Carboxymethylated degraded polysaccharides from Enteromorpha prolifera: Preparation and in vitro antioxidant activity

Structural characterizations and antiaging activities of hydrolyzed low-molecular-weight polysaccharides from Polygoni Multiflori Radix Praeparata

Natural polysaccharides as the primary active components derived from herbal medicine often face challenges due to their large molecular weights, varying chemical structures and poor bioavailability, which significantly restrict their bioactive mechanism investigation and clinical applications. To improve the bioavailability and clarify the antiaging mechanism of polysaccharides from Polygoni Multiflori Radix Praeparata, the high-molecular-weight polysaccharides (PRP) were hydrolyzed into two low-molecular-weight fractions (PRP1 and PRP2) by hydrogen peroxide-ascorbic acid method. The results of structural characterization showed that they were glucans with the molecular weights of 13.43 kDa and 5.97 kDa, respectively. Compared with PRP and PRP1, PRP2 exhibited the most potent antiaging activity in D-galactose-treated T lymphocytes, attributed to its shorter chain length and lower molecular weight. Furthermore, oral administration with PRP2 not only decreased the levels of senescence-associated secretory phenotype (SASP)-related inflammatory cytokines, elevated the counts of T cells, NK cells, and macrophages in the blood, but also reduced the expressions of p16 and p21 proteins in spleen tissues of naturally aged C57BL/6J mice and two fast-aging (ERCC2+/- and TERT-/-) mice. Mechanistically, PRP2 competitively bound with Keap1 and subsequently activated Nrf2/HO-1 pathway. Therefore, PRP2 could be explored as a potential candidate for treatment of age-related diseases and overall aging.

Durable fibrous nanohybrid sunscreen films with in-situ fabricated enteromorpha polysaccharides for enhanced UV protection

Enteromorpha, a coastal green algae species, contains polysaccharides with excellent water solubility, biocompatibility, and antioxidant properties, making them ideal for skincare applications as natural antioxidant additives. This study introduces a modified electrospinning technique to fabricate fibrous nanohybrid sunscreen films incorporating Enteromorpha polysaccharides (EPPs) integrated with polyvinyl butyral (PVB) and titanium oxide (TiO2). The resulting film harnesses EPPs' antioxidant capabilities to protect skin from free radicals generated by TiO2 photocatalysis, while the PVB matrix and electrospun fibers provide water resistance and breathability. The nanohybrid film demonstrated remarkable photostability, maintaining its UV-blocking efficiency even after exposure to 365 nm UV radiation. Additionally, water immersion reduced its UV-blocking rate by only 2 %, confirming its strong water stability. Microscopic analysis showed no residual traces on porcine skin, effectively addressing concerns of pore-clogging and skin irritation often associated with traditional sunscreens.

Structural characterization of Dendrobium huoshanense polysaccharides and its gastroprotective effect on acetic acid-induced gastric ulcer in mice

Dendrobium huoshanense (DH) is a medicinal plant known for its efficacy in improving gastrointestinal diseases. In this study, a novel polysaccharide, DHPs-1, was isolated and purified from DH, and its structural characteristics were analyzed using advanced methodologies, including monosaccharide composition analysis, methylation, FT-IR spectroscopy, and NMR. The gastroprotective effect of DHPs-1 was assessed using a mouse model of chronic gastric ulcers induced by acetic acid. The results revealed that DHPs-1 is primarily composed of mannose (Man) and glucose (Glc) with a molecular weight of 3.137 × 106 Da. The purified polysaccharide DHPs-1 is primarily composed of →4)-β-D-Glcp-(1 → and →4)-β-D-Manp-(1→, with an acetyl substitution at the C-2 position of Man. DHPs-1 exhibited a pronounced protective effect against acetic acid-induced chronic gastric ulcers in mice by modulating gastric defense factors and inflammatory mediators. Furthermore, DHPs-1 downregulated the expression of p-p65/p-IκBα in gastric tissues, thereby mitigating gastric mucosal injury. These findings suggest that DHPs-1 has the potential to serve as an effective gastric mucosal protective agent and could be developed into functional foods and dietary supplements.

Enzymatic degraded polysaccharides from Enteromorpha prolifera inhibit the growth of THP-1 cells and induce apoptosis via the mitochondrial pathway

Polysaccharides from Enteromorpha prolifera (EP) is a kind of sulfated polysaccharides with complex structure. Several reports have showed that EP play roles in antioxidant and anti-inflammatory, while, whose function in anti-leukemia is still poorly understood. In this work, EPH were the hydrolysis products of EP by ulvan lyase EPL15085, which displayed lower molecular weight and enhanced sulfate groups than EP. Importantly, EPH exhibited effective inhibitory effect on the human leukemia monocyte cell line, THP-1 cells, however, the EP treated group showed no significant change. Results of JC-1 staining and ROS assay showed mitochondrial dysfunction after EPH treatment, and the increased rate of Bax/Bcl ultimately activated Caspase family proteins to induce apoptosis, indicating the mitochondrial pathway was involved. This study demonstrates the enzymatic products of EP showed enhanced effect on anti-leukemia, which would provide insights for approaches to uncover novel physiological functions of marine polysaccharides and potential therapy for acute myeloid leukemia patients.

Effects of ultrasound treatment on structural and functional properties of radish seed protein

Dried radish seed is a traditional Chinese herbal medicine that is rich in oil and protein. Radish seed meal, which is a byproduct of oil production, is high in protein (30%-35%). In order to develop a novel plant protein with excellent functional properties, this study investigated the effects of ultrasound treatment (20 kHz, amplitude of 40%, 0-10 min) on the physicochemical, functional, and antioxidant properties of radish seed protein (RSP) extracted from radish seed meal. The molecular weight of RSPs was 11-75 kDa. Ultrasonic treatments at 2-10 min reduced the particle size, narrowed the size distribution, and increased the surface negative charge of RSP. RSP solubility increased from 77.69% ± 0.69% to 88.50% ± 1.36% after ultrasound treatment for 10 min, resulting in optimal foaming and emulsifying properties of RSP. However, the foam stability of RSP decreased after sonication for 10 min. By contrast, the antioxidant activities of RSP increased significantly with extended sonication duration. Although sodium dodecyl sulfate-polyacrylamide gel electrophoresis results showed that sonication had few effects on RSP digestibility, the antioxidant capacities of the digested products during simulated intestinal digestion were enhanced, indicating RSP to be a good resource of antioxidant peptides. These results provide a fundamental basis for the use of ultrasound to enhance the functional and antioxidant abilities of RSP, promoting its application in food industry and the bioactive peptide field.

