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)-, ß-Glc(1→3)-, and ß-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.

Gamma-Irradiation-Induced Degradation of the Water-Soluble Polysaccharide from Auricularia polytricha and Its Anti-Hypercholesterolemic Activity.

The water-soluble polysaccharides (APPs) isolated from the edible mushroom Auricularia polytricha were irradiated by γ-ray at doses of 10, 100, and 1000 kGy. The effect of gamma irradiation on the degradation of the polysaccharide was investigated. After irradiation treatment, the viscosity and molecular weight of APPs decreased with the increase in the irradiation dose. The changes in the enthalpy of APPs after irradiation treatment were observed. Meanwhile, SEM showed that R-APPs were crushed into fragments and the surfaces became smooth and wrinkled after irradiation. In further spectrum analysis, it was found that the glycoside bonds of the polysaccharides were broken and accompanied by the formation of double bonds. This suggested that gamma irradiation could cause the depolymerization and oxidation of polysaccharides. In addition, irradiated APPs could reduce the body weight of hyperlipidemia mice. The levels of serum and liver TC, TG, and serum LDH-c significantly decreased in hyperlipidemia mice after treatment by irradiated APPs. It indicated that gamma irradiation significantly improved the anti-hypolipidemic activity of APPs. The relationship between the physicochemical properties and hypolipidemic activity of polysaccharides was interpreted, which provides a theoretical basis for the further development of APP products. Gamma irradiation is a viable technology for macromolecular modification for degradation.

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.

A New Lectin from Auricularia auricula Inhibited the Proliferation of Lung Cancer Cells and Improved Pulmonary Flora.

Lectins are widely distributed in the natural world and are usually involved in antitumor activities. Auricularia auricula (A. auricula) is a medicinal and edible homologous fungus. A. auricula contains many active ingredients, such as polysaccharides, melanin, flavonoids, adenosine, sterols, alkaloids, and terpenes. In this study, we expected to isolate and purify lectin from A. auricula, determine the glycoside bond type and sugar-specific protein of A. auricula lectin (AAL), and finally, determine its antitumor activities. We used ammonium sulfate fractionation, ion exchange chromatography, and affinity chromatography to separate and purify lectin from A. auricula. The result was a 25 kDa AAL with a relative molecular mass of 18913.22. Protein identification results suggested that this lectin contained four peptide chains by comparing with the UniProt database. The FT-IR and ß-elimination reaction demonstrated that the connection between the oligosaccharide and polypeptide of AAL was an N-glucoside bond. Analyses of its physical and chemical properties showed that AAL was a temperature-sensitive and acidic/alkaline-dependent glycoprotein. Additionally, the anticancer experiment manifested that AAL inhibited the proliferation of A549, and the IC50 value was 28.19 ± 1.92 µg/mL. RNA sequencing dataset analyses detected that AAL may regulate the expression of JUN, TLR4, and MYD88 to suppress tumor proliferation. Through the pulmonary flora analysis, the bacterial structure of each phylum in the lectin treatment group was more reasonable, and the colonization ability of the normal microflora was improved, indicating that lectin treatment could significantly improve the bacterial diversity characteristics.

Antioxidation, anti-hyperlipidaemia and hepatoprotection of polysaccharides from Auricularia auricular residue.

As hyperlipidemia was a pathological progress by lipid dysfunctions, the present object was to investigate the hypolipidemic and hepatoprotective effects of Auricularia auricular residue polysaccharides (RPS) against HFE (high-fat emulsion) toxicities in mice. The structure analysis showed that the RPS was pyranose-polysaccharides mainly composed of glucose with the weight-average molecular weight of 2.00 × 105 Da. The in vivo experiments demonstrated that the RPS had potential hepatoprotections by enhancing the antioxidant and anti-hyperlipidaemia status, and could inhibit the increasing body weights. Besides, the RPS could improve the glucose utilization with the oral glucose tolerance test (120 min) of 5.04 ± 0.12 mmol/L at the dose of 400 mg/kg bw. The results in present study demonstrated that RPS could be used as a functional foods and natural medicines against the HFE-induced hyperlipidemia and its complications.

Ultrasonic-assisted extraction of polysaccharides from Auricularia auricula and effects of its acid hydrolysate on the biological function of Caenorhabditis elegans.

