Degradation of sulphated polysaccharides from Grateloupia livida and antioxidant activity of the degraded components

Effect of extrusion using plasma-activated water on the structural, physicochemical, antioxidant and in vitro digestive properties of yam flour

The synergistic effects of plasma-activated water (PAW) and twin-screw extrusion (TSE) on the structural, physicochemical, antioxidant, and digestive properties of yam flour (YF) were studied. Compared to common TSE, PAW-TSE reduced the protein, starch, and polyphenol contents, swelling power, and gel property of YF, while PAW-TSE enhanced the flavonoid content, whiteness index, solubility, and antioxidant property of YF. Moreover, the results of structural characterization and differential scanning calorimetry indicated that the long-range or short-range ordering, and gelatinization enthalpy of starch in YF were reduced after PAW-TSE, while the structure ordering of proteins in YF increased. Furthermore, the in vitro digestibility results demonstrated a reduction in the rate of enzymatic hydrolysis, coupled with an increase in total contents of slowly digestible and resistant starch after PAW-TSE. It should be noted that TSE using PAW prepared by a longer plasma treatment resulted in a more significant improvement effect on YF.

Physicochemical properties, structure and biological activity of ginger polysaccharide: Effect of microwave infrared dual-field coupled drying

Ginger was dried by microwave infrared dual-field coupled drying (MIDFCD). The composition, structure, physicochemical properties and biological activity of ginger polysaccharides at various stages of MIDFCD were investigated. The MIDFCD significantly impacted the chemical composition, molecular weight (Mw), microstructure, and physicochemical properties of ginger polysaccharides. However, there were no notable differences in functional group composition. The Mw and chemical composition were notably influenced by microwave-infrared exposure and prolonged drying time. The degradation of polysaccharides due to high temperatures in the later stage resulted in further decreases in Mw and alterations in monosaccharide composition. These changes in chemical composition and Mw affected thermal properties, crystallization properties, particle size, rheological properties, antioxidant capacity, and hypoglycemic activity. These findings suggest that MIDFCD enhances the quality and bioactivity of natural polysaccharides. This study offers theoretical support for MIDFCD processing and the value-added utilization of ginger.

Effect of H2O2/ascorbic acid degradation and gradient ethanol precipitation on the physicochemical properties and biological activities of pectin polysaccharides from Satsuma Mandarin

In this work, three degraded polysaccharides (DMPP-40, DMPP-60, DMPP-80) were successfully obtained by H2O2/ascorbic acid degradation and gradient ethanol precipitation from Satsuma mandarin peel pectin (MPP), and their physicochemical properties, antioxidant and prebiotic activities were investigated. The molecular weight of MPP, DMPP-40, DMPP-60, DMPP-80 were determined to be 336.83 ± 10.57, 18.93 ± 0.54, 26.07 ± 0.83 and 8.71 ± 0.27 kDa, respectively. The ethanol concentration significantly affected the physicochemical properties of DMPPs. DMPP-60 showed the highest yield (69.07 %) and uronic acid content (64.85 %), DMPP-80 showed the lowest molecular weight (8.71 kDa), and the composition and proportion of monosaccharides of DMPPs were significantly different. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (1H NMR) confirmed that DMPPs exhibited similar functional groups, while X-ray diffraction (XRD) indicated that DMPP-40 possessed some crystallographic sequences. Scanning electron microscopy (SEM) images directly verified the fragmented structure and reduced surface area of DMPPs. Besides, the H2O2/ascorbic acid treatment could obviously reduce the apparent viscosity and thermal stability of MPP. Meanwhile, the results of bioactivity assay showed that DMPPs possessed better antioxidant activity and probiotics pro-proliferative effects compared with MPP. DMPP-80 could significantly inhibit lipopolysaccharides (LPS)-stimulated production of inflammatory factors (including nitric oxide (NO), interleukin (IL)-6, tumor necrosis factor (TNF)-α and interleukin (IL)-1β) in RAW264.7 cells. Results suggest that the H2O2/ascorbic acid combined with gradient ethanol precipitation has potential applications in degradation and separation of MPP to improve its biological activities.

