Effect of steam explosion pretreatment on the structure and bioactivity of Ampelopsis grossedentata polysaccharides

Polysaccharides isolated from Ampelopsis grossedentata and their immunomodulatory activity

To explore the immunomodulatory activity of polysaccharides from Ampelopsis grossedentata, two polysaccharides named AGP1 and AGP2 were isolated and purified by DEAE-cellulose 52 column and Sephacryl S-300HR chromatography. AGP1 and AGP2 were composed of fucose, arabinose, rhamnose, galactose, glucose, mannose, galacturonic acid, and glucuronic acid, with a ratio of 0.5: 10.2: 0.9: 31.8: 7.4: 3.4: 21.6: 24.2 and 0.4: 6.0: 0.5: 23.3: 3.3: 6.2: 33.5: 26.8, respectively. The average molecular weights of AGP1 and AGP2 were found to be 6.60 × 105 Da and 7.24 × 105 Da, respectively. AGP1 contained →4,6)-Galp-(1 → glycosidic linkages, while AGP2 contained →2)-Galp-(1 → and →2,3,4)-Glcp-(1 → glycosidic linkages. The structures of AGPs were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and scanning electron microscope. The immunomodulatory activity of AGPs was investigated in RAW264.7 cells, and the results indicated that AGPs significantly activated macrophages, promoted cells differentiation and NO secretion, increased the expression of IL-6 and TNF-α, and induced macrophage M1 polarization. Transcriptomic analysis indicated that AGP1 and AGP2 regulated a total of 1043 and 970 differentially expressed genes respectively, which were identified in different immune related signaling pathways. Moreover, the immunoblot demonstrated that AGPs exerted immune-promoting effects through the TLR4, MAPK and NF-κB signaling pathways in macrophages. Consequently, AGPs have potent immunomodulatory activity and can be considered as immunomodulators in medical and food industries.

Inhibition mechanisms of α-glucosidase by eight catechins: Kinetic, molecular docking, and surface plasmon resonance analysis

α-Glucosidase is considered to be one of the effective targets for the treatment of type 2 diabetes. This study examined the inhibitory mechanisms of eight catechins on α-glucosidase, including both the free forms (C, EC, GC, EGC) and esterified forms (CG, ECG, GCG, EGCG). Enzyme kinetics and molecular docking studies demonstrated that catechins primarily inhibit α-glucosidase by binding through hydrogen bonds and hydrophobic interactions, with esterified catechins exhibiting stronger inhibitory effects. The structural changes of the proteins following binding were further explored using fluorescence spectroscopy and atomic force microscopy (AFM). Fluorescence spectroscopy revealed that catechins altered the microenvironment around the fluorescent amino acids within the enzyme (such as tyrosine and tryptophan), resulting in slight unfolding of the protein structure. AFM further confirmed that catechin binding to α-glucosidase induced protein aggregation, with esterified catechins exhibiting a more pronounced effect. All of the above findings were based on static model studies. Moreover, the binding kinetics of catechins with α-glucosidase were innovatively investigated using surface plasmon resonance (SPR), revealing that esterified catechins bound more rapidly and displayed higher affinity. The presence of the gallate group in esterified catechins was identified as crucial for their binding to α-glucosidase, resulting in a more significant inhibitory effect. These findings suggested that dietary intake of catechins, especially esterified form, may more effectively inhibit the activity of α-glucosidase.

Enhancing the Hypolipidemic and Functional Properties of Flammulina velutipes Root Dietary Fiber via Steam Explosion