Ultrasonic-assisted plasma-activated water extraction of polysaccharide from Hemerocallis citrina Baroni: Structural characterization and antioxidant mechanism in vitro

Natural polysaccharides derived from Hemerocallis citrina Baroni exhibit significant biological activity. To enhance extraction efficiency and antioxidant activity, ultrasonic-assised plasma-activated water (PAW) was utilized to extract polysaccharides from Hemerocallis citrina Baroni. PAW demonstrated enhanced permeability and diffusion capabilities due to a reduced percentage of fully hydrogen-bonded structures, along with optimal pH (3.4) and conductivity (157.20 μS/cm). Compared to other methods, PAW significantly improved the extraction efficiency of polysaccharides to 38.24 %. Hemerocallis citrina Baroni polysaccharides predominantly consisted of α-pyranose sugars with sugar uronic acids, and ultrasound-assisted PAW did not alter their major functional groups. The extracted Hemerocallis citrina Baroni polysaccharides exhibited a semi-rigid triple-helical structure. Importantly, these polysaccharides displayed strong antioxidant activity, with ABTS+, DPPH, and O2- radical scavenging rates of 66.31 %, 65.98 %, and 47.73 % respectively. This study provides an effective method for extracting natural plant polysaccharides and offers valuable insights into their potential applications in the food industry and beyond.

Water-soluble polysaccharides extracted from Enteromorpha prolifera/PVA composite film functionalized as ε-polylysine with improved mechanical and antibacterial properties

The issue of environmental protection has received sustained and widespread attention. In order to reduce environmental pollution related to traditional plastics, it is an incessant demand to design novel environment-friendly food packaging materials with excellent performance. Sulfated polysaccharide extracted from the "green tide" marine pollution Enteromorpha prolifera (SPE) has been innovatively transformed into a film-forming material for better utilization. The insufficient mechanical properties and limited functionalities, however, hinder its wide application. In this study, polyvinyl alcohol (PVA) was blended to enhance its mechanical properties and ε-polylysine (ε-PL) was incorporated to endow it with antimicrobial performance. A novel and biodegradable film composed of SPE, PVA, and ε-PL was fabricated by casting method. We further determined the physicochemical properties of composited films. Mechanical performance test revealed the tensile strength of SPE-PVA-PL films increased from 5.56 MPa to 6.65 MPa and the E% increased from 128.8 % to 246.9 % compared with that of SPE-PVA films. Antimicrobial tests showed the excellent antibacterial activity of SPE-PVA-PL films against representative microbial species, Staphylococcus aureus and Escherichia coli. The results of this study suggested that the SPE-based composite film has the potential to be used as a potential food packaging and wound dressing materials.

Study on the Structural Features of Eight Dendrobium Polysaccharides and Their Protective Effects on Gastric Mucosa

This study aimed to analyze the structure of polysaccharides from eight different Dendrobium species and their protective effects on gastric mucosa. Ultraviolet (UV) analysis showed that the contents of eight polysaccharides ranged from 51.89 ± 6.91% to 80.57 ± 11.63%; the degree of acetylation ranged from 0.17 ± 0.03 to 0.48 ± 0.03. High-performance liquid chromatography (HPLC) results showed that these polysaccharides were mainly composed of mannose (Man) and glucose (Glc) with a small amount of galactose (Gal) and arabinose (Ara), and the monosaccharide ratios of different Dendrobium species were different. High-performance size exclusion chromatography-multi angle light scattering-refractive index detector (HPSEC-MALS-RID) showed that the molecular weight (Mw) of all Dendrobium polysaccharides was >1 × 105 Da; D. huoshanense had the lowest molecular weight. Subsequently, an ethanol injured GES-1 cell model was constructed to evaluate the gastric mucosal protective potential of polysaccharides from eight different Dendrobium species. The results showed that the protective effect of the low concentration 50 μg/mL DHP treatment group was similar to that of the control group (p > 0.05), and the cell viability could reach 97.32% of that of the control group. Based on the polysaccharide composition, different kinds of Dendrobium have different degrees of migration and repair effects on GES-1 damaged cells, and the effect of DHP is slightly better than that of other varieties (83.13 ± 1.05%). Additionally, Dendrobium polysaccharides alleviated ethanol-induced oxidative stress and inflammatory response in gastric mucosal cells by enhancing the activity of antioxidant enzymes (superoxide dismutase, glutathione peroxidase, catalase) and reducing the levels of malondialdehyde and reactive oxygen species. Overall, DHP can most effectively protect gastric mucosa. These findings enhance our understanding of the relationship between the structure and biological activity of Dendrobium polysaccharides, providing a foundation for the quality control of Dendrobium. Furthermore, these findings offer theoretical support for the development of Dendrobium polysaccharides as nutraceuticals to treat digestive system diseases.

Polysaccharides and oligosaccharides originated from green algae: structure, extraction, purification, activity and applications

With the proceeding of global warming and water eutrophication, the phenomenon of green tide has garnered significant societal interest. Consequently, researchers had increasingly focused on the potential applications of green algae biomass, particularly its polysaccharides. The polysaccharide serves as the primary active constituent of green algae and has demonstrated numerous advantageous biological activities, including antioxidant, antiviral, anticoagulant, hypolipidemic and immuno-modulatory activities. The favorable bioavailability and solubility of green algae oligosaccharides are attributed to their low molecular weight. So there has been a growing interest in researching green algae polysaccharides and oligosaccharides for the utilization of marine biological resources. This review summarized the extraction, purification, chemical structure, composition, biological activity, and potential applications prospect of polysaccharides and oligosaccharides derived from green algae. The review could be helpful for expanding the applications of polysaccharides and oligosaccharides of green algae.