Effect of H2O2-VC degradation on structural characteristics and immunomodulatory activity of larch arabinogalactan

The arabinogalactan in the representative softwood biomass of larch was degraded using an environmentally friendly hydrogen peroxide and vitamin C (H2O2-VC) system to improve its immunomodulatory activity. Through the H2O2-VC degradation mechanism, hydroxyl radicals are generated, which then target the hydrogen atoms within polysaccharides, resulting in the breaking of glycosidic bonds. Given the impact of oxidative degradation on polysaccharides, we identified three specific arabinogalactan degradation products distinguished by their arabinosyl side chain compositions. The primary structures of the degradation products were investigated using Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Congo red staining showed that the degradation products were absent in the triple-helix structure. The results of the in vitro immunological experiments indicated that an appropriate reduction in the molar ratio of arabinose to galactose enhanced the immunostimulatory effects on RAW 264.7 cells. In addition, the immunostimulatory pathway mediated by arabinogalactan was explored by toll-like receptor 4 (TLR4) inhibitor (TAK-242) These findings provide novel insights into the understanding of the relationship between the structure of arabinogalactan and its biological activity.

Prebiotic characteristics of degraded polysaccharides from Acanthopanax senticosus polysaccharide on broilers gut microbiota based on in vitro digestion and fecal fermentation

This study aimed to evaluate the effect of low molecular weight Acanthopanax polysaccharides on simulated digestion, probiotics, and intestinal flora of broilers in vitro. The experiments were carried out by H2O2-Vc degradation of Acanthopanax polysaccharides, in vitro simulated digestion to evaluate the digestive performance of polysaccharides with different molecular weights, in vitro probiotic evaluation of the probiotic effect of polysaccharides on lactobacilli and bifidobacteria, in vitro anaerobic fermentation and high-throughput sequencing of 16S rRNA genes to study the impact of Acanthopanax polysaccharides on the intestinal flora of broilers, and the effect of Acanthopanax polysaccharides on the short-chain fatty acids of intestines were determined by GC-MS method. The results showed that the molecular weight of Acanthopanax polysaccharide (ASPS) was 9,543 Da, and the molecular weights of polysaccharides ASPS-1 and ASPS-2 were reduced to 4,288 Da and 3,822 Da after degradation, and the particle sizes, PDIs, and viscosities were also significantly decreased. ASPS-1 has anti-digestive properties and better in vitro probiotic properties. The addition of ASPS-1 regulates the structure of intestinal microorganisms by regulating fecalibacterium to produce short-chain fatty acids, promoting the colonization of beneficial bacteria such as fecalibacterium, paraprevotella and diminishing the prevalence of detrimental bacteria such as Fusobacteria. Interestingly the ASPS-1 group found higher levels of Paraprevotella, which degraded trypsin in the gut, reducing inflammation, acted as a gut protector, and was influential in increasing the levels of acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, and total SCFAs in the fermented feces. Therefore, the degraded ASPS-1 can better regulate the structure of intestinal flora and promote the production of SCFAs, creating possibilities for its use as a potential prebiotic, which is conducive to the intestinal health of poultry.

Effects of UV/H2O2 Degradation on the Physicochemical and Antibacterial Properties of Fucoidan