Flammulina velutipes is an edible mushroom widely cultivated in China. As a by-product of Flammulina velutipes, the roots are rich in high-quality dietary fiber (DF). In order to obtain high-quality soluble dietary fiber (SDF), steam explosion (SE) is used as an effective modification method to improve the extraction rate and avoid the loss of active substances. Mounting evidence shows that SDF alleviates lipid metabolism disorders. However, it is not well understood how the influence of SDF with SE pretreatment could benefit lipid metabolism. In this study, we extracted a soluble dietary fiber from Flammulina velutipes root with an SE treatment, named SE-SDF, using enzymatic assisted extraction. The physicochemical and structural properties of the SE-SDF were investigated, and its hypolipidemic effects were also analyzed using oleic-acid-induced HepG2 cells. In addition, the anti-obesity and hypolipidemic effects of SE-SDF were investigated using a high-fat diet (HFD) mouse model. The results indicate that SE treatment (1.0 MPa, 105 s) increased the SDF content to 8.73 ± 0.23%. The SE-SDF was primarily composed of glucose, galactose, and mannose. In HFD-fed mice, SE-SDF significantly reduced weight gain and improved lipid profiles, while restoring liver function and reducing injury. This work provides an effective method for the processing of fungi waste and adds to its economic value. In future studies, the structural characteristics and the anti-obesity and gut microbiota regulation mechanisms of SE-SDF will be explored in depth, supporting its high-value utilization in healthcare products.

Effects of steam explosion pretreatment on the digestive properties and gut microbiota of Laminaria japonica polysaccharide

BACKGROUND

Laminaria japonica polysaccharide, which is an important bioactive substance of Laminaria japonica with anti-inflammatory and antioxidant effects. In this study, the molecular weight, functional groups and surface morphology were investigated to evaluate the digestive properties of Laminaria japonica polysaccharide before and after steam explosion.

RESULTS

The results indicated that the Laminaria japonica polysaccharide entered the large intestine to be utilized by the gut microbiota after passing through the oral, gastric and small intestinal. Meanwhile, Laminaria japonica polysaccharide of steam explosion promoted the growth of beneficial bacteria Phascolarctobacterium and Intestinimonas, and increased the content of acetic, propionic and butyric acids, which was 2.29-folds, 2.60-folds and 1.63-folds higher than the control group after 48 h of fermentation.

CONCLUSION

This study reveals that the effect of steam explosion pretreatment on the digestion in vitro and gut microbiota of Laminaria japonica polysaccharide will provide a basic theoretical basis for the potential application of Laminaria japonica polysaccharide as a prebiotic in the food industry. © 2024 Society of Chemical Industry.

Areca nut polysaccharide induces M1 macrophage polarization through the NF-κB and MAPK pathways independent of TLR2 and TLR4 signaling

In this study, the structure of Areca nut polysaccharide (ANP) was characterized, and its effects on macrophage activation and the underlying molecular mechanisms were investigated. ANP was identified as a glucan with a molecular weight of 24.5 kDa, and its structure was analyzed using XRD, SEM, FT-IR, methylation, and NMR techniques. The main chain of ANP is composed of →4)-α-D-Glcp-(1 → and →4,6)-α-D-Glcp-(1→, with a branched α-D-Glcp-(1 → chain. Furthermore, the activation of macrophages by ANP was explored. Stimulation of RAW264.7 cells with ANP in vitro increased the expression of inflammatory cytokines (TNF-α and IL-6) and NO levels. Flow cytometry showed that ANP induced M1 macrophage polarization. RNA-seq and Western blot analyses revealed that ANP activated the NF-κB and MAPK pathways. Importantly, TLR2- and TLR4- specific antibodies did not affect ANP-induced M1 polarization, whereas endocytosis inhibitors reduced the production of inflammatory cytokines in ANP-treated macrophages. In conclusion, ANP engages macrophages without interacting with TLR2 and TLR4 receptors, inducing M1 polarization through the NF-κB and MAPK signaling pathways.

Effect of steam explosion pretreatment on the fermentation characteristics of polysaccharides from tea residue