Polysaccharides from Artemisia argyi leaves: Environmentally friendly ultrasound-assisted extraction and antifatigue activities

Artemisia argyi leaf polysaccharide (AALPs) were prepared through ultrasound-assisted extraction (UAE), and their antifatigue activities were evaluated. Extraction was optimized using response surface methodology (RSM), which yielded the following optimal UAE conditions: ultrasonication power of 300 W, extraction temperature of 51 °C, liquid:solid ratio of 20 mL/g, and ultrasonication time of 47 mins. The above optimal conditions resulted in the maximum extraction rate of 10.49 %. Compared with hot water extraction (HWE), UAE supported higher yields and total sugar, uronic acid, and sulfate contents of AALPs. Meanwhile, AALP prepared through UAE (AALP-U) exhibited higher stability due to its smaller particle size and higher absolute value of zeta potential than AALP prepared through HWE (AALP-H). In addition, AALP-U demonstrated stronger antioxidant activity than AALP-H. In forced swimming tests on mice, AALP-U could significantly prolong swimming time with a dose-dependent effect, increase liver and muscle glycogen levels, and improve other biochemical indices, thus showing great potential for application in functional food.

Chemically modified seaweed polysaccharides: Improved functional and biological properties and prospective in food applications

Seaweed polysaccharides are natural biomacromolecules with unique physicochemical properties (e.g., good gelling, emulsifying, and film-forming properties) and diverse biological activities (e.g., anticoagulant, antioxidant, immunoregulatory, and antitumor effects). Furthermore, they are nontoxic, biocompatible and biodegradable, and abundant in resources. Therefore, they have been widely utilized in food, cosmetics, and pharmaceutical industries. However, their properties and bioactivities sometimes are not satisfactory for some purposes. Modification of polysaccharides can impart the amphiphilicity and new functions to the biopolymers and change the structure and conformation, thus effectively improving their functional properties and biological activities so as to meet the requirement for targeted applications. This review outlined the modification methods of representative red algae polysaccharides (carrageenan and agar), brown algae polysaccharides (fucoidan, alginate, and laminaran), and green algae polysaccharides (ulvan) that have potential food applications, including etherification, esterification, degradation, sulfation, phosphorylation, selenylation, and so on. The improved functional properties and bioactivities of the modified seaweed polysaccharides and their potential food applications are also summarized.

Biochemical Characterization of a Novel Thermostable Ulvan Lyase from Tamlana fucoidanivorans CW2-9

Ulvan is a complex sulfated polysaccharide extracted from Ulva, and ulvan lyases can degrade ulvan through a β-elimination mechanism to obtain oligosaccharides. In this study, a new ulvan lyase, EPL15085, which belongs to the polysaccharide lyase (PL) 28 family from Tamlana fucoidanivorans CW2-9, was characterized in detail. The optimal pH and salinity are 9.0 and 0.4 M NaCl, respectively. The Km and Vmax of recombinant EPL15085 toward ulvan are 0.80 mg·mL-1 and 11.22 μmol·min -1 mg-1·mL-1, respectively. Unexpectedly, it is very resistant to high temperatures. After treatment at 100 °C, EPL15085 maintained its ability to degrade ulvan. Molecular dynamics simulation analysis and site-directed mutagenesis analysis indicated that the strong rigidity of the disulfide bond between Cys74-Cys102 in the N-terminus is related to its thermostability. In addition, oligosaccharides with disaccharides and tetrasaccharides were the end products of EPL15085. Based on molecular docking and site-directed mutagenesis analysis, Tyr177 and Leu134 are considered to be the crucial residues for enzyme activity. In conclusion, our study identified a new PL28 family of ulvan lyases, EPL15085, with excellent heat resistance that can expand the database of ulvan lyases and provide the possibility to make full use of ulvan.

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.

Structural characterization and preventive effect on alcoholic gastric mucosa and liver injury of a novel polysaccharide from Dendrobium officinale

In this study, a polysaccharide (DOP) with molecular weight of 8.25 × 105 Da and monosaccharide composition of mannose (Man) and glucose (Glc) at a molar ratio of 4.2: 1 was isolated from Dendrobium officinale. The preventive effect on alcoholic gastric mucosa and liver injury of DOP was also investigated. In vitro data exhibited that the IC50 values of 1, 1-diphenyl-2-picrylhydrazy (DPPH) radical scavenging ability and Fe2+ chelating capacity were 2.762 mg/mL and 6.667 mg/mL, respectively. Both the alcoholic gastric mucosal injury (AGMI) and alcoholic liver injury (ALI) animal models were used to investigate the gastrotrophic and hepatoprotective abilities of DOP. After administration of DOP, both gastric mucosal index (TNF-α, IL-6, PGE2, SOD, and MDA) and hepatic indicators (ALT, AST, SOD and MDA) improved compared to non-DOP groups. Histopathological results displayed that the DOP groups improved gastric epithelial defect and inflammatory cell redness caused by AGMI, and decreased vacuolization, hepatocyte necrosis and fibrosis caused by ALI. The results might be related to adjusting inflammatory factors, eliminating free radicals, and inhibiting lipid peroxidation capacities. These results manifested that DOP may be a therapeutic reagent to attenuate alcohol gastric mucosal and liver injury.

Research progress on the hypoglycemic activity and mechanisms of natural polysaccharides

The incidence of diabetes, as a metabolic disease characterized by high blood sugar levels, is increasing every year. The predominantly western medicine treatment is associated with certain side effects, which has prompted people to turn their attention to natural active substances. Natural polysaccharide is a safe and low-toxic natural substance with various biological activities. Hypoglycemic activity is one of the important biological activities of natural polysaccharides, which has great potential for development. A systematic review of the latest research progress and possible molecular mechanisms of hypoglycemic activity of natural polysaccharides is of great significance for better understanding them. In this review, we systematically reviewed the relationship between the hypoglycemic activity of polysaccharides and their structure in terms of molecular weight, monosaccharide composition, and glycosidic bonds, and summarized underlying molecular mechanisms the hypoglycemic activity of natural polysaccharides. In addition, the potential mechanisms of natural polysaccharides improving the complications of diabetes were analyzed and discussed. This paper provides some valuable insights and important guidance for further research on the hypoglycemic mechanisms of natural polysaccharides.

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.

