Hypoglycemic benefit and potential mechanism of a polysaccharide from Hericium erinaceus in streptozotoxin-induced diabetic rats

Recent insights into Hericium erinaceus polysaccharides: Gastrointestinal, gut microbiota, microbial metabolites, overall health and structure-function correlation

Hericium erinaceus polysaccharides (HEPs) have attracted significant interest due to their potential to support gastrointestinal health and modulate gut microbiota. However, while promising findings exist, a comprehensive understanding of the structure-function relationships and the mechanisms by which HEPs influence gut health and microbial metabolites remains limited. This review synthesizes recent advances in HEPs, detailing their bioactivity in gastrointestinal protection mechanisms, modulation of gut microbiota, production of key metabolites, regulation of immune responses, enhancement of intestinal barrier integrity, and interactions within the microbiota-gut-brain axis, thereby improving overall host health. Additionally, we explore the structural diversity of HEPs in relation to their biological functions, as well as advancements in HEP modification and drug delivery systems. As the potential for HEPs in the food and pharmaceutical industries grows, this review provides valuable insights into innovative approaches for utilizing HEPs to support intestinal health and overall well-being. These findings underscore the therapeutic potential of HEPs and their broad-ranging health benefits.

Protective Effects of Polygonatum sibiricum Polysaccharides Against Type 2 Diabetic Mice Induced by High-Fat Diet and Low-Dose Streptozotocin

Polysaccharides possessing hypoglycemic effects have shown promising results in treating diabetes. Polygonatum sibiricum polysaccharide (PSP) is one of the most active ingredients in the Chinese medicine P. sibiricum Redoute with many biological activities. However, its efficacy in alleviating type 2 diabetes mellitus (T2DM) remains unexplored. Our aim is to evaluate the protective effect of PSP against T2DM by measuring body weight and serum biochemical indicators, examining the histopathological images of pancreatic and liver tissues, detecting fecal short-chain fatty acid (SCFA) content, and analyzing the intestinal flora diversity and the microbiota structure in T2DM mice. The findings indicated that PSP treatment in T2DM mice could obviously decrease the fasting blood glucose and fasting insulin levels, ameliorate glucose tolerance, insulin resistance, lipid, and inflammatory factor levels, attenuate pancreatic and liver damage, and increase the fecal SCFA content. In addition, PSP could modulate the composition of gut microbiota in T2DM mice, resulting in the relative abundance of Firmicutes decreasing and that of Bacteroidetes increasing, along with the abundance of beneficial flora significantly increasing, especially SCFA-producing bacteria. The findings indicate that PSP administration protected against diabetes by controlling disordered glucolipid metabolism and modulating the gut microbiota, which provides a valuable strategy for the utilization of PSP to treat T2DM.

Characterization, Optimization, and Scaling-up of Submerged Inonotus hispidus Mycelial Fermentation for Enhanced Biomass and Polysaccharide Production

This study was to establish an efficient strategy based on inoculum-morphology control for the submerged mycelial fermentation of an edible and medicinal fungus, Inonotus hispidus. Two major morphological forms of the mycelial inoculum were compared, dispersed mycelial fragments versus aggregated mycelial clumps. The dispersed one was more favorable for the fermentation, starting with a shorter lag period and attaining a higher biomass yield and more uniform mycelium pellets in shake flasks. The mycelial pellets taken from the shake flask culture on day 6 were fragmented at 26,000 rpm in a homogenizer, and a shear time of 3 min provided the optimal inoculum. The inoculum and culture conditions were further verified in 5-L stirred tank fermenters and then the fermentation was scaled-up in a 100-L stirred tank. With the optimized inoculum and process conditions plus a fed-batch operation, much higher productivities, including 22.23 g/L biomass, 3.31 g/L EPS, and 5.21 g/L IPS, were achieved in the 100-L fermenter than in the flask culture. A composition analysis showed that the I. hispidus mycelium produced by the fermentation was rich in protein, dietary fiber, and polysaccharides which may be beneficial to health. Overall, the results have shown that the inoculum characteristics including age, morphology, and state of aggregation have significant impact on the productivity of mycelial biomass and polysaccharides in a submerged mycelial fermentation of the I. hispidus fungus.

