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

Screening and Identification of Soil Selenium-Enriched Strains and Application in Auricularia auricula

Selenium (Se) is an essential trace element for human physiological metabolism. The application of organic Se as a source to cultivate Se-rich plants for micronutrient supplementation has been receiving increasing attention. In our study, a bacterial strain named H1 was isolated from the soil in Heilongjiang Province, China, and under optimal culture conditions, the unit Se content could reach 3000 μg·g-1 and its 16S ribosomal DNA sequence seemed to be a new molecular record of an Enterobacter species. After the domestication of Se tolerance and Se-rich experiments, H1 can be used as a Se source for cultivation of Se-rich Auricularia auricula. The results showed that soluble protein, soluble sugar, free amino acid and vitamin C contents in Auricularia auricula were notably increased by 28.7%, 21.8%, 32.5% and 39.2% under the treatment of Se concentration of 0.24 mg·kg-1, respectively. These findings enhance our understanding that H1 is more conducive to Se uptake and nutrient accumulation.

Fractionation and antioxidation activities of polysaccharides from Zanthoxylum bungeanum Maxim

Zanthoxylum bungeanum has a lengthy history of widespread use as a food ingredient in China. However, the composition of Zanthoxylum bungeanum polysaccharide remains ambiguous, and the antioxidant effect has received limited attention. This study aimed to extract water-soluble polysaccharide from the dried pericarp of Zanthoxylum bungeanum, referred to as WZBP, which was fractionated into a neutral component (WZBP-N) and three pectic components (WZBP-A-I, WZBP-A-II, WZBP-A-III). The findings indicated that WZBP-A-III is a pectic polysaccharide "smooth region" without many side chains. All components of WZBP exhibited a notable capacity for scavenging free radicals, with WZBP-A-III demonstrating the most potent antioxidation activity, and WZBP-A-III also observed to effectively extend the lifespan of Drosophila melanogaster and enhanced the activity of antioxidant enzymes. These results provide valuable insight and direction for future research on Zanthoxylum bungeanum polysaccharide as an antioxidant agent.

Ultrasound assisted wall-breaking extraction and primary structures, bioactivities, rheological properties of novel Exidia yadongensis polysaccharide

New natural multifunctional polysaccharide and its innovatory extraction technology may be urgently needed for food industries. Our aims were to establish new extraction method and investigate the primary structures, bioactivities and rheological properties of novel E. yadongensis polysaccharide (EYP). Ultrasound assisted mechanical wall-breaking extraction (MAUE) was successfully established for the EYP extraction from a new E. yadongensis. Based on the MAUE with RSM, the polysaccharide yield of 17.92 ± 0.56 % with the optimal parameters of five extraction factors were obtained, and current MAUE was characterized by its high yield, low extraction temperature and short ultrasound time. After the isolation and purification, the EYP as a protein-bound polysaccharide was obtained. FT-IR and NMR analysis showed that the main backbone of the EYP comprised of (1 → 4)-β-D-glucopyranosyl and (1 → 6)-ɑ-D-mannopyranosyl groups; EYP exhibited significant antioxidant, antibacterial, antitumor, antidiabetic activities, and good viscoelastic properties in low pH solutions (P < 0.05). The EYP may be used as a natural functional and cohesive agent in food industries.

Effects of ultrasonic-enzymatic-assisted ethanol precipitation method on the physicochemical characteristics, antioxidant and hypoglycemic activities of Tremella fuciformis polysaccharides