Ultrasonic/cellulase-assisted extraction of polysaccharide from Garcinia mangostana rinds and its carboxymethylated derivative

Response surface methodology was selected to explore the ultrasonic-assisted cellulase extraction conditions of Garcinia mangostana rind polysaccharides (GMRPs), and the optimum values of each condition were as follows: ratio of raw material to liquid of 1:50 g/mL, ultrasonic time of 40 min, enzyme concentration of 4 %, and ultrasonic power of 179 W. Based on the above conditions, the average extraction rate of GMRPs was 15.56 %. GMRPs were modified by carboxymethylation, and the relationship between the amount of chloroacetic acid and the substitution degree of carboxymethylated derivative was compared. Based on the results of single factor experiment, it was shown that the amount of chloroacetic acid significantly affected the degree of substitution of derivative products. The above research provides some valuable theoretical references for the preparation of GMRPs and its carboxymethylation products.

Slit dual-frequency ultrasound-assisted pulping of Lycium barbarum fresh fruit to improve the dissolution of polysaccharides and in situ real-time monitoring

In this study, the slit dual-frequency ultrasound-assisted pulping of fresh Lycium barbarum fruit was optimized to improve the dissolution of polysaccharides. The microscopic mechanism of polysaccharide dissolution was explored through establishing polysaccharides dissolution kinetics model and visualizing the multi-physical fields during ultrasonic process, and an in situ real-time monitoring model was established by the relationship between the chemical value and spectral information collected by near-infrared spectroscopy. The results showed that, under optimal conditions, treatment with ultrasound (28-33 kHz, 250 W, 30 min) not only significantly promoted the dissolution rate of polysaccharides in Lycium barbarum pulp (LBPPs, increased by 43.64 %, p < 0.01), reduced its molecular weight, but also improved the arabinose molar ratio, the uniformity of polysaccharide particles, and the antioxidant activity of LBPPs. Correlation analysis indicated that ultrasonic treatment is closely related to LBPPs content, particle size and scavenging capacity against superoxide anion radicals (ptotal sugar content < 0.01, pparticle size < 0.05 and psuperoxide anion scavenging < 0.05). Moreover, the in situ real-time monitoring model for the pulping process could quantitatively predict LBPPs dissolution rate and its superoxide anion radical scavenging capacity with good calibration and prediction performance (Rc = 0.9841, RMSECV = 0.0873, Rp = 0.9772, RMSEP = 0.0530; Rc = 0.9874, RMSECV = 0.1246, Rp = 0.9868, RMSEP = 0.0665). These results indicated that slit dual-frequency ultrasound has great potential in improving the quality of Lycium barbarum pulp, which may provide theoretical support for the industrial development of intelligent systems for polysaccharides preparation.

Structural Modification and Biological Activity of Polysaccharides

Natural polysaccharides are macromolecular substances with a wide range of biological activities. The structural modification of polysaccharides by chemical means can enhance their biological activity. This paper reviews the latest research reports on the chemical modification of natural polysaccharides. At present, the modification methods of polysaccharides mainly include sulfation, phosphorylation, carboxymethylation, socialization, methylation and acetylation. The chemical and physical structures of the modified polysaccharides were detected via ultraviolet spectroscopy, FT-IR, high-performance liquid chromatography, ultraviolet spectroscopy, gas chromatography-mass spectrometry, nuclear magnetic resonance and scanning electron microscopy. Modern pharmacological studies have shown that the modified polysaccharide has various biological activities, such as antioxidant, antitumor, immune regulation, antiviral, antibacterial and anticoagulant functions in vitro. This review provides fresh ideas for the research and application of polysaccharide structure modification.

Antioxidant Activities of Natural Polysaccharides and Their Derivatives for Biomedical and Medicinal Applications

Many chronic diseases such as Alzheimer's disease, diabetes, and cardiovascular diseases are closely related to in vivo oxidative stress caused by excessive reactive oxygen species (ROS). Natural polysaccharides, as a kind of biomacromolecule with good biocompatibility, have been widely used in biomedical and medicinal applications due to their superior antioxidant properties. In this review, scientometric analysis of the highly cited papers in the Web of Science (WOS) database finds that antioxidant activity is the most widely studied and popular among pharmacological effects of natural polysaccharides. The antioxidant mechanisms of natural polysaccharides mainly contain the regulation of signal transduction pathways, the activation of enzymes, and the scavenging of free radicals. We continuously discuss the antioxidant activities of natural polysaccharides and their derivatives. At the same time, we summarize their applications in the field of pharmaceutics/drug delivery, tissue engineering, and antimicrobial food additives/packaging materials. Overall, this review provides up-to-date information for the further development and application of natural polysaccharides with antioxidant activities.

Effects of ultrasound-assisted H2O2 on the solubilization and antioxidant activity of yeast β-glucan

Yeast β-glucan (YG) possess an extensive range of biological activities, such as the inhibition of oxidation, but the poor water solubility of macromolecular YG limits its application. In this study, through the combined degradation of ultrasonic waves and H₂O₂, and the optimization of the main process parameters for solubilizing YG by response surface methodology (RSM), a new product of YG_UH was generated. The molecular weight, structural characteristics and degradation kinetics before and after solubilization were evaluated. The results showed that the optimal solubilization conditions were reaction time: 4 h, ultrasonic power: 3 W/mL, H₂O₂ concentration: 24 %. Under these conditions, ultrasound-assisted H₂O₂ increased the solubility (from 13.60 % to 70.00 %) and reduced molecular weight (from 6.73 × 10⁶ Da to 1.22 × 10⁶ Da). Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), Congo red (CR), scanning electron microscopy (SEM) revealed that ultrasound-assisted H₂O₂ increased the conformation's flexibility greatly, without changing the main structure of YG. More importantly, solubilization of YG improved free radical scavenging activity with YG_UH exhibiting the highest levels of DPPH and ABTS⁺ free radical scavenging activity. These results revealed that ultrasound-assisted H₂O₂ degradation could be a suitable way to increase the solubility of YG for producing value-added YG.