The applications of fucoidan in the food industry were limited due to its high molecular weight and low solubility. Moderate degradation was required to depolymerize fucoidan. A few studies have reported that fucoidan has potential antibacterial activity, but its antibacterial mechanism needs further investigation. In this study, the degraded fucoidans were obtained after ultraviolet/hydrogen peroxide treatment (UV/H2O2) at different times. Their physicochemical properties and antibacterial activities against Staphylococcus aureus and Escherichia coli were investigated. The results showed that the average molecular weights of degraded fucoidans were significantly decreased (up to 22.04 times). They were mainly composed of fucose, galactose, and some glucuronic acid. Fucoidan degraded for 90 min (DFuc-90) showed the strongest antibacterial activities against Staphylococcus aureus and Escherichia coli, with inhibition zones of 27.70 + 0.84 mm and 9.25 + 0.61 mm, respectively. The minimum inhibitory concentrations (MIC) were 8 mg/mL and 4 mg/mL, respectively. DFuc-90 could inhibit the bacteria by damaging the cell wall, accumulating intracellular reactive oxygen species, reducing adenosine triphosphate synthesis, and inhibiting bacterial metabolic activity. Therefore, UV/H2O2 treatment could effectively degrade fucoidan and enhance its antibacterial activity.

Preparation, antibacterial activity, and structure-activity relationship of low molecular weight κ-carrageenan

κ-Carrageenan (KC) is a polysaccharide widely used in food industry. It has been widely studied for its excellent physicochemical and beneficial properties. However, the high molecular weight and high viscosity of KC make it difficult to be absorbed and to exert its' biological activities, thus limit its extensive industrial application. In order to solve this problem, five low molecular weight κ-carrageenans (DCPs) were prepared by the degradation of KC using hydrogen peroxide (H2O2) and ascorbic acid (AH2). The chemical compositions and structure characteristics of the DCPs were then determined. The results showed that H2O2 and AH2 could effectively degrade KC to DCPs, and DCPs remained the basic skeletal structure of KC. DCPs showed good antibacterial activities against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis. The Minimum Inhibitory Concentration (MIC) of DCPs with the highest antibacterial effects were 5.25, 4.5, 5.25, and 4.5 mg/mL, respectively. This is due to the underlying mechanism of DCPs that bind to the bacterial membrane proteins and change the membrane permeability, thus exerting antibacterial activity. In addition, Spearman's rank correlation and Ridge regression analysis revealed that the molecular weight and the contents of 3,6-anhydro-D-galactose, aldehyde group, carboxyl, and sulfate were the main structural characteristics affecting the antibacterial activity. Our findings reveal that the H2O2-AH2 degradation treatment could significantly improve the antibacterial activity of KC and provide insights into the quantitative structure-activity relationships of the antibacterial activity of DCPs.

Efficient degradation and enhanced α-glucosidase inhibitory activity of apricot polysaccharides through non-thermal plasma assisted non-metallic Fenton reaction

Dielectric barrier discharge (DBD) was a commonly used non-thermal plasma (CP) technology. This paper aimed to enhance the biological activity of apricot polysaccharides (AP) by using dielectric barrier discharge (DBD-CP) assisted H2O2-VC Fenton reaction for degradation. The degradation conditions were optimized through response surface methodology. The molecular weight (Mw) of degraded apricot polysaccharides (DAP) was 19.71 kDa, which was 7.25 % of AP. The inhibition rate of DAP (2 mg/mL) was 82.8 ± 3.27 %, which was 106.87 % higher than that of AP. DBD-CP/H2O2-VC degradation changed the monosaccharide composition of AP and improved the linearity of polysaccharide chains. In addition, a novel apricot polysaccharide DAP-2 with a Mw of only 6.60 kDa was isolated from DAP. The repeating units of the main chain of DAP-2 were →4)-α-D-GalpA-(1 →, the branch chain was mainly composed of α-D-GalpA-(1 → 2)-α-L-Rhap-(1→ connected to O-3 position →3,4)-α-D-GalpA-(1→. The complex structure formed by the combination of DAP-2 and α-glucosidase was stable. DAP-2 had a higher α-glucosidase binding ability than the acarbose. These results suggested that DAP-2 had the potential to be developed as a potential hypoglycemic functional food and drug.