This investigation involved the extraction of a novel polysaccharide from the spore fermentation broth of Tremella fuciformis using a method that combined ultrasonic and enzymatic assistance with ethanol precipitation. It was then compared with enzymatic and ultrasonic extraction methods. The objective of this research is to offer a reference point for expanding the application of ultrasonic-assisted enzymatic extraction technology in T. fuciformis polysaccharides (TFPs). Based on single-factor experiments, Box-Behnken was used to optimize the extraction conditions of TFPs by ultrasonic-enzymatic-assisted ethanol precipitation extraction. The results revealed an optimal combination of enzymes, with a cellulase-to-papain ratio of 2:1, an enzyme addition of 4000U/100 mL, an enzymolysis temperature of 49 °C, ultrasonicpower at 3 W/mL and an ultrasonictime of 20 min. The extraction rate of TFPs and α- amylase inhibition rates were 23.94 % and 61.44 %, respectively. Comparing the physicochemical properties, structural characterization and in vitro activity of TFPs extracted through different methods, the results showed that ultrasonic treatment significantly influences the apparent morphology of polysaccharide and could enhance its in vitro biological activity. However, different extraction techniques exhibit insubstantial impact on the chemical composition, glycosidic bonds or glycosidic ring configurations within the polysaccharides. Among them, ultrasonic-enzymatic-assisted ethanol precipitation extraction of polysaccharide has the highest extraction rate and the lowest viscosity. It has significant effects on ABTS+ scavenging activity, α- amylase inhibition rate and glucose dialysis retardation index, polysaccharide treated with ultrasonic-enzymatic showed the best performance. These findings suggest that ultrasonic-enzymatic-assisted ethanol precipitation extraction can enhance the activities of TFPs, thereby providing a valuable insight for their future development and application.

A Neutral Polysaccharide from Spores of Ophiocordyceps gracilis Regulates Oxidative Stress via NRF2/FNIP1 Pathway

Ophiocordyceps gracilis (O. gracilis) is a parasitic fungus used in traditional Chinese medicine and functional foods. In this study, a neutral heteropolysaccharide (GSP-1a) was isolated from spores of O. gracilis, and its structure and antioxidant capacities were investigated. GSP-1a was found to have a molecular weight of 72.8 kDa and primarily consisted of mannose (42.28%), galactose (35.7%), and glucose (22.02%). The backbone of GSP-1a was composed of various sugar residues, including →6)-α-D-Manp-(1→, →2,6)-α-D-Manp-(1→, →2,4,6)-α-D-Manp-(1→, →6)-α-D-Glcp-(1→, and →3,6)-α-D-Glcp-(1→, with some branches consisting of →6)-α-D-Manp-(1→ and α-D-Gal-(1→. In vitro, antioxidant activity assays demonstrated that GSP-1a exhibited scavenging effects on hydroxyl radical (•OH), 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical cation (ABTS•+), and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•). Moreover, GSP-1a was found to alleviate H2O2-induced oxidative stress in HepG2 cells by reducing the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), while enhancing the activities of superoxide dismutase (SOD). Furthermore, GSP-1a upregulated the mRNA expression of antioxidant enzymes such as Ho-1, Gclm, and Nqo1, and regulated the NRF2/KEAP1 and FNIP1/FEM1B pathways. The findings elucidated the structural types of GSP-1a and provided a reliable theoretical basis for its usage as a natural antioxidant in functional foods or medicine.

Antioxidant potential evaluation of polysaccharides from Camellia oleifera Abel in vitro and in vivo

The extraction process, structural characterization and free radical scavenging ability of polysaccharides from Camellia oleifera have already been widely studied. However, the antioxidant activities are still lack of systematic experiments. In this study, we used Hep G2 cells and Caenorhabditis elegans to evaluate the antioxidant potential of polysaccharides that from C. oleifera flowers (P-CF), leaves (P-CL), seed cakes (P-CC) and fruit shells (P-CS). The results showed all these polysaccharides could protect cells from oxidative damage induced by t-BHP. The highest cell viabilities were 66.46 ± 1.36 % (P-CF), 55.2 ± 2.93 % (P-CL), 54.49 ± 1.29 % (P-CC) and 61.45 ± 1.67 % (P-CS), respectively. Studies have shown that four polysaccharides may protect cells from apoptosis by reducing ROS levels and maintaining MMP balance. Moreover, P-CF, P-CL, P-CC and P-CS increased the survival rate of C. elegans under thermal stress, which reduced the production of ROS by 56.1 ± 0.67 %, 59.37 ± 1.79 %, 16.63 ± 2.51 % and 27.55 ± 2.62 %, respectively. P-CF and P-CL showed stronger protective effects on C. elegans by increasing the nuclear entry rate of DAF-16 and stimulating the expression of SOD-3. Our study suggested that C. oleifera polysaccharides have the potential to develop into a natural supplement agent.

