Effects of UV/H2O2 degradation and step gradient ethanol precipitation on Sargassum fusiforme polysaccharides: Physicochemical characterization and protective effects against intestinal epithelial injury

In vitro fermentation characteristics and modulation effects of polysaccharide fractions from Schisandra sphenanthera on intestinal microflora

Schisandra Sphenanthera polysaccharides fractions (SSPs), namely SSP40, SSP60, and SSP80, were obtained by gradient precipitation with 40 %, 60 %, and 80 % (v/v) ethanol, respectively. It was found that gradient ethanol precipitation (GEP) significantly affected the physicochemical and structural characteristics of SSPs, including molecular weight, monosaccharide composition, and surface morphology. Compared to fractions SSP40 and SSP60, SSP80 was observed to have a lower molecular weight (22.58 kDa) and certain specific monosaccharide composition, such as lower glucose content and higher galactose, arabinose, rhamnose, and galacturonic acid content. Furthermore, the apparent porosity of the SSPs increased with increasing ethanol concentration in GEP. After fermentation at 37 °C for 48 h, fraction SSP80 prominently promoted the production of more short-chain fatty acids (SCFAs), increasing from an initial 1.39 ± 0.08 to 26.75 ± 0.54 mmol/L. The SSP fraction types extracted by GEP greatly affected the modulation of the intestinal microflora at different levels. The SSP80 fraction with excellent structure demonstrated the best ability to modulate the intestinal microflora by increasing the relative abundance of Bacteroides, Faecalibacterium and Dialister and decreasing the relative abundance of Escherichia-Shigella. The remarkable differences in modulating the intestinal microflora confirmed the importance of carefully selecting GEP to fraction SSPs that promote health.

Physicochemical properties and fermentation characteristics of a novel polysaccharide degraded from Flammulina velutipes residues polysaccharide

Flammulina velutipes (F. velutipes) residues polysaccharide (FVRP) is a high molecular weight polysaccharide with diverse bioactivities extracted from F. velutipes residues (FVR). However, high molecular weight polysaccharides have been shown to face significant challenges in crossing the cell membrane barrier, thereby limiting their absorption and application in the body. Therefore, an ultrasonic-assisted H2O2-Fe3+ method was employed for the first time to degrade FVRP, resulting in the production of a new polysaccharide, FVRPF. Compared with FVRP, there was no significant difference in the main chemical structure of FVRPF, but the monosaccharide composition ratio varied. and FVRPF had lower molecular weight and stronger antioxidant capacity. Moreover, FVRPF could be degraded by human microbiota, modulate gut microbiota composition, and increase the production of total short-chain fatty acids (SCFAs). These findings suggest that FVRPF holds potential as a promising prebiotic for applications in the food and pharmaceutical industries.

Marine peptides as potential anti-aging agents: Preparation, characterization, mechanisms of action, and future perspectives

Aging is a universal biological process characterized by a decline in physiological functions, leading to increased susceptibility to diseases. With global aging trends, understanding and mitigating the aging process is paramount. Recent studies highlight marine peptides as promising bioactive substances with potential anti-aging properties. This review critically examines the potential of marine peptides as novel food ingredients in anti-aging, exploring their sources, preparation methods, physicochemical properties, and the underlying mechanisms through which they impact the aging process. Marine peptides exhibit significant potential in targeting aging, extending lifespan, and enhancing healthspan. They act through mechanisms such as reducing oxidative stress and inflammation, modulating mitochondrial dysfunction, inducing autophagy, maintaining extracellular matrix homeostasis, and regulating longevity-related pathways. Despite challenges in stability, bioavailability, and scalability, marine peptides offer significant potential in health, nutraceuticals, and pharmaceuticals, warranting further research and development in anti-aging.

