Potential applications of alginate oligosaccharides for biomedicine - A mini review

Alginate oligosaccharide prevents renal ischemia-reperfusion injury in rats via MRC1-mediated pathway

Acute kidney injury (AKI) is a clinical syndrome that is defined as a sudden decline in renal function and characterized by inflammation and tubular injury. Alginate oligosaccharide (AOSC), a natural product obtained from alginate by acidolysis and hydrolysis, shows activities of antioxidant, immunomodulation, and anti-inflammation. In this study, we investigated the potential of AOSC in the treatment of AKI. Renal ischemia-reperfusion (I/R) was induced in male rats by clipping both the renal artery and vein for 45 min followed by reperfusion for 24 h. The rats were treated with AOSC (100 mg/kg, i.g.) before surgery. At the end of the experiments, both kidneys were collected for protein, mRNA measurement, or histological analysis. We showed that AOSC pretreatment significantly improved glomerular and tubular function in the kidney of I/R rats. AOSC markedly inhibited I/R-induced activation of TLR4/MyD88/NF-κB/IL-1β inflammatory signaling and prevented apoptosis in the kidney. In HK2 cells subjected to hypoxia/reoxygenation (H/R) stimulation, AOSC (250-1000 μg/ml) dose-dependently prevented pro-inflammatory responses and cell apoptosis. Transcriptomic analysis revealed that I/R increased the expression levels of mannose receptor type C1 (MRC1) in the kidney, which was markedly inhibited by AOSC. Molecular docking showed that AOSC interacted with E725, N727, E733, T743, S745, and N747 of MRC1 through hydrogen bonds. MRC1 gene knockout significantly improved renal function and attenuated I/R-induced kidney inflammation and apoptosis in mice. In line with this, AOSC failed to prevent I/R-induced kidney injury in MRC1 gene knockout mice. UPLC analysis showed that the protection of AOSC in HK2 cells subjected to H/R was likely attributed to MRC1-mediated intracellular endocytosis. In conclusion, AOSC prevents I/R-induced AKI, which is at least partially mediated by MRC1.

A review on polysaccharide-based tumor targeted drug nanodelivery systems

The tumor-targeted drug delivery system (TTDNS) uses nanocarriers to transport chemotherapeutic agents to target tumor cells or tissues precisely. This innovative approach considerably increases the effective concentration of these drugs at the tumor site, thereby enhancing their therapeutic efficacy. Many chemotherapeutic agents face challenges, such as low bioavailability, high cytotoxicity, and inadequate drug resistance. To address these obstacles, TTDNS comprising natural polysaccharides have gained increasing popularity in the field of nanotechnology owing to their ability to improve safety, bioavailability, and biocompatibility while reducing toxicity. In addition, it enhances permeability and allows for controlled drug delivery and release. This review focuses on the sources of natural polysaccharides and their direct and indirect mechanisms of anti-tumor activity. We also explored the preparation of various polysaccharide-based nanocarriers, including nanoparticles, nanoemulsions, nanohydrogels, nanoliposomes, nanocapsules, nanomicelles, nanocrystals, and nanofibers. Furthermore, this review delves into the versatile applications of polysaccharide-based nanocarriers, elucidating their capabilities for in vivo targeting, controlled release, and responsiveness to endogenous and exogenous stimuli, such as pH, reactive oxygen species, glutathione, light, ultrasound, and magnetic fields. This sophisticated design substantially enhances the chemotherapeutic efficacy of the encapsulated drugs at tumor sites and provides a basis for preclinical and clinical research. However, the in vivo stability, drug loading, and permeability of these preparations into tumor tissues still need to be improved. Most of the currently developed biomarker-sensitive polysaccharide nanocarriers are still in the laboratory stage, more innovative delivery mechanisms and clinical studies are needed to develop commercial nanocarriers for medical use.

Seaweed-derived laminarin and alginate as potential chemotherapeutical agents: An updated comprehensive review considering cancer treatment

Seaweed-derived bioactive substances such as polysaccharides have proven to be effective chemotherapeutic and chemopreventive agents. Laminarin and alginate antioxidant properties aid in the prevention of cancer through dynamic modulation of critical intracellular signaling pathways via apoptosis which produce low cytotoxicity and potential chemotherapeutic effects. Understanding the effects of laminarin and alginate on human cancer cells and their molecular roles in cell death pathways can help to develop a novel chemoprevention strategy. This review emphasizes the importance of apoptosis-modulating laminarin and alginate in a range of malignancies as well as their extraction, molecular structure, and weight. In addition, future nano-formulation enhancements for greater clinical efficacy are discussed. Laminarin and alginate are perfect ingredients because of their distinct physicochemical and biological characteristics and their use-based delivery systems in cancer. The effectiveness of laminarin and alginate against cancer and more preclinical and clinical trials will open up as new chemotherapeutic natural drugs which lead to established as potential cancer drugs.

Effect of Sodium Alginate-Bulk Chitosan/Chitosan Nanoparticle Wall Matrix on the Viability of Lactobacillus plantarum Under Simulated Gastrointestinal Fluids

The viability of probiotic cells decreases during passage through the gastrointestinal tract. The process of probiotics encapsulation with sodium alginate and chitosan polymers was carried out to protect the Lactobacillus plantarum in adverse conditions. Lactobacillus plantarum was entrapped in sodium alginate/chitosan (SA/BChi) and sodium alginate/nano-chitosan (SA/NChi) wall materials. Encapsulating L. plantarum with SA/BChi and SA/NChi resulted in a high encapsulation efficiency % of ~ 86.41 to 91.09%. In addition, coating bacteria cells in encapsulants improved the survivability of the cells under the simulated gastrointestinal fluids by ~ 52.61% in SA/Chi and 58.04% in SA/NChi compared to 29% for unencapsulated forms. Probiotic beads under field emission-scanning electron microscopy (FE-SEM) were morphologically compact with a cracked appearance of SA/NChi beads. The Fourier transform-infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) showed vigorous electrostatic interaction between polymers, as well as the high melting points, which corroborate the previous investigations in the field for using SA/BChi or SA/NChi as a promising encapsulating agent for ameliorating the survivability of probiotics under harsh conditions. The distinctive properties possessed by the two coatings make them excellent candidates for use as polymeric carriers in probiotic delivery systems.

Molecular Engineering of Alginate Lyases and the Potential Agricultural Applications of Their Enzymatic Products

Alginate lyases, enzymes that degrade alginate into unsaturated oligosaccharides, have attracted significant attention for their potential applications across various fields, particularly in agriculture. This review focuses on the molecular engineering of alginate lyases to enhance their activity, stability, and specificity as well as the agricultural applications of the resulting enzymatic products, known as alginate oligosaccharides (AOS). We start by summarizing the sources and classification of alginate lyases, followed by recent advances in their engineering through directed evolution, rational design, truncation of noncatalytic domains, and conserved domain reconstruction. We then explore the diverse agricultural applications of AOS, including their ability to promote plant growth, to increase the content of active plant components, to extend fruit shelf life, and to enhance plant resistance to abiotic stresses. Furthermore, the potential value of AOS as feed additives and preservatives in shrimp-based products is also assessed. This review will not only lay a solid theoretical foundation but also serve as a catalyst for the innovative development and practical application of high-value enzymatic preparations and utilization of AOS-related products, providing new solutions for sustainable agriculture and the food industry.

Direct Influence of the Conserved Motif in PL7 Family Alginate Lyases on Enzyme Cold Adaptability

Alginate lyase, a vital component of polysaccharide lyases, is instrumental in the efficient degradation of alginate and the production of single oligosaccharides. Although numerous alginate lyases have been characterized, only a few display extreme cold adaptability in the range of 0-20 °C. In this study, we identified a novel cold-adapted alginate lyase, Aly423, from Tamlana laminarinivorans PT2-4 isolated from Sargassum. Phylogenetic classification, enzyme structure, and catalytic property analyses confirmed that Aly423 could be classified as a member of subfamily 5 of the PL7 family and exhibited significant cold adaptability at low temperatures. Further analysis of the secondary structure and homology modeling of several cold-adapted enzymes revealed two variable amino acid sites in the conserved amino acid motif (YFK*G*Y) of Aly423, which may affect the cold adaptation mechanism. Point mutation experiments demonstrated that mutant A304T significantly altered the temperature adaptation of Aly423, highlighting the critical role of this amino acid site in the cold-adaptation mechanism of the enzyme. In summary, we effectively enhanced the enzymatic activity of the PL7 alginate cold-adapted enzyme through a rational design using computational methods. This advancement is of significant importance for the efficient utilization of sodium alginate in the food, agricultural, and pharmaceutical industries under low-temperature conditions.