Hericium erinaceus Protein Alleviates High-Fat Diet-Induced Hepatic Lipid Accumulation and Oxidative Stress In Vivo

Dietary interventions with food-derived natural products have emerged as a promising strategy to alleviate obesity. This study aims to investigate the anti-obesity effect of Hericium erinaceus protein (HEP) and its underlying mechanism. Our results demonstrated that HEP exhibited excellent radical scavenging activity in vitro. In vivo, HEP intervention reduced pancreatic lipase activity in the intestine and enhanced fat excretion, thereby inhibiting the absorption of dietary fats. Meanwhile, HEP ameliorated the body weight and organ indexes, dyslipidemia, insulin resistance, hepatic steatosis, and liver oxidative stress injuries in obese mice. The results of real-time PCR (qRT-PCR) and Western blot analyses indicated that HEP upregulated the expression of peroxisome proliferator-activated receptor α (PPARα), subsequently upregulated the expression of liver fatty acid oxidation-related genes (lipoprotein lipase (LPL), carnitine palmitoyltransferase 1a (CPT-1a), and acyl-CoA oxidase 1 (ACOX1)) and downregulated the expression of lipogenesis-related genes (sterol regulatory element-binding protein-1c (SREBP-1c), stearoyl-coenzyme A desaturase 1 (SCD-1), and fatty acid synthase (FASN)), thereby ameliorating lipid metabolism disorders. Therefore, these findings demonstrated that HEP exerted protective effects on lipid metabolism disorders by activating the PPARα pathway, indicating its potential as a dietary supplement for the prevention and amelioration of obesity.

In vitro digestion and fecal fermentation behaviors of exopolysaccharide from Morchella esculenta and its impacts on hypoglycemic activity via PI3K/Akt signaling and gut microbiota modulation

This study aimed to evaluate the effects of gastrointestinal digestion on the physicochemical properties and hypoglycemic activity of extracellular polysaccharides from Morchella esculenta (MEPS). The results showed that the MEPS digestibility was 22.57 % after saliva-gastrointestinal digestion and only partial degradation had occurred. Contrarily, after 48 h of fecal fermentation, its molecular weight and molar ratios of the monosaccharide composition varied significantly due to being utilized by human gut microbiota, and the final fermentation rate was 76.89 %. Furthermore, the MEPS-I, the final product of saliva-gastrointestinal digestion still retained significant hypoglycemic activity, it alleviated insulin resistance and increased the IR cells glucose consumption by activating PI3K/AKT signaling pathway. MEPS-I treatment reduced the proportion of Firmicutes to Bacteroidetes, and the relative abundance of beneficial bacteria that enhanced insulin sensitivity and glucose uptake was promoted. This research can provide a theoretical basis for the further development of Morchella esculenta as a health functional food.

Functions and mechanisms of nonstarch polysaccharides in monogastric animal production

As natural active ingredients, polysaccharides are a class of biological macromolecules that are ubiquitous in living organisms and have antibacterial, antioxidant, antitumor and intestinal flora-regulating functions. Nonstarch polysaccharides (NSPs) are an important class of polysaccharides that include both soluble and insoluble nonstarch polysaccharides. As green feed additives, NSPs play important roles in promoting immunity and disease resistance in the body, regulating the intestinal microbial balance and improving the quality of animal products. NSPs regulate cell signal transduction mainly via interactions between short-chain fatty acids and G protein-coupled receptors and inhibiting the histone deacetylation pathway to protect the intestinal barrier in animals. In this paper, the composition, physiological functions, and molecular mechanisms of the gut protective effects of NSPs are reviewed to provide a reference for the application of NSPs in monogastric animal production.

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.

Quercetin protects against hyperglycemia-induced retinopathy in Sprague Dawley rats by regulating the gut-retina axis and nuclear factor erythroid-2-related factor 2 pathway

Hyperglycemia-related retinopathy is a disease with a high blindness rate. Recent reports indicate that many flavonol compounds have the potential to prevent the occurrence of disease in the retina by regulating the gut-retina axis. Here, we hypothesized that quercetin could alleviate the symptoms of retinopathy. To clarify the mechanism, Sprague Dawley rats were fed a high-fat diet containing quercetin for 12 weeks and injected with streptozotocin in the ninth week. Additionally, neomycin and ampicillin were used to establish a pseudo-sterile rat model. Afterward, changes in the retina were investigated by using electroretinogram and optical coherence tomography. Blood and tissue samples were collected and biochemical components were analyzed. The extent of intestinal injury was determined via hematoxylin-eosin staining. Microbial community structure was analyzed by using 16S ribosomal RNA sequencing. Finally, the expression of genes was analyzed using real-time polymerase chain reaction. The results showed that quercetin reduced the decline in electroretinography amplitude and outer nuclear layer thickness, increased the activities of antioxidant enzymes, decreased the contents of proinflammatory factors and blood glucose, enhanced the concentration of insulin, and inhibited intestinal dysbiosis and improved gut morphology. Importantly, the underexpression of nuclear factor erythroid-2 related factor 2 in the retina was reversed by quercetin. However, trend changes were no longer significant in most of the indicators after antibiotic treatment. In summary, quercetin has therapeutic effects on retinopathy by regulating the gut-retina axis and nuclear factor erythroid-2 related factor 2 pathway, and the presence of gut microbiota helps quercetin exert its effects on the retina.

