROS synthesis particularly at the concentration of 100 μg/mL. In-depth analysis through RT-PCR revealed that the fraction stimulated synthesis of several inflammatory mediators, elucidating the mode of action through TLR/ NF-κB pathway. Therefore, the findings collectively suggest that RP-CAP possesses great potential to serve as a healthimproving component in functional food and pharmaceutical sectors.

Characterization and biological activities of polysaccharides extracted from Auricularia auricula with different extraction methods

Polysaccharides derived from Auricularia auricula exhibit diverse biological activities and hold significant potential for commercial utilization as functional food ingredients. In this investigation, polysaccharides from A. auricula were obtained using six extraction techniques (ammonium oxalate solution extraction, sodium hydroxide solution extraction, hot water extraction, pectinase and cellulase-assisted extraction, ultrasonic-assisted extraction, and microwave-assisted extraction). Subsequently, a comprehensive comparison was conducted to evaluate their physicochemical properties and biological functionalities. The ammonium oxalate solution extraction method yielded a higher extraction rate (11.76%) and polysaccharide content (84.12%), as well as a higher uronic acid content (10.13%). Although the six Auricularia polysaccharides had different molecular weight distributions, monosaccharide molar ratios, similar monosaccharide compositions, and characteristic functional groups of polysaccharides, they exhibited different surface morphology. In vitro assays showed that polysaccharides extracted by ammonium oxalate solution possessed good scavenging ability against DPPH free radical, hydroxyl free radical and superoxide anion free radical as well as reduction power of iron ion. At the same time, both polysaccharides extracted by ammonium oxalate solution and sodium hydroxide solution promoted NO production in mouse macrophages along with the secretion of cytokines TNF-α, IL-1β, and IL-6. These results indicated significant differences in the structure and characteristics among Auricularia polysaccharides prepared by various extraction methods, which may be related to the variety or origin of A. auricula; furthermore, their bioactivities varied accordingly in vitro assays where the ammonium oxalate solution extraction method was found more beneficial for obtaining high-quality bioactive Auricularia polysaccharides.

Auricularia auricula polysaccharides attenuate obesity in mice through gut commensal Papillibacter cinnamivorans

INTRODUCTION

Auricularia auricula is a well-known traditional edible and medical fungus with high nutritional and pharmacological values, as well as metabolic and immunoregulatory properties. Nondigestible fermentable polysaccharides are identified as primary bioactive constituents of Auricularia auricula extracts. However, the exact mechanisms underlying the effects of Auricularia auricula polysaccharides (AAP) on obesity and related metabolic endpoints, including the role of the gut microbiota, remain insufficiently understood.

METHODS

The effects of AAP on obesity were assessed within high-fat diet (HFD)-based mice through obesity trait analysis and metabolomic profiling. To determine the mechanistic role of the gut microbiota in observed anti-obesogenic effects AAP, faecal microbiota transplantation (FMT) and pseudo-germ-free mice model treated with antibiotics were also applied, together with 16S rRNA genomic-derived taxonomic profiling.

RESULTS

High-fat diet (HFD) murine exposure to AAP thwarted weight gains, reduced fat depositing and enhanced glucose tolerance, together with upregulating thermogenesis proteomic biomarkers within adipose tissue. Serum metabolome indicated these effects were associated with changes in fatty acid metabolism. Intestine-dwelling microbial population assessments discovered that AAP selectively enhanced Papillibacter cinnamivorans, a commensal bacterium with reduced presence in HFD mice. Notably, HFD mice treated with oral formulations of P. cinnamivorans attenuated obesity, which was linked to decreased intestinal lipid transportation and hepatic thermogenesis. Mechanistically, it was demonstrated that P. cinnamivorans regulated intestinal lipids metabolism and liver thermogenesis by reducing the proinflammatory response and gut permeability in a JAK-STAT signaling-related manner.

CONCLUSION

Datasets from the present study show that AAP thwarted dietary-driven obesity and metabolism-based disorders by regulating intestinal lipid transportation, a mechanism that is dependent on the gut commensal P. cinnamivorans. These results indicated AAP and P. cinnamivorans as newly identified pre- and probiotics that could serve as novel therapeutics against obesity.