Ethylenediamine-modified alginate - A hemocompatible platform for polymer-drug conjugates

The study is dedicated to the synthesis, rheological properties, hemocompatibility, and further modification of water-soluble derivatives of sodium alginate containing fragments of ethylenediamine (Alg-EDA). Alg-EDA with an equal ratio of amide/amine groups and varying degrees of substitution were synthesized by the carbodiimide method. The influence of the molecular weight of Alg-EDA on the attachment of bioactive molecules such as hydroxybenzoic and ferulic acids was determined. Modification of alginate with ethylenediamine fragments leads to a reduction in dynamic viscosity and sensitivity to Ca2+ ions (internal gelation method). Alg-EDA derivatives, with differ in molecular weight and degree of substitution with phenolic acids, are characterized by high hemocompatibility (in vitro tests: erythrocyte hemolysis, blood recalcification time, activated partial thromboplastin time). Antioxidant properties of the synthesized alginate derivatives were characterized using models of varying complexity (including cellular models). It was found that Alg-EDA, at a concentration of 0.5 mg/mL, had a statistically significant membrane-protective activity under conditions of acute oxidative stress induced by both H2O2 and AAPH. Derivatives with lower molecular weight were more effective than high molecular weight ones. Modification of polysaccharides by the fragments of phenolic acids into the structure contributed to the enhancement of antioxidant properties. The hemocompatible macromolecular antioxidants synthesized in this study are promising for further in-depth investigation for the creation of biomedical materials.

Lithium Coupled with C6-Carboxyl Improves the Efficacy of Oligoguluronate in DSS-Induced Ulcerative Colitis in C57BL/6J Mice

Oligoguluronate lithium (OGLi) was prepared for the purpose of enhancing the anti-ulcerative colitis (UC) activities of OG, in which lithium (Li+) is coupled with the C6-carboxyl of G residue. The therapeutic effects of OGLi on dextran sulfate (DSS)-induced UC mice were investigated, and oligoguluronate sodium (OGNa) and lithium carbonate (LC) were used as contrasts. The effects of OGLi, OGNa and LC on the treatment of UC mice were studied by monitoring body weight change and evaluating colon length, the disease activity index (DAI), histopathological examination and gut microbiota regulation. The results showed that compared with OGNa and LC, OGLi significantly reduced the clinical symptoms and histopathological changes associated with UC in the acute model. It was worth noting that OGLi significantly changed the gut microbiota characteristics of the DSS-treated mice and corrected the typical dysbacteriosis of DSS-induced UC. This intervention resulted in increasing the abundance of norank_f_Muribaculaceae and Ileibacterium spp. while reducing the levels of Escherichia-Shigella spp. and Romboutsia spp. The OGLi could significantly increase the diversity of intestinal microorganisms in the short term. All of these discoveries demonstrate that lithium collaboratively enhances the anti-UC efficacy of OG, which will help to create OG-based drugs for the treatment of UC.

Expression, Purification, and Characterisation of Recombinant Alginate Lyase (Flammeovirga AL2) for the Bioconversion of Alginate into Alginate Oligosaccharides

Alginate, a polysaccharide found in brown seaweeds, has regularly gained attention for its potential use as a source of bioactive compounds. However, it is structurally complex with a high molecular weight, limiting its application. Alginate oligosaccharides (AOS) are small, soluble fragments, making them more bioavailable. Alginate hydrolysis by enzymes is the preferred method for AOS production. Commercially available alginate lyases are limited, expensive, and sometimes exhibit unsatisfactory activity, making the search for novel alginate lyases with improved activity indispensable. The aims of this study were to codon-optimise, synthesise, express, purify, and characterise a recombinant alginate lyase, AL2, from Flammeovirga sp. strain MY04 and to compare it to a commercial alginate lyase. Expression was successfully performed using Escherichia coli ArcticExpress (DE3) RP cells, and the protein was purified through affinity chromatography. The recombinant enzyme was characterised by pH optimum studies, and temperature optimum and stability experiments. The optimal reaction conditions for AL2 were pH 9.0 and 37 °C, while for the commercial enzyme, the optimal conditions were pH 8.0 and 37 °C. At optimal reaction conditions, the specific activity of AL2 was 151.6 ± 12.8 µmol h-1 mg-1 protein and 96.9 ± 13.1 µmol h-1 mg-1 protein for the commercial alginate lyase. Moreover, AL2 displayed impressive activity in breaking down alginate into AOS. Hence, AL2 shows potential for use as an industrial enzyme for the hydrolysis of alginate into alginate oligosaccharides. Additional studies should be carried out to further characterise this enzyme, improve its purity, and optimise its activity.

Alginate Oligosaccharides Enhance Gut Microbiota and Intestinal Barrier Function, Alleviating Host Damage Induced by Deoxynivalenol in Mice

BACKGROUND

Alginate oligosaccharides (AOS) exhibits notable effects in terms of anti-inflammatory, antibacterial, and antioxidant properties. Deoxynivalenol (DON) has the potential to trigger intestinal inflammation by upregulating pro-inflammatory cytokines and apoptosis, thereby compromising the integrity of the intestinal barrier function and perturbing the balance of the gut microbiota.

OBJECTIVES

We assessed the impact of AOS on mitigating DON-induced intestinal damage and systemic inflammation in mice.

METHODS

After a 1-wk acclimatization period, the mice were divided into 4 groups. For 3 wk, the AOS and AOS + DON groups were gavaged daily with 200 μL of AOS [200 mg/kg body weight (BW)], whereas the CON and DON groups received an equivalent volume of sterile Phosphate-Buffered Saline (PBS). Subsequently, for 1 wk, the DON and AOS + DON groups received 100 μL of DON (4.8 mg/kg BW) daily, whereas the control (CON) and AOS groups continued receiving PBS.

RESULTS

After administering DON via gavage to mice, there was a significant decrease (P < 0.05) in body weights compared with the CON group. Interestingly, AOS exhibited a tendency to mitigate this weight loss in the AOS + DON group. In the feces of mice treated with both AOS and DON, the concentration of DON significantly increased (P < 0.05) compared with the DON group alone. Histological analysis revealed that DON exposure caused increased intestinal damage, including shortened villi and eroded epithelial cells, which was ameliorated by presupplementation with AOS, alleviating harm to the intestinal barrier function. In both jejunum and colon tissues, DON exposure significantly reduced (P < 0.05) the expression of tight junction proteins (claudin and occludin in the colon) and the mucin protein mucin 2, compared with the CON group. Prophylactic administration of AOS alleviated these reductions, thereby improving the expression levels of these key proteins. Additionally, AOS supplementation protected DON-exposed mice by increasing the abundance of probiotics such as Bifidobacterium, Faecalibaculum, and Romboutsia. These gut microbes are known to enhance (P < 0.05) anti-inflammatory responses and the production of short-chain fatty acids (SCFAs), including total SCFAs, acetate, and valerate, compared with the DON group.

CONCLUSIONS

This study unveils that AOS not only enhances gut microbiota and intestinal barrier function but also significantly mitigates DON-induced intestinal damage.

Alginate from Ericaria crinita Possesses Antioxidant Activity and Attenuates Systemic Inflammation via Downregulation of Pro-Inflammatory Cytokines

Alginates are anionic polysaccharides present in the cell walls of brown seaweeds. Various biological activities of alginate and its derivatives have been described. In this study, we assessed the potential of alginate obtained from Ericaria crinita (formerly Cystoseira crinita) to scavenge free radicals and function as a ferric ion reductor. The anti-inflammatory effect on the serum levels of TNF-α, IL-1β, IL-6, and IL-10 of rats with LPS-induced systemic inflammation after 14 days of treatment was also examined. Ericaria crinita alginate showed antioxidant activities of IC50 = 505 µg/mL (DPPH) and OD700 > 2 (ferric reducing power). A significant decrease in serum levels of IL-1β was observed only in animals treated with the polysaccharide at a dose of 100 mg/kg bw. Both doses of E. crinita alginate (25 and 100 mg/kg bw) significantly reduced the serum concentrations of pro-inflammatory cytokines TNF-α and IL-6, but no statistical significance was observed in the levels of the anti-inflammatory cytokine IL-10. Our findings show the potential of E. crinita alginate to act as an antioxidant and anti-inflammatory agent. It is likely that the exhibited antioxidant ability of the polysaccharide contributes to its antiphlogistic effects. More in-depth studies are needed to fully understand the specific mechanisms and the molecular pathways involved in these activities.