Enzyme-assisted extraction, characterization, and in vitro antioxidant activity of polysaccharides from Potentilla anserina L

Introduction

Potentilla anserina (Potentilla anserina L.), also known as ginseng fruit, is a plant that can be used as both medicine and food. Potentilla anserina L. has high medical value in Chinese medicine, such as strengthening the spleen and stomach, replenishing qi and blood, and astringing hemostasis.

Methods

In this study, polysaccharides of Potentilla anserina L. were extracted from the root using an enzyme-assisted extraction method. According to the principle of Box-Behnken design, response surface methodology was designed to optimize the extraction conditions. Fourier transform infrared spectroscopy and scanning electron microscopy were used to investigate the structure and appearance of Potentilla anserina L. polysaccharides. The monosaccharide composition of Potentilla anserina L. polysaccharides was determined using high-performance liquid chromatography. The antioxidant activities were also studied.

Results

Under the optimal extraction conditions (the ratio of solid to liquid, 1:15; ratio of cellulase to pectinase, 1:2; extraction pH, 8.0; enzyme reaction temperature, 60°C), the extraction yield of Potentilla anserina L. polysaccharides was 19.80 ± 0.01%, equal to the model prediction value 19.84%. The data of Fourier transform infrared spectrum, scanning electron microscopy, and high-performance liquid chromatography showed that the Potentilla anserina L. polysaccharide was a kind of α-pyran polysaccharide, mainly consisting of galactose, glucose, rhamnose, and arabinose. The antioxidant results showed that Potentilla anserina L. polysaccharides had a strong hydroxyl radical scavenging ability (IC₅₀ = 0.367 mg/mL), superoxide anion scavenging ability (IC₅₀ = 45.017 mg/mL), and a certain degree of total reducing ability.

Discussion

Enzyme-assisted extraction is an efficient method to extract Potentilla anserina L. polysaccharides. The Potentilla anserina L. polysaccharides could have potential use in functional foods as a natural antioxidant.

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.

Preparation, characterization of Auricularia auricula polysaccharide-based films and application in meat preservation

In order to find a degradable biofilm，edible films of Auricularia auricula polysaccharide (AAP) were prepared and characterized optically, morphologically, and mechanically in terms of barrier, bactericidal, and antioxidant properties and evaluated for their potential application in cold meat packaging. The results showed that films prepared from 40 % AAP had the best mechanical properties, with smooth and homogeneous surfaces, good water barrier properties and also good preservation of cold meat. Thus, Auricularia auricula polysaccharide is a composite membrane additive with great potential for application.

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.

Corrigendum: Compounds purified from edible fungi fight against chronic inflammation through oxidative stress regulation

[This corrects the article DOI: 10.3389/fphar.2022.974794.].

Isolation, Purification, and Antioxidant Activities of Polysaccharides from Choerospondias axillaris Leaves

