Preparation of the Auricularia auricular polysaccharides simulated hydrolysates and their hypoglycaemic effect

Cultivation of a Wild Strain of Wood Ear Auricularia cornea from Brazil

Auricularia cornea has become one of the most important cultivated mushrooms worldwide. Although not remarkably flavorful, Auricularia species are very versatile and rehydrate easily after drying, adding a unique and pleasing texture to the dishes. In this study, we collected, identified, and domesticated a wild strain of A. cornea from the Brazilian Atlantic Rainforest. The wild strain was evaluated for mycelial growth at different temperatures and substrates, biological efficiency, and nutritional composition. The temperature that best favored the A. cornea mycelium growth was 30 °C, and the substrate was sterile Eucalyptus sawdust. The highest biological efficiency value obtained was 106.90 ± 13.28%. Nutritional analysis showed that the produced wood ears contained 71.02% carbohydrates, 19.63% crude fiber, 11.59% crude protein, 10.19% crude fat, and 4.24% ash on dry matter basis. For the mineral content profile, the elements K and P were the most abundant. This is the first report on cultivation of a wild strain of A. cornea from Brazil.

Structural properties, bioactivities, structure-activity relationships and bio-applications of polysaccharides from Auricularia auricula: A review

Auricularia auricula (A. auricula), is a medicinal and edible fungus in China for thousands of years with rich nutrition and delicious taste. The main active ingredient of A. auricula is polysaccharide, which has antitumor, hypoglycemic, antioxidant, and immune regulation bioactivities. It is widely recognized that the biological activity of polysaccharides is closely related to the chemical structure and advanced structure. In terms of polysaccharides extracted from A. auricula (AAPs), there were distinguished structures reported due to the different original resources and extraction methods, leading to various bioactivities. However, the structure-activity relationship of AAPs has scarcely been reviewed till now. In addition, polysaccharides were found to have specific self-assembly properties recently, together with their bioactivities, endowing them with unique physicochemical properties. Nowadays, an increasing number of polysaccharides, such as cellulose, chitin, and pectin, have been used to construct various functional materials in the fields of food, cosmetics, and biomedical materials. Therefore, the construction of functional materials by AAPs is of great research significance. This article aims to provide a systematic review of the structure-activity relationship of AAPs and summarize the functional materials constructed based on AAPs to provide theoretical references for further research and application of AAPs.

L-Theanine Ameliorates Obesity-Related Complications Induced by High-Fat Diet in Mice: Insights from Transcriptomics and Metabolomics

Obesity is a major public health concern globally. Plant-based ingredients have been proposed as alternative treatments for obesity. L-Theanine (THE), a unique nutraceutical component of tea, is known for its neuroprotective and cognitive benefits. However, there are few reports on THE's effects and mechanisms in improving obesity and its complications. In this study, the alleviating effects and potential mechanisms of THE on obesity-related complications (ORCs) induced by a high-fat diet(HFD) in mice were explored by performing biochemical, hepatic transcriptomics, and plasma metabolomics analyses. The results indicated THE (900 mg/kg of body weight) was effective in mitigating ORCs by decreasing body weight gain and fat deposition, improving glycolipid metabolism disorders, inflammation dysregulation, and alleviating fatty liver formation due to long-term HFD. The hepatic transcriptomics data suggested that THE intervention suppresses the lipid metabolism and inflammation pathways in HFD-fed mice, thereby inhibiting hepatic steatosis and inflammation. Moreover, plasma metabolomics analysis revealed that THE exhibited positive effects on the homeostasis of plasma metabolite balance, such as phosphatidylcholine (PC(14:0/18:1)), phosphatidylethanolamine (Lyso-PE(14:0)), phosphatidic acid (PA(16:0e/18:0)), stigmasterol, and deoxycholic acid glycine conjugate. These metabolites were strongly correlated with ORC-related indicators. Our results indicated that THE, as a functional food additive, possesses potential for ORC alleviation. However, the exact molecular mechanism of how THE alleviates ORCs needs to be investigated in the future.

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.

Multiple fingerprint and pattern recognition analysis on polysaccharides of four edible mushrooms