Degradation of Natural Undaria pinnatifida into Unsaturated Guluronic Acid Oligosaccharides by a Single Alginate Lyase

Here, we report on a bifunctional alginate lyase (Vnalg7) expressed in Pichia pastoris, which can degrade natural Undaria pinnatifida into unsaturated guluronic acid di- and trisaccharide without pretreatment. The enzyme activity of Vnalg7 (3620.00 U/mL-culture) was 15.81-fold higher than that of the original alg (228.90 U/mL-culture), following engineering modification. The degradation rate reached 52.75%, and reducing sugar reached 30.30 mg/mL after combining Vnalg7 (200.00 U/mL-culture) and 14% (w/v) U. pinnatifida for 6 h. Analysis of the action mode indicated that Vnalg7 could degrade many substrates to produce a variety of unsaturated alginate oligosaccharides (AOSs), and the minimal substrate was tetrasaccharide. Site-directed mutagenesis showed that Glu238, Glu241, Glu312, Arg236, His307, Lys414, and Tyr418 are essential catalytic sites, while Glu334, Glu344, and Asp311 play auxiliary roles. Mechanism analysis revealed the enzymatic degradation pattern of Vnalg7, which mainly recognizes and attacks the third glycosidic linkage from the reducing end of oligosaccharide substrate. Our findings provide a novel alginate lyase tool and a sustainable and commercial production strategy for value-added biomolecules using seaweeds.

Biomedical potentials of alginate via physical, chemical, and biological modifications

Alginate is a linear polysaccharide with a modifiable structure and abundant functional groups, offers immense potential for tailoring diverse alginate-based materials to meet the demands of biomedical applications. Given the advancements in modification techniques, it is significant to analyze and summarize the modification of alginate by physical, chemical and biological methods. These approaches provide plentiful information on the preparation, characterization and application of alginate-based materials. Physical modification generally involves blending and physical crosslinking, while chemical modification relies on chemical reactions, mainly including acylation, sulfation, phosphorylation, carbodiimide coupling, nucleophilic substitution, graft copolymerization, terminal modification, and degradation. Chemical modified alginate contains chemically crosslinked alginate, grafted alginate and oligo-alginate. Biological modification associated with various enzymes to realize the hydrolysis or grafting. These diverse modifications hold great promise in fully harnessing the potential of alginate for its burgeoning biomedical applications in the future. In summary, this review provides a comprehensive discussion and summary of different modification methods applied to improve the properties of alginate while expanding its biomedical potentials.

Alginate oligosaccharide supplementation improves boar semen quality under heat stress

Heat stress is a serious problem that affects animal husbandry by reducing growth and reproductive performance of animals. Adding plant extracts to the diet is an effective way to help overcome this problem. Alginate oligosaccharide (AOS) is a natural non-toxic antioxidant with multiple biological activities. This study analyzed the potential mechanism of AOS in alleviating heat stress and improving semen quality in boars through a combination of multiple omics tools. The results indicated that AOS could significantly increase sperm motility (P < 0.001) and sperm concentration (P < 0.05). At the same time, AOS improved the antioxidant capacity of blood and semen, and increased blood testosterone (P < 0.05) level. AOS could improve the metabolites in sperm, change the composition of gut microbiota, increase the relative abundance of beneficial bacteria such as Pseudomonas (P < 0.01), Escherichia-Shigella (P < 0.05), Bifidobacterium (P < 0.01), reduce the relative abundance of harmful bacteria such as Prevotella_9 (P < 0.05), Prevotellaceae_UCG-001 (P < 0.01), and increase the content of short chain fatty acids. Proteomic results showed that AOS increased proteins related to spermatogenesis, while decreasing heat shock protein 70 (P < 0.05) and heat shock protein 90 (P < 0.01). These results were verified using immunofluorescence staining technology. There was a good correlation among sperm quality, sperm metabolome, sperm proteome, and gut microbiota. In conclusion, AOS can be used as a feed additive to increase the semen quality of boars to enhance reproductive performance under heat stress.

Potential therapeutic natural compounds for the treatment of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a complicated neurodegenerative disease with cognitive impairment occurring in the older people, in which extracellular accumulation of β-amyloid and intracellular aggregation of hyperphosphorylated tau are regarded as the prevailing theories. However, the exact AD mechanism has not been determined. Moreover, there is no effective treatment available in phase III trials to eradicate AD, which is imperative to explore novel treatments.

PURPOSE

A number of up-to-date pre-clinical studies on cognitive impairment is beneficial to clarify the pathology of AD. This review recapitulates several advances in AD pathobiology and discusses the neuroprotective effects of natural compounds, such as phenolic compounds, natural polysaccharides and oligosaccharides, peptide, and lipids, underscoring the therapeutic potential for AD.

METHODS

Electronic databases involving PubMed, Web of Science, and Google Scholar were searched up to October 2023. Articles were conducted using the keywords like Alzheimer's disease, pathogenic mechanisms, natural compounds, and neuroprotection.

RESULT

This review summarized several AD pathologies and the neuroprotective effects of natural compounds such as natural polysaccharides and oligosaccharides, peptide, and lipids.

CONCLUSION

We have discussed the pathogenic mechanisms of AD and the effect natural products on neurodegenerative diseases particularly in treating AD. Specifically, we investigated the molecular pathways and links between natural compounds and Alzheimer's disease such as through NF-κB, Nrf2, and mTOR pathway. Further investigation is necessary in exploring the bioactivity and effectiveness of natural compounds in clinical trials, which may provide a promising treatment for AD patients.

Biopolymer-Based Nanomedicine for Cancer Therapy: Opportunities and Challenges

Cancer, as the foremost challenge among human diseases, has plagued medical professionals for many years. While there have been numerous treatment approaches in clinical practice, they often cause additional harm to patients. The emergence of nanotechnology has brought new directions for cancer treatment, which can deliver anticancer drugs specifically to tumor areas. This article first introduces the application scenarios of nanotherapies and treatment strategies of nanomedicine. Then, the noteworthy characteristics exhibited by biopolymer materials were described, which make biopolymers stand out in polymeric nanomedicine delivery. Next, we focus on summarizing the state-of-art studies of five categories of proteins (Albumin, Gelatin, Silk fibroin, Zein, Ferritin), nine varieties of polysaccharides (Chitosan, Starch, Hyaluronic acid, Dextran, cellulose, Fucoidan, Carrageenan, Lignin, Pectin) and liposomes in the field of anticancer drug delivery. Finally, we also provide a summary of the advantages and limitations of these biopolymers, discuss the prevailing impediments to their application, and discuss in detail the prospective research directions. This review not only helps readers understand the current development status of nano anticancer drug delivery systems based on biopolymers, but also is helpful for readers to understand the properties of various biopolymers and find suitable solutions in this field through comparative reading.

A tough and bioadhesive injectable hydrogel formed with maleimidyl alginate and pristine gelatin

Injectable hydrogels have wide applications in clinical practice. However, the development of tough and bioadhesive ones based on biopolymers, along with biofriendly and robust crosslinking strategies, still represents a great challenge. Herein, we report an injectable hydrogel composed of maleimidyl alginate and pristine gelatin, for which the precursor solutions could self-crosslink via mild Michael-type addition without any catalyst or external energy upon mixing. This hydrogel is tough and bioadhesive, which can maintain intactness as well as adherence to the defect of porcine skin under fierce bending and twisting, warm water bath, and boiling water shower. Besides, it is biocompatible, bioactive and biodegradable, which could support the growth and remodeling of cells by affording an extracellular matrix-like environment. As a proof of application, we demonstrate that this hydrogel could significantly accelerate diabetic skin wound healing, thereby holding great potential in healthcare.