The extraction, characterization and antioxidant activity of polysaccharides from Choerospondias axillaris leaves were investigated in the present study. Two purified polysaccharide fractions, CALP-1 and CALP-2, were isolated from crude Choerospondias axillaris leaf polysaccharides (CALP) by DEAE-52 cellulose chromatography and Sephadex G-100 column chromatography. The characteristics of CAL-1 and CALP-2 were determined by using High-performance Gel Permeation Chromatography (HPGPC), High-Performance Anion-Exchange Chromatography, HPAEC (HPAEC-PAD) and Fourier transform infrared spectroscopy (FTIR). CALP-1 with molecular weight of 11.20 KDa was comprised of Rhamnose, Arabinose, Galactose, Glucose, Xylose, Mannose and galacturonic acid in a molar ratio of 5.16:2.31:5.50:27.18:1.00:0.76:1.07. CAL-2 with molecular weight of 8.03 KDa consisted of Rhamnose, Arabinose, Galactose, Glucose, and galacturonic acid at a ratio of 1.38:3.63:18.84:8.28:1.45. FTIR revealed that CALP-1 and CALP-2 were acidic polysaccharides. The antioxidant activity of crude CALP, CALP-1 and CALP-2 was evaluated in vitro. The fraction CALP-2 was demonstrated to be of polysaccharide nature containing a large percentage of Galactose but no Xylose and Mannose. The antioxidant activity assays showed that CALP-1 and CALP-2 exhibited antioxidant and scavenging activities on hydroxyl and DPPH radicals in vitro. Compared with pure polysaccharide, crude CALP exhibited stronger anti-oxidant activities. These results will provide a better understanding of Choerospondias axillaris leaf polysaccharide and promote the potential applications of Choerospondias axillaris leaf polysaccharide in the pharmacological field and as a natural antioxidant.

Formation Optimization, Characterization and Antioxidant Activity of Auricularia auricula-judae Polysaccharide Nanoparticles Obtained via Antisolvent Precipitation

Auricularia auricula-judae polysaccharide (AAP)-based nanoparticles (NPs) prepared via an anti-solvent precipitation approach were studied. Response surface methodology (RSM) design was carried out on the basis of single factor experiments, using average size and polydispersity index (PDI) as indicators. The optimal preparation conditions were determined to include an AAP concentration of 1 mg/mL, a pH of 8, and an anti-solvent/solvent volume ratio of 6. The average particle sizes of the AAP-NPs, PDI and electrical characteristic (ζ-potential) were found to be 150.27 ± 3.21 nm, 0.135 ± 0.012 and -31.10 ± 0.52 mV, respectively. Furthermore, Fourier transform infrared spectroscopy (FTIR) was used to determine the chemical structure of the AAP-NPs. It was observed that the intensity of AAP-NPs in the wide spectral band of 3000-3750 cm^-1 was significantly stronger than that of the AAP, as was the characteristic peak of carboxyl anion, and the characteristic band moved to shorter wavelengths. Subsequent thermogravimetric analysis showed that the antisolvent precipitation method improved the thermal stability of the AAP, while scanning electron microscopy (SEM) and X-ray diffraction (XRD) showed that the morphology of AAP-NPs was uniform and well-distributed, and that their single crystal structures had remained unaffected during the process. Moreover, the DPPH and ABTS scavenging activities of AAP-NPs were increased, and the IC50 values were 0.544 ± 0.241 mg/mL and 0.755 ± 0.226 mg/mL, respectively.

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.

Compounds purified from edible fungi fight against chronic inflammation through oxidative stress regulation

Chronic inflammation is associated with various chronic diseases, including cardiovascular disease, neurodegenerative disease, and cancer, which severely affect the health and quality of life of people. Oxidative stress induced by unbalanced production and elimination of reactive oxygen species (ROS) is one of the essential risk factors for chronic inflammation. Recent studies, including the studies of mushrooms, which have received considerable attention, report that the antioxidant effects of natural compounds have more advantages than synthetic antioxidants. Mushrooms have been consumed by humans as precious nourishment for 3,000 years, and so far, more than 350 types have been identified in China. Mushrooms are rich in polysaccharides, peptides, polyphenols, alkaloids, and terpenoids and are associated with several healthy biological functions, especially antioxidant properties. As such, the extracts purified from mushrooms could activate the expression of antioxidant enzymes through the Keap1/Nrf2/ARE pathway to neutralize excessive ROS and inhibit ROS-induced chronic inflammation through the NF-κB pathway. Recently, the antioxidant properties of mushrooms have been successfully applied to treating cardiovascular disease (CAD), neurodegenerative diseases, diabetes mellitus, and cancer. The present review summarizes the antioxidant properties and the mechanism of compounds purified from mushrooms, emphasizing the oxidative stress regulation of mushrooms to fight against chronic inflammation.