Green tea residues are the by-product of tea processing and they contain a large number of bioactive ingredients. Steam explosion has been recognized as one of the most innovative pretreatments for modifying the physicochemical characteristic of polysaccharides from lignocellulosic materials. However, the comparison of biological activity of steam exploded (SE-GTR) and unexploded (UN-GTR) green tea residue polysaccharides was still unclear, which prompted the determination of the efficacy of steam explosion in tea residue resource utilization. In this study, the effects of two extracted polysaccharides UN-GTR and SE-GTR on human gut microbiota in vitro fermentation were conducted. The results showed that after steam explosion pretreatment, SE-GTR displayed more loose and porous structures, resulting in higher polysaccharide content (2483.44±0.5 μg/mg) compared to UN-GTR (1903.56±2.6 μg/mg). In addition, after 24 h fermentation, gut microbiota produced more beneficial metabolites by SE-GTR. The largest SCFAs produced among samples was acetic acid, propionic acid and butyric acid. Furthermore, SE-GTR could regulate the composition and diversity of microbial community, increasing the abundance of beneficial bacteria, such as Bifidobacterium. These results revealed that steam explosion pretreatment could be a promising and efficient approach to enhance the antioxidant activity and bioavailability of polysaccharides isolated from tea residues.

Functional Properties, Rheological Characteristics, Simulated Digestion, and Fermentation by Human Fecal Microbiota of Polysaccharide from Morchella importuna

Morchella importuna polysaccharide (MIP) has been proven to have obvious hypoglycemic effects on mice with type 2 diabetes (T2DM). This study looked at the functional and rheological characteristics of MIP, and investigated the effects of MIP on the human fecal microbiota through in vitro fermentation experiments. The outcomes demonstrate the excellent oil-holding capacity, emulsifying, foaming, and rheological characteristics of MIP. After salivary gastrointestinal digestion, the Mw of MIP decreased from 398.2 kDa and 21.5 kDa to 21.9 kDa and 11.7 kDa. By 16S rRNA sequencing of bacteria fermented in vitro, it was found that MIP did not improve the richness and diversity of intestinal microorganisms, but it may exert an anti-T2DM function by significantly increasing the relative abundance of Firmicutes and promoting Ruminococcaceae_UCG_014, Bacteroides, and Blautia proliferation. Escherichia-Shigella could also be inhibited to improve the intestinal microenvironment. In addition, the fermentation of MIP increased the total short-chain fatty acid (SCFA) concentration from 3.23 mmol/L to 39.12 mmol/L, and the propionic acid content increased significantly. In summary, MIP has excellent processing performance and is expected to exert potential anti-T2DM activity through the human intestinal microbiota, which has broad market prospects.

Steam Explosion Pretreatment of Polysaccharide from Hypsizygus marmoreus: Structure and Antioxidant Activity

This paper investigated the effects of steam explosion (SE) pretreatment on the structural characteristics and antioxidant activity of Hypsizygus marmoreus polysaccharides (HPS). Hypsizygus marmoreus samples were pretreated at different SE temperatures (120-200 °C) and polysaccharides were extracted using the water extraction and alcohol precipitation method. The results showed that SE pretreatment improved the extraction rate of HPS. Under the conditions of SE treatment time of 60 s and temperature of 160 °C, the extraction rate of HPS was the highest (8.78 ± 0.24%). After SE pretreatment, the structural changes of HPS tended to enhance the antioxidant activity, which showed that the content of Gal and Man in the monosaccharide composition increased and the molecular weight decreased. When testing antioxidant activity in vitro, the ability of SE-pretreated HPS to scavenge DPPH radicals, hydroxyl radicals, and superoxide anion radicals was better than that of HPS without SE pretreatment. Our findings shed light on SE pretreatment as an efficient method for extracting active polysaccharides, providing a new way to improve their extraction rate and biological activity.

Steam Explosion-Assisted Extraction of Polysaccharides from Pleurotus eryngii and Its Influence on Structural Characteristics and Antioxidant Activity

Pleurotus eryngii (PE) has been sought after for its various health benefits and high content of phenolic compounds. This study explored the feasibility of steam explosion (SE)-assisted extraction of polysaccharides with high antioxidant capacities from PE. An orthogonal experimental design (OED) was used to optimize the SE-assisted extraction of PE. The influence of the optimized SE-assisted extraction on the physicochemical properties of PE polysaccharides was determined by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), monosaccharide compositional analysis and antioxidant capacity assays. Under optimal SE conditions, SE-assisted extraction increased the polysaccharide yield by 138% compared to extraction without SE-assistance. In addition, SEM demonstrated that SE-assisted extraction markedly altered the spatial structure of Pleurotus eryngii polysaccharides (PEP), and monosaccharide compositional analysis revealed that this pretreatment significantly increased the proportions of some monosaccharides, such as glucose, rhamnose and arabinose, in the isolated PEP. FTIR spectra indicated no change in the major chemical functional groups of PEP. PEP extracted by SE-assisted extraction had significantly increased free radical scavenging and antioxidant capacities. In conclusion, SE-assisted extraction appears to be a novel polysaccharide extraction technology, which markedly increases extraction yields and efficiency and can increase the biological activity of polysaccharide extracts.