High efficient preparation of low molecular weight galactomannan from Leucaena leucocephala galactomannan through the combination of hydrogen peroxide and oxalic acid

Researchers have always been interested in polysaccharide degradation because of the increased biological activity and usability following degradation. In this work, low molecular weight galactomannan (LMW-GM) was produced through the degradation of galactomannan by H2O2 and oxalic acid (OA). The optimal reaction conditions were found by conducting the response surface optimization experiment based on single-factor experiment and kinetics analysis. Under these conditions, the LMW-GM yield was 69.48 ± 1.02 %. Ultimately, an analysis of the degradation process revealed that OA attacked GM indiscriminately, and H2O2 has a stronger effect on the removal of branched chains while degrading GM. Hence, the degradation steps were rearranged as H2O2 was added 20 min before OA at a constant total time. The LMW-GM yield was successfully increased to 76.49 ± 1.27 %. The goal of this work is hopefully to give a theoretical foundation for the low-cost preparation and industrial production of the degradation of galactomannan.

Exploring the partial degradation of polysaccharides: Structure, mechanism, bioactivities, and perspectives

Polysaccharides are promising biomolecules with lowtoxicity and diverse bioactivities in food processing and clinical drug development. However, an essential prerequisite for their applications is the fine structure characterization. Due to the complexity of polysaccharide structure, partial degradation is a powerful tool for fine structure analysis, which can effectively provide valid information on the structure of backbone and branching glycosidic fragments of complex polysaccharides. This review aims to conclude current methods of partial degradation employed for polysaccharide structural characterization, discuss the molecular mechanisms, and describe the molecular structure and solution properties of degraded polysaccharides. In addition, the effects of polysaccharide degradation on the conformational relationships between the molecular structure and bioactivities, such as antioxidant, antitumor, and immunomodulatory activities, are also discussed. Finally, we summarize the prospects and current challenges for the partial degradation of polysaccharides. This review will be of great value for the scientific elucidation of polysaccharide fine structures and potential applications.

Insights into the mechanisms underlying the degradation of xylooligosaccharides in UV/H2O2 system

UV/H₂O₂ process is increasingly used to degrade carbohydrates, though the underlying mechanisms remain unclear. This study aimed to fill this knowledge gap, focusing on mechanisms and energy consumption involved in hydroxyl radical (•OH)-mediated degradation of xylooligosaccharides (XOSs) in UV/H₂O₂ system. Results showed that UV photolysis of H₂O₂ generated large amounts of •OH radicals, and degradation kinetics of XOSs fitted with a pseudo-first-order model. Xylobiose (X₂) and xylotriose (X₃), main oligomers in XOSs, were attacked easier by •OH radicals. Their hydroxyl groups were largely converted to carbonyl groups and then carboxy groups. The cleavage rate of glucosidic bonds was slightly higher than that of pyranose ring, and exo-site glucosidic bonds were more easily cleaved than endo-site bonds. The terminal hydroxyl groups of xylitol were more efficiently oxidized than other hydroxyl groups of it, causing an initial accumulation of xylose. Oxidation products from xylitol and xylose included ketoses, aldoses, hydroxy acids and aldonic acids, indicating the complexity of •OH radical-induced XOSs degradation. Quantum chemistry calculations revealed 18 energetically viable reaction mechanisms, with the conversion of hydroxy-alkoxyl radicals to hydroxy acids being the most energetically favorable (energy barriers <0.90 kcal/mol). This study will provide more understanding of •OH radicals-mediated degradation of carbohydrates.

Structural characterization and immunomodulatory activity of an exopolysaccharide from marine-derived Aspergillus versicolor SCAU141