Mycelial biomass and intracellular polysaccharides production, characterization, and activities in Auricularia auricula-judae cultured with different carbon sources

The carbon source, an essential factor for submerged culture, affects fungal polysaccharides production, structures, and activities. This study investigated the impact of carbon sources, including glucose, fructose, sucrose, and mannose, on mycelial biomass and the production, structural characterization, and bioactivities of intracellular polysaccharides (IPS) produced by submerged culture of Auricularia auricula-judae. Results showed that mycelial biomass and IPS production varied with different carbon sources, where using glucose as the carbon source produced the highest mycelial biomass (17.22 ± 0.29 g/L) and IPS (1.62 ± 0.04 g/L). Additionally, carbon sources were found to affect the molecular weight (Mw) distributions, monosaccharide compositions, structural characterization, and activities of IPSs. IPS produced with glucose as the carbon source exhibited the best in vitro antioxidant activities and had the strongest protection against alloxan-damaged islet cells. Correlation analysis revealed that Mw correlated positively with mycelial biomass (r = 0.97) and IPS yield (r = 1.00), while IPS antioxidant activities correlated positively with Mw and negatively with mannose content; the protective activity of IPS was positively related to its reducing power. These findings indicate a critical structure-function relationship for IPS and lay the foundation for utilizing liquid-fermented A. aruicula-judae mycelia and the IPS in functional food production.

Nanoparticles prepared by polysaccharides extracted from Biyang floral mushroom loaded with resveratrol: Characterization, bioactivity and release behavior under in vitro digestion

Resveratrol (RES) is a common active factor in the functional food field, but poor water solubility and low bioavailability have limited its application. In the present study, the novel nanoparticles (RES-CBFMP NPs) using floral mushroom polysaccharide as the wall material have been developed for delivering RES, aiming to overcome its application shortcomings. After ratio optimization, RES-CBFMP NPs (RES-CBFMP,1:8 w/w), which combined through the hydrogen bonds between RES and CBFMP, showed the best overall performance, with the encapsulation efficiency (EE) of 49.74 ± 0.16%, loading efficiency (LE) of 5.53 ± 0.02%, particle size of 158.56 ± 1.97 nm and zeta-potential of -17.56 ± 0.24 mV. In addition, RES-CBFMP NPs exhibited good physicochemical stabilities, sustained gastrointestinal digestive release property, as well as improved in vitro antioxidant and anticancer activities. This study may contribute to the development of RES oral delivery systems and the application of hydrophobic active molecules in the functional food field.

Application of definitive screening design to optimization of the protein extraction and functional properties of proteins in Auricularia auricula

BACKGROUND

Auricularia auricula (A. auricula) is one of the most abundant sources of plant protein in edible fungi. Problems of low protein yield exist in traditional methods of protein extraction such as alkali extraction and ultrasonic-assisted alkali after pretreatment with enzymes. Thus, the protein extraction process was investigated and optimized using a definitive screening design from A. auricula to improve the protein yield under practical operating conditions of temperature, the concentration of NaCl, meal/water ratio, extraction time and pH.

RESULTS

The yield of protein isolates of the isoelectric-ammonium sulfate precipitation (9.34% w/w) was obtained almost three times and the protein content (55.23% w/w) was approximately 1.6 times that of the traditional extraction method of isoelectric precipitation. Next, the optimized method was successfully applied to the analysis of the functional properties of the protein. A. auricula protein isolate (AAPI) had better solubility, emulsification and foaming capacity than soy protein isolate (SPI) and pea protein isolate (PPI), and the oil holding capacity of AAPI exhibited extremely well, which was approximately five times that of SPI and six times that of PPI. The texture properties of AAPI gel were similar to those of PPI gels.

CONCLUSION

AAPI extracted by the optimized method had a satisfactory yield and had the potential to substitute plant-originated proteins in food processing. © 2022 Society of Chemical Industry.

The Current State and Future Prospects of Auricularia auricula's Polysaccharide Processing Technology Portfolio

Auricularia auricula polysaccharides (AAP) have been widely studied in the field of medicine and healthcare because of their unique structure and physiological activity. Many species of Auricularia auricula polysaccharides have been extracted, isolated, and purified by different methods, and their structures have been analyzed. Auricularia auricula polysaccharides have been proven to have beneficial effects on the human body, including slowing the aging process, controlling the intestinal system, and treating cardiovascular disorders. In this paper, the extraction, isolation, and purification of AAP from Auricularia auricula, as well as research in the field of medicine and healthcare, have pointed to the shortcomings and limitations of these methods. We also suggest future research directions for Auricularia auricula polysaccharides; standardized processing methods must be confirmed, and officially approved AAPs are needed for commercial applications. Finally, an optimistic outlook on the development of AAPs is given.