A review on the hypoglycemic effect, mechanism and application development of natural dietary polysaccharides

Diabetes mellitus (DM) as one chronic metabolic disease was greatly increased over recent decades. The major agents treating diabetes have noticeable side effects as well as the tolerability problems. The bioactive dietary polysaccharides from abundant natural resources exhibit good hypoglycemic effect with rare adverse effects, which might serve as a candidate to prevent and treat diabetes. However, the correlations between the hypoglycemic mechanism of polysaccharides and their structure were not mentioned in several studies, what's more, most of the current hypoglycemic studies on polysaccharides were based on in vitro and in vivo experiments, and there was a lack of knowledge about the effects in human clinical trials. The aim of this review is to discuss recent literature about the variety of dietary polysaccharides with hypoglycemic activity, as well the mechanism of action and the structure-function relationship are highlighted. Meanwhile, the application of dietary polysaccharides in functional foods and clinical medicine are realized with an in-depth understanding. So as to promote the exploration of dietary polysaccharides in low glycemic healthy foods or clinical medicine to prevent and treat diabetes.

Structural characterization of Hericium erinaceus polysaccharides and the mechanism of anti-T2DM by modulating the gut microbiota and metabolites

A low molecular weight polysaccharides of HEP-1, with molecular weights of 1.67 × 10⁴ Da and composition of →6)-β-D-Glcp-(1→, →3)-β-D-Glcp-(1→, β-D-Glcp-(1→ and →3,6)-β-D-Glcp-(1→, was isolated and characterized from the fruiting body of Hericium erinaceus. The results indicated that HEP-1 showed potential effects against T2DM-induced imbalance of glucose and lipid metabolism by promoting the serum glucose uptake by hepatic glycogen synthesis via activating the IRS/PI3K/AKT signaling pathway, and inhibiting fatty acid synthesis and reducing hepatic lipid accumulation via activating the AMPK/SREBP-1c signaling pathways. Besides, HEP-1 promoted the production of beneficial bacteria in the gut, and increased the beneficial metabolites in liver through the gut-liver axis, consequently, resisting the occurrence of T2DM.

Mushroom polysaccharides with potential in anti-diabetes: Biological mechanisms, extraction, and future perspectives: A review

Diabetes mellitus (DM) is a global health threat. Searching for anti-diabetic components from natural resources is of intense interest to scientists. Mushroom polysaccharides have received growing attention in anti-diabetes fields due to their advantages in broad resources, structure diversity, and multiple bioactivities, which are considered an unlimited source of healthy active components potentially applied in functional foods and nutraceuticals. In this review, the current knowledge about the roles of oxidative stress in the pathogenesis of DM, the extraction method of mushroom polysaccharides, and their potential biological mechanisms associated with anti-diabetes, including antioxidant, hypolipidemic, anti-inflammatory, and gut microbiota modulatory actions, were summarized based on a variety of in vitro and in vivo studies, with aiming at better understanding the roles of mushroom polysaccharides in the prevention and management of DM and its complications. Finally, future perspectives including bridging the gap between the intervention of mushroom polysaccharides and the modulation of insulin signaling pathway, revealing structure-bioactivity of mushroom polysaccharides, developing synergistic foods, conducting well-controlled clinical trials that may be very helpful in discovering valuable mushroom polysaccharides and better applications of mushroom polysaccharides in diabetic control were proposed.