Until now, relatively little is known about marine-derived fungal polysaccharides and their activities. Exopolysaccharide AVP141-A was isolated from the broth of marine-derived fungus Aspergillus versicolor SCAU141 and purified by Diethylaminoethyl-Sepharose Fast Flow and Sephadex G-100. The structural characteristics of AVP141-A was studied by chemical analysis together with high-performance gel permeation chromatography, ion chromatography, Fourier-transform infrared spectroscopy, gas chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy. The results showed that AVP141-A with the molecular weight of 5.10 kDa was mainly composed of →4)-α-D-Glcp-(1→, branched by α-D-Glcp-(1→ and →6)-α-D-Glcp-(1→ at C-6 positions of the glucan backbone. In particular, sulfate ester (approximately 3.62 %) was found in AVP141-A, which was frequently considered to occur in marine-derived microbial polysaccharides rather than other microbial polysaccharides. Furthermore, AVP141-A significantly enhanced the activity of the inflammatory factors NO, COX-2 and TNF-α in RAW264.7 macrophages by activating the MAPK/p38 and NF-κB/p65 pathways. In addition, metabolomic analysis revealed that most of the pathways with significant changes in RAW264.7 macrophages treated with AVP141-A were amino acid-related pathways, and arginine was the characteristic metabolite. In conclusion, this study identified AVP141-A as a marine fungus-derived sulfated exopolysaccharide with potential for development as an immune activator.

Structural Characteristics of Rehmannia glutinosa Polysaccharides Treated Using Different Decolorization Processes and Their Antioxidant Effects in Intestinal Epithelial Cells

Polysaccharide decolorization is a key determinant of polysaccharide structure. In this study, two purified Rehmannia glutinosa polysaccharides, RGP−1−A and RGP−2−A, were obtained after decolorization using the AB-8 macroporous resin and H₂O₂, respectively. RGP−1−A (molecular weight (Mw) = 18,964 Da) and RGP−2−A (Mw = 3305 Da) were acidic and neutral heteropolysaccharides, respectively, and were both polycrystalline in structure. FTIR analysis revealed that RGP−1−A was a sulfate polysaccharide, while RGP−2−A had no sulfate group. Experiments on IPEC-1 cells showed that RGPs alleviated oxidative stress by regulating the Nrf2/Keap1 pathway. These findings were confirmed by the upregulation of Nrf2, NQO1, and HO-1; the subsequent increase in the levels of antioxidant indicators (SOD, LDH, CAT, and MDA); and the restoration of mitochondrial membrane potential. Overall, the antioxidant capacity of RGP−1−A was significantly higher than that of RGP−2−A. These results suggest that RGPs may be a potential natural antioxidant and could be developed into functional foods.

Influence of Molecular Weight of Polysaccharides from Laminaria japonica to LJP-Based Hydrogels: Anti-Inflammatory Activity in the Wound Healing Process

In this study, polysaccharides from Laminaria japonica (LJP) were produced by the treatment of ultraviolet/hydrogen peroxide (UV/H2O2) degradation into different molecular weights. Then, the degraded LJP were used to prepare LJP/chitosan/PVA hydrogel wound dressings. As the molecular weight of LJP decreased from 315 kDa to 20 kDa, the swelling ratio of the LJP-based hydrogels rose from 14.38 ± 0.60 to 20.47 ± 0.42 folds of the original weight. However, the mechanical properties of LJP-based hydrogels slightly decreased. With the extension of the UV/H2O2 degradation time, the molecular weight of LJP gradually decreased, and the anti-inflammatory activities of LJP-based hydrogels gradually increased. LJP that were degraded for 60 min (60-gel) showed the best inhibition effects on proinflammatory cytokines, while the contents of TNF-α, IL-6, and IL-1β decreased by 57.33%, 44.80%, and 67.72%, respectively, compared with the Model group. The above results suggested that low Mw LJP-based hydrogels showed great potential for a wound dressing application.

Characterization and Antioxidant Activity of Mannans from Saccharomyces cerevisiae with Different Molecular Weight

Polysaccharides were extracted from natural sources with various biological activities, which are strongly influenced by their chemical structure and molecular weight. In this research, mannans polysaccharides were obtained from Saccharomyces cerevisiae by ethanol precipitation. The molecular weight of YM50, YM70, and YM90 mannans was 172.90 kDa, 87.09 kDa, and 54.05 kDa, respectively. Scanning electron microscopy of YM 90 mannans showed a rough surface with numerous cavities, while the surfaces of YM50 and YM70 were relatively smooth. Sepharose CL-6B and FTIR indicated that mannans had the characteristic bands of polysaccharides. The antioxidant activities of polysaccharides were evaluated in vitro using various assays. Mannans showed a good scavenging activity of DPPH radicals which depend on the molecular weight and concentration, and a higher scavenging activity of hydroxyl radical than ferric-reducing power activities. For the three types of mannans, cytotoxicity and hemolytic activity were rarely detected in mice erythrocytes and Caco-2 cells. Those results could contribute to the further application of mannans from Saccharomyces cerevisiae in the food and medicine industry.