Alginate Oligosaccharides Protect Gastric Epithelial Cells against Oxidative Stress Damage through Induction of the Nrf2 Pathway

Gastric diseases represent a significant global public health challenge, characterized by molecular dysregulation in redox homeostasis and heightened oxidative stress. Although prior preclinical studies have demonstrated the cytoprotective antioxidant effects of alginate oligosaccharides (AOSs) through the Nrf2 pathway, whether such mechanisms apply to gastric diseases remains unclear. In this study, we used the GES-1 gastric cell line exposed to hydrogen peroxide (H2O2) as a damage model to investigate the impact of AOS on cell viability and its associated mechanisms. Our results revealed that pre-incubation with AOS for either 4 h or 24 h significantly improved the viability of GES-1 cells exposed to H2O2. In addition, AOS reduced the intracellular ROS levels, activating the Nrf2 signaling pathway, with increased Nrf2 protein and mRNA expression and a significant upregulation of the target genes HO-1 and NQO1. The activation of Nrf2 was correlated with decreased Keap1 protein expression and an increased level of the autophagy protein p62/SQSTM1, suggesting the activation of Nrf2 through a noncanonical pathway. This study suggests that AOS is a potential treatment for protecting gastric epithelial cells from oxidative stress by activating the p62/SQSTM1-Keap1-Nrf2 axis and laying the foundation for future investigations about its specific therapeutic mechanisms.

Unveiling the trifecta of cyanobacterial quorum sensing: LuxI, LuxR and LuxS as the intricate machinery for harmful algal bloom formation in freshwater ecosystems

Harmful algal blooms (HABs) are causing significant disruptions in freshwater ecosystems, primarily due to the proliferation of cyanobacteria. These blooms have a widespread impact on various lakes globally, leading to profound environmental and health consequences. Cyanobacteria, with their ability to produce diverse toxins, pose a particular concern as they negatively affect the well-being of humans and animals, exacerbating the situation. Notably, cyanobacteria utilize quorum sensing (QS) as a complex communication mechanism that facilitates coordinated growth and toxin production. QS plays a critical role in regulating the dynamics of HABs. However, recent advances in control and mitigation strategies have shown promising results in effectively managing and reducing the occurrence of HABs. This comprehensive review explores the intricate aspects of cyanobacteria development in freshwater ecosystems, explicitly focusing on deciphering the signaling molecules associated with QS and their corresponding genes. Furthermore, a concise overview of diverse measures implemented to efficiently control and mitigate the spread of these bacteria will be provided, shedding light on the ongoing global efforts to address this urgent environmental issue. By deepening our understanding of the mechanisms driving cyanobacteria growth and developing targeted control strategies, we hope to safeguard freshwater ecosystems and protect the health of humans and animals from the detrimental impacts of HABs.

Bioarchitectural Design of Bioactive Biopolymers: Structure-Function Paradigm for Diabetic Wound Healing

Chronic wounds such as diabetic ulcers are a major complication in diabetes caused by hyperglycemia, prolonged inflammation, high oxidative stress, and bacterial bioburden. Bioactive biopolymers have been found to have a biological response in wound tissue microenvironments and are used for developing advanced tissue engineering strategies to enhance wound healing. These biopolymers possess innate bioactivity and are biodegradable, with favourable mechanical properties. However, their bioactivity is highly dependent on their structural properties, which need to be carefully considered while developing wound healing strategies. Biopolymers such as alginate, chitosan, hyaluronic acid, and collagen have previously been used in wound healing solutions but the modulation of structural/physico-chemical properties for differential bioactivity have not been the prime focus. Factors such as molecular weight, degree of polymerization, amino acid sequences, and hierarchical structures can have a spectrum of immunomodulatory, anti-bacterial, and anti-oxidant properties that could determine the fate of the wound. The current narrative review addresses the structure-function relationship in bioactive biopolymers for promoting healing in chronic wounds with emphasis on diabetic ulcers. This review highlights the need for characterization of the biopolymers under research while designing biomaterials to maximize the inherent bioactive potency for better tissue regeneration outcomes, especially in the context of diabetic ulcers.

Development and Evaluation of Alginate- and Carrageenan-Incorporated Scaffold for Bone Regeneration: An In Vitro Study

INTRODUCTION

Periodontitis, a persistent inflammatory condition, results in the deterioration of both the hard and soft tissues in the periodontium, leading to the formation of intrabony defects. Restoring the lost tissues, particularly bone, is possible through tissue engineering techniques utilizing scaffolds made from different polymers. Consequently, this research focuses on creating and assessing a scaffold infused with alginate (Sigma Aldrich, Gillingham, UK) and carrageenan (Sigma Aldrich, Gillingham, UK) for the purpose of bone regeneration.

METHODS

An in vitro investigation was conducted to assess the characteristics of the recently formulated scaffold. Spectroscopic analysis, tensile strength testing, scanning electron microscopy (SEM) analysis, and degradation testing were carried out to evaluate both the physical and biological attributes of the scaffold.

RESULTS

IBM SPSS Statistics for Windows, V. 1.2 (IBM Corp., Armonk, NY, USA) was used for statistical analysis. A one-way ANOVA test was done to determine the significance of tensile strength, and a paired t-test was done to check the significance of the degradation test. The in vitro research unveiled notable distinctions in the physical and biological attributes between the scaffold infused with alginate and carrageenan and the PerioCol® (p<0.05).

CONCLUSION

The scaffold incorporating alginate and carrageenan demonstrated superior outcomes concerning parameters such as tensile stress and strain, degradation rate, percentage bone volume, and object surface density when contrasted with the conventional PerioCol®. Therefore, the scaffold infused with alginate and carrageenan emerges as a promising candidate for bone regeneration.

Metabolomic analysis reveals biogenic selenium nanoparticles improve the meat quality of thigh muscle in heat-stressed broilers is related to the regulation of ferroptosis pathway

Heat stress (HS) causes oxidative damage and abnormal metabolism of muscle, thus impairing the meat quality in broilers. Selenium is an indispensable element for enhancing antioxidant systems. In our previous study, we synthesized a novel type of biogenic selenium nanoparticles synthesized with alginate oligosaccharides (SeNPs-AOS), and found that the particle size of Se is 80 nm and the Se content is 8% in the SeNPs-AOS; and dietary 5 mg/kg SeNPs-AOS has been shown to be effective against HS in broilers. However, whether SeNPs-AOS can mitigate HS-induced the impairment of thigh muscle quality in broilers is still unclear. Therefore, the purpose of this study was to investigate the protective effects of dietary SeNPs-AOS on meat quality, antioxidant capacity, and metabolomics of thigh muscle in broilers under HS. A total of 192 twenty-one-day-old Arbor Acres broilers were randomly divided into 4 groups with 6 replicates per group (8 broilers per replicate) according to a 2 × 2 experimental design: thermoneutral group (TN, broilers raised under 23±1.5°C); TN+SeNPs-AOS group (TN group supplemented 5 mg/kg SeNPS-AOS); HS group (broilers raised under 33 ± 2°C for 10 h/d); and HS + SeNPs-AOS group (HS group supplemented 5 mg/kg SeNPS-AOS). The results showed that HS increased the freezing loss, cooking loss, and malondialdehyde (MDA) content of thigh muscle, whereas decreased the total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities, as well as downregulated the mRNA expression of SOD2, CAT, GPX3, nuclear factor erythroid 2-related factor 2 (Nrf2), selenoprotein S (SELENOS), solute carrier family 7 member 11 (SLC7A11), GPX4, and ferroportin 1 (Fpn1) of thigh muscle (P < 0.05). Dietary SeNPS-AOS reduced the b* value, elevated the pH0min value and the activities of T-SOD, GSH-Px, glutathione S-transferase (GST) and the mRNA expression levels of GSTT1, GSTA3, GPX1, GPX3, ferritin heavy polypeptide-1 (FTH1), and Fpn1 of thigh muscle in broilers under HS (P < 0.05). Nontargeted metabolomics analysis identified a total of 79 metabolites with significant differences among the four groups, and the differential metabolites were mainly enriched in 8 metabolic pathways including glutathione metabolism and ferroptosis (P < 0.05). In summary, dietary 5 mg/kg SeNPs-AOS (Se content of 8%) could alleviate HS-induced impairment of meat quality by improving the oxidative damage, metabolic disorders and ferroptosis of thigh muscle in broilers challenged with HS. Suggesting that the SeNPs-AOS may be used as a novel nano-modifier for meat quality in broilers raised in thermal environment.