Effects of Auricularia auricula Polysaccharides on Gut Microbiota Composition in Type 2 Diabetic Mice

In previous studies, Auriculariaauricula polysaccharides (AAP) has been found to improve type 2 diabetes mellitus, but its mechanism remains unclear. In this study, we sought to demonstrate that AAP achieves remission by altering the gut microbiota in mice with type 2 diabetes. We successfully constructed a type 2 diabetes mellitus (T2DM) model induced by a high-fat diet (HFD) combined with streptozotocin (STZ), following which fasting blood glucose (FBG) levels and oral glucose tolerance test (OTGG) were observed to decrease significantly after 5 weeks of AAP intervention. Furthermore, AAP enhanced the activities of total superoxide dismutase (T-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), and reduced the content of malondialdehyde (MDA) to alleviate the oxidative stress injury. AAP-M (200 mg/kg/d) displayed the best improvement effect. Moreover, 16S rRNA results showed that AAP decreased the abundance of Firmicutes and increased that of Bacteroidetes. The abundance of beneficial genera such as Faecalibaculum, Dubosiella, Alloprevotella, and those belonging to the family Lachnospiraceae was increased due to the intake of AAP. AAP could reduced the abundance of Desulfovibrio, Enterorhabdus, and Helicobacter. In all, these results suggest that AAP can improve the disorders of glucose and lipid metabolism by regulating the structure of the gut microbiota.

The HbA1c and blood glucose response to selenium-rich polysaccharide from Fomes fomentarius loaded solid lipid nanoparticles as a potential antidiabetic agent in rats

Fomes fomentarius is a medicinal fungus used in traditional Chinese medicine to treat various illnesses. Antidiabetic effects of F. fomentarius extracts have been reported recently. In this study, F. fomentarius extracellular polysaccharide (PS) was prepared, and then to enhance its antidiabetic effects, Na₂SeO₃ was added to the culture medium, and selenium-polysaccharide (PS-Se) was obtained. Also, solid lipid nanoparticles containing PS (SLN-PS) and PS-Se (SLN-PS-Se) were synthesized by the microemulsion method to compare their effects with free polysaccharides in streptozotocin (STZ) diabetic rats. Optimized SLNs had a size of 170.5 nm and drug loading of 9.27 %. EDS analysis confirmed that Se presence in PS-Se. Characterization analyses such as FTIR, DSC, TGA, and XRD suggested that SLNs have good thermal stability and crystalline nature. Release of PS from SLNs demonstrated sustained profile, and MTT assay proved that PSs and SLNs have no cytotoxicity. Furthermore, oral administration of PS, PS-Se, SLN-PS, and SLN-PS-Se for 28 days to diabetic rats significantly declined blood glucose by 48.24 %, 49.96 %, 55.50 %, and 60.47 %, respectively. Also, insulin secretion and body weight improved, and HbA1c levels decreased. Treatment by PS, PS-Se, SLN-PS, and SLN-PS-Se alleviated lipid profiles, liver enzymes, and serum proteins. Liver anti-oxidant parameters and histopathological observation of the liver, pancreas, and kidney confirmed that F. fomentarius PSs and SLNs have antidiabetic impacts. Moreover, supplementation of PS with selenium improves its anti-hyperglycemic effects. Finally, SLN-PS and SLN-PS-Se showed a higher antidiabetic impact than free PS and PS-Se.

The Antioxidant Properties of Mushroom Polysaccharides can Potentially Mitigate Oxidative Stress, Beta-Cell Dysfunction and Insulin Resistance

Diabetes mellitus is a prevalent metabolic and endocrine illness affecting people all over the world and is of serious health and financial concern. Antidiabetic medicine delivered through pharmacotherapy, including synthetic antidiabetic drugs, are known to have several negative effects. Fortunately, several natural polysaccharides have antidiabetic properties, and the use of these polysaccharides as adjuncts to conventional therapy is becoming more common, particularly in underdeveloped nations. Oxidative stress has a critical role in the development of diabetes mellitus (DM). The review of current literature presented here focusses, therefore, on the antioxidant properties of mushroom polysaccharides used in the management of diabetic complications, and discusses whether these antioxidant properties contribute to the deactivation of the oxidative stress-related signalling pathways, and to the amelioration of β-cell dysfunction and insulin resistance. In this study, we conducted a systematic review of the relevant information concerning the antioxidant and antidiabetic effects of mushrooms from electronic databases, such as PubMed, Scopus or Google Scholar, for the period 1994 to 2021. In total, 104 different polysaccharides from mushrooms have been found to have antidiabetic effects. Most of the literature on mushroom polysaccharides has demonstrated the beneficial effects of these polysaccharides on reactive oxygen and nitrogen species (RONS) levels. This review discuss the effects of these polysaccharides on hyperglycemia and other alternative antioxidant therapies for diabetic complications through their applications and limits, in order to gain a better understanding of how they can be used to treat DM. Preclinical and phytochemical investigations have found that most of the active polysaccharides extracted from mushrooms have antioxidant activity, reducing oxidative stress and preventing the development of DM. Further research is necessary to confirm whether mushroom polysaccharides can effectively alleviate hyperglycemia, and the mechanisms by which they do this, and to investigate whether these polysaccharides might be utilized as a complementary therapy for the prevention and management of DM in the future.