A review on extraction, purification, structural characteristics, biological activities, applications of polysaccharides from Hovenia dulcis Thunb. (Guai Zao)

Hovenia dulcis Thunb. (H. dulcis) is a widely distributed plant with a long history of cultivation and consumption. As a common plant, it has economic, edible and medicinal value. H. dulcis polysaccharides are one of their main bioactive ingredients and have many health benefits, such as anti-diabetes, antioxidation, anti-glycosylation, anti-fatigue, immune regulation activities and alcoholic liver disease protection activity. In this paper, the research progress of H. dulcis polysaccharides in extraction, purification, structural characteristics, biological activities, existing and potential applications were reviewed, which could provide new valuable insights for future studies.

Extraction and characterization of polysaccharides from blackcurrant fruits and its inhibitory effects on acetylcholinesterase

Microwave assisted aqueous two-phase system (MA-ATPS) was used to simultaneously extract two polysaccharides from blackcurrant. Under the suitable ATPS (ethanol/(NH4)2SO4, 26.75 %/18.98 %) combining with the optimal MA conditions (liquid-to-material ratio 58.5 mL/g, time 9.5 min, temperature 60.5 °C, power 587 W) predicted by response surface methodology, the yields of the top/bottom phase polysaccharides were 13.08 ± 0.37 % and 42.65 ± 0.89 %, respectively. After purification through column chromatography, the top phase polysaccharide (PRTP) and bottom phase polysaccharide (PRBP) were obtained. FT-IR, methylation and NMR analyses confirmed that the repeating unit in the backbone of PRTP was →2, 5)-α-L-Araf-(1 → 3)-α-D-Manp-(1 → 6)-β-D-Galp-(1 → 6)-α-D-Glcp-(1 → 4)-α-L-Rhap-(1 → 4)-α-D-GalAp-(1→, while the possible unit in PRBP was →4)-α-L-Rhap-(1 → 3)-α-D-Manp-(1 → 6)-β-D-Galp-(1 → 6)-α-D-Glcp-(1 → 2, 5)-α-L-Araf-(1 → 4)-α-D-GalAp-(1→. PRBP with relatively low molecular weight exhibited better stability, rheological property, free radical scavenging and acetylcholinesterase (AChE) inhibitory activities than PRTP. PRTP and PRBP were reversible mixed-type inhibitors for AChE, and the conformation of AChE was changed after binding with the polysaccharides. Molecular docking, fluorescence and isothermal titration calorimetry assays revealed that PRTP and PRBP quenched the fluorescence through static quenching mechanism, and the van der Waals interactions and hydrogen bonding played key roles in the stability of polysaccharide-enzyme complexes. This study provided a theoretical basis for blackcurrant polysaccharides as AChE inhibitors to treat Alzheimer's disease.

Purslane (Portulacae oleracea L.) polysaccharide relieves cadmium-induced colonic impairments by restricting Cd accumulation and inhibiting inflammatory responses

This study aimed to assess the protective effects of purslane polysaccharide (PP) on colonic impairments in mice exposed to cadmium (Cd). C57BL/6 mice were administered with PP (200-800 mg/kg/day) by gavage for 4 weeks after treatment with 100 mg·L-1 CdCl2. PP significantly reduced Cd accumulation in the colon tissue and promoted the excretion of Cd in the feces. PP could reduce the expression levels of inflammatory factors (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6) and inhibit the activation of the TLR4/MyD88/NF-κB signaling pathway. In addition, the results of 16S rRNA analysis revealed that PP significantly increased the abundance of probiotics (Lactobacillus), while decreased the abundance of pathogenic bacteria (Lachnospiraceae_NK4A136_group). Following the augmentation of beneficial intestinal bacteria, the treatment with PP led to an increase in the levels of intestinal microbial metabolites, specifically short-chain fatty acids (SCFAs). The SCFAs are known for their anti-inflammatory properties, immune-regulatory effects, and promotion of intestinal barrier function. Additionally, the results suggested that PP effectively impeded the enterohepatic circulation by inhibiting the FXR-FGF15 axis in the intestines of Cd-exposed mice. In summary, PP mitigated the toxic effects of Cd by limiting its accumulation and suppressing inflammatory responses in colon.