Quality analysis of edible mushrooms based on polysaccharides is generally difficult due to their complicated structures and hard separation. Here, multiple fingerprint analysis of polysaccharides based on chromatographic and spectrometric techniques were developed, and then applied in comparative analysis of Auricularia heimuer (AH), Auricularia cornea (AC), Auricularia cornea 'Yu Muer' (ACY) and Tremella fuciformis (TF). Firstly, polysaccharides were obtained with the molecular weights between 1.783 × 106 and 6.774 × 106 Da. Then, complete hydrolysis by TFA and enzyme digestion by cellulase were employed and subsequently analyzed by HPLC-UV, GC-MS, HILIC-HPLC-ELSD and HILIC-HPLC-ESI--HCD-MS/MS, and ATR-FT-IR were used to characterize the functional groups of intact polysaccharides. By chemometric analysis, differential markers of d-xyl, l-fuc, l-arb, d-glc, disaccharide and hexasaccharide were selected, and AC and ACY were proved to be same species from the viewpoint of polysaccharides firstly. Furthermore, the structures of oligomers with DPs of 2-8 and →4)-β-d-Glcp-(1→ unit with different contents were inferred by combinatory analysis of ESI--MS/MS, glycosidic linkage, monosaccharide compositions and functional groups. In conclusion, the combinatory method of multiple fingerprint and pattern recognition is powerful not only for structural elucidation of polysaccharides, but also for quality analysis and species differentiation of edible mushrooms from the perspective of biological polysaccharides.

Preparation of Auricularia auricula polysaccharides and their protective effect on acute oxidative stress injury of Caenorhabditis elegans

This research enhanced the extraction procedure for Auricularia auricula crude polysaccharides by utilizing a modified Fenton reagent as a solvent, and obtained A. auricula polysaccharides (AAPs-VH) via alcohol precipitation and deproteinization. The HPLC profile revealed that the purified AAPs-VH using Sepharose 6FF was mainly a heteropolysaccharide, consisting primarily of mannose, glucuronic acid, glucose, and xylose. The Mw and Mn of the purified AAPs-VH were 87.646 kDa and 48.854 kDa, respectively. The FT-IR and NMR spectra revealed that the purified AAPs-VH belonged to pyranose and were mainly formed by (1 → 3)-linked-β-D glucan formation. In vivo experiments conducted with Caenorhabditis elegans, AAPs-VH was found to notably influence the lifespan, improve the antioxidant system, and decrease the level of cell apoptosis. This might be achieved by up-regulating the expression of genes in the IIS and TOR pathways. The study concludes that the modified Fenton reagent can increase Auricularia auricula polysaccharide solubleness and active sites, which may be an essential prompt for future studies.

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.

Sodium alginate-based drug delivery for diabetes management: A review

Diabetes mellitus (DM) is among the biggest global health problems of the 21st century, which is characterised by insufficient insulin secretion and results in the augmentation of blood sugar levels. The current foundation of hyperglycemia therapy is oral antihyperglycemic medications like biguanides, sulphonylureas, α-glucosidase inhibitors, peroxisome proliferator-activated receptor gamma (PPAR-γ) agonists, sodium-glucose co-transporter 2 (SGLT-2) inhibitors, dipeptidyl peptidase-4 (DPP-4) inhibitors and others. Many naturally occurring substances have shown promise in treating hyperglycemia. Inadequate prologitivity of action, restricted bioavailability, site specificity, and dose-related side effects are some problems with currently available anti-diabetic medications. Sodium alginate has shown promise as a drug delivery mechanism, potentially solving issues with current therapies for several substances. This review summarizes the research on the efficacy of drug delivery systems based on alginate for transporting oral hypoglycemic medicines, phytochemicals, and insulin for treating hyperglycemia.

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

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.

Recent Advances in Chain Conformation and Bioactivities of Triple-Helix Polysaccharides

Natural polysaccharides derived from renewable biomass sources are regarded as environmentally friendly and sustainable polymers. As the third most abundant biomacromolecule in nature, after proteins and nucleic acids, polysaccharides are also closely related with many different life activities. In particular, β-glucans are one of the most widely reported bioactive polysaccharides and are usually considered as biological response modifiers. Among them, β-glucans with triple-helix conformation have been the hottest and most well-researched polysaccharides at present, especially lentinan and schizophyllan, which are clinically used as cancer therapies in some Asian countries. Thus, creation of these active triple-helix polysaccharides is beneficial to the research and development of sustainable "green" biopolymers in the fields of food and life sciences. Therefore, full fundamental research of triple-helix polysaccharides is essential to discover more applications for polysaccharides. In this Review, the recent research progress of chain conformations, bioactivities, and structure-function relationships of triple-helix β-glucans is summarized. The main contents include the characterization methods of the macromolecular conformation, proof of triple helices, bioactivities, and structure-function relationships. We believe that the governments, enterprises, universities, and institutes dealing with the survival and health of human beings can expect the development of natural bioproducts in the future. Hence, a deep understanding of β-glucans with triple-helix chain conformation is necessary for application of natural medicines and biologics for a sustainable world.