Extraction, Physicochemical Properties, Anti-Aging, and Antioxidant Activities of Polysaccharides from Industrial Hemp Residues

A large amount of hemp polysaccharides remain in industrial hemp residues (IHR) after cannabidiol extraction, resulting in the waste of resources. Therefore, the systematic study of hemp polysaccharides is beneficial to the development of IHR in the future. In this study, the extraction of industrial hemp residues polysaccharide (IHRPs) was optimized by single-factor experiment and orthogonal experimental design. The optimum heating extraction conditions were extraction temperature 98 °C, solid–liquid ratio 1:10, extraction time 1 h, number of successive extractions 2, and pH at 4. The extraction ratio and the polysaccharide content were 20.12 ± 0.55% and 12.35 ± 0.26% at the conditions, respectively. Besides, the best alcohol precipitation conditions were pumping with 2 L/h, stirring continuously, and ice-water bath for 4 h. The crude IHRPs was further purified by column chromatography and the polysaccharide/protein contents of purified IHRPs were 34.44% and 1.61%. IHRPs was mainly made up of ten monosaccharides and some non-sugar components including organic acids, flavonoids, steroids, and glycoside. The FT-IR demonstrated the polysaccharide skeleton of IHRPs. Moreover, the DPPH and ABTS scavenging rate of IHRPs were 76.00% and 99.05% at the concentrations of 1 mg/mL. IHRPs could promote the epidermal cells proliferation and healing of cell scratches. Meanwhile, IHRPs could promoted the expression of anti-aging-related genes. Overall, IHRPs could be a desirable natural source of antioxidants and anti-aging products in many aspects.

The Characterization and Functional Properties of Euglena gracilis Paramylon Treated with Different Methods

Euglena gracilis paramylon (EGP) is a polymeric polysaccharide composed of linear β-1,3 glucan. The water insolubility of EGP severely limits its application. This work aimed to improve the functional characteristics of EGP by hydrogen peroxide (H₂O₂) degradation and carboxymethylated modification. The results showed that the crystallinity of EGP degraded by H₂O₂ and carboxymethylated modification decreased by 14% and 46%, and the thermal degradation temperature was significantly descending in a crystallinity-dependent manner. In addition, the results showed that H₂O₂ degradation and carboxymethylation significantly improved the adsorption capacity of EGP for oil, dyes, and metal ions, and their water solubility increased by 9% and 85%. This result will provide a valuable theoretical basis for the development and utilization of EGP.

Characterization and Antibacterial Activities of Carboxymethylated Paramylon from Euglena gracilis

Paramylon from Euglena gracilis (EGP) is a polymeric polysaccharide composed of linear β-1,3 glucan. EGP has been proved to have antibacterial activity, but its effect is weak due to its water insolubility and high crystallinity. In order to change this deficiency, this experiment carried out carboxymethylated modification of EGP. Three carboxymethylated derivatives, C-EGP1, C-EGP2, and C-EGP3, with a degree of substitution (DS) of 0.14, 0.55, and 0.78, respectively, were synthesized by varying reaction conditions, such as the mass of chloroacetic acid and temperature. Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR) analysis confirmed the success of the carboxymethylated modification. The Congo red (CR) experiment, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetry (TG) were used to study the conformation, surface morphology, crystalline nature, and thermostability of the carboxymethylated EGP. The results showed that carboxymethylation did not change the triple helix structure of the EGP, but that the fundamental particles’ surface morphology was destroyed, and the crystallization area and thermal stability decreased obviously. In addition, the water solubility test and antibacterial experiment showed that the water solubility and antibacterial activity of the EGP after carboxymethylation were obviously improved, and that the water solubility of C-EGP1, C-EGP2, and C-EGP3 increased by 53.31%, 75.52%, and 80.96% respectively. The antibacterial test indicated that C-EGP3 had the best effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with minimum inhibitory concentration (MIC) values of 12.50 mg/mL and 6.25 mg/mL. The diameters of the inhibition zone of C-EGP3 on E. coli and S. aureus were 11.24 ± 0.15 mm and 12.05 ± 0.09 mm, and the antibacterial rate increased by 41.33% and 43.67%.

Structure and physicochemical properties of polysaccharides from Poria cocos extracted by deep eutectic solvent

Poria cocos, a famous traditional Chinese medicine and a well-known food or food supplement, has shown therapeutic potential against cancer and the uneasiness of the mind. In addition, polysaccharides (PCPs) in this fungus were found to be various bioactive. In this work, one such PCP, PCP-1, extracted by deep eutectic solvent (DES) and separated using Sephadex G-15 columns, was characterized using GC-MS, HPGPC, FT-IR, and NMR, while also tested for physicochemical properties. Results indicated that PCP-1 contained 96.89 ± 3.21% total sugars and was a glucan with molecular weight of 3.2 kD. The main glycosidic linkage was 1,3-linked Glcp with 96.82 mol% content and a triple helix structure, and β-D-Glcp-(1 → linkage connected to the main chain through an O-6 atom was the backbone structure. In terms of the physicochemical property, PCP-1 was soluble in water, but not in organic solvent, and processed a relative high water-holding capacity (8.64 ± 0.14 g/g) and low oil-holding capacity (2.52 ± 0.21 g/g). In addition, in vitro, PCP-1 was found to have the ability of scavenging DPPH, hydroxyl free radical, superoxide anion radical and reducing ferric at different levels. This research would be useful for the further application of PCP-1.

Preparation, characterization and immunoregulatory activity of derivatives of polysaccharide from Atractylodes lancea (Thunb.) DC

A polysaccharide (ALP-1) extracted from Atractylodes lancea (Thunb.) DC. was carboxymethylated (C-ALP-1), phosphorylated (P-ALP-1) and acetylated (A-ALP-1) to improve its physicochemical properties and bioactivities. The solubility of all derivatives was increased, and the solubility of A-ALP-1 increased to 137.5 mg/mL, which was much higher than the solubility of ALP-1 (15.0 mg/mL). The results of HPSEC-MALLS-RID showed that the molecular weight of polysaccharides was slightly increased after the modification, and the root mean square radius of rotation (Rz) and morphology of polysaccharides in solution were also changed. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) results confirmed that the surface morphology of ALP-1 changed dramatically and the crystallinity decreased after structural modification. From thermal analysis results, the T₅₀ of ALP-1, C-ALP-1, P-ALP-1 and A-ALP-1 were 281.34, 292.14, 333.75 and 298.70 °C, which showed that derivatives had stronger thermal stability than ALP-1. The immunomodulatory activity studies displayed that P-ALP-1 showed the best ability to stimulate RAW264.7 macrophages to release NO, and A-ALP-1 showed the best capacity to stimulate TNF-α and IL-6 releasing. These results indicated that chemical modification could enhance the solubility, the thermal stability and immunomodulatory activity of polysaccharides, which is beneficial for the development and utilization of natural polysaccharides.