A comprehensive review of vine tea: Origin, research on Materia Medica, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Vine tea is a popular folk tea that has been consumed in China for more than 1200 years. It is often used in ethnic medicine by ethnic groups in southwest China with at least 35 aliases in 10 provinces. In coastal areas, vine tea is mostly used to treat heatstroke, aphtha, aphonia, toothache, etc. In contrast, in the southwest inland regions, vine tea is mostly used to clear away heat and toxic materials, antiphlogosis and relieving sore-throat, lowering blood pressure and lipid levels, and alleviating fatigue. Three main species have been used as the source of vine tea, Nekemias grossedentata, Nekemias cantonensis and Nekemias megalophylla. Among them, the leaves of Nekemias grossedentata were considered as new food resource in complicance with regulations, according to the Food Safety Standards published by the Monitoring and Evaluation Department of the National Health and Family Planning Commission in China.

AIM OF THE STUDY

At present, the comprehensively summary of Materia Medica on the history and source of vine tea is currently unavailable. The current article summed up the Materia Medica, species origin and pharmacological effects of all 3 major species used in vine tea to fill the knowledge gaps. We also aim to provide a reference for future research on historical textual, resource development and medicinal utilization of vine tea.

MATERIALS AND METHODS

Adhering to the literature screening methodology outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), this review encompasses 148 scholarly research papers from three database, paper ancient books, local chronicles and folklore through field investigations. We then comprehensively summarized and discussed research progresses in scientific and application studies of vine tea.

RESULTS

The historical records indicated that vine tea could have been used as early as Southern and Northern Dynasties (AC 420-589). Nekemias grossedentata, Nekemias cantonensis and Nekemias megalophylla, were used to considered as vine tea in the ethnic medicine. The main phytochemicals found in three plants are flavonoids, polyphenols and terpenoids, among which dihydromyricetin (DHM) is the most important and most studied active substance. The key words "Ampelopsis grossedentata" (Synonym of Nekemias grossedentata) and "dihydromyricetin/DHM" showed the highest frequency over the last 27 year based on the research trend analysis. And the ethnopharmacology studies drawn the main activities of vine tea are antioxidant, antibacterial, hepatoprotective, neuroprotective and anti-atherosclerosis activities.

CONCLUSIONS

This review systematically summarized and discussed vine tea from the following five aspects, history, genetic relationship, phytochemistry, research trend and ethnopharmacology. Vine tea has a long historical usage in Chinese ethnic medicine. Its outstanding therapeutic efficacies have attracted extensive attention in other places in the world at present. Nekemias cantonensis and Nekemias megalophylla are quite similar to Nekemias grossedentata in terms of many aspects. However, the current research has a narrow focus on mainly Nekemias grossedentata and DHM. We propose that future studies could be carried out to determine the synergistic effect of multi-components and multi-targets of vine tea including all 3 species to provide valuable knowledge.

The Principle of Steam Explosion Technology and Its Application in Food Processing By-Products

Steam explosion technology is an emerging pretreatment method that has shown great promise for food processing due to its ability to efficiently destroy the natural barrier structure of materials. This narrative review summarizes the principle of steam explosion technology, its similarities and differences with traditional screw extrusion technology, and the factors that affect the technology. In addition, we reviewed the applications in food processing by-products in recent years. The results of the current study indicate that moderate steam explosion treatment can improve the quality and extraction rate of the target products. Finally, we provided an outlook on the development of steam explosion technology with a reference for a wider application of this technology in the food processing field.