Efficient degradation and enhanced anticomplementary activity of Belamcanda chinensis (L.) DC. polysaccharides via trifluoroacetic acid treatment with different degrees

The degradation of Belamcanda chinensis (L.) DC. polysaccharides was carried out by five concentrations of trifluoroacetic acid (TFA) (1-5 mol/L), and their physicochemical properties, degradation kinetics and anticomplementary activity were investigated. The findings revealed a notable reduction in the molecular weight of BCP, from an initial value of 2.622 × 105 g/mol to a final value of 6.255 × 104 g/mol, and the water solubility index increased from 90.66 ± 0.42 % to 97.78 ± 0.43 %. The degraded polysaccharides of B. chinensis exhibited a comparable monosaccharide composition comprising Man, GalA, Glc, Gal, and Ara. As the concentration of TFA increased, the degradation rate constant increased from 1.468 × 10-3 to 5.943 × 10-3, and the process followed the first-order degradation kinetic model (R2 > 0.97) and the random fracture model (R2 > 0.96). Furthermore, the five degraded polysaccharides still exhibit good thermal stability. In vitro experiments showed that DBCP-3 exhibited more potent anticomplementary activity than the original polysaccharides and positive drugs, which was strongly correlated with its Mw (r = 0.6-0.8), inhibiting complement activation by blocking C2 and C4. These results indicated that TFA degradation has a positive effect on polysaccharides, of which DBCP-3 is expected to treat diseases involving hyperactivation of the complement system.

Effect of ultrasound assisted H2O2/Vc treatment on the hyperbranched Lignosus rhinocerotis polysaccharide: Structures, hydrophobic microdomains, and antitumor activity

The effect of ultrasonic intensity (28.14, 70.35, and 112.56 W/cm2) on Lignosus rhinocerotis polysaccharide (LRP) degraded by ultrasound assisted H2O2/Vc system (U-H/V) was investigated. U-H/V broke the molecular chain of LRP and improved the conformational flexibility, decreasing the molecular weight, intrinsic viscosity ([η]) and particle size. The functional groups and hyperbranched structure of LRP were almost stable after U-H/V treatment, however, the triple helix structure of LRP was partially disrupted. With increasing ultrasonic intensity, the critical aggregation concentration increased from 0.59 mg/mL to 1.57 mg/mL, and the hydrophobic microdomains reduced. Furthermore, the LRP treated with U-H/V significantly inhibited HepG2 cell proliferation by inducing apoptosis. The increase in antitumor activity of LRP was closely associated with the reduction of molecular weight, [η], particle size and hydrophobic microdomains. These results revealed that U-H/V treatment facilitates the degradation of LRP and provides a better insight into the structure-antitumor activity relationship of LRP.

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.

Degradation Mechanisms of Six Typical Glucosidic Bonds of Disaccharides Induced by Free Radicals

Increasing hydrogen peroxide (H2O2)-based systems have been developed to degrade various polysaccharides due to the presence of highly reactive free radicals, but published degradation mechanisms are still limited. Therefore, this study aimed to clarify the degradation mechanism of six typical glucosidic bonds from different disaccharides in an ultraviolet (UV)/H2O2 system. The results showed that the H2O2 concentration, disaccharide concentration, and radiation intensity were important factors affecting pseudo-first-order kinetic constants. Hydroxyl radical, superoxide radical, and UV alone contributed 58.37, 18.52, and 19.17% to degradation, respectively. The apparent degradation rates ranked in the order of cellobiose ≈ lactose > trehalose ≈ isomaltose > turanose > sucrose ≈ maltose. The reaction pathways were then deduced after identifying their degradation products. According to quantum chemical calculations, the cleavage of α-glycosidic bonds was more kinetically unfavorable than that of β-glycosidic bonds. Additionally, the order of apparent degradation rates depended on the energy barriers for the formation of disaccharide-based alkoxyl radicals. Moreover, energy barriers for homolytic scissions of glucosidic C1-O or C7-O sites of these alkoxyl radicals ranked in the sequence: α-(1 → 2) ≈ α-(1 → 3) < α-(1 → 4) < β-(1 → 4) < α-(1 → 6) < α-(1 → 1) glucosidic bonds. This study helps to explain the mechanisms of carbohydrate degradation by free radicals.