Structural characterization, antioxidant activity and anti-inflammatory of the phosphorylated polysaccharide from Pholiota nameko

In this study, a novel polysaccharide (SPN) was extracted by high-temperature pressure method and purified by a DEAE-52 column and a Sephadx G-100 gel column. PPN was obtained after phosphorylation of SPN. The differences of structural features, antioxidant activity, and anti-inflammatory effect of the two polysaccharides were investigated by chemical methods and RAW 264.7 cell model. SPN (Mw = 15.8 kDa) and PPN (Mw = 27.7 kDa) are an acidic polysaccharide with β-pyranose configuration, mainly containing rhamnose, mannose, glucose, arabinose, and galacose. FI-IR, NMR, and SEM spectra showed phosphorylation of SPN changed its structure. In methylation analysis, the major chains of SPN and PPN were 1,4-linked Glcp, 1,6-linked Galp, 1,2-linked Rhap, and 1.6-linked Manp with terminals of t-linked Glcp, t-linked Araf. The side chain of SPN was 1,4,6-linked Galp, 1,2,5-linked Araf, while the side chain of PPN was 1,4,6-linked Galp, 1,2,4-linked Glcp. In antioxidant activity experiments, the free radical scavenging rate of PPN was stronger than that of SPN. Also, PPN always has better anti-inflammatory on RAW 264.7 cells induced by LPS than that of SPN in same concentration, and it plays an anti-inflammatory role by inhibiting PI3K/AKT/mTOR pathway. The results indicated polysaccharide could significantly improve its antioxidant and anti-inflammatory function after phosphorylation. This study provides a potentially antioxidant and anti-inflammatory health food and drug.

Comparison of characterization and antioxidant activity of different citrus peel pectins

Pectins obtained from citrus peel of different cultivars and growth regions were compared based on physicochemical properties and antioxidant activity in vitro. The physicochemical features were elucidated using Fourier transform infrared (FT-IR), molecular weight distribution, monosaccharide composition, thermal behaviors and flow behaviors. Results showed that the different cultivars and growing areas have significant effects on the properties of citrus peel pectins (CPPs). Citrus peel pectins extracted by acetic acid were highly heterogeneous polysaccharides with broad molecular weight distributions and had high proportions of the RG-I domain. Among the 10 kinds of citrus peel pectins, Shatangju (CPP-6) and Xuecheng (CPP-7) own superior antioxidant biological activity and Dahongpao (CPP-3) and Buzhihuo (CPP-9) had excellent functional properties (thermal stability and viscosity). According to the correlation analysis, molecular weight, galacturonic acid content and degree of methyl-esterification were beneficial to increase the thermal stability and viscosity of citrus peel pectins, while the rhamnose content, rhamnogalacturonan I region and lower molecular weight can improve citrus peel pectins antioxidant activity. Our findings suggest that CPP-6 and CPP-7 may be useful as a potential natural antioxidant in pharmaceutical and cosmetic industries. Meanwhile, CPP-3 has great application potential in high temperature food and CPP-9 can be used as a thickener or stabilizer in the food industry.