The present study was designed to explore the in vivo-antioxidant capacity and the probable mechanism of AAPs-H, prepared from Auricularia auricula polysaccharides with the optimal extraction conditions by Box-Behnken design and acid hydrolysis, using Caenorhabditis elegans as a model organism. The effects of AAPs-H on the locomotion behavior, life span, antioxidant-related enzymes activities, and antioxidants levels in C. elegans were studied. Furthermore, the potentials of AAPs-H in up-regulating the expression of antioxidant-related genes in C. elegans, such as skn-1, sod-3 and sir-2.1, were also discussed. AAPs-H demonstrated a highly significant protective effect against the damage caused by paraquat, could significantly increase U-Turn frequency of worms (p < 0.01), extend their lifespan, enhance antioxidant systems including GR by 63.96% (p < 0.05), GSH-Px by 71.16% (p < 0.01), SOD by 78.65% (p < 0.01) and CAT by 98.52% (p < 0.01), increase the level of GSH by 28.12% (p < 0.05), and decrease the level of MDA by 39.29% (p < 0.01). The qRT-PCR results showed that AAPs-H could up regulate mRNA expression levels of skn-1, sod-1, sod-2, sod-3 and sir-2.1 in wild-type C. elegans (>1.6 fold) when treated with the concentration of 0.4 mg/mL (p < 0.05 or p < 0.01). Our studies provide evidence that AAPs-H improves antioxidant defense system, and up-regulation of oxidative stress related genes for prevention of stress damage in C. elegans.

Phagocytosis enhancement, endotoxin tolerance, and signal mechanisms of immunologically active glucuronoxylomannan from Auricularia auricula-judae.

Glucuronoxylomannan (AAPS) from the edible wood ear mushroom Auricularia auricula-judae has been demonstrated to exhibit immunostimulatory properties through its binding to TLR4. However, the mechanisms of immune modulation by AAPS in mammalian cells remains unclear. In the present study, we demonstrated that AAPS induced immunostimulatory effects were regulated by reactive oxygen species, mitogen-activated protein kinases, protein kinase C-α and NF-κB. AAPS remarkably increased the phagocytosis and bactericidal activity of macrophages. In lipopolysaccharide-activated macrophages, AAPS induced endotoxin tolerance like effect characterized by the downregulation of nitric oxide, interleukin-6 and TNF-α via the downregulation of NF-κB activation. Our findings provide firm scientific evidences for the immunoenhancing properties of wood ear mushroom, and the potential of AAPS to be strong candidates for the development of new carbohydrate-based nutraceutical supplements in the management of immunity related disorders in the future.

Purification, characterization and in vitro antioxidant activity of a polysaccharide AAP-3-1 from Auricularia auricula.

The objective was to investigate the in vitro antioxidant activity of a novel polysaccharide AAP-3-1 from Auricularia auricula. AAP-3-1 was isolated from the fruiting bodies of A. auricula by hot water extraction and ethanol precipitation and was purified by DEAE FF ion exchange chromatography and Superdex 200 gel filtration chromatography. The molecular weight and monosaccharide composition were determined by high performance gel permeation chromatography and high-performance liquid chromatography, respectively. Ultraviolet visible spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy were used for structural characterization. The results showed that AAP-3-1 is a heteropolysaccharide and is mainly composed of mannose and glucose in a molar ratio of 1.4:1 with a molecular weight of 320.9 kDa. AAP-3-1 exhibited antioxidant activity in a concentration-dependent manner and the scavenging rates at 1.6 mg/mL on superoxide anions and hydroxyl and 1,1-diphenyl-2-picrylhydrazyl radicals were 88.13%, 93.03% and 68.31%, respectively. AAP-3-1 effectively ameliorated 2,2'-azobis-2-methyl-propanimidamide-induced oxidative stress in HepG2 cells by inhibiting reactive oxygen species generation, decreasing the content of malondialdehyde, and increasing the activities of superoxide dismutase, glutathione peroxidase and catalase. The results indicated that the antioxidant mechanism of AAP-3-1 was associated with both non-enzymatic and enzymatic defense systems.

Influence of Nigerian Jelly Ear Culinary-Medicinal Mushroom, Auricularia auricula-judae (Agaricomycetes), on Humoral and Cellular Immunity.