pH-Sensitive Targeting of Tumors with Chemotherapy-Laden Nanoparticles: Progress and Challenges

Accumulating chemotherapeutic drugs such as doxorubicin within a tumor while limiting the drug dose to normal tissues is a central goal of drug delivery with nanoparticles. Liposomal products such as Doxil® represent one of the marked successes of nanoparticle-based strategies. To replicate this success for cancer treatment, many approaches with nanoparticles are being explored in order to direct and release chemotherapeutic agents to achieve higher accumulation in tumors. A promising approach has been stimulus-based therapy, such as the release of chemotherapeutic agents from the nanoparticles in the acidic environments of the tumor matrix or the tumor endosomes. Upon reaching the acidic environments of the tumor, the particles, which are made up of pH-dependent polymers, become charged and release the entrapped chemotherapy agents. This review discusses recent advances in and prospects for pH-dependent histidine-based nanoparticles that deliver chemotherapeutic agents to tumors. The strategies used by investigators include an array of histidine-containing peptides and polymers which form micelles, mixed micelles, nanovesicles, polyplexes, and coat particles. To date, several promising histidine-based nanoparticles have been demonstrated to produce marked inhibition of tumor growth, but challenges remain for successful outcomes in clinical trials. The lessons learned from these histidine-containing particles will provide insight in the development of improved pH-dependent polymeric delivery systems for chemotherapy.

Transcriptome analysis reveals immune and metabolic regulation effects of Poria cocos polysaccharides on Bombyx mori larvae

Poria cocos polysaccharides (PS) have been used as Chinese traditional medicine with various pharmacological effects, including antiviral, anti-oxidative, and immunomodulatory activities. Herein Bombyx mori silkworm was used as a model animal to evaluate the immunomodulatory effects of PS via detecting the changes of innate immune parameters and explore the underlying molecular mechanism of the immunoregulatory effect of PS using Illumina HiSeq Xten platform. The results presented here demonstrated that a hemocoel injection of PS significantly enhanced the cellular immunity of silkworm, including hemocyte phagocytosis, microaggregation, and spreading ability. A total of 335 differentially expressed genes (DEGs) were screened, including 214 upregulated genes and 121 downregulated genes by differential expression analysis. Gene annotation and enrichment analyses showed that many DEGs related to immune signal recognition, detoxification, proPO activation, carbohydrate metabolism, and lipid metabolism were significantly upregulated in the treatment group. The Kyoto Encyclopedia of Genes and Genomes-based Gene Set Enrichment Analysis also revealed that the more highly expressed gene sets in the PS treatment silkworm were mainly related to immune signal transduction pathways and energy metabolism. In addition, the activity of four enzymes related to immunity and energy metabolism—including phenoloxidase, glucose-6-phosphate dehydrogenase, hexokinase, and fatty acid synthetase—were all significantly increased in the larvae injected with PS. We performed qRT-PCR to examine the expression profile of immune and metabolic-related genes, which further verified the reliability of our transcriptome data and suggested that PS can regulate the immunity of silkworm by enhancing the cellular immunity and modulating the expression levels of genes related to immune responses and physiological metabolism. These findings will lay a scientific foundation for the use of PS as an immunomodulator in disease prevention in human beings or animals.

A Review of Development and Utilization for Edible Fungal Polysaccharides: Extraction, Chemical Characteristics, and Bioactivities

Edible fungi, commonly known as mushrooms, are precious medicinal and edible homologous gifts from nature to us. Because of their distinctive flavor and exceptional nutritional and medicinal value, they have been a frequent visitor to people’s dining tables and have become a hot star in the healthcare, pharmaceutical, and cosmetics industries. Edible fungal polysaccharides (EFPs) are an essential nutrient for edible fungi to exert bioactivity. They have attracted much attention because of their antioxidant, immunomodulatory, antitumor, hypoglycemic, and hypolipidemic bioactivities. As a result, EFPs have demonstrated outstanding potential over the past few decades in various disciplines, including molecular biology, immunology, biotechnology, and pharmaceutical chemistry. However, the complexity of EFPs and the significant impact of mushroom variety and extraction techniques on their bioactivities prevents a complete investigation of their biological features. Therefore, the authors of this paper thoroughly reviewed the comparison of different extraction methods of EFPs and their advantages and disadvantages. In addition, the molecular weight, monosaccharide composition, and glycosidic bond type and backbone structure of EFPs are described in detail. Moreover, the in vitro and in vivo bioactivities of EFPs extracted by different methods and their potential regulatory mechanisms are summarized. These provide a valuable reference for improving the extraction process of EFPs and their production and development in the pharmaceutical field.