Interaction between nanometer calcium oxalate and renal epithelial cells repaired with carboxymethylated polysaccharides

OBJECTIVE

Injury of renal tubular epithelial cells (HK-2) is an important cause of kidney stone formation. In this article, the repairing effect of polysaccharide (PCP0) extracted from the traditional Chinese medicine Poria cocos and its carboxymethylated derivatives on damaged HK-2 cells was studied, and the differences in adhesion and endocytosis of the cells to nanometer calcium oxalate monohydrate (COM) before and after repair were explored.

METHODS

Sodium oxalate (2.8 mmol/L) was used to damage HK-2 cells to establish a damage model, and then Poria cocos polysaccharides (PCPs) with different carboxyl (COOH) contents were used to repair the damaged cells. The changes in the biochemical indicators of the cells before and after the repair and the changes in the ability to adhere to and internalize nano-COM were detected.

RESULTS

The natural PCPs (PCP0, COOH content = 2.56%) were carboxymethylated, and three carboxylated modified Poria cocos with 7.48% (PCP1), 12.07% (PCP2), and 17.18% (PCP3) COOH contents were obtained. PCPs could repair the damaged HK-2 cells, and the cell viability was enhanced after repair. The cell morphology was gradually repaired, the proliferation and healing rate were increased. The ROS production was reduced, and the polarity of the mitochondrial membrane potential was restored. The level of intracellular Ca²⁺ ions decreased, and the autophagy response was weakened.

CONCLUSION

The cells repaired by PCPs inhibited the adhesion to nano-COM and simultaneously promoted the endocytosis of nano-COM. The endocytic crystals mainly accumulated in the lysosome. Inhibiting adhesion and increasing endocytosis could reduce the nucleation, growth, and aggregation of cell surface crystals, thereby inhibiting the formation of kidney stones. With the increase of COOH content in PCPs, its ability to repair damaged cells, inhibit crystal adhesion, and promote crystal endocytosis all increased, that is, PCP3 with the highest COOH content showed the best ability to inhibit stone formation.

Seaweed-Derived Polysaccharides Attenuate Heat Stress-Induced Splenic Oxidative Stress and Inflammatory Response via Regulating Nrf2 and NF-κB Signaling Pathways

With global warming, heat stress (HS) has become a worldwide concern in both humans and animals. The ameliorative effect of seaweed (Enteromorpha prolifera) derived polysaccharides (SDP) on HS-induced oxidative stress and the inflammatory response of an immune organ (spleen) was evaluated using an animal model (Gallus gallus domesticus). In total, 144 animals were used in this 4-week trial and randomly assigned to the following three groups: thermoneutral zone, HS, and HS group supplemented with 1000 mg/kg SDP. Dietary SDP improved the antioxidant capacity and reduced the malondialdehyde (MDA) of the spleen when exposed to HS, regulated via enhancing nuclear factor erythroid 2-related factor-2 (Nrf2) signaling. Furthermore, the inclusion of SDP reduced the levels of pro-inflammatory cytokines and alleviated HS-induced splenic inflammatory response by suppressing the nuclear factor-kappa B (NF-κB) p65 signaling. These findings suggest that the SDP from E. prolifera can be used as a functional food and/or feed supplement to attenuate HS-induced oxidative stress and inflammatory responses of the immune organs. Moreover, the results could contribute to the development of high-value marine products from seaweed for potential use in humans and animals, owing to their antioxidant and anti-inflammatory effects.

Carboxymethylation modification, characterization, antioxidant activity and anti-UVC ability of Sargassum fusiforme polysaccharide

Taking the degree of substitution (DS) as the index, the carboxymethylation conditions of Sargassum fusiforme polysaccharide (SFP) were studied. According to the single factor experiment results, the optimum experimental conditions were obtained: sodium hydroxide concentration, 15% (20 mL); alkalization temperature, 50 °C; dosage of chloroacetic acid 1.5 g; etherification time, 2 h, and the Carboxymethyl Sargassum fusiforme polysaccharide (CSFP) with the highest DS (0.635) was obtained. And then, the physicochemical properties, structural information and bioactivity of SFP and CSFP were characterized. The SFP and CSFP were composed of four monosaccharides, with a small amount of protein, and their molecular weights to 780.2 kDa and 386.3 kDa respectively. The results of FTIR and NMR showed that the carboxymethyl was successfully grafted onto the C-4 and C-6 of sugar chain. The results of anti UVC experiment showed that SFP and CSFP had a certain negative effect on cell activity, and the degree of damage caused by UVC radiation was weakened, and the anti UVC performance of CSFP was better than that of SFP.

Structure characterization and bioactivity of neutral polysaccharides from different sources of Polygonatum Mill

Polygonati rhizoma (PR), a traditional medical and edible product, is rich in polysaccharides and exhibits physiological activity, including antioxidant, hypoglycemic and hypolipidemic properties. Neutral polysaccharides have been reported to be one of the main active ingredients of Polygonatum, with many of these fractions being responsible for the biological activity. This behavior was shown to be closely connected to the chemical structure, monosaccharide composition, and glycosidic bond type. There are few reports on the chemical constituents of the neutral polysaccharides from different sources of PR. In this study, neutral polysaccharides of PR from four different regions of China (Chun'an (Zhejiang), Xixia (Henan), Danfeng (Shanxi), and Pan'an (Zhejiang)), named CAZJ, XXHN, DFSX, and PAZJ, respectively, were isolated by anion-exchange and gel-permeation chromatography. Structures of the four polysaccharides were investigated. The results showed that all of them were mainly glucose and mannose, while the monosaccharide composition and content of polysaccharides from different sources varied. The molecular weights of CAZJ, XXHN, DFSX, and PAZJ were 14.119, 22.352, 18.127, and 15.699 kDa, respectively. Infrared spectra illustrated the existence of α-glycosidic bond and β-glycosidic bond in the polysaccharides. CAZJ, XXHN, and DFSX possessed a pyranose ring structure, whereas PAZJ had a furanose ring structure. Congo red test indicated that XXHN, DFSX, and PAZJ had a triple-helix structure. X-ray diffraction showed that the polysaccharides consisted of crystalline and amorphous regions. All four polysaccharides exhibited different degrees of antioxidant and hypoglycemic activities with a dose-dependent manner in the 1.0-10.0 mg/mL concentration range. Correlation analysis revealed that the bioactivities of polysaccharides was significantly related to monosaccharide composition, uronic acid, and protein content. The results suggested that neutral polysaccharides could be used as potential natural antioxidants and hypoglycemic agents for functional and nutraceutical applications.