Extraction of Pectin from Passion Fruit Peel: Composition, Structural Characterization and Emulsion Stability

Extraction methods directly affect pectin extraction yield and physicochemical and structural characteristics. The effects of acid extraction (AE), ultrasonic-assisted acid extraction (UA), steam explosion pretreatment combined with acid extraction (SEA) and ultrasonic-assisted SEA (USEA) on the yield, structure, and properties of passion fruit pectin were studied. The pectin yield of UA was 6.5%, equivalent to that of AE at 60 min (5.3%), but the emulsion stability of UA pectin was poor. The pectin obtained by USEA improved emulsion stability. Compared with UA, it had higher protein content (0.62%), rhamnogalacturonan I (18.44%) and lower molecular weight (0.72 × 10⁵ Da). In addition, SEA and USEA had high pectin extraction yields (9.9% and 10.7%) and the pectin obtained from them had lower degrees of esterification (59.3% and 68.5%), but poor thermal stability. The results showed that ultrasonic-assisted steam explosion pretreatment combined with acid extraction is a high-efficiency and high-yield method. This method obtains pectin with good emulsifying stability from passion fruit peel.

In Vitro Digestion and Fecal Fermentation of Peach Gum Polysaccharides with Different Molecular Weights and Their Impacts on Gut Microbiota

In the present study, we investigated the in vitro digestion and fermentation characteristics of three peach gum polysaccharides (PGPs) of different molecular weights; i.e., AEPG2 (1.64 × 107 g/mol), DPG2 (5.21 × 105 g/mol), and LP100R (8.50 × 104 g/mol). We observed that PGPs were indigestible during the oral, gastrointestinal, and intestinal stages. However, they were utilized by the gut microbiota with utilization rates in the order of DPG2 > AEPG2 > LP100R. Furthermore, arabinose in PGPs was preferentially utilized by the gut microbiota followed by galactose and xylose. Fermentation of peach gum polysaccharides could significantly increase the production of short-chain fatty acids (SCFAs), especially n-butyric acid. In addition, PGPs with different molecular weights values were predominantly fermented by different bacterial species. AEPG2 and DPG2 were fermented by the Bacteroidetes bacteria Bacteroides, while the dominant n-butyrate-producing bacteria was Faecalibacterium. While the LP100R was fermented by Bacteroides, Parabacteroides, Phascolarctobacterium, Dialister, Lachnospiraceae, and Blautia, the dominant n-butyrate-producing bacteria was Megamonas. These results indicated that PGPs are potential prebiotics for the food industry.

Structural characteristics of polysaccharide from Zingiber striolatum and its effects on gut microbiota composition in obese mice

To investigate a polysaccharide from Zingiber striolatum favorably modulates gut microbiota in mice fed a high-fat diet. Z. striolatum was utilized to extract the crude polysaccharide CZSP, which was subsequently refined using DEAE-52 cellulose and Sephadex G-150 to yield the novel polysaccharide Zingiber strioatum pure polysaccharide-1 (ZSPP-1). ZSPP-1 was an acidic heteroglycan made up of galactose, mannose, glucose, xylose, arabinose, glucuronic acid, and galacturonic acid with an average molecular weight of 1.57 × 106 Da. The structure of ZSPP-1 was investigated by FT-IR, methylation and NMR analysis, and the results denoted that the linkage structure types include T-Manp-linked, β-Xylp-(1,2)-linked, β-Galp-(1,4)-linked, α-GlcpA-(1,6)-linked, β-Arap-(1,4)-linked, α-Glcp-(1,3,4,6)-linked, α-Glcp-(1,2)-linked, and β-T-Xylp-linked, in which β-Galp-(1,4)-linked and α-GalpA-(1,4)-linked might be the main linkage. The results of the intervention experiments showed that ZSPP-1 changed the intestinal flora structure of the Firmicutes and Bacteroidetes in obese mice, and promoted the growth of beneficial bacteria such as Akkermansia, Lactobacillus, and Bacteroides in the intestine. It also restored the imbalanced flora structure due to high-fat diet to normal. It also restored the imbalanced flora structure due to high-fat diet to normal. Z. striolatum polysaccharides presented a considerable advantage in alleviating high-fat diet induced obesity, which indicates that it can be further exploited as a natural functional food resource.