Advances in alginate lyases and the potential application of enzymatic prepared alginate oligosaccharides: A mini review

Alginate is mainly a linear polysaccharide composed of randomly arranged β-D-mannuronic acid and α-L-guluronic acid linked by α, β-(1,4)-glycosidic bonds. Alginate lyases degrade alginate mainly adopting a β-elimination mechanism, breaking the glycosidic bonds between the monomers and forming a double bond between the C4 and C5 sugar rings to produce alginate oligosaccharides consisting of 2-25 monomers, which have various physiological functions. Thus, it can be used for the continuous industrial production of alginate oligosaccharides with a specific degree of polymerization, in accordance with the requirements of green exploitation of marine resources. With the development of structural analysis, the quantity of characterized alginate lyase structures is progressively growing, leading to a concomitant improvement in understanding the catalytic mechanism. Additionally, the use of molecular modification methods including rational design, truncated expression of non-catalytic domains, and recombination of conserved domains can improve the catalytic properties of the original enzyme, enabling researchers to screen out the enzyme with the expected excellent performance with high success rate and less workload. This review presents the latest findings on the catalytic mechanism of alginate lyases and outlines the methods for molecular modifications. Moreover, it explores the connection between the degree of polymerization and the physiological functions of alginate oligosaccharides, providing a reference for enzymatic preparation development and utilization.

In situ generation of hybrid alginate hydrogels for enhanced breast tumor ferrotherapy through multiplex magnifying redox imbalances

Ferroptosis has drawn great attention to tumor treatments over the past decade. However, how to specifically boost tumoral redox imbalance by simultaneously superimposing iron-mediated reactive oxygen species and undermining antioxidative pathways at the tumor site is still a significant challenge in ferroptosis-based tumor ferrotherapy. In this study, we designed an in situ generable hydrogel that contains paclitaxel/chlorin e6-loaded iron-based metal-organic framework (Fe-MOF) nanoparticles for enhanced breast tumor ferrotherapy by multiplex magnifying redox imbalance. The polysaccharide sodium alginate can crosslink with tumoral calcium ions to generate a hydrogel patch, which promotes the retention of Fe-MOF and therapeutic molecules. The Fe-MOF holds peroxidase/glutathione oxidase mimicking properties, resulting in OH generation via the Fenton reaction and glutathione consumption. Local ultrasound treatment facilitates the release of therapeutics and stimulates the generation of signet oxygen by activating the sonosensitizer chlorin e6. In the meanwhile, the low-dose paclitaxel reduces tumoral pH value by downregulating the glutaminolysis-related gene (SLC7A11) which in turn enhances the catalytic activity of Fe-MOF and inhibits antioxidative pathways, respectively. Both in vivo and in vitro experiments show that our designed hybrid hydrogels can induce significant ferrotherapeutic effects by augmenting the tumoral oxidative stresses.

Algae in Biomedicine

Algae, which live in marine or freshwater, are photosynthetic organisms. They vary greatly in size, morphology, and degree of complexity of their body structures. Algae are generally divided into two main groups, microalgae, which are small in size, and macroalgae, which are larger in size. These aquatic organisms have rich and valuable compounds including sterols, polysaccharides, pigments, fatty acids, proteins, enzymes, minerals, and vitamins that could be used in different application fields due to their bioactive functions. In recent years, algae and their components have attracted interest in biomedicine and health applications as their bioactive components could show antioxidant, anticancer, anti-inflammatory, antiviral, antiangiogenic, antidiabetic, antiobesity, immunostimulatory, vaccine adjuvant, and hypolipidemic activities. In this chapter, these activities and bioactive components underlying these properties are reviewed.

A non-thermal modification method to promote the interaction of zein-alginate oligosaccharides composites for better encapsulation and stability-Cold plasma

This current research explored the application of cold plasma (CP) treatment to modify zein-alginate oligosaccharide (zein-AOS) composites in an ethanol-water solution. Anti-solvent method was used to prepare zein-AOS nanoparticles (NPs), and the objective was to investigate the mechanism by which CP promotes interaction between protein and saccharides. Characterization results indicated that CP treatment improved hydrogen bonding and electrostatic interaction between zein and AOS. The CP zein-AOS NPs underwent dispersion and rearrangement, resulting in smaller aggregates with better dispersibility. Among the various induction conditions tested, the zein-AOS85 NPs (induced at 85 W for 2 min) exhibited superior performance as delivery wall materials, with smaller particle size (234.67 nm), larger specific surface area (9.443 m2/g), and higher surface charge (-35.43 mV). In addition, zein-AOS85 showed high stability when used as delivery wall material, providing more binding sites and self-assembly dynamics for nutrients. Curcumin was used as the nutrient model in this study, and CP was found to enhance hydrogen bonding, electrostatic interaction, and hydrophobic interaction between zein, AOS, and nutrients, resulting in increased encapsulation efficiency (EE) from 63.80 % to 85.17 %. The delivery system also exhibited good pH, ionic strength, storage, and dispersion stability.

Advances in oligosaccharides production from brown seaweeds: extraction, characterization, antimetabolic syndrome, and other potential applications

Brown seaweeds are a promising source of bioactive substances, particularly oligosaccharides. This group has recently gained considerable attention due to its diverse cell wall composition, structure, and wide-spectrum bioactivities. This review article provides a comprehensive update on advances in oligosaccharides (OSs) production from brown seaweeds and their potential health applications. It focuses on advances in feedstock pretreatment, extraction, characterization, and purification prior to OS use for potential health applications. Brown seaweed oligosaccharides (BSOSs) are extracted using various methods. Among these, enzymatic hydrolysis is the most preferred, with high specificity, mild reaction conditions, and low energy consumption. However, the enzyme selection and hydrolysis conditions need to be optimized for desirable yield and oligosaccharides composition. Characterization of oligosaccharides is essential to determine their structure and properties related to bioactivities and to predict their most suitable application. This is well covered in this review. Analytical techniques such as high-performance liquid chromatography (HPLC), gas chromatography (GC), and nuclear magnetic resonance (NMR) spectroscopy are commonly applied to analyze oligosaccharides. BSOSs exhibit a range of biological properties, mainly antimicrobial, anti-inflammatory, and prebiotic properties among others. Importantly, BSOSs have been linked to possible health advantages, including metabolic syndrome management. Metabolic syndrome is a cluster of conditions, such as obesity, hypertension, and dyslipidemia, which increase the risk of cardiovascular disease and type 2 diabetes. Furthermore, oligosaccharides have potential applications in the food and pharmaceutical industries. Future research should focus on improving industrial-scale oligosaccharide extraction and purification, as well as researching their potential utility in the treatment of various health disorders.[Figure: see text].

Polyguluronic acid alleviates doxorubicin-induced cardiotoxicity by suppressing Peli1-NLRP3 inflammasome-mediated pyroptosis

Polyguluronic acid (PG), a polysaccharide from alginate, possesses excellent bioactivities. We prepared high-purity PG with 10.41 kDa molecular weight (Mw) and a 59 average degree of polymerization (DP) by acid hydrolysis, three pH grades, Q-Sepharose column elution, and Sephadex G-25 column desalination. Then, we evaluated the PG protective effects on doxorubicin-induced cardiotoxicity (DIC) in vitro and in vivo. The nontoxic PG enhanced cellular viability, reduced cell pyroptosis morphology, diminished the LDH and IL-1β release, and downregulated expressions of ASC oligomerization, NLRP3, cl-CASP1, and GSDMD, by which PG protected the cardiomyocytes from NLRP3 inflammasome-mediated pyroptosis in doxorubicin-stimulated HL-1 cells and C57BL/6J mice. The probable underlying mechanism may be that PG downregulated doxorubicin -induced Peli1, the deficiency of which could inhibit doxorubicin-induced NLRP3 inflammasome-mediated pyroptosis. These results suggested that polysaccharide PG from alginate could prevent DIC and may be a potential therapeutic agent or bioactive material for preventing DIC.

Ions-Induced Alginate Gelation According to Elemental Analysis and a Combinatorial Approach

This study considers the potential of elemental analysis of polysaccharide ionotropic gels in elucidating the junction zones for different divalent cations. The developed algorithm ensures the correct separation of contributions from physically adsorbed and structure-forming ionic compounds, with the obtained results scaled to alginate C12 block. Possible versions of chain association into dimers and their subsequent integration into flat junction zones were analyzed within the framework of the "egg-box" model. The application of combinatorial analysis made it possible to derive theoretical relations to find the probability of various types of egg-box cell occurrences for alginate chains with arbitrary monomeric units ratio μ = M/G, which makes it possible to compare experimental data for alginates of different origins. Based on literature data and obtained chemical formulas, the possible correspondence of concrete biopolymer cells to those most preferable for filling by alkaline earth cations was established. The identified features of elemental composition suggest the formation of composite hydrated complexes with the participation of transition metal cations. The possibility of quantitatively assessing ordered secondary structures formed due to the physical sorption of ions and molecules from environment, correlating with the sorption capabilities of Me2+ alginate, was established.