Structural Elucidation and Antioxidant Activities of a Neutral Polysaccharide From Arecanut (Areca catechu L.)

A novel neutral polysaccharide designated as PAP1b was isolated from Areca catechu L. by hot water extraction, ethanol precipitation, and column chromatography. PAP1b was mainly composed of mannose, galactose, xylose, and arabinose in a ratio of 4.1:3.3:0.9:1.7, with an average molecular weight of 37.3 kDa. Structural characterization indicated that the backbone of PAP1b appeared to be composed mainly of → 6-β-Manp-(1 →, → 4)-α-Galp-(1 → and → 3,6)-β-Manp-(1 →) residues with some branches, and terminal of (1 →)-linked-β-Manp residues. The results of bioactivity experiments showed that PAP1b had antioxidant in vitro, esspecially on scavenging DPPH and hydroxyl radicals. Therefore, the polysaccharide from Areca catechu L. could be used as a potential antioxidant in functional food.

Effect of Polysaccharides From Enteromorpha intestinalis on Intestinal Function in Sprague Dawley Rats

This study aims to determine the effect of polysaccharides extracted from Enteromorpha intestinalis (EI) on the intestinal function of Sprague Dawley (SD) rats. The polysaccharides were extracted from the green alga using water and alkaline solution, where these extracts were named WPEI and APEI, respectively. The dried powder of EI was labeled as DPEI. Proximate compositions, minerals, and amino acids of the DPEI, WPEI, and APEI were determined. The growth-promoting effect of the polysaccharides on selected intestinal microflora was determined based on the plate count method. In contrast, the in vivo effect of DPEI and its polysaccharides on the intestinal function of the SD rats was determined. These rats were fed with 1% WPEI, APEI, and DPEI. The result showed that APEI had lower total sugars and total proteins content than the WPEI. WPEI did not contain arabinose. The WPEI and APEI also had a better ability to promote microbial growth than the DPEI. The in vivo study showed that WPEI improved intestinal peristalsis and other intestinal functions compared with the other rat groups. The average final body weight of the experimental rats treated with DPEI was also lower than the other groups. The pH value of the feces of all treated rats was lower than the control rats, and the moisture content of the fecal samples of these experimental groups was higher than the control group. Also, the intestinal activated carbon propulsion of the WPEI, APEI, and DPEI fed rats increased. Among the short-chain fatty acids content determined in the fecal samples, the propionic acid content of the WPEI group was significantly highest. Therefore, WPEI had the best effect in improving intestinal digestion.

Structural characterization of ulvans extracted from blade (Ulva ohnoi) and filamentous (Ulva tepida and Ulva prolifera) species of cultivated Ulva

Ulvans from Ulva ohnoi, Ulva tepida and Ulva prolifera were extracted under mild acidic conditions, isolated and their composition and structure determined. The ulvans contained mostly rhamnose (31.6-46.7 mol%) and glucuronic acid (26.6-37.5 mol%), with smaller amounts of xylose (3.4-10.4 mol%) and iduronic acid (3.1-7.6 mol%). In addition, the ulvan samples also contained galactose (4.4-26.0 mol%). Glycosyl linkage analysis showed that ulvan from U. ohnoi contained mostly →4)-GlcpA-(1→ and →3,4)-Rhap-(1→. Preparation of partially methylated alditol acetate standards of idose showed that U. ohnoi contained →4)-IdopA-(1→. In addition to these residues, glycosyl linkage analysis of U. tepida and U. prolifera showed the presence of →2,3,4)-Rhap-(1→, →4)-Xylp-(1→, →2,4)-GlcpA-(1→ and →3,4)-GlcpA-(1→. These two species also contained galactose linkages. These data, together with nuclear magnetic resonance (NMR) spectroscopy indicated that U. ohnoi comprised mostly of type A_3S ulvanobiuronic acid repeats [→4)-β-D-GlcpA-(1→4)-α-L-Rhap3S-(1→], together with smaller amounts of type B_3S ulvanobiuronic acid repeats [→4)-α-L-IdopA-(1→4)-α-L-Rhap3S-(1→] and ulvanobiose (U_3S [→4)-β-D-Xylp-(1→4)-α-L-Rhap3S-(1→]). NMR spectra of U. tepida and U. prolifera showed resonances not detected in U. ohnoi, highlighting the complexity of the ulvans from these species. Regardless of the structural diversity of the ulvan samples there was very little antioxidant or inhibitory activity detected on enzymatic processes investigated.

Physicochemical properties, structural characterization and biological activities of polysaccharides from quinoa (Chenopodium quinoa Willd.) seeds

In this paper, membrane separation technology was employed to separate polysaccharide fractions from the water extract of quinoa seeds. The chemical composition, structure characteristic and morphology were analyzed by chemical methods and instrumental analysis including HPLC-DAD, UV, FT-IR, Congo red test, SEM, AFM, XRD, TGA and NMR. Results indicated that three polysaccharide fractions named as QPs-I, QPs-II and QPs-III were successfully separated using microfiltration and ultrafiltration membrane with MWCO of 300 and 10 kDa in sequence. The Mw and polysaccharide content of three fractions were QPs-I (4609 Da, 33.75%), QPs-II (15,932 Da, 45.31%) and QPs-III (960,895 Da, 34.65%), respectively. The polysaccharide in three fractions was heteropolysaccharide that mainly consisted of glucose, galactose and arabinose, with their combined monosaccharide percentage being 91.17% in QPs-I, 87.81% in QPs-II, and 91.72% in QPs-III, respectively. All three polysaccharide fractions contained triple-helix structure. Biological experiment showed that antioxidant and antidiabetic activities in dose-dependent manners and also revealed immunoregulatory activity on RAW264.7 cells. These results indicated that QPs has the potential to be used in a natural agent in antioxidant, antidiabetic and immunoregulation functional food.