Structural characterization and hypolipidemic activity of Gracilaria lemaneiformis polysaccharide and its degradation products

This research aimed to analyze structural characterization and hypolipidemic activity in vitro of G. lemaneiformis polysaccharide (GLP) and its degradation products. The results presented that the content of galacturonic acid declined and glucuronic acid level enhanced, average particle size decreased from 99.9 μm to 25.7 μm, and color brightness of polysaccharide strengthened after degraded by H₂O₂-Vc. There was no significant change in thermal stability of polysaccharide before and after degradation. It was observed in AFM analysis, polysaccharide changed to smaller, delicacy and dispersion after degradation. As seen in FT-IR, H₂O₂-Vc degradation never change the structure of polysaccharide. Polysaccharide and its degradation products showed a significant inhibition effect on pancreatic lipase and cholesterol esterase in a dose-dependent manner, which presented the mixed type of competitive and non-competitive for pancreatic lipase, and non-competitive for cholesterol esterase, respectively. The fluorescence quenching type was static on pancreatic lipase and dynamic on cholesterol esterase.

Using One-pot Fermentation Technology to Prepare Enzyme Cocktail to Sustainably Produce Low Molecular Weight Galactomannans from Sesbania cannabina Seeds

Enzymatic hydrolysis using β-mannanase and α-galactosidase is necessary to produce low molecular weight galactomannan (LMW-GM) from galactomannans (GM) in the leguminous seeds. In this study, different ratios of avicel and melibiose were used as the inductors (carbon sources) for Trichoderma reesei to metabolize the enzyme cocktail containing β-mannanase and α-galactosidase using one-pot fermentation technology. The obtained enzyme cocktail was used to efficiently produce LMW-GM from GM in Sesbania cannabina seeds. Results showed that 15 g/L avicel and 10 g/L melibiose were the best carbon sources to prepare enzyme cocktail containing β-mannanase and α-galactosidase with activities of 3.69 ± 0.27 U/mL and 0.51 ± 0.02 U/mL, respectively. Specifically, melibiose could effectively induce the metabolite product of α-galactosidase by T. reesei, which showed good performance in degrading the galactose substituent from GM backbone. The degradation of galactose alleviated the spatial site-blocking effect for enzymatic hydrolysis by β-mannanase and improved the yield of LMW-GM. This research can lay the foundation for the industrial technology amplification of LMW-GM production for further application.

Optimized Degradation and Inhibition of α-glucosidase Activity by Gracilaria lemaneiformis Polysaccharide and Its Production In Vitro

Gracilaria lemaneiformis polysaccharide (GLP) exhibits good physiological activities, and it is more beneficial as it is degraded. After its degradation by hydrogen peroxide combined with vitamin C (H₂O₂-Vc) and optimized by Box–Behnken Design (BBD), a new product of GLP-HV will be generated. While using GLP as control, two products of GLP-H (H₂O₂-treated) and GLP-V (Vc-treated) were also produced. These products chemical characteristics (total sugar content, molecular weight, monosaccharide composition, UV spectrum, morphological structure, and hypolipidemic activity in vitro) were assessed. The results showed that the optimal conditions for H₂O₂-Vc degradation were as follows: H₂O₂-Vc concentration was 18.7 mM, reaction time was 0.5 h, and reaction temperature was 56 °C. The total sugar content of GLP and its degradation products (GLP-HV, GLP-H and GLP-V) were more than 97%, and their monosaccharides are mainly glucose and galactose. The SEM analysis demonstrated that H₂O₂-Vc made the structure loose and broken. Moreover, GLP, GLP-HV, GLP-H, and GLP-V had significantly inhibition effect on α-glucosidase, and their IC₅₀ value were 3.957, 0.265, 1.651, and 1.923 mg/mL, respectively. GLP-HV had the best inhibition effect on α-glucosidase in a dose-dependent manner, which was the mixed type of competitive and non-competitive. It had a certain quenching effect on fluorescence of α-glucosidase, which may be dynamic quenching.