Characterization and Heterologous Expression of UDP-Glucose 4-Epimerase From a Hericium erinaceus Mutant with High Polysaccharide Production

Hericium erinaceus is an important medicinal fungus in traditional Chinese medicine because of its polysaccharides and other natural products. Compared terpenoids and polyketides, the analysis of synthetic pathway of polysaccharides is more difficult because of the many genes involved in central metabolism. In previous studies, A6180, encoding a putative UDP-glucose 4-epimerase (UGE) in an H. erinaceus mutant with high production of active polysaccharides, was significantly upregulated. Since there is no reliable genetic manipulation technology for H. erinaceus, we employed Escherichia coli and Saccharomyces cerevisiae to study the function and activity of A6180. The recombinant overexpression vector pET22b-A6180 was constructed for heterologous expression in E. coli. The enzymatic properties of the recombinant protein were investigated. It showed that the recombinant A6180 could strongly convert UDP-α-D-glucose into UDP-α-D-galactose under optimal conditions (pH 6.0, 30°C). In addition, when A6180 was introduced into S. cerevisiae BY4742, xylose was detected in the polysaccharide composition of the yeast transformant. This suggested that the protein coded by A6180 might be a multifunctional enzyme. The generated polysaccharides with a new composition of sugars showed enhanced macrophage activity in vitro. These results indicate that A6180 plays an important role in the structure and activity of polysaccharides. It is a promising strategy for producing polysaccharides with higher activity by introducing A6180 into polysaccharide-producing mushrooms.

Hypoglycemic effects of Auricularia auricula polysaccharides on high fat diet and streptozotocin-induced diabetic mice using metabolomics analysis

This study evaluated the hypoglycemic effect of Auricularia auricula polysaccharides (AAPs) on streptozotocin-induced type 2 diabetes mellitus (T2DM) mice using metabolomic analysis. The results of fasting blood glucose, oral glucose tolerance test, fasting serum insulin level, Homeostatic Model Assessment of Insulin Resistance index, TC, TG, HDL-C, LDL-C, and histopathological observation demonstrated that 200 mg per kg body weight per day AAP led to significant hypoglycemic activities. The metabolic profile of the mice was significantly changed after AAP intervention. 45 differential metabolites were screened as biomarkers for AAP adjuvant treatment, and AAPs' effects on the metabolism of amino acids, unsaturated fatty acids, bile acids, and glycerophospholipids were analyzed. Thus, the current results elucidated the metabolic pathway of AAPs for T2DM alleviation and provided guidance for functional food adjuvant development for T2DM treatment.

Isolation, structural characterization and neuroprotective activity of exopolysaccharide from Paecilomyces cicada TJJ1213

Two exopolysaccharide fractions (EPS1 and EPS2) were obtained from Paecilomyces cicadae TJJ 1213, and their structures were elucidated. The EPS1 and EPS2 were mainly composed of mannose and galactose with molar ratios of 3.2: 1.0 and 2.7: 1.0, respectively. They possessed average molecular weights of 1.69 × 10⁶ and 8.06 × 10⁵ Da, respectively. Structural characterization indicated that the backbone of EPS1 was consisted of →4)-α-D-Manp (1→, →3,4)-α-D-Manp (1 → and →2,6)-α-D-Manp (1→, →6)-α-D-Galp (1→, →6)-β-D-Galp (1→, and side chain was consisted of α-D-Manp residue. The backbone of EPS2 was composed of →6)-β-D-Galp-(1→, →4)-α-D-Manp-(1→, →2,6)-α-D-Manp-(1 → and →6)-α-D-Galp-(1→, and the branching point was also consisted of α-D-Manp residue. In addition, EPS1 and EPS2 had potential in protective effects of PC12 cells against hydrogen peroxide induced oxidative stress by inhibiting the production of ROS, reducing LDH leakage and alleviating mitochondrial damage. These results indicated that EPS1 and EPS2 might serve as therapeutic agents for neuronal disorders.