The fruiting body of Auricularia auricula-judae has received attention in folk medicine due to its possible medicinal values. Therefore, this study evaluated the immunomodulatory effects of the hot aqueous extract (AAAJ) and the ß-D-glucan-rich polysaccharide fraction of A. auricula-judae (BGPA) on specific and nonspecific humoral and cell mediated immune responses in immunocompetent and immunosuppressed mice. Oral supplementation with AAAJ or BGPA (100, 200, or 400 mg/kg) produced significantly high titers of total OVA specific or TT specific IgG1 and IgG2a compared with the levels in untreated control. Oral administration of AAAJ or BGPA (100, 200, or 400 mg/kg) evoked a significant increase in carbon clearance at all doses, indicating stimulation of the reticuloendothelial system, and potentiated the delayed-type hypersensitivity reaction induced by sheep red blood cells (SRBC) compared with the untreated mice. Total lymphocyte count, neutrophil count, and lymphocytes count increased significantly (P < 0.05) at all doses, following acute administration of AAAJ or BGPA (100, 200, or 400 mg/kg), showing increased protection toward cyclophosphamide induced myelosuppression compared with the untreated negative control group. In the hemolytic complement assay, AAAJ and BGPA at all doses significantly (P < 0.05) inhibited the hemolytic activity of the complement proteins on the sensitized SRBC. The present study reveals that the extract holds promise as an immunomodulatory agent and strengthens the rationale for its use in traditional medicine.

Enzymatic hydrolysis of polysaccharide from Auricularia auricula and characterization of the degradation product.

An efficient enzymatic hydrolysis method was developed and optimized for the degradation of auricularia auricula polysaccharide (AAP) and the degradation product of AAP was characterized. Cellulase was used for the degradation of AAP. The yield of reducing sugar and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rate were used as indices to optimize the enzymatic hydrolysis of AAP, based on response surface methodology (RSM). The resulting optimal enzymolysis conditions were as follows: enzyme dosage, 13,500 U/g; enzymolysis temperature, 50 °C; and pH, 4.2. Under these conditions, the actual yield of reducing sugar was 16.50 mg/mL and the DPPH radical scavenging rate was 87.97%. The degradation product of AAP (C-EAAP) was homogeneous and contained alpha and beta glycoside bonds, but did not contain protein or nucleic acid. The molecular weight of the degradation product was 5.94 × 105 Da. Monosaccharide composition analysis revealed that C-EAAP was composed of mannose (57.1%), glucuronic acid (10.0%), rhamnose (0.4%), glucose (22.5%), galactose (2.9%), xylose (6.0%), and fucose (1.1%). The antioxidant activity of the polysaccharide indicated that C-EAAP had better antioxidant activity than AAP. The scavenging rates of C-EAAP for hydroxyl radicals (·OH) and superoxide anion radicals (O2-·) were 1.65 and 1.90 times those of AAP.

A comparison study on digestion, anti-inflammatory and functional properties of polysaccharides from four Auricularia species.

Four Auricularia polysaccharides (A.cornea (ACP), A.auricula (AAP), A.polytricha (APP) and M.fungus (MFP)) were researched to evaluate the effect of Auricularia species on digestion, anti-inflammatory and function of polysaccharides. The results showed that the molecular weights of ACP and MFP were significantly reduced in gastric juice from 30 min to 150 min (p < 0.05), the polysaccharides were degraded into small molecules and their structures were changed after digestion. The inhibition rate of α-amylase and α-glucosidase of APP were 71.21% and 82.01%, respectively, APP had a better hypolipidemic activity and the inhibitory activity was 89.5%. AAP, APP, and MFP could significantly promoted cell proliferation at 400 µg/mL. Four polysaccharides could inhibit inflammatory factors, so all polysaccharides have the good anti-inflammatory activity. The minimal inhibitory concentration (MIC) of APP against E. coli and S. typhi were 1.25% and 1.0%, respectively. There were significant differences in the digestion, anti-inflammatory and function of Auricularia polysaccharides among different species (p < 0.05).

Isolation, structural characterization and bioactivities of polysaccharides and its derivatives from Auricularia-A review.

Auricularia mushrooms are known for their bioactive compounds, mostly polysaccharides, which have numerous biological activities, such as antioxidant, antitumor, immunomodulatory, hyperlipidemic, antidiabetic, anticoagulant and hepatoprotective effects. Over the past decades, there has been a consistent focus on the isolation, chemical properties and bioactivities of polysaccharides from Auricularia. This review will cover what is known about Auricularia polysaccharides (AP) especially for several common species, including A. auricula-judae, A. auricula, A. polytricha, and A. cornea var. Li. The isolation and purifications, structural characterizations, chemical modifications, and biological activities of these AP and their derivatives will be discussed, thus to provide a foundation for the further investigation, production, and application of AP as functional foods and therapeutic agents.