Antioxidant, Anti-Tumour, and Anticoagulant Activities of Polysaccharide from Calocybe indica (APK2)

The initial structural features and in vitro biological study of crude polysaccharides from Calocybe indica (CICP) extracted by hot water followed by ethanol precipitation was investigated. High-performance gel permeation chromatography, HPLC-DAD, UV, IR and NMR spectroscopy, X-ray diffraction, scanning electron microscopy, and Congo red methods were used to determine structural features. The results revealed that CICP is a hetero-polysaccharide with a molecular weight of 9.371 × 10⁴ Da and 2.457 × 10³ Da which is composed of xylose, mannose, fucose, rhamnose, arabinose, galactose, and glucose. The antioxidant activity of CICP was evaluated using radical scavenging activity (three methods), reducing ability (three methods), metal chelating activity, and lipid peroxidation inhibition activity (two methods). It was found that the antioxidant capacity is concentration-dependent and EC₅₀ values were found to be 1.99–3.82 mg/mL (radical scavenging activities), 0.78–2.78 mg/mL (reducing ability), 4.11 mg/mL (metal chelating activity), and 0.56–4.18 mg/mL (lipid peroxidation inhibition activity). In vitro anticoagulant assay revealed that CICP could prolong activated partial thromboplastin time (APTT), thrombin time (TT), but not prothrombin time (PT). CICP exhibited antiproliferative activity on HeLa, PC3, HT29, HepG2, and Jurkat cell lines with IC₅₀ (μg/mL) values of 148.40, 143.60,151.00, 168.30, and 156.30, respectively. The above findings suggested that CICP could be considered a natural antioxidant and cancer preventative.

Comparison on chemical features and antioxidant activity of polysaccharides from Auricularia auricula by three different enzymes

To investigate and compare the chemical features and antioxidant activities of Auricularia auricula polysaccharides (AAPs), three different AAPs (AAP-M, AAP-D, and AAP-C) were prepared by mannanase, β-dextranase, and cellulase. Their chemical features were determined using high-performance liquid chromatography and infrared spectroscopy. The antioxidant properties were performed both in vitro and in vivo. Results showed that the surface morphology of the A. auricula cell wall treated with three enzymes was slightly different under scanning electron microscopy. The extraction yields of AAP-M, AAP-D, and AAP-C were 18.33% ± 1.93%, 26.42% ± 0.87%, and 17.17% ± 0.08% under optimal conditions, respectively. The monosaccharide composition, molecular weight (AAP-M, AAP-D, and AAP-C were 1.03E+03 kDa, 1.76E+03 kDa, and 1.15E+03 kDa, respectively), and antioxidant activities of the three AAPs were different. AAP-C composed of mannose, glucuronic acid, glucose, and galactose, exhibiting the remarkable ability of scavenging ABTS⁺ , DPPH, and H₂ O₂ (IC₅₀ was 0.065, 0.081, and 0.293 mg/ml, respectively). Moreover, AAP-C could significantly prolonged the lifespan of Caenorhabditis elegans under oxidative stress (p < .05). The results showed that cellulase could be served as an efficient enzyme to prepare AAPs with higher antioxidant capacity. PRACTICAL APPLICATIONS: According to the statistics of China Edible Fungi Association in 2019, the output of Auricularia auricula was accounting for 17.54% of the total output of edible fungi. AAPs account for more than 60% of the fruiting bodies and have various biological activities. Cell wall breaking is an important process of extracting AAPs which has always been the bottleneck restricting the production of AAPs. The traditional chemical acid-base method will pollute the environment, and the yield of hot water extraction is low. In contrast, the bioenzyme method widely used because of its mild conditions and environmental friendly. In this paper, three common bioenzymes which have been widely used in food industry were used to extract AAPs, and Box-Behnken design to improve the yield of AAPs. The results show that AAP-C had high yield and strong antioxidant activity. This study could provide a reference for the industrial production of AAPs.