Intervention effects of sulfate glycosaminoglycan from swim bladder against arsenic-induced damage in IEC-6 cells

In this study, a purified macromolecular sulfate glycosaminoglycan whose structural characterization is similar to chondroitin sulfate from the swim bladder of Aristichthys nobilis, named SBSG, was used to explore the intervention effects on arsenic-induced intestinal epithelial cells (IEC-6) damage. Arsenic exposure led to cell membrane rupture, mitochondrial dysfunction, oxidative damage, and down-regulation of tight junction proteins expression. Treatment with SBSG could alleviate arsenic exposure-induced cell damage by decreasing the extracellular lactate dehydrogenase activity and influencing mitochondrial membrane potential, reactive oxygen species level, malondialdehyde content, and anti-oxidative enzyme activity. On the other hand, SBSG could promote nitric oxide production to achieve potential immunoregulation. The Western blot showed that intervention of SBSG mainly could restrain the activation of the JNK signaling pathway and up-regulate the expression of ZO-1 against arsenic-induced cell damage. This study provides a new perspective for understanding the heavy metal detoxification of SBSG on the intestinal and indicates that SBSG could be used as natural antioxidant resistant to heavy metal toxicity.

Ultrasound-assisted hydrogen peroxide-ascorbic acid method to degrade sweet corncob polysaccharides can help treat type 2 diabetes via multiple pathways in vivo

In this study, we aimed to investigate the impact of various ultrasound durations on the structure and bioactivity of sweet corncob polysaccharides treated with ultrasound-assisted degradation using hydrogen peroxide and ascorbic acid (H2O2-Vc). We subjected sweet corncob polysaccharides to ultrasound treatment for 0, 30, 60, and 90 min alongside the H2O2-Vc method. We then analyzed their chemical composition and structure. Additionally, we administered these polysaccharides to mice with type 2 diabetes (T2DM) through gavage at a dosage of 200 mg/kg/day. The results indicated a significant reduction in the molecular weight of the degraded sweet corncob polysaccharides, while their composition remained relatively stable. However, the basic structure of the polysaccharides was retained. In vivo experiments demonstrated that ultrasound-assisted degradation of these polysaccharides had a positive impact on T2DM, particularly the 60-minute ultrasound treatment (UH-DSCBP-60 min), which effectively controlled blood glucose levels by regulating glycolipid metabolism in the livers of mice with T2DM. This approach also reduced inflammation and oxidative stress levels and inhibited disaccharide activity in the small intestine. We demonstrated that ultrasound can positively affect the sweet corncob polysaccharides hypoglycemic activity. The findings of our study provide a theoretical foundation for the valuable utilization of sweet corncob polysaccharides.

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.

The cellular uptake of Cordyceps sinensis exopolysaccharide‑selenium nanoparticles and their induced apoptosis of HepG2 cells via mitochondria- and death receptor-mediated pathways

This wok investigated the effects of Cordyceps sinensis exopolysaccharide‑selenium nanoparticles (EPS-SeNPs), EPS-Se-1, EPS-Se-2, EPS-Se-3, and EPS-Se-4) with particle sizes (79-124 nm) and Se contents (20.11-40.80 μg/mg) on endocytosis and antitumor activity against human hepatocellular carcinoma (HepG2) cells and revealed the apoptosis-related mechanisms. EPS-SeNPs inhibited HepG2 cells proliferation in a dose and Se content-dependent manner by disrupting cell membrane and mitochondrial integrity, promoting reactive oxygen species production. EPS-SeNPs were endocytosed by HepG2 cells through a clathrin-mediated pathway and followed the quasi-first-order kinetics model, indicating physical adsorption played a dominant role in cellular uptake behavior of EPS-SeNPs. Notably, EPS-Se-3 with the lowest particle size (79 nm) showed the highest antitumor activity and the strongest ability to promote cell apoptosis. Western blotting results revealed that EPS-Se-3 increased expressions of Bax, Cytochrome c, cleaved caspase-9, cleaved caspase-3, Fas, p53, and cleaved caspase-8, while decreased the expressions of Bcl-2 and PARP, as contrast to that of control. Overall, EPS-SeNPs induced cell apoptosis through intrinsic mitochondria-mediated and extrinsic death receptor-mediated pathways.