Principle and Application of Steam Explosion Technology in Modification of Food Fiber

Steam explosion is a widely used hydrothermal pretreatment method, also known as autohydrolysis, which has become a popular pretreatment method due to its lower energy consumption and lower chemical usage. In this review, we summarized the technical principle of steam explosion, and its definition, modification and application in dietary fiber, which have been explored by researchers in recent years. The principle and application of steam explosion technology in the modification of food dietary fiber were analyzed. The change in dietary fiber structure; physical, chemical, and functional characteristics; the advantages and disadvantages of the method; and future development trends were discussed, with the aim to strengthen the economic value and utilization of plants with high dietary fiber content and their byproducts.

Effect of steam explosion pretreatment on polysaccharide isolated from Poria cocos: Structure and immunostimulatory activity

This study aimed to examine the effects of steam explosion (SE) pretreatment on the structural characteristics and immunostimulatory activity of polysaccharide from Poria cocos. Results showed that the average molecular weights of native polysaccharide (PCP) and SE-pretreated polysaccharide (SEPCP) were 18.67 and 6.52 kDa, respectively. PCP and SEPCP shared the same profiles of monosaccharides (mannose, glucose, galactose, and fucose) in different composition ratios, that is, PCP in a molar percentage of 13.5:33:40.3:13.2 and SEPCP in a molar percentage of 2.1:90.3:5.8:1.8. The surface structure of PCP showed smooth and densely spherical particles, whereas SEPCP had a rough surface and porous honeycomb structure. The main linkage types of PCP comprised 1,6-α-d-Galp, 1,2,6-α-d-Glcp, and T-α-d-Manp, whereas SEPCP primarily contained 1,3-β-d-Glcp backbone and T-β-d-Glcp branches. Compared with PCP, we further revealed that SEPCP had a better immune enhancement on the phagocytic ability, NO production, and the secretion levels of TNF-α and IL-6 in RAW 264.7 cells. Collectively, our observations supported that SE pretreatment could help to change the structure and improve the immunostimulatory activity of polysaccharide from P. cocos. PRACTICAL APPLICATIONS: SE technology is extensively used to extract bioactive components with improved yields owing to this technology's benefits of low energy consumption and high efficiency. SE pretreatment was found to contribute to the destruction of cell-wall structure, which could help to enhance the extraction yields of P. cocos polysaccharide (PCP). Meanwhile, SE pretreatment also could change the structural features and improve the immunostimulatory activity of PCP. This study revealed that more bioactive PCP with strengthened immunoregulatory effect was obtained pretreated by SE. This study was able to provide the effective information on the application of steam explosion technology to promote the further development and utilization of PCP in the pharmaceutical and functional food fields.

Structural characterization, antioxidant, and anti-inflammatory activity of polysaccharides from Plumula Nelumbinis

A polysaccharide from Plumula Nelumbinis (PNP), was isolated and purified. PNP had a molecular weight of 450 kDa and consisted five monosaccharides, including rhamnose, galacturonic acid, xylose, galactose, and arabinose. The methylation and nuclear magnetic resonance (NMR) analysis revealed that the main glycosidic linkage types of PNP were →5)-α-L-Araf-(1→, →3)-β-D-Galp-(1→, β-D-Xylp-(→1, →3,4)-β-D-Rhap-(1→, →4)-β-D-GalpA-(1→. In the range of 25-1200 μg/mL, PNP had no cytotoxicity to RAW264.7 cells. PNP could protect RAW264.7 cell from oxidative damage by reducing the production of ROS and MDA and the secretion of LDH, enhancing the activity of SOD, CAT, and GSH-Px, and increasing the content of GSH. Anti-inflammatory activity experiments showed that PNP inhibited the expression of NO, TNF-α, INF-γ, IL-1β, and IL-6. PNP could inhibit the activation of MAPK/NF-κB cell pathways. PNP could be used as a potential natural antioxidant and anti-inflammatory substance in functional foods and pharmaceuticals.