Antioxidant and immune-modulating activities of egg yolk protein extracts

Egg yolk is widely used to extract lecithin, which is utilized in the food and cosmetics industry. After lecithin is removed, the rest of egg yolk is generated as a by-product. Thus, it is necessary to properly utilize it. In this study, egg yolk protein extracts were produced using ethanol (EYE-E) and water (EYE-W). Their antioxidant and immunomodulatory effects were then evaluated. Antioxidant activities of EYE-E and EYE-W were determined using cellular antioxidant capacity (CAC) assay and comet assay. EYE-E and EYE-W showed significant (p<0.05) scavenging effects on intracellular reactive oxygen species (ROS) in a dose dependent manner. At a concentration of 50 μg/mL, EYE-W showed higher (p<0.05) antioxidant activity than EYE-E. EYE-E and EYE-W also exhibited protective effects against DNA damage caused by oxidative stress. After treatment with EYE-E and EYE-W, DNA damage level of 48.7% due to oxidative stress was decreased to 36.2% and 31.8% levels, respectively. In addition, EYE-E and EYE-W showed immunomodulatory effects by regulating Th1 cytokines (TNF-α and IL-2) and Th2 cytokines (IL-10 and IL-4) in Balb/c mouse splenocytes. These data suggest that EYE-E and EYE-W could be used as functional food ingredients with excellent antioxidant and immunomodulatory activities in the food industry.

Effects of Auricularia auricula-judae polysaccharide on pasting, gelatinization, rheology, structural properties and in vitro digestibility of kidney bean starch

Auricularia auricula-judae polysaccharide (AP) has unique molecular structures and multiple bioactivities with excellent gel-forming property and thermal tolerance. However, few researches focus on the interactions between AP and legume starches. In this study, the effects of AP on the pasting, gelatinization, rheology, microstructure, and in vitro digestibility of kidney bean starch (KBST) were evaluated. The pasting, gelling and structural properties of AP-KBST mixtures were characterized by rapid visco analyzer, rheometry, texture analyzer, laser particle analyzer, low-field nuclear magnetic resonance, Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. And an in vitro method was employed to measure the digestibility of AP-KBST composites. The pasting viscosity, swelling degree of starch granules, viscoelasticity, gel strength, cold storage stability and water-retention capacity of KBST were enhanced with increasing AP concentration. The combination of AP and KBST exhibited a higher short-range ordered and a firmer and denser structure than that of KBST alone. Moreover, AP increased the contents of resistant starch and slowly digestible starch, which were positively correlated with the storage modulus and the degree of order, thereby suggesting that the formation of strong and ordered gel network structure by synergistic interactions between AP and KBST was responsible for the reduced starch digestibility.

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 water-soluble selenium-enriched polysaccharide produced by Pleurotus ostreatus: Purification, characterization, antioxidant and antitumor activities in vitro

The development and application of new selenium-enriched polysaccharides has become a critical topic in recent years. In this study, a natural selenium-enriched polysaccharide fraction (Se-POP-21) produced by Pleurotus ostreatus was purified, characterized, and investigated the antioxidant and antitumor activities in vitro. The Se-POP-21 was mainly composed of mannose, glucose, galactose and arabinose, with a molar ratio of 18.01:2.40:26.15:7.34, of which molecular weight was 15,888 Da and the selenium content was 5.31 μg/g. Spectral analysis demonstrated that Se-POP-21 represented a non-triple helix pyranopolysaccharide and selenium occurred in the form of C-O-Se and SeO. Molecular size and morphology studies showed that Se-POP-21 exhibited a spherical shape with a particle size distribution between 100 and 200 nm, even though Se-POP-21 aggregates were also found with a size between 500 and 600 nm. In addition, Se-POP-21 showed strong scavenging capacity to DPPH and hydroxyl radical. More, cell experiments showed that Se-POP-21 could reduce viability of A549, SKOV3, HepG2 and MCF-7 cells, induce apoptosis and inhibit metastasis of A549 cells. A potential mechanism was that Se-POP-21 inhibited the epithelial-to-mesenchymal transition of cancer cells. Se-POP-21 featured no significant effect on normal cells. Se-POP-21 showed great potential to develop into a natural antioxidant or low-toxic antitumor drug.