Enhanced In Vitro Anti-Photoaging Effect of Degraded Seaweed Polysaccharides by UV/H2O2 Treatment

The high molecular weight and poor solubility of seaweed polysaccharides have limited their function and application. In this study, ultraviolet/hydrogen peroxide (UV/H2O2) treatment was used to prepare low-molecular-weight seaweed polysaccharides from Sargassum fusiforme. The effects of UV/H2O2 treatment on the physicochemical properties and anti-photoaging activity of S. fusiforme polysaccharides were studied. UV/H2O2 treatment effectively degraded polysaccharides from S. fusiforme (DSFPs), reducing their molecular weight from 271 kDa to 26 kDa after 2 h treatment. The treatment did not affect the functional groups in DSFPs but changed their molar percentage of monosaccharide composition and morphology. The effects of the treatment on the anti-photoaging function of S. fusiforme polysaccharides were investigated using human epidermal HaCaT cells in vitro. DFSPs significantly improved the cell viability and hydroxyproline secretion of UVB-irradiated HaCaT cells. In particular, DSFP-45 obtained from UV/H2O2 treatment for 45 min showed the best anti-photoaging effect. Moreover, DSFP-45 significantly increased the content and expression of collagen I and decreased those of pro-inflammatory cytokines, including interleukin-1β, interleukin-6, and tumor necrosis factor-α. Thus, UV/H2O2 treatment could effectively improve the anti-photoaging activity of S. fusiforme polysaccharides. These results provide some insights for developing novel and efficient anti-photoaging drugs or functional foods from seaweed polysaccharides.

Porphyran from Porphyra haitanensis Enhances Intestinal Barrier Function and Regulates Gut Microbiota Composition

In this study, the effects of a homogenous porphyran from Porphyra haitanensis (PHP) on the intestinal barrier and gut microbiota were investigated. The results showed that oral administration of PHP resulted in a higher luminal moisture content and a lower pH environment for the growth of beneficial bacteria in the colon of mice. PHP significantly increased the production of total short-chain fatty acids during the fermentation process. PHP made the intestinal epithelial cells of mice arrange more tidily and tightly with a significant increase in mucosal thickness. PHP also increased the amount of mucin-producing goblet cells and the expression of mucin in the colon, which maintained the structure and function of the intestinal mucosal barrier. Moreover, PHP up-regulated the expression of tight junctions including ZO-1 and occludin, improving the intestinal physical barrier function. The results of 16S rRNA sequencing showed that PHP regulated the composition of gut microbiota in mice, increasing the richness and diversity of gut microbiota and the ratio of Firmicutes to Bacteroidetes. This study revealed that the intake of PHP is beneficial for the gastrointestinal tract and PHP could be a potential source of prebiotics in the functional food and pharmaceutical industries.

Inhibitory effects of fucoidan from Laminaria japonica against some pathogenic bacteria and SARS-CoV-2 depend on its large molecular weight

Fucoidan is a highly sulfated polysaccharide with a wide range of bioactivities, including anti-pathogenic activity. However, the relationship between structure and activity of fucoidan in inhibiting pathogen infections remains unclear. Here, different-molecular-weight fucoidans were prepared by photocatalytic degradation followed by membrane ultrafiltration, and their chemical structures and anti-pathogenic microbiota activity were compared. Results showed that photocatalytic degradation could effectively degrade fucoidan while its structure block and sulfate groups were not destroyed obviously. Fucoidan (90.8 kDa) of 5 mg/mL could inhibit the growth of S. aureus, S. typhimurium and E. coli, but its degradation products, Dfuc1 (19.2 kDa) and Dfuc2 (5.5 kDa), demonstrated lower inhibitory effect. In addition, compared to Dfuc1 and Dfuc2, fucoidan showed stronger capability to prevent the adhesion of S. aureus, L. monocytogenes, V. parahaemolyticus and S. typhimurium to HT-29 cells. Moreover, the inhibitory effect against SARS-CoV-2 and the binding activity to S protein were also positively correlated to molecular weight. These results indicate that natural fucoidan with higher molecular weight are more effective to inhibit these pathogenic bacteria and SARS-CoV-2, providing a better understanding of the relationship between structure and activity of fucoidan against pathogenic microbiota.