Living, quiescent Lactobacillus plantarum Lp90 probiotic, delivered topically to full thickness tissues in vitro via a just-add-water cream delivery system, stimulates the expression of elastin protein

INTRODUCTION

Delivering living probiotics to the skin can be challenging as most water-containing cosmetic products require preservatives to maintain product stability. A recently introduced powdered technology [Stratabiosys™, Vantage Personal Care] allows for quiescent probiotic powders to be stored for extended periods of time. The powders can then be reconstituted to creams at the point of use by adding water and mixing and were examined in vitro on reconstructed human full thickness tissues to see if the probiotic had any influence of several important biomolecules expressed in the skin.

MATERIALS AND METHODS

A probiotic powder containing 200 M CFU/gram of living quiescent Lactobacillus plantarum Lp90 was reconstituted to a cream by adding ultrapure water and gently mixing the components at room temperature to quickly produce a cream. The resulting cream was tested topically on Epiderm® Full Thickness Tissues by treating the tissues for 24 h, removing the cream with a PBS rinse and then repeating the treatment for another 24 h. The resulting tissues were examined for four strategically important skin biomolecules including Type 1A collagen, elastin, filaggrin and hyaluronic acid. The probiotic-containing powder was tested against untreated tissues and powders not containing probiotics and powders containing measured amounts of one of two cryoprotectants known to be used to maintain the integrity of the quiescent probiotics during drying of the quiescent probiotic powders.

RESULTS

It was found that topical treatment on Epiderm® tissues with creams containing 2 M (1%), 4 M (2%) and 6 M (3%) CFU/gram prepared from a base powder containing 200 M CFU/gram of Lactobacillus plantarum Lp90 stimulated elastin expression in a dose dependent fashion. There was no effect on the other biomolecules examined in the studies. In addition, it was found that creams made from powders containing only the known cryoprotectants, not bacteria, had no influence on elastin expression.

CONCLUSION

The results of this study demonstrate that topical delivery of probiotics is possible from powders containing quiescent probiotic powders converted to creams just prior to application to the tissues. In the case of a powder containing Lactobacillus plantarum Lp90, topical application significantly increased expression of elastin in the skin replicants after 48 h of exposure to the cream made with the probiotic. The elastin-stimulating effects are not coming from the oligosaccharide cryoprotectants used to maintain the probiotic powders in their quiescent, dried state. The results indicate that it is the living Lactobacillus plantarum probiotic that is stimulating the elastin expression in the skin tissues.

Advances in oligosaccharides production from algal sources and potential applications

In recent years, algal-derived glycans and oligosaccharides have become increasingly important in health applications due to higher bioactivities than plant-derived oligosaccharides. The marine organisms have complex, and highly branched glycans and more reactive groups to elicit greater bioactivities. However, complex and large molecules have limited use in broad commercial applications due to dissolution limitations. In comparison to these, oligosaccharides show better solubility and retain their bioactivities, hence, offering better applications opportunity. Accordingly, efforts are being made to develop a cost-effective method for enzymatic extraction of oligosaccharides from algal polysaccharides and algal biomass. Yet detailed structural characterization of algal-derived glycans is required to produce and characterize the potential biomolecules for improved bioactivity and commercial applications. Some macroalgae and microalgae are being evaluated as in vivo biofactories for efficient clinical trials, which could be very helpful in understanding the therapeutic responses. This review discusses the recent advancements in the production of oligosaccharides from microalgae. It also discusses the bottlenecks of the oligosaccharides research, technological limitations, and probable solutions to these problems. Furthermore, it presents the emerging bioactivities of algal oligosaccharides and their promising potential for possible biotherapeutic application.

Improving the thermostability of a novel PL-6 family alginate lyase by rational design engineering for industrial preparation of alginate oligosaccharides

Alginate is degraded into alginate oligosaccharides with various biological activities by enzymes. However, the thermostability of the enzyme limits its industrial application. In this study, a novel PL-6 alginate lyase, AlyRm6A from Rhodothermus marinus 4252 was expressed and characterized. In addition, an efficient comprehensive strategy was proposed, including automatic design of heat-resistant mutants, multiple computer-aided ΔΔGfold value calculation, and conservative analysis of mutation sites. AlyRm6A has naturally high thermostability. Compared with the WT, T43I and Q216I kept their original activities, and their half-lives were increased from 3.68 h to 4.29 h and 4.54 h, melting point temperatures increased from 61.5 °C to 62.9 °C and 63.5 °C, respectively. The results of circular dichroism showed that both the mutants and the wild type had the characteristic peaks of β-sheet at 195 nm and 216 nm, which indicated that there was no significant effect on the secondary structure of the protein. Molecular dynamics simulation (MD) analyses suggest that the enhancement of the hydrophobic interaction network, improvement of molecular rigidity, and denser structure could improve the stability of AlyRm6A. To the best of our knowledge, our findings indicate that AlyRm6A mutants exhibit the highest thermostability among the characterized PL-6 alginate lyases, making them potential candidates for industrial production of alginate oligosaccharides.

Combined transcriptomic and metabolomic analysis of alginate oligosaccharides alleviating salt stress in rice seedlings

BACKGROUND

Salt stress is one of the key factors limiting rice production. Alginate oligosaccharides (AOS) enhance plant stress resistance. However, the molecular mechanism underlying salt tolerance in rice induced by AOS remains unclear. FL478, which is a salt-tolerant indica recombinant inbred line and IR29, a salt-sensitive rice cultivar, were used to comprehensively analyze the effects of AOS sprayed on leaves in terms of transcriptomic and metabolite profiles of rice seedlings under salt stress.

RESULTS

In this experiment, exogenous application of AOS increased SOD, CAT and APX activities, as well as GSH and ASA levels to reduce the damage to leaf membrane, increased rice stem diameter, the number of root tips, aboveground and subterranean biomass, and improved rice salt tolerance. Comparative transcriptomic analyses showed that the regulation of AOS combined with salt treatment induced the differential expression of 305 and 1030 genes in FL478 and IR29. The expressed genes enriched in KEGG pathway analysis were associated with antioxidant levels, photosynthesis, cell wall synthesis, and signal transduction. The genes associated with light-trapping proteins and RLCK receptor cytoplasmic kinases, including CBA, LHCB, and Lhcp genes, were fregulated in response to salt stress. Treatment with AOS combined with salt induced the differential expression of 22 and 50 metabolites in FL478 and IR29. These metabolites were mainly related to the metabolism of amino and nucleotide sugars, tryptophan, histidine, and β -alanine. The abundance of metabolites associated with antioxidant activity, such as 6-hydroxymelatonin, wedelolactone and L-histidine increased significantly. Combined transcriptomic and metabolomic analyses revealed that dehydroascorbic acid in the glutathione and ascorbic acid cycles plays a vital role in salt tolerance mediated by AOS.

CONCLUSION

AOS activate signal transduction, regulate photosynthesis, cell wall formation, and multiple antioxidant pathways in response to salt stress. This study provides a molecular basis for the alleviation of salt stress-induced damage by AOS in rice.

Recent advances in natural gums as additives to help the construction and application of edible biopolymer gels: the example of hydrogels and oleogels

Novel, innovative approaches like edible gels (hydrogels and oleogels) are important food materials with great scientific interest due to their positive impacts on structural and functional foods and other unique properties. Biopolymers (protein, starch and other polysaccharides) can be excellent and cost-effective materials for the formed edible gels. Recently, natural gums, although also as biopolymers, are preferred as additives to further improve the textural and functional properties of edible gels, which have received extensive attention. However, these studies have not been outlined in previous reviews. In this review, we highlighted the advantages of gums as additives to construct edible gels. Moreover, the various roles (including electrostatic or covalent interactions) for natural gums in regulation of food gel properties (solvent-holding and rheological properties) are highlighted. Finally, the use of natural gums as additives to improve the stability and targeted delivery of phytochemicals in food gels and their application in food systems are summarized. The information covered in this article may be useful for the design of functional foods that can better meet personalized needs of people.

Structure-Activity Relationships of Low Molecular Weight Alginate Oligosaccharide Therapy against Pseudomonas aeruginosa

Low molecular weight alginate oligosaccharides have been shown to exhibit anti-microbial activity against a range of multi-drug resistant bacteria, including Pseudomonas aeruginosa. Previous studies suggested that the disruption of calcium (Ca2+)-DNA binding within bacterial biofilms and dysregulation of quorum sensing (QS) were key factors in these observed effects. To further investigate the contribution of Ca2+ binding, G-block (OligoG) and M-block alginate oligosaccharides (OligoM) with comparable average size DPn 19 but contrasting Ca2+ binding properties were prepared. Fourier-transform infrared spectroscopy demonstrated prolonged binding of alginate oligosaccharides to the pseudomonal cell membrane even after hydrodynamic shear treatment. Molecular dynamics simulations and isothermal titration calorimetry revealed that OligoG exhibited stronger interactions with bacterial LPS than OligoM, although this difference was not mirrored by differential reductions in bacterial growth. While confocal laser scanning microscopy showed that both agents demonstrated similar dose-dependent reductions in biofilm formation, OligoG exhibited a stronger QS inhibitory effect and increased potentiation of the antibiotic azithromycin in minimum inhibitory concentration and biofilm assays. This study demonstrates that the anti-microbial effects of alginate oligosaccharides are not purely influenced by Ca2+-dependent processes but also by electrostatic interactions that are common to both G-block and M-block structures.

Directed preparation, structure-activity relationship and applications of alginate oligosaccharides with specific structures: A systematic review

The alginate oligosaccharides (AOS) possess versatile activities (such as antioxidant, anti-inflammatory, antitumor, and immune-regulatory activities) and have been the research topic in marine bioresource utilization fields. The degree of polymerization (DP) and the β-D-mannuronic acid (M)/α-L-guluronic acid (G)-units ratio strongly affect the functionality of AOS. Therefore, directed preparation of AOS with specific structures is essential for expanding the applications of alginate polysaccharides and has been the research topic in the marine bioresource field. Alginate lyases could efficiently degrade alginate and specifically produce AOS with specific structures. Therefore, enzymatic preparation of AOS with specific structures has drawn increasing attention. Herein, we systematically summarized the current research progress on the structure-function relation of AOS and focuses on the application of the enzymatic properties of alginate lyase to the specific preparation of various types of AOS. At the same time, current challenges and opportunities for AOS applications are presented to guide and improve the preparation and application of AOS in the future.

Role of Polysaccharides from Marine Seaweed as Feed Additives for Methane Mitigation in Ruminants: A Critical Review

Given the increasing concerns regarding greenhouse gas emissions associated with livestock production, the need to discover effective strategies to mitigate methane production in ruminants is clear. Marine algal polysaccharides have emerged as a promising research avenue because of their abundance and sustainability. Polysaccharides, such as alginate, laminaran, and fucoidan, which are extracted from marine seaweeds, have demonstrated the potential to reduce methane emissions by influencing the microbial populations in the rumen. This comprehensive review extensively examines the available literature and considers the effectiveness, challenges, and prospects of using marine seaweed polysaccharides as feed additives. The findings emphasise that marine algal polysaccharides can modulate rumen fermentation, promote the growth of beneficial microorganisms, and inhibit methanogenic archaea, ultimately leading to decreases in methane emissions. However, we must understand the long-term effects and address the obstacles to practical implementation. Further research is warranted to optimise dosage levels, evaluate potential effects on animal health, and assess economic feasibility. This critical review provides insights for researchers, policymakers, and industry stakeholders dedicated to advancing sustainable livestock production and methane mitigation.

Polysaccharides from the Sargassum and Brown Algae Genus: Extraction, Purification, and Their Potential Therapeutic Applications

Brown macroalgae represent one of the most proliferative groups of living organisms in aquatic environments. Due to their abundance, they often cause problems in aquatic and terrestrial ecosystems, resulting in health problems in humans and the death of various aquatic species. To resolve this, the application of Sargassum has been sought in different research areas, such as food, pharmaceuticals, and cosmetics, since Sargassum is an easy target for study and simple to obtain. In addition, its high content of biocompounds, such as polysaccharides, phenols, and amino acids, among others, has attracted attention. One of the valuable components of brown macroalgae is their polysaccharides, which present interesting bioactivities, such as antiviral, antimicrobial, and antitumoral, among others. There is a wide variety of methods of extraction currently used to obtain these polysaccharides, such as supercritical fluid extraction (SFE), pressurized liquid extraction (PLE), subcritical water extraction (SCWE), ultrasound-assisted extraction (UAE), enzyme-assisted extraction (EAE), and microwave-assisted extraction (MAE). Therefore, this work covers the most current information on the methods of extraction, as well as the purification used to obtain a polysaccharide from Sargassum that is able to be utilized as alginates, fucoidans, and laminarins. In addition, a compilation of bioactivities involving brown algae polysaccharides in in vivo and in vitro studies is also presented, along with challenges in the research and marketing of Sargassum-based products that are commercially available.

Polysaccharide-Based Stimulus-Responsive Nanomedicines for Combination Cancer Immunotherapy

Cancer immunotherapy is a promising antitumor approach, whereas nontherapeutic side effects, tumor microenvironment (TME) intricacy, and low tumor immunogenicity limit its therapeutic efficacy. In recent years, combination immunotherapy with other therapies has been proven to considerably increase antitumor efficacy. However, achieving codelivery of the drugs to the tumor site remains a major challenge. Stimulus-responsive nanodelivery systems show controlled drug delivery and precise drug release. Polysaccharides, a family of potential biomaterials, are widely used in the development of stimulus-responsive nanomedicines due to their unique physicochemical properties, biocompatibility, and modifiability. Here, the antitumor activity of polysaccharides and several combined immunotherapy strategies (e.g., immunotherapy combined with chemotherapy, photodynamic therapy, or photothermal therapy) are summarized. More importantly, the recent progress of polysaccharide-based stimulus-responsive nanomedicines for combination cancer immunotherapy is discussed, with the focus on construction of nanomedicine, targeted delivery, drug release, and enhanced antitumor effects. Finally, the limitations and application prospects of this new field are discussed.

Recent advances in the production, properties and applications of alginate oligosaccharides - a mini review

Alginate oligosaccharides (AOS) made from the degradation of alginate, to some extent, makes up for the poor solubility and bioavailability of alginate as a macromolecular substance and possess several beneficial biological activities that are absent in alginate. These properties include prebiotic, glycolipid regulatory, immunomodulatory, antimicrobial, antioxidant, anti-tumor, promoting plant growth and other activities. Consequently, AOS has significant potential for use in the agricultural, biomedical, and food industries, and has been the focus of research in the field of marine biological resources. This review comprehensively covers methods (physical, chemical, and enzymatic methods) for the production of AOS from alginate. More importantly, this paper reviews recent advances in the biological activity and potentially industrial and therapeutic applications of AOS, providing a reference for future research and applications of AOS.

Diversity of Bioinspired Hydrogels: From Structure to Applications

Hydrogels are three-dimensional networks with a variety of structures and functions that have a remarkable ability to absorb huge amounts of water or biological fluids. They can incorporate active compounds and release them in a controlled manner. Hydrogels can also be designed to be sensitive to external stimuli: temperature, pH, ionic strength, electrical or magnetic stimuli, specific molecules, etc. Alternative methods for the development of various hydrogels have been outlined in the literature over time. Some hydrogels are toxic and therefore are avoided when obtaining biomaterials, pharmaceuticals, or therapeutic products. Nature is a permanent source of inspiration for new structures and new functionalities of more and more competitive materials. Natural compounds present a series of physico-chemical and biological characteristics suitable for biomaterials, such as biocompatibility, antimicrobial properties, biodegradability, and nontoxicity. Thus, they can generate microenvironments comparable to the intracellular or extracellular matrices in the human body. This paper discusses the main advantages of the presence of biomolecules (polysaccharides, proteins, and polypeptides) in hydrogels. Structural aspects induced by natural compounds and their specific properties are emphasized. The most suitable applications will be highlighted, including drug delivery, self-healing materials for regenerative medicine, cell culture, wound dressings, 3D bioprinting, foods, etc.

Structures, Properties, and Bioengineering Applications of Alginates and Hyaluronic Acid

In recent years, polymeric materials have been used in a wide range of applications in a variety of fields. In particular, in the field of bioengineering, the use of natural biomaterials offers a possible new avenue for the development of products with better biocompatibility, biodegradability, and non-toxicity. This paper reviews the structural and physicochemical properties of alginate and hyaluronic acid, as well as the applications of the modified cross-linked derivatives in tissue engineering and drug delivery. This paper summarizes the application of alginate and hyaluronic acid in bone tissue engineering, wound dressings, and drug carriers. We provide some ideas on how to replace or combine alginate-based composites with hyaluronic-acid-based composites in tissue engineering and drug delivery to achieve better eco-economic value.

Copper-containing chitosan-based hydrogels enabled 3D-printed scaffolds to accelerate bone repair and eliminate MRSA-related infection

Bone defect combined with drug-resistant bacteria-related infection is a thorny challenge in clinic. Herein, 3D-printed polyhydroxyalkanoates/β-tricalcium phosphate (PHA/β-TCP, PT) scaffolds were prepared by fused deposition modeling. Then copper-containing carboxymethyl chitosan/alginate (CA/Cu) hydrogels were integrated with the scaffolds via a facile and low-cost chemical crosslinking method. The resultant PT/CA/Cu scaffolds could not only promote proliferation but also osteogenic differentiation of preosteoblasts in vitro. Moreover, PT/CA/Cu scaffolds exhibited a strong antibacterial activity towards a broad-spectrum of bacteria including methicillin-resistant Staphylococcus aureus (MRSA) through inducing the intercellular generation of reactive oxygen species. In vivo experiments further demonstrated that PT/CA/Cu scaffolds significantly accelerated bone repair of cranial defects and efficiently eliminated MRSA-related infection, showing potential for application in infected bone defect therapy.

Discontinuous low temperature stress and plant growth regulators during the germination period promote roots growth in alfalfa (Medicago sativa L.)

In high-cold regions, alfalfa is susceptible to cold damage during the seed germination. The effects of discontinuous low temperature stress and plant growth regulators (PGRs) on alfalfa were studied in response to the high day/night temperature differentials in the area. The experiments included seed germination, seedling cold tolerance and plant recovery. Variable temperatures (VT) of 0 °C/15 °C, 5 °C/20 °C and 10 °C/25 °C were set and seeds were soaked with alginate oligosaccharides (AOS), brassinolide (BR) and diethyl aminoethyl hexanoate (DA-6) during the germination period. Parameters such as seed germination and mean germination time (MGT), phenylalanine ammonia-lyase (PAL) activity and oligomeric proanthocyanidins (OPC) content of early seedlings, dry matter accumulation and root crown of the restored plants were analysed. The results showed that low variable-temperature (LVT) stress prolonged the MGT but had little inhibitory effect on germination percentage. Early seedlings adapted to LVT stress by regulating their own water and OPC content, PAL activity and other parameters. LVT induced early alfalfa seedlings to increase their underground biomass by shortening root length and increasing root diameter, and those that had accumulated more underground biomass had faster growth rates and higher total biomass when the ambient temperature rose. AOS also promoted an increase in root crown diameter and root dry weight. This research proved that LVT stress and AOS during the germination process can lead to better growth of alfalfa in high cold regions.

Cold plasma treatment with alginate oligosaccharide improves the digestive stability and bioavailability of nutrient-delivered particles: An in vitro INFOGEST gastrointestinal study

To improve the stability and bioavailability of the delivered hydrophobic nutrients, the zein-based delivery system was modified by alginate oligosaccharide (AOS), cold plasma (CP) treatments, and synergistically. The digestive behavior of each was investigated in an INFOGEST static in vitro digestion model. The results showed that AOS and CP treatments and their synergistic effects improved the dispersion and stability of the delivery system, leading to a more concentrated particle size distribution and higher particle surface charge. Both CP treatments and AOS increased the release rate of Curcumin (Cur) at small intestine (11.8 % to 20.5 % and 11.8 % to 24.64 %, respectively), and the synergistic effect was higher (11.8 % to 43.84 %). The wall material modified showed a higher encapsulation efficiency of Cur (52.83 % to 85.17 %). Cur release rate measurements showed that the wall material modified could have a positive effect on the slow release of Cur. SDS-page electrophoresis revealed that the slow release was due to the enhanced resistance of wall material to digestive fluids. Thus, treatment with AOS and CP treatments, and the synergism are suitable for modifying zein-based delivery systems for the encapsulation, stabilization, and slow release of hydrophobic nutrients during digestion in the field of functional foods.

Polysaccharides for Medical Technology: Properties and Applications

Over the past decade, the use of polysaccharides has gained tremendous attention in the field of medical technology. They have been applied in various sectors such as tissue engineering, drug delivery system, face mask, and bio-sensing. This review article provides an overview and background of polysaccharides for biomedical uses. Different types of polysaccharides, for example, cellulose and its derivatives, chitin and chitosan, hyaluronic acid, alginate, and pectin are presented. They are fabricated in various forms such as hydrogels, nanoparticles, membranes, and as porous mediums. Successful development and improvement of polysaccharide-based materials will effectively help users to enhance their quality of personal health, decrease cost, and eventually increase the quality of life with respect to sustainability.

An exploration of alginate oligosaccharides modulating intestinal inflammatory networks via gut microbiota

Alginate oligosaccharides (AOS) can be obtained by acidolysis and enzymatic hydrolysis. The products obtained by different methods have different structures and physiological functions. AOS have received increasing interest because of their many health-promoting properties. AOS have been reported to exert protective roles for intestinal homeostasis by modulating gut microbiota, which is closely associated with intestinal inflammation, gut barrier strength, bacterial infection, tissue injury, and biological activities. However, the roles of AOS in intestinal inflammation network remain not well understood. A review of published reports may help us to establish the linkage that AOS may improve intestinal inflammation network by affecting T helper type 1 (Th1) Th2, Th9, Th17, Th22 and regulatory T (Treg) cells, and their secreted cytokines [the hub genes of protein-protein interaction networks include interleukin-1 beta (IL-1β), IL-2, IL-4, IL-6, IL-10 and tumor necrosis factor alpha (TNF-α)] via the regulation of probiotics. The potential functional roles of molecular mechanisms are explored in this study. However, the exact mechanism for the direct interaction between AOS and probiotics or pathogenic bacteria is not yet fully understood. AOS receptors may be located on the plasma membrane of gut microbiota and will be a key solution to address such an important issue. The present paper provides a better understanding of the protecting functions of AOS on intestinal inflammation and immunity.

Ameliorative Effect of Mannuronate Oligosaccharides on Hyperuricemic Mice via Promoting Uric Acid Excretion and Modulating Gut Microbiota

Mannuronate oligosaccharide (MOS) is α-D-mannuronic acid polymer with 1,4-glycosidic linkages that possesses beneficial biological properties. The aim of this study was to investigate the hypouricemic effect of MOS in hyperuricemic mice and demonstrate the possible protective mechanisms involved. In this research, 200 mg/kg/day of MOS was orally administered to hyperuricemic mice for four weeks. The results showed that the MOS treatment significantly reduced the serum uric acid (SUA) level from 176.4 ± 7.9 μmol/L to 135.7 ± 10.9 μmol/L (p < 0.05). MOS alleviated the inflammatory response in the kidney. Moreover, MOS promoted uric acid excretion by regulating the protein levels of renal GLUT9, URAT1 and intestinal GLUT9, ABCG2. MOS modulated the gut microbiota in hyperuricemic mice and decreased the levels of Tyzzerella. In addition, research using antibiotic-induced pseudo-sterile mice demonstrated that the gut microbiota played a crucial role in reducing elevated serum uric acid of MOS in mice. In conclusion, MOS may be a potential candidate for alleviating HUA symptoms and regulating gut microbiota.

Mediation of synergistic chemotherapy and gene therapy via nanoparticles based on chitosan and ionic polysaccharides

Nanoparticles (NPs)-based on various ionic polysaccharides, including chitosan, hyaluronic acid, and alginate have been frequently summarized for controlled release applications, however, most of the published reviews, to our knowledge, focused on the delivery of a single therapeutic agent. A comprehensive summarization of the co-delivery of multiple therapeutic agents by the ionic polysaccharides-based NPs, especially on the optimization of the polysaccharide structure for overcoming various extracellular and intracellular barriers toward maximized synergistic effects, to our knowledge, has been rarely explored so far. For this purpose, the strategies used for overcoming various extracellular and intracellular barriers in vivo were introduced first to provide guidance for the rational design of ionic polysaccharides-based NPs with desired features, including long-term circulation, enhanced cellular internalization, controllable drug/gene release, endosomal escape and improved nucleus localization. Next, four preparation strategies were summarized including three physical methods of polyelectrolyte complexation, ionic crosslinking, and self-assembly and a chemical conjugation approach. The challenges and future trends of this rapidly developing field were finally discussed in the concluding remarks. The important guidelines on the rational design of ionic polysaccharides-based NPs for maximized synergistic efficiency drawn in this review will promote the future generation and clinical translation of polysaccharides-based NPs for cancer therapy.