Application of X-ray diffraction and energy dispersive spectroscopy in the isolation of sulfated polysaccharide from Porphyra haitanensis and its antioxidant capacity under in vitro digestion

BACKGROUND

The separation and purification of Porphyra haitanensis polysaccharide (PHP), and the determination of changes in molecular weight (Mw) and antioxidant capacity after in vitro digestion, were undertaken.

RESULTS

Analysis of two polysaccharide fractions (PHP0.5-1-UF and PHP1.0-1-UF) by various techniques showed that they were very pure sulfated polysaccharides without pigment or protein. PHP0.5-1-UF was filamentous or 'tape-like' sheets, whereas PHP1.0-1-UF had some filaments and large numbers of rounded aggregates. The Mw of PHP, PHP0.5-1-UF and PHP1.0-1-UF was 2.06 × 10⁶ (±2.02%), 6.68 × 10⁶ (±3.17%), and 1.14 × 10⁶ (±3.44%) (g mol^-1 ), respectively. After in vitro digestion, the Mw of PHP, PHP0.5-1-UF, and PHP1.0-1-UF decreased. Their antioxidant capacities were markedly higher than before digestion, especially PHP0.5-1-UF and its digestion products, which might be related to the reductions in Mw.

CONCLUSION

These findings provide a greater understanding of the separation and purification of sulfated polysaccharides and the influence of digestion on biological activity. They also contribute to the practical application of sulfated polysaccharides in functional foods. © 2021 Society of Chemical Industry.

Preparation of low molecular chitosan by microwave-induced plasma desorption/ionization technology

Compared with high molecular weight chitosan (HMWC), low molecular weight chitosan (LMWC) has better solubility and biological activity. However, there is no quick and environmentally friendly to prepare low molecular chitosan. In this study, microwave induced plasma desorption/ionization (MIPDI) was used for the first time to prepare LMWC through the degradation processes of HMWC. The results showed that MIPDI has the most abundant ∙OH content at the gas-liquid interface, and the active particles represented by ∙OH can degrade chitosan with a molecular weight of 540 KDa into soluble chitosan (≤ 10 KDa), and the yield of soluble chitosan can reach 61% in 60 min. Moreover, a series of characterization results showed that the chain structure and crystal structure gradually degraded as the treatment time increased while the chemical structure of chitosan did not change significantly. Antibacterial experiments also indicated that the antimicrobial property of LMWC obtained by MIPDI degradation was improved. In short, this method has proven to be a new, fast and green processing method for the preparation of low molecular chitosan.

Free radical-mediated degradation of polysaccharides: Mechanism of free radical formation and degradation, influence factors and product properties

Increasing studies focus on the degradation of polysaccharides by free radicals. The review mainly provides an overview of degradation of polysaccharides by free radicals generated from hydrogen peroxide (H₂O₂). Evidence suggests that free radicals generated from H₂O₂ can be generated by various mechanisms. It broke glycosidic bonds mainly through hydrogen abstraction, causing the degradation of polysaccharides. Its degradation efficiency is affected by many factors, such as the concentration of polysaccharides and H₂O₂, temperature and pH. In addition, free radical degradation could change the physicochemical and structural properties of polysaccharides, such as water solubility, thermal stability, molecular weight, monosaccharide composition, apparent morphology, and chain conformation, but it had little effects on the primary structure of polysaccharides. Besides, free radical degradation could also improve the bioactivities of polysaccharides, including antioxidant, antitumor and anticoagulant activities.