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.

Regulatory effects of marine polysaccharides on gut microbiota dysbiosis: A review

The gut microbiota dysbiosis is a state which the physiological combinations of flora are transformed into pathological combinations caused by factors such as diets, pollution, and drugs. Increasing evidence shows that dysbiosis is closely related to many diseases. With the continuous development and utilization of marine resources, marine polysaccharides have been found to regulate dysbiosis in many studies. In this review, we introduce the types of dysbiosis and the degree of it caused by different factors. We highlight the regulating effects of marine polysaccharides on dysbiosis as a potential prebiotic. The mechanisms of marine polysaccharides to regulate dysbiosis including protection of intestinal barrier, regulatory effect on gut microbiota, alteration for related metabolites, and some other possible mechanisms were summarized. And we aim to provide some references for the high-value utilization of marine polysaccharides and new targets for the treatment of gut microbiota dysbiosis by this review.

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.

Advances in anti-cancer effects and underlying mechanisms of marine algae polysaccharides

Cancer is a leading cause of death in both developing and developed countries. With the increase in the average global life expectancy, it has become a major health problem and burden for most public healthcare systems worldwide. Due to the fewer side effects of natural compounds than of chemotherapeutic drugs, increasing scientific attention is being focused on the development of anti-cancer drugs derived from natural sources. Marine algae are an interesting source of functional compounds with diverse health-promoting activities. Among these compounds, polysaccharides have attracted considerable interest for many years because of their excellent anti-cancer abilities. They improve the efficacy of conventional chemotherapeutic drugs with relatively low toxicity to normal human cells. However, there are few reviews summarising the unique anti-cancer effects and underlying mechanisms of marine algae polysaccharides (MAPs). Thus, the current review focuses on updating the advances in the discovery and evaluation of MAPs with anti-cancer properties and the elucidation of their mechanisms of action, including the signalling pathways involved. This review aims to provide a deeper understanding of the anti-cancer functions of the natural compounds derived from medicinal marine algae and thereby offer a new perspective on cancer prevention and therapy with high effectiveness and safety.

Sargassum fusiforme Polysaccharide-Based Hydrogel Microspheres Enhance Crystal Violet Dye Adsorption Properties

In this study, a polysaccharide-based hydrogel microsphere (SFP/SA) was prepared using S. fusiforme polysaccharide (SFP) and sodium alginate (SA). Fourier transform infrared spectroscopy (FT-IR) demonstrated that SFP was effectively loaded onto the hydrogel microsphere. Texture profile analysis (TPA) and differential scanning calorimetry (DSC) showed that, with the increase of SFP concentration, the hardness of SFP/SA decreased, while the springiness and cohesiveness of SFP/SA increased, and the thermal stability of SFP/SA improved. The equilibrium adsorption capacity of SFP/SA increased from 8.20 mg/g (without SFP) to 67.95 mg/g (SFP accounted 80%) without swelling, and from 35.05 mg/g (without SFP) to 81.98 mg/g (SFP accounted 80%) after 24 h swelling. The adsorption of crystal violet (CV) dye by SFP/SA followed pseudo-first order and pseudo-second order kinetics (both with R2 > 0.99). The diffusion of intraparticle in CV dye was not the only influencing factor. Moreover, the adsorption of CV dye for SFP/SA (SFP accounted 60%) fit the Langmuir and Temkin isotherm models. SFP/SA exhibited good regenerative adsorption capacity. Its adsorption rate remained at > 97% at the 10th consecutive cycle while SFP accounted for 80%. The results showed that the addition of Sargassum fusiforme polysaccharide could increase the springiness, cohesiveness and thermal stability of the hydrogel microsphere, as well as improve the adsorption capacity of crystal violet dye.