First demonstration of protective effects of purified mushroom polysaccharide-peptides against fatty liver injury and the mechanisms involved

Fatty liver (FLD) disease is a consequence of metabolic syndrome, which is a health problem worldwide with a phenomenal rise in prevalence. In this study, two hepatoprotective polysaccharide-peptides were extracted from the mushroom Auricularia polytricha followed by chromatographic fractionation of the extract on the ion exchanger DEAE-cellulose and gel filtration on Sephadex-200 to yield two purified fractions: APPI and APPII. The monosaccharide compositions, FT-IR, N-terminal sequences, internal peptide sequences and molecular weights of the two fractions were determined. Furthermore, their hepatoprotective effect on human hepatoma HepG2 cells in vitro and in an animal model of fatty liver disease was evidenced by the findings that APPI and APPII diminished lipid deposit in cells, blood and the liver, increased cellular antioxidant activity and viability, and protected the liver against injury. The mechanistic study revealed that APPI and APPII activated the adiponectin pathway, up-regulated expression of genes controlling free fatty acid (FFA) oxidation, such as AMPK, CPTl, ACOX1 and PPARα genes, enhanced lipid metabolism, preserved hepatic function, promoted the antioxidant defense system and reduced lipid peroxidation. Hence the bioactive compounds of A. polytricha could serve as therapeutic agents in the food and pharmaceutical industries.

Antioxidant and Hypoglycemic Effects of Acidic-Extractable Polysaccharides from Cordyceps militaris on Type 2 Diabetes Mice

The present work was performed to evaluate the effect of acidic-extractable polysaccharides (AE-PS) from fruit bodies of Cordyceps militaris on type 2 diabetes mellitus (T2DM) and its structural characteristics. The T2DM mice induced by high-fat diet (HFD) and streptozotocin (STZ) were administered with 100 and 400 mg/kg AE-PS for 4 weeks. Our work proved that AE-PS decreased the levels of serum lipid, lipid peroxidation, and blood glucose; improved glucose and insulin resistance; enhanced antioxidant enzyme activities; and attenuated the injuries of the liver, kidney, and pancreas in T2DM mice. These results might offer references for the exploitation of AE-PS as functional foods or natural drug source for preventing and treating HFD- and STZ-induced T2DM. Moreover, gas chromatography (GC) results revealed that AE-PS was heterogeneous and composed of fucose, ribose, arabinose, xylose, mannose, galactose, and glucose with mass percentages of 1.23%, 0.57%, 0.29%, 2.12%, 2.73%, 4.66%, and 88.4%, respectively. Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) analysis indicated that AE-PS was a pyran-type polysaccharide with α- and β-configurations.

Characterization and Attenuation of Streptozotocin-Induced Diabetic Organ Damage by Polysaccharides from Spent Mushroom Substrate (Pleurotus eryngii)

The aim of this work was to characterize spent mushroom substrate polysaccharides (MSP) from Pleurotus eryngii and their antioxidant and organ protective effects in streptozotocin- (STZ-) induced diabetic mice. The enzymatic-, acidic-, and alkalic- (En-, Ac-, and Al-) MSP were extracted from P. eryngii with snailase (4%), hydrochloric acid (1 mol/l), and sodium hydroxide (1 mol/l), respectively. The characterizations were evaluated by spectral analysis. In animal experiments, the enzymatic activities, lipid peroxide contents, and serum lipid parameters were measured, and histological observations of the liver, kidney, pancreas, and heart were conducted. The results demonstrated that treatment with En-, Ac-, and Al-MSP increased the organ enzymatic activities, decreased the organ lipid peroxide contents, mitigated the serum biochemistry values, and ameliorated the histopathology of diabetic mice, indicating that En-, Ac-, and Al-MSP could potentially be used as functional foods for the prevention of diabetes.

Preparation, characterization and in vivo antidiabetic effects of polysaccharides from Pachyrrhizus erosus

Polysaccharides were extracted from Pachyrrhizus erosus (PEP) and three fractions (PEP60, PEP80 and PEP95) were separated by ethanol precipitation. Antidiabetic activities of three fractions were evaluated by streptozotocin-induced diabetic mouse model. Three PEP fractions reduced fasting blood glucose levels in mice, and regulated the levels of glycated serum protein, total triglyceride and total cholesterol in serum. In liver, the levels of glycogen content, glutathione peroxidase and superoxide dismutase activities and lipid peroxidation were recovered by PEP fractions. The histological analysis indicated that PEP fractions could protect the tissue structures of pancreas, liver and kidney from diabetic damages. In kidney, PEP fractions decreased the mesangial matrix index and inhibited the expression of transforming growth factor-β1. PEP95 showed stronger antidiabetic activity than PEP60 and PEP80. PEP95-DS was separated from PEP95 by DEAE-cellulose and Sephadex G-100 column chromatography. The chemical characteristics of PEP95-DS were evaluated. The average molecular weight of PEP95-DS was 11.4kDa, and it was composed of mannose: rhamnose: glucosamine: glucose: galactose: xylose: arabinose was 5.4:1.7:8.5:160.7:11.8:1:2.7. Furthermore, the spectral characteristics of PEP95-DS were analyzed. Our results indicated PEP could be used as a function ingredient in foods to prevent oxidation and diabetes.