Isolation and Purification, Structural Characterization and Antioxidant Activities of a Novel Hetero-Polysaccharide from Steam Exploded Wheat Germ

A purified polysaccharide, designated as SE-WGPI, was isolated from wheat germ modified by steam explosion. The primary structure characteristics were determined by HPGPC, GC, periodate oxidation-Smith degradation, methylation analysis, FT-IR, NMR and Congo red test. The results showed that SE-WGPI was a homogeneous hetero-polysaccharide with the average molecular weight of 5.6 × 103 Da. The monosaccharide composition mainly consisted of glucose, arabinose and xylose with a molar ratio of 59.51: 20.71: 19.77. The main backbone of SE-WGPI consisted of →4,6)-α-D-Glcp(1→6)-α-D-Glcp(1→3)-β-D-Xylp(1→5)-α-L-Araf(1→ and the side chain was α-D-Glcp(1→ linked at the C4-position of →4,6)-α-D-Glcp(1→. SE-WGPI likely has a complex netted structure with triple helix conformation and good thermal stability. In addition, SE-WGPI had valid in vitro radical scavenging activities on DPPH and hydroxyl radicals. This study may provide structural information of SE-WGPI for its promising application in the fields of functional foods or medicines.

Structural characterization and immunomodulatory effects of extracellular polysaccharide from Lactobacillus paracasei VL8 obtained by gradient ethanol precipitation

In this study, gradient ethanol precipitation method was applied to obtain the extracellular polysaccharides of Lactobacillus paracasei VL8 (VL8-EPS). The yields, physicochemical properties, and immunomodulatory effects of VL8-EPS obtained by precipitation at different ethanol concentrations (30%, 50%, and 70%, v/v) were compared. The results showed that VL8-EPSs were high molecular weight sulfated heteropolysaccharides, composed mainly of glucose and galactose, and the alteration of ethanol concentration had an effect on their chemical compositions, molecular weight distributions, monosaccharide composition, and surface structure, while the primary structure remained the same. Among the three polysaccharide fractions, VL8-EPS50 displayed better immunomodulatory activities compared with VL8-EPS30 and VL8-EPS70. VL8-EPS50 was found to exert immunomodulatory effects by enhancing the phagocytic activity of RAW264.7 cells and to promote their secretion of more nitric oxide; it also showed stronger thermal and solution stability. In summary, there was a correlation between the structural characteristics of polysaccharides and their immunomodulatory activity, and VL8-EPS50 was preferentially used for in vivo immunomodulatory activity. Practical Application This study opens up the source of raw materials for functional foods, which can provide some theoretical basis for the research and development of extracellular polysaccharides of lactic acid bacteria and promote their application in the future development of food industry.

Isolation, purification, structural characterization, and hypoglycemic activity assessment of polysaccharides from Hovenia dulcis (Guai Zao)

Hovenia dulcis polysaccharides (HDPs) have a variety of important biological activities associated with potential applications in food engineering, pharmacy science, and health care. Herein, we isolated and purified polysaccharides from H. dulcis. Chemical composition analysis revealed that the purified polysaccharides (HDPs-2A) were composed of different molar ratios of mannose, Rha, GalA, GlcA, Glc, Gal, and Ara and had a molecular weight of 372.91 kDa. The structure of HDPs-2A was assessed by FT-IR, periodate oxidation, Smith degradation, methylation analysis, and NMR, allowing us to determine that the backbone of HDPs-2A is composed primarily of →5)-α-L-Araf-(1→, →5)-α-L-Araf-(1→, →3,5)-α-L-Araf-(1→, →6)-β-D-Galp-(1→, →3,6)-β-D-Galp-(1→, T-β-D-Galp, →3)-β-D-Galp-(1→, and T-α-D-Glcp. The results of atomic force microscopy (AFM) showed that HDPs-2A present an irregular polymer particle morphology in water. X-ray diffraction (XRD) results showed that HDPs-2A have a single crystal structure. Finally, we demonstrated that HDPs-2A have a good therapeutic effect on a rat model of type 2 diabetes.