Extraction Techniques, Biological Activities and Health Benefits of Marine Algae Enteromorpha prolifera Polysaccharide

There is increasing interest in the use of marine algae as functional food additives for improving human health. Enteromorpha (Ulva) prolifera (E. prolifera) is a seaweed green alga (Chlorophyta) that contains many bioactive compounds, of which polysaccharide is the main component. With the advancement of technology in the methods of extraction and analysis, recent studies in in vitro and animals model showed that polysaccharides derived from E. prolifera exert various biological activities, such as gut microbiota modulation, immunomodulation, antioxidant, antidiabetic, antimicrobial, and hypolipidemic. Research evidence has shown that methods of extraction and molecular modification, such as degradation, carboxymethylation, and sulfonation could alter the biological activities of polysaccharides. Therefore, in this review, we discussed the different extraction techniques, structural-activity relationship, and health benefits of sulfated polysaccharides derived from E. prolifera, and suggested future research avenues. This review helps to advance the extraction techniques and promote the application of marine algae polysaccharides as functional food and therapeutic agent.

Degraded polysaccharides from Porphyra haitanensis: purification, physico-chemical properties, antioxidant and immunomodulatory activities

To explore effect of the structural properties of porphyra haitanensis polysaccharide on its biological activity, degraded porphyra polysaccharides were separated and purified by Cellulose DEAE-52 and Sephadex G-100 chromatography, obtaining three purified components (P1, P2 and P3). All the three components were sulfate polysaccharides containing the repeating units of → 3) β-D-galactose (1 → 4) 3,6-anhydro-α-L-galactose (1 →, and → 3) β-D-galactose (1 → 4) α-L-galactose-6-S (1 →, and → 3) 6-O-methyl-β-D-galactose (1 → 4) 3,6-anhydro-α-L-galactose (1 →. The molecular weight of the three fractions was measured to be 300.3, 130.4 and 115.1 kDa, respectively. Their antioxidant activity was investigated by the determination of the free radical scavenging effect and ferric reducing power. It was found that P1, P2 and P3 possessed marked antioxidant activity. It was also found that they appreciably enhanced the proliferation, phagocytic ability and nitric oxide secretion in RAW264.7 cells. Lower molecular weight and higher sulfate content were beneficial to bioactivities of P. haitanensis polysaccharides. Overall, P2 and P3 possess superior immuno-modulatory activity to that of P1 and PHP. Thus, the current work will provide the basis for the better utilization of P. haitanensis to develop the related functional foods.

Seaweed polysaccharides: Emerging extraction technologies, chemical modifications and bioactive properties

Nowadays, consumers are increasingly aware of the relationship between diet and health, showing a greater preference of products from natural origin. In the last decade, seaweeds have outlined as one of the natural sources with more potential to obtain bioactive carbohydrates. Numerous seaweed polysaccharides have aroused the interest of the scientific community, due to their biological activities and their high potential on biomedical, functional food and technological applications. To obtain polysaccharides from seaweeds, it is necessary to find methodologies that improve both yield and quality and that they are profitable. Nowadays, environmentally friendly extraction technologies are a viable alternative to conventional methods for obtaining these products, providing several advantages like reduced number of solvents, energy and time. On the other hand, chemical modification of their structure is a useful approach to improve their solubility and biological properties, and thus enhance the extent of their potential applications since some uses of polysaccharides are still limited. The present review aimed to compile current information about the most relevant seaweed polysaccharides, available extraction and modification methods, as well as a summary of their biological activities, to evaluate knowledge gaps and future trends for the industrial applications of these compounds.Key teaching pointsStructure and biological functions of main seaweed polysaccharides.Emerging extraction methods for sulfate polysaccharides.Chemical modification of seaweeds polysaccharides.Potential industrial applications of seaweed polysaccharides.Biological activities, knowledge gaps and future trends of seaweed polysaccharides.

Ocean acidification exacerbates copper toxicity in both juvenile and adult stages of the green tide alga Ulva linza

The toxicity of heavy metals to coastal organisms can be modulated by changes in pH due to progressive ocean acidification (OA). We investigated the combined impacts of copper and OA on different stages of the green macroalga Ulva linza, which is widely distributed in coastal waters, by growing the alga under the addition of Cu (control, 0.125 (medium, MCu), and 0.25 (high) μM, HCu) and elevated pCO₂ of 1,000 μatm, predicted in the context of global change. The relative growth rates decreased significantly in both juvenile and adult thalli at HCu under OA conditions. The net photosynthetic and respiration rates, as well as the relative electron transfer rates for the adult thalli, also decreased under the combined impacts of HCu and OA, although no significant changes in the contents of photosynthetic pigments were detected. Our results suggest that Cu and OA act synergistically to reduce the growth and photosynthetic performance of U. linza, potentially prolonging its life cycle.

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.

Preparation Optimization, Characterization, and Antioxidant and Prebiotic Activities of Carboxymethylated Polysaccharides from Jujube

In this study, jujube polysaccharides (JP) were extracted from Jinsixiaozao, and carboxymethylated jujube polysaccharides (CMJP) were prepared. The optimum carboxymethylation conditions optimized by Response Surface Methodology (RSM) were as follows: the reaction temperature was 60°C, the concentration of sodium hydroxide (NaOH) solution was 2.8 mol/L, and the content of chloroacetic acid was 2.12% with a degree of substitution (DS) of 0.2275 ± 0.0108. Physicochemical characterizations and in vitro antioxidant and prebiotic activities of JP and CMJP were evaluated. Compared with unmodified JP, water solubility and viscosity were improved in CMJP. Chemical analysis revealed that CMJP was composed of Rha: Ara: Xyl: Glc: Gal = 0.18 : 9.09 : 0.45 : 0.36 : 0.98 with a molecular weight of 3.04 × 105 Da. The signals of carboxymethyl were observed at 1600, 1420, and 1328 cm−1 in FT-IR. In addition, CMJP showed obviously strong hydroxyl radical scavenging ability compared with JP and also exhibited stronger abilities than JP on the proliferation growth of Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus rhamnosus strains. These results indicated that CMJP could be explored as a promising resource for the development of functional foods.