Polysaccharides from fungi: A review on their extraction, purification, structural features, and biological activities

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A variety of extraction methods of polysaccharides from fungi are reviewed and compared.

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Purification methods, structure of fungal polysaccharides were reviewed.

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Diverse biological activities of fungal polysaccharides were outlined.

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Structure-activity relationships of fungal polysaccharides were discussed.

Fungi, as the unique natural resource, are rich in polysaccharides, proteins, fats, vitamins, and other components. Therefore, they have good medical and nutritional values. Polysaccharides are considered one of the most important bioactive components in fungi. Increasing researches have confirmed that fungal polysaccharides have various biological activities, such as antioxidant, immunomodulatory, anti-tumor, hepatoprotective, anti-aging, anti-inflammatory, and radioprotective activities. Consequently, the research progresses and future prospects of fungal polysaccharides must be systematically reviewed to promote their better understanding. This paper reviewed the extraction, purification, structure, biological activity, and underlying molecular mechanisms of fungal polysaccharides. Moreover, the structure–activity relationships of fungal polysaccharides were emphasized and discussed. This review can provide scientific basis for the research and industrial utilization of fungal polysaccharides.

Comparative Characterization and Immunomodulatory Activities of Polysaccharides Extracted from the Radix of Platycodon grandiflorum with Different Extraction Methods

Platycodon grandiflorum is an edible and medicinal plant, and polysaccharides are one of its important components. To further improve the utilization rate of P. grandiflorum, we investigated the effects of four different extraction methods, including hot water, ultrasonic-assisted, acid-assisted, and alkali-assisted extractions, on the polysaccharides, which were named PG-H, PG-U, PG-C, and PG-A. The findings indicated that the extraction method had a significant impact on the yield, characteristics, and immunoregulatory activity. We observed that the yields decreased in the following order: PG-H, PG-U, PG-C, and PG-A. Galacturonic acid, glucose, galactose, and arabinose were the most prevalent monosaccharides in the four PGs. However, their proportions varied. In addition, the difference between the content of glucose and galacturonic acid was more significant. PG-U had the highest glucose content, whereas PG-C had the lowest. Galacturonic acid content was highest in PG-A, while the lowest in PG-U. The molecular weight decreased in the order of PG-U, PG-H, PG-C, and PG-A; the particle size was in the order of PG-U, PG-A, PG-H, and PG-C. Moreover, the extraction method had a great impact on immunoregulatory activity. The ability to stimulate the immune function of macrophages was as follows: PG-A > PG-C > PG-U > PG-H. The results indicated that PGs, with lower molecular weights and higher GalA content, exhibited better immune-stimulating activity. And more important the AAE method was a good way to extract polysaccharides from Platycodon grandiflorum for use as a functional product and immunological adjuvant.

Two glycoproteins from medicinal insect Periplaneta americana (L.) promote diabetic wound healing via macrophage polarization modulation

Along with the increasing attempts to explore the wound healing effective substances of Periplaneta americana (L.) (PA), a medicinal insect in traditional Chinese medicine, researchers' attention turned to the endogenetic macromolecules, such as polysaccharides and peptides. Herein, we innovatively isolated two glycoproteins from PA, named PAGP-1 and PAGP-2, which were obtained by Cellulose DE-52 chromatography and purified by Sephadex G-100 gel in succession. The structural characterization of the two PAGPs were performed, including molecular weight, amino acid and monosaccharide composition, morphology analysis, FT-IR and ¹H NMR analysis, CD spectroscopy, and glycosides linkage. As a result, two PAGPs belonged to O-glycopeptide bonds linked glycoproteins. The content of carbohydrate and protein of PAGP-1 was approximately 25.23% and 65.92% respectively, which of PAGP-2 was approximately 25.71% and 71.23%. Based on the remarkable anti-inflammatory effects of PAGPs on LPS-induced RAW264.7 cells, the topical administration of PAGP-1 and PAGP-2 could significantly accelerate full-thickness wound healing in diabetic mice, involving to alleviate the inflammation, increase the ratio of type I and type III collagen fibers, and promote the polarization of macrophages M1 to M2. In short, this study provides clear evidence that the glycoproteins would be the potential wound healing bioactive substances in PA.