Degradation of Codium cylindricum polysaccharides by H2O2-Vc-ultrasonic and H2O2-Fe2+-ultrasonic treatment: Structural characterization and antioxidant activity

In this study, two degraded polysaccharides were obtained by H₂O₂-Vc-ultrasonic and H₂O₂-Fe²⁺-ultrasonic treatment from Codium cylindricum. The basic structure of polysaccharides was characterized and the relationship between structure and antioxidant activity was studied. FTIR spectrum indicated that the degraded polysaccharides had similar functional groups (OH, CH, CO group) with ordinary polysaccharides. LC-MS analysis showed that the degraded polysaccharides were composed of the same monosaccharide units (mannose, galactose, arabinose, glucose, ribose) with Codium cylindricum polysaccharides, but the molar ratio was different. Meanwhile, the molecular weight and morphological feature of polysaccharides had been changed after degradation. Additionally, the antioxidant activity assay revealed that two degraded polysaccharides with lower molecular weight possessed better antioxidant property than ordinary polysaccharides. These results suggested that the basic structure of polysaccharides had not been damaged by two degradation methods, while the antioxidant activity was significantly enhanced.

Structural characteristics and anti-inflammatory activity of UV/H2O2-treated algal sulfated polysaccharide from Gracilaria lemaneiformis

The study aimed to study the effects on structural characteristics and anti-inflammatory activities of algal sulfated polysaccharides isolated from Gracilaria lemaneiformis (GLP) after a combined treatment of UV irradiation (average irradiance of 6500 mJ/cm²) and H₂O₂ (50 mmol/L) for various time periods up to 60 min. After a 30-min treatment, the molecular weight and particle size of GLP was decreased by 15 and 2.6 fold, respectively with small but significant decrease in the contents of total sugars, uronic acids and proteins. There seemed to have no starch and the presence of longer side chains of branches in the GLP samples before and after UV/H₂O₂ treatment based on the I₂-KI assay. Scanning electron microscope and atomic force microscope analysis confirmed that the UV/H₂O₂ treatment could modify the surface morphology of GLP. GLP treated for 5 min possessed the strongest in vitro anti-inflammatory activity by inhibiting the production of nitric oxide, tumor necrosis factor-α and interleukin-6 by 60.49%, 62.81% and 36.29%, respectively in IEC-6 cells when compared to the model. Therefore, UV/H₂O₂ treatment had the potential to enhance the anti-inflammatory activity of algal sulfated polysaccharides.

Hydrogen Peroxide Effects on Natural-Sourced Polysacchrides: Free Radical Formation/Production, Degradation Process, and Reaction Mechanism-A Critical Synopsis

Numerous reactive oxygen species (ROS) entities exist, and hydrogen peroxide (H2O2) is very key among them as it is well known to possess a stable but poor reactivity capable of generating free radicals. Considered among reactive atoms, molecules, and compounds with electron-rich sites, free radicals emerging from metabolic reactions during cellular respirations can induce oxidative stress and cause cellular structure damage, resulting in diverse life-threatening diseases when produced in excess. Therefore, an antioxidant is needed to curb the overproduction of free radicals especially in biological systems (in vivo and in vitro). Despite the inherent properties limiting its bioactivities, polysaccharides from natural sources increasingly gain research attention given their position as a functional ingredient. Improving the functionality and bioactivity of polysaccharides have been established through degradation of their molecular integrity. In this critical synopsis; we articulate the effects of H2O2 on the degradation of polysaccharides from natural sources. Specifically, the synopsis focused on free radical formation/production, polysaccharide degradation processes with H2O2, the effects of polysaccharide degradation on the structural characteristics; physicochemical properties; and bioactivities; in addition to the antioxidant capability. The degradation mechanisms involving polysaccharide's antioxidative property; with some examples and their respective sources are briefly summarised.