Alginate oligosaccharide improves lipid metabolism and inflammation by modulating gut microbiota in high-fat diet fed mice

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.

Role of Phytobiotics in Modulating Transcriptomic Profile in Carps: A Mini-Review

Carp is a key aquaculture species worldwide. The intensification of carp farming, aimed at meeting the high demand for protein sources for human consumption, has resulted in adverse effects such as poor water quality, increased stress, and disease outbreaks. While antibiotics have been utilized to mitigate these issues, their use poses risks to both public health and the environment. As a result, alternative and more sustainable practices have been adopted to manage the health of farmed carp, including the use of probiotics, prebiotics, phytobiotics, and vaccines to prevent disease outbreaks. Phytobiotics, being both cost-effective and abundant, have gained widespread acceptance. They offer various benefits in carp farming, such as improved growth performance, enhanced immune system, increased antioxidant capacity, stress alleviation from abiotic factors, and enhanced disease resistance. Currently, a focal point of research involves employing molecular approaches to assess the impacts of phytobiotics in aquatic animals. Gene expression, the process by which genetic information encoded is translated into function, along with transcription profiling, serves as a crucial tool for detecting changes in gene expression within cells. These changes provide valuable insights into the growth rate, immune system, and flesh quality of aquatic animals. This review delves into the positive impacts of phytobiotics on immune responses, growth, antioxidant capabilities, and flesh quality, all discerned through gene expression changes in carp species. Furthermore, this paper explores existing research gaps and outlines future prospects for the utilization of phytobiotics in aquaculture.

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].

Unraveling the bioactive interplay: seaweed polysaccharide, polyphenol and their gut modulation effect

Seaweed is rich in many unique bioactive compounds such as polyphenols and sulfated polysaccharides that are not found in terrestrial plant. The discovery of numerous biological activities from seaweed has made seaweed an attractive functional food source with the potential to be exploited for human health benefits. During food processing and digestion, cell wall polysaccharide and polyphenols commonly interact, and this may influence the nutritional properties of food. Interactions between cell wall polysaccharide and polyphenols in plant-based system has been extensively studied. However, similar interactions in seaweed have received little attention despite the vast disparity between the structural and chemical composition of plant and seaweed cell wall. This poses a challenge in extracting seaweed bioactive compounds with intact biological properties. This review aims to summarize the cell wall polysaccharide and polyphenols present in brown, red and green seaweed, and current knowledge on their potential interactions. Moreover, this review gives an overview of the gut modulation effect of seaweed polysaccharide and polyphenol.

A Recombinant Alginate Lyase Algt1 with Potential in Preparing Alginate Oligosaccharides at High-Concentration Substrate

Alginate lyase has been demonstrated as an efficient tool in the preparation of functional oligosaccharides (AOS) from alginate. The high viscosity resulting from the high concentration of alginate poses a limiting factor affecting enzymatic hydrolysis, particularly in the preparation of the fragments with low degrees of polymerization (DP). Herein, a PL7 family alginate lyase Algt from Microbulbifer thermotolerans DSM 19189 was developed and expressed in Pichia pastoris. The recombinant alginate lyase Algt1 was constructed by adopting the structural domain truncation strategy, and the enzymatic activity towards the alginate was improved from 53.9 U/mg to 212.86 U/mg compared to Algt. Algt1 was stable when incubated at 40 °C for 90 min, remaining with approximately 80.9% of initial activity. The analyses of thin-layer chromatography (TLC), fast protein liquid chromatography (FPLC), and electrospray ionization mass spectrometry (ESI-MS) demonstrated that the DP of the minimum identifiable substrate of Algt1 was five, and the main hydrolysis products were AOS with DP 1-4. Additionally, 1-L the enzymatic hydrolysis system demonstrated that Algt1 exhibited an effective degradation at alginate concentrations of up to 20%, with the resulting products of monosaccharides (14.02%), disaccharides (21.10%), trisaccharides (37.08%), and tetrasaccharides (27.80%). These superior properties of Algt1 make it possible to efficiently generate functional AOS with low DP in industrial processing.

Three alginate lyases provide a new gut Bacteroides ovatus isolate with the ability to grow on alginate

Humans consume alginate in the form of seaweed, food hydrocolloids, and encapsulations, making the digestion of this mannuronic acid (M) and guluronic acid (G) polymer of key interest for human health. To increase knowledge on alginate degradation in the gut, a gene catalog from human feces was mined for potential alginate lyases (ALs). The predicted ALs were present in nine species of the Bacteroidetes phylum, of which two required supplementation of an endo-acting AL, expected to mimic cross-feeding in the gut. However, only a new isolate grew on alginate. Whole-genome sequencing of this alginate-utilizing isolate suggested that it is a new Bacteroides ovatus strain harboring a polysaccharide utilization locus (PUL) containing three ALs of families: PL6, PL17, and PL38. The BoPL6 degraded polyG to oligosaccharides of DP 1-3, and BoPL17 released 4,5-unsaturated monouronate from polyM. BoPL38 degraded both alginates, polyM, polyG, and polyMG, in endo-mode; hence, it was assumed to deliver oligosaccharide substrates for BoPL6 and BoPL17, corresponding well with synergistic action on alginate. BoPL17 and BoPL38 crystal structures, determined at 1.61 and 2.11 Å, respectively, showed (α/α)6-barrel + anti-parallel β-sheet and (α/α)7-barrel folds, distinctive for these PL families. BoPL17 had a more open active site than the two homologous structures. BoPL38 was very similar to the structure of an uncharacterized PL38, albeit with a different triad of residues possibly interacting with substrate in the presumed active site tunnel. Altogether, the study provides unique functional and structural insights into alginate-degrading lyases of a PUL in a human gut bacterium.IMPORTANCEHuman ingestion of sustainable biopolymers calls for insight into their utilization in our gut. Seaweed is one such resource with alginate, a major cell wall component, used as a food hydrocolloid and for encapsulation of pharmaceuticals and probiotics. Knowledge is sparse on the molecular basis for alginate utilization in the gut. We identified a new Bacteroides ovatus strain from human feces that grew on alginate and encoded three alginate lyases in a gene cluster. BoPL6 and BoPL17 show complementary specificity toward guluronate (G) and mannuronate (M) residues, releasing unsaturated oligosaccharides and monouronic acids. BoPL38 produces oligosaccharides degraded by BoPL6 and BoPL17 from both alginates, G-, M-, and MG-substrates. Enzymatic and structural characterization discloses the mode of action and synergistic degradation of alginate by these alginate lyases. Other bacteria were cross-feeding on alginate oligosaccharides produced by an endo-acting alginate lyase. Hence, there is an interdependent community in our guts that can utilize alginate.

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.

In-depth insight into correlations between gut microbiota and dietary fiber elucidates a dietary causal relationship with host health

Dietary fiber exerts a wide range of biological benefits on host health, which not only provides a powerful source of nutrition for gut microbiota but also supplies key microbial metabolites that directly affect host health. This review mainly focuses on the decomposition and metabolism of dietary fiber and the essential genera Bacteroides and Bifidobacterium in dietary fiber fermentation. Dietary fiber plays an essential role in host health by impacting outcomes related to obesity, enteritis, immune health, cancer and neurodegenerative diseases. Additionally, the gut microbiota-independent pathway of dietary fiber affecting host health is also discussed. Personalized dietary fiber intake combined with microbiome, genetics, epigenetics, lifestyle and other factors has been highlighted for development in the future. A higher level of evidence is needed to demonstrate which microbial phenotype benefits from which kind of dietary fiber. In-depth insights into the correlation between gut microbiota and dietary fiber provide strong theoretical support for the precise application of dietary fiber, which elucidates a dietary causal relationship with host health.

Research Advances in the High-Value Utilization of Peanut Meal Resources and Its Hydrolysates: A Review

Peanut meal (PM) is a by-product of extracting oil from peanut kernels. Although peanut meal contains protein, carbohydrates, minerals, vitamins, and small amounts of polyphenols and fiber, it has long been used as a feed in the poultry and livestock industries due to its coarse texture and unpleasant taste. It is less commonly utilized in the food processing industry. In recent years, there has been an increasing amount of research conducted on the deep processing of by-products from oil crops, resulting in the high-value processing and utilization of by-products from various oil crops. These include peanut meal, which undergoes treatments such as enzymatic hydrolysis in industries like food, chemical, and aquaculture. The proteins, lipids, polyphenols, fibers, and other components present in these by-products and hydrolysates can be incorporated into products for further utilization. This review focuses on the research progress in various fields, such as the food processing, breeding, and industrial fields, regarding the high-value utilization of peanut meal and its hydrolysates. The aim is to provide valuable insights and strategies for maximizing the utilization of peanut meal resources.

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.

The impact of common pharmaceutical excipients on the gut microbiota

INTRODUCTION

Increasing attention is being afforded to understanding the bidirectional relationships that exist between oral medications and the gut microbiota, in an attempt to optimize pharmacokinetic performance and mitigate unwanted side effects. While a wealth of research has investigated the direct impact of active pharmaceutical ingredients (APIs) on the gut microbiota, the interactions between inactive pharmaceutical ingredients (i.e. excipients) and the gut microbiota are commonly overlooked, despite excipients typically representing over 90% of the final dosage form.

AREAS COVERED

Known excipient-gut microbiota interactions for various classes of inactive pharmaceutical ingredients, including solubilizing agents, binders, fillers, sweeteners, and color additives, are reviewed in detail.

EXPERT OPINION

Clear evidence indicates that orally administered pharmaceutical excipients directly interact with gut microbes and can either positively or negatively impact gut microbiota diversity and composition. However, these relationships and mechanisms are commonly overlooked during drug formulation, despite the potential for excipient-microbiota interactions to alter drug pharmacokinetics and interfere with host metabolic health. The insights derived from this review will inform pharmaceutical scientists with the necessary design considerations for mitigating potential adverse pharmacomicrobiomic interactions when formulating oral dosage forms, ultimately providing clear avenues for improving therapeutic safety and efficacy.

Beneficial effects of seaweed-derived components on metabolic syndrome via gut microbiota modulation

Metabolic syndrome comprises a group of conditions that collectively increase the risk of abdominal obesity, diabetes, atherosclerosis, cardiovascular diseases, and cancer. Gut microbiota is involved in the pathogenesis of metabolic syndrome, and microbial diversity and function are strongly affected by diet. In recent years, epidemiological evidence has shown that the dietary intake of seaweed can prevent metabolic syndrome via gut microbiota modulation. In this review, we summarize the current in vivo studies that have reported the prevention and treatment of metabolic syndrome via seaweed-derived components by regulating the gut microbiota and the production of short-chain fatty acids. Among the surveyed related articles, animal studies revealed that these bioactive components mainly modulate the gut microbiota by reversing the Firmicutes/Bacteroidetes ratio, increasing the relative abundance of beneficial bacteria, such as Bacteroides, Akkermansia, Lactobacillus, or decreasing the abundance of harmful bacteria, such as Lachnospiraceae, Desulfovibrio, Lachnoclostridium. The regulated microbiota is thought to affect host health by improving gut barrier functions, reducing LPS-induced inflammation or oxidative stress, and increasing bile acid production. Furthermore, these compounds increase the production of short-chain fatty acids and influence glucose and lipid metabolism. Thus, the interaction between the gut microbiota and seaweed-derived bioactive components plays a critical regulatory role in human health, and these compounds have the potential to be used for drug development. However, further animal studies and human clinical trials are required to confirm the functional roles and mechanisms of these components in balancing the gut microbiota and managing host health.

Protective effects of Liupao tea against high-fat diet/cold exposure-induced irritable bowel syndrome in rats

Liupao tea as a type of dark tea can relieve irritable bowel syndrome by regulating gut microbiota, but the mechanism has not been fully explained. An ultra-high performance liquid chromatography along with quadrupole time of flight tandem mass spectrometry was used to analyze the phytochemicals in Liupao tea. Then, we explored the effects of Liupao tea against IBS. From the results of chemical analysis, we identified catechins, polyphenols, amino acids, caffeine, polysaccharides and other components in Liupao tea. The open-field test, gastrointestinal function-related indexes, histochemical assays, measurements of cytokine and aquaporin 3 (AQP3), and determination of serum metabolites were utilized to monitor the physiological consequences of Liupao tea administration in rats with irritable bowel syndrome. The results showed that Liupao tea had a significant protective effect on irritable bowel syndrome. Liupao tea increased locomotive velocity while reducing interleukin-6, interleukin-1β, and tumor necrosis factor-α levels, as well as gastrointestinal injury. Moreover, Liupao tea increased the AQP3 levels of renal tissues but reduced the AQP3 levels of gastrointestinal tissues. Liupao tea reduced the Firmicutes/Bacteroides ratio and significantly reconstructed the microbial pattern. Liupao tea relieved irritable bowel syndrome by repairing gastrointestinal dysfunction, regulating the secretion of pro-inflammatory cytokines, modulating water metabolism, and restoring microbial homeostasis.

Influence of Intestinal Barrier on Alleviating an Increase in Blood Pressure by Sodium Alginate Intake in 2-Kidney, 1-Clip Renovascular Hypertensive Rats

Sodium alginate (SALG) is a substance derived from brown seaweed that has been shown to reduce blood pressure (BP). However, its effects on renovascular hypertension caused by 2-kidney, 1-clip (2K1C) are not yet clear. Previous research suggests that hypertensive rats have increased intestinal permeability, and that SALG improves the gut barrier in inflammatory bowel disease mouse models. Therefore, the goal of this study was to determine whether the antihypertensive effects of SALG involve the intestinal barrier in 2K1C rats. Rats were fed either a 1.0% SALG diet or a control diet for six weeks after being subjected to 2K1C surgery or a sham operation. The systolic BP was measured weekly, and the mean arterial BP was measured at the end of the study. Intestinal samples were taken for analysis, and plasma lipopolysaccharide (LPS) levels were measured. The results showed that BP in 2K1C rats was significantly higher than in SHAM rats when fed CTL, but not when fed SALG. The gut barrier in 2K1C rats was improved by SALG intake. Plasma LPS levels also differed depending on the animal model and diet. In conclusion, dietary SALG may alleviate 2K1C renovascular hypertension by altering the gut barrier.

Potential of algae-derived alginate oligosaccharides and β-glucan to counter inflammation in adult zebrafish intestine

Alginate oligosaccharides (AOS) are natural bioactive compounds with anti-inflammatory properties. We performed a feeding trial employing a zebrafish (Danio rerio) model of soybean-induced intestinal inflammation. Five groups of fish were fed different diets: a control (CT) diet, a soybean meal (SBM) diet, a soybean meal+β-glucan (BG) diet and 2 soybean meal+AOS diets (alginate products differing in the content of low molecular weight fractions - AL, with 31% < 3kDa and AH, with 3% < 3kDa). We analyzed the intestinal transcriptomic and plasma metabolomic profiles of the study groups. In addition, we assessed the expression of inflammatory marker genes and histological alterations in the intestine. Dietary algal β-(1, 3)-glucan and AOS were able to bring the expression of certain inflammatory genes altered by dietary SBM to a level similar to that in the control group. Intestinal transcriptomic analysis indicated that dietary SBM changed the expression of genes linked to inflammation, endoplasmic reticulum, reproduction and cell motility. The AL diet suppressed the expression of genes related to complement activation, inflammatory and humoral response, which can likely have an inflammation alleviation effect. On the other hand, the AH diet reduced the expression of genes, causing an enrichment of negative regulation of immune system process. The BG diet suppressed several immune genes linked to the endopeptidase activity and proteolysis. The plasma metabolomic profile further revealed that dietary SBM can alter inflammation-linked metabolites such as itaconic acid, taurochenodeoxycholic acid and enriched the arginine biosynthesis pathway. The diet AL helped in elevating one of the short chain fatty acids, namely 2-hydroxybutyric acid while the BG diet increased the abundance of a vitamin, pantothenic acid. Histological evaluation revealed the advantage of the AL diet: it increased the goblet cell number and length of villi of the intestinal mucosa. Overall, our results indicate that dietary AOS with an appropriate amount of < 3kDa can stall the inflammatory responses in zebrafish.

Response of Salmonella enterica serovar Typhimurium to alginate oligosaccharides fermented with fecal inoculum: integrated transcriptomic and metabolomic analyses

Alginate oligosaccharides (AOS), extracted from marine brown algae, are a common functional feed additive; however, it remains unclear whether they modulate the gut microbiota and microbial metabolites. The response of Salmonella enterica serovar Typhimurium, a common poultry pathogen, to AOS fermented with chicken fecal inocula was investigated using metabolomic and transcriptomic analyses. Single-strain cultivation tests showed that AOS did not directly inhibit the growth of S. Typhimurium. However, when AOS were fermented by chicken fecal microbiota, the supernatant of fermented AOS (F-AOS) exhibited remarkable antibacterial activity against S. Typhimurium, decreasing the abundance ratio of S. Typhimurium in the fecal microbiota from 18.94 to 2.94%. Transcriptomic analyses showed that the 855 differentially expressed genes induced by F-AOS were mainly enriched in porphyrin and chlorophyll metabolism, oxidative phosphorylation, and Salmonella infection-related pathways. RT-qPCR confirmed that F-AOS downregulated key genes involved in flagellar assembly and the type III secretory system of S. Typhimurium, indicating metabolites in F-AOS can influence the growth and metabolism of S. Typhimurium. Metabolomic analyses showed that 205 microbial metabolites were significantly altered in F-AOS. Among them, the increase in indolelactic acid and 3-indolepropionic acid levels were further confirmed using HPLC. This study provides a new perspective for the application of AOS as a feed additive against pathogenic intestinal bacteria.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-023-00176-z.

Effect of long-term exposure to dyeing wastewater treatment plant effluent on growth and gut microbiota of adult zebrafish (Danio rerio)

Strict standards have been put forward for the treatment and discharge of dyeing wastewater worldwide. However, there are still traces amount of pollutants, especially emerging pollutants in dyeing wastewater treatment plant (DWTP) effluent. Few studies have focused on the chronic biological toxicity effect and mechanism of DWTP effluent. In this study, 3-month chronic compound toxic effects were investigated by the exposure of DWTP effluent using adult zebrafish. Significantly higher mortality and fatness and significantly lower body weight and body length were found in the treatment group. In addition, long-term exposure to DWTP effluent also obviously reduced liver-body weight ratio of zebrafish, causing abnormal liver development of zebrafish. Moreover, DWTP effluent led to obvious changes in the gut microbiota and microbial diversity of zebrafish. At phylum level, significantly higher of Verrucomicrobia but lower Tenericutes, Actinobacteria, and Chloroflexi were found in the control group. At genus level, the treatment group had significantly higher abundance of Lactobacillus, but significantly lower abundance of Akkermansia, Prevotella, Bacteroides, and Sutterella. These results suggested that long-term exposure to DWTP effluent led to imbalance of gut microbiota in zebrafish. In general, this research indicated that DWTP effluent pollutants could result in negative health outcomes to aquatic organisms.

Fecal Microbiota, Forage Nutrients, and Metabolic Responses of Horses Grazing Warm- and Cool-Season Grass Pastures

Integrating warm-season grasses into cool-season equine grazing systems can increase pasture availability during summer months. The objective of this study was to evaluate effects of this management strategy on the fecal microbiome and relationships between fecal microbiota, forage nutrients, and metabolic responses of grazing horses. Fecal samples were collected from 8 mares after grazing cool-season pasture in spring, warm-season pasture in summer, and cool-season pasture in fall as well as after adaptation to standardized hay diets prior to spring grazing and at the end of the grazing season. Random forest classification was able to predict forage type based on microbial composition (accuracy: 0.90 ± 0.09); regression predicted forage crude protein (CP) and non-structural carbohydrate (NSC) concentrations (p < 0.0001). Akkermansia and Clostridium butyricum were enriched in horses grazing warm-season pasture and were positively correlated with CP and negatively with NSC; Clostridum butyricum was negatively correlated with peak plasma glucose concentrations following oral sugar tests (p ≤ 0.05). These results indicate that distinct shifts in the equine fecal microbiota occur in response different forages. Based on relationships identified between the microbiota, forage nutrients, and metabolic responses, further research should focus on the roles of Akkermansia spp. and Clostridium butyricum within the equine hindgut.

Alginate Oligosaccharides Repair Liver Injury by Improving Anti-Inflammatory Capacity in a Busulfan-Induced Mouse Model

Liver diseases are associated with many factors, including medicines and alcoholics, which have become a global problem. It is crucial to overcome this problem. Liver diseases always come with inflammatory complications, which might be a potential target to deal with this issue. Alginate oligosaccharides (AOS) have been demonstrated to have many beneficial effects, especially anti-inflammation. In this study, 40 mg/kg body weight (BW) of busulfan was intraperitoneally injected once, and then the mice were dosed with ddH₂O or AOS 10 mg/kg BW every day by oral gavage for five weeks. We investigated AOS as a potential no-side-effect and low-cost therapy for liver diseases. For the first time, we discovered that AOS 10 mg/kg recovered liver injury by decreasing the inflammation-related factors. Moreover, AOS 10 mg/kg could improve the blood metabolites related to immune and anti-tumor effects, and thus, ameliorated impaired liver function. The results indicate that AOS may be a potential therapy to deal with liver damage, especially in inflammatory conditions.

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.

Process and applications of alginate oligosaccharides with emphasis on health beneficial perspectives

Alginates are linear polymers comprising 40% of the dry weight of algae possess various applications in food and biomedical industries. Alginate oligosaccharides (AOS), a degradation product of alginate, is now gaining much attention for their beneficial role in food, pharmaceutical and agricultural industries. Hence this review was aimed to compile the information on alginate and AOS (prepared from seaweeds) during 1994-2020. As per our knowledge, this is the first review on the potential use of alginate oligosaccharides in different fields. The alginate derivatives are grouped according to their applications. They are involved in the isolation process and show antimicrobial, antioxidant, anti-inflammatory, antihypertension, anticancer, and immunostimulatory properties. AOS also have significant applications in prebiotics, nutritional supplements, plant growth development and others products.

LD5 Produces Alginate Oligosaccharides with High Degree of Polymerization

Alginate oligosaccharides (AOS) and their derivatives become popular due to their favorable biological activity, and the key to producing functional AOS is to find efficient alginate lyases. This study showed one alginate lyase TsAly7A found in Thalassomonas sp. LD5, which was predicted to have excellent industrial properties. Bioinformatics analysis and enzymatic properties of recombinant TsAly7A (rTsAly7A) were investigated. TsAly7A belonged to the fifth subfamily of polysaccharide lyase family 7 (PL7). The optimal temperature and pH of rTsAly7A was 30 °C and 9.1 in Glycine-NaOH buffer, respectively. The pH stability of rTsAly7A under alkaline conditions was pretty good and it can remain at above 90% of the initial activity at pH 8.9 in Glycine-NaOH buffer for 12 h. In the presence of 100 mM NaCl, rTsAly7A showed the highest activity, while in the absence of NaCl, 50% of the highest activity was observed. The rTsAly7A was an endo-type alginate lyase, and its end-products of alginate degradation were unsaturated oligosaccharides (degree of polymerization 2-6). Collectively, the rTsAly7A may be a good industrial production tool for producing AOS with high degree of polymerization.

A Comprehensive Review of the Cardioprotective Effect of Marine Algae Polysaccharide on the Gut Microbiota

Cardiovascular disease (CVD) is the number one cause of death worldwide. Recent evidence has demonstrated an association between the gut microbiota and CVD, including heart failure, cerebrovascular illness, hypertension, and stroke. Marine algal polysaccharides (MAPs) are valuable natural sources of diverse bioactive compounds. MAPs have many pharmaceutical activities, including antioxidant, anti-inflammatory, immunomodulatory, and antidiabetic effects. Most MAPs are not utilized in the upper gastrointestinal tract; however, they are fermented by intestinal flora. The relationship between MAPs and the intestinal microbiota has drawn attention in CVD research. Hence, this review highlights the main action by which MAPs are known to affect CVD by maintaining homeostasis in the gut microbiome and producing gut microbiota-generated functional metabolites and short chain fatty acids. In addition, the effects of trimethylamine N-oxide on the gut microbiota composition, bile acid signaling properties, and CVD prevention are also discussed. This review supports the idea that focusing on the interactions between the host and gut microbiota may be promising for the prevention or treatment of CVD. MAPs are a potential sustainable source for the production of functional foods or nutraceutical products for preventing or treating CVD.

Direct Action of Non-Digestible Oligosaccharides against a Leaky Gut

The epithelial monolayer is the primary determinant of mucosal barrier function, and tight junction (TJ) complexes seal the paracellular space between the adjacent epithelial cells and represent the main "gate-keepers" of the paracellular route. Impaired TJ functionality results in increased permeation of the "pro-inflammatory" luminal contents to the circulation that induces local and systemic inflammatory and immune responses, ultimately triggering and/or perpetuating (chronic) systemic inflammatory disorders. Increased gut leakiness is associated with intestinal and systemic disease states such as inflammatory bowel disease and neurodegenerative diseases such as Parkinson's disease. Modulation of TJ dynamics is an appealing strategy aiming at inflammatory conditions associated with compromised intestinal epithelial function. Recently there has been a growing interest in nutraceuticals, particularly in non-digestible oligosaccharides (NDOs). NDOs confer innumerable health benefits via microbiome-shaping and gut microbiota-related immune responses, including enhancement of epithelial barrier integrity. Emerging evidence supports that NDOs also exert health-beneficial effects on microbiota independently via direct interactions with intestinal epithelial and immune cells. Among these valuable features, NDOs promote barrier function by directly regulating TJs via AMPK-, PKC-, MAPK-, and TLR-associated pathways. This review provides a comprehensive overview of the epithelial barrier-protective effects of different NDOs with a special focus on their microbiota-independent modulation of TJs.

Alginate oligosaccharide modulates immune response, fat metabolism, and the gut bacterial community in grass carp (Ctenopharyngodon idellus)

Alginate oligosaccharide (AOS) is widely used in agriculture because of its many excellent biological properties. However, the possible beneficial effects of AOS and their underlying mechanisms are currently not well known in grass carp (Ctenopharyngodon idellus). Here, grass carp were fed diets supplemented with 5, 10, or 20 g/kg AOS for six weeks. HE and PAS staining showed that the diets of AOS significantly increased the number of goblet cells in the intestinal. According to transcriptome and quantitative real-time PCR (qRT-PCR) data, AOS-supplemented diets activated the expression of fat metabolism-related pathways and genes. The 16S rRNA sequencing results showed that supplementation with AOS affected the distribution and abundance of the gut bacterial assembly. qRT-PCR and activity assays revealed that the AOS diets significantly increased the antioxidant resistance in gut of grass carp, and down-regulated the expression of inflammatory and up-regulated anti-inflammatory cytokines. Finally, the Aeromonas hydrophila infection assay suggested that the mortality in the groups fed dietary AOS was slightly lower than that in the control. Therefore, supplementing the diet of grass carp with an appropriate amount of AOS can improve fat metabolism and immune responses and alter the intestinal bacterial community, which may help to fight bacterial infection.

The combination of sodium alginate and chlorogenic acid enhances the therapeutic effect on ulcerative colitis by the regulation of inflammation and the intestinal flora

Chlorogenic acid (CA) and sodium alginate (SA) each have good therapeutic effects on ulcerative colitis (UC) owing to their antioxidant and anti-inflammatory activity. This study aimed to investigate the effects of CA alone and in combination with SA on inflammatory cells and UC mice. In the Lipopolysaccharide (LPS)-induced RAW 264.7 inflammatory cell model, Nitric oxide (NO) and interleukin-6 (IL-6) levels were significantly lower after treatment with CA plus SA than with CA alone. In the DSS-induced UC mouse model, compared with CA alone, CA plus SA showed a better ability to alleviate weight loss, reduce the disease activity index (DAI), improve the colonic mucosa, reduce the expression of inflammatory factors in the serum and myeloperoxidase (MPO) in colonic tissue, increase superoxide dismutase (SOD) levels, protect the intestinal mucosa and regulate the abundance of Actinobacteriota, Lactobacillus, Bifidobacterium, Bacteroides, Subdoligranulum and Streptococcus. Thus, CA plus SA can improve the therapeutic efficacy of CA in UC by regulating inflammatory factors, oxidative stress, and the intestinal flora and by protecting ulcerative wounds. These findings broaden our understanding of the role of the combination of SA and CA in enhancing the effects of CA on UC and provide strategies for prevention and treatment.

C-phycocyanin alleviated cisplatin-induced oxidative stress and inflammation via gut microbiota—metabolites axis in mice

C-phycocyanin is a natural protein extracted from Spirulina platensis. We aim to investigate the preventive effect of C-phycocyanin on cisplatin chemotherapy-induced oxidative damage and inflammation. The result showed that C-phycocyanin treatment reduced cisplatin-induced mortality and inflammation including decreased levels of serum IL6, kidney MCP1, and liver IL1β. Furthermore, C-phycocyanin also exerted antioxidant effects on mice, including increased GSH-Px, GGT, and GSH levels in the liver and increased CAT and SOD levels in the kidney. HepG2 cells experiments showed that C-phycocyanin exhibited none of the prevention effects on cisplatin injury. Faecalibaculum showed the greatest reduction among genera after cisplatin treatment, which was related to the enrichment of Romboutsia and Lactobacillus genera. C-phycocyanin treatment reduced the populations of harmful bacteria of Enterococcus faecalis, which was positively correlated with inflammation induced by cisplatin. C-phycocyanin increased the contents of 23-nordeoxycholic acid and β-muricholic acid. Moreover, C-phycocyanin increased amino acid-related metabolites, Nα-acetyl-arginine and trimethyl-lysine contents, and decreased fatty acid esters of hydroxy fatty acids (FAHFAs) contents. In conclusion, C-phycocyanin inhibited inflammation via the 23-nordeoxycholic acid-Enterococcus faecalis-inflammation axis, and enhanced the antioxidant capacity of kidney via Lactobacillus-NRF2 pathway. C-phycocyanin alleviated cisplatin injury via the modulation of gut microbiota, especially Lactobacillus and Enterococcus, as well as regulation of metabolites, especially bile acid and FAHFAs, which highlight the effect of C-phycocyanin and provide a new strategy to prevent cisplatin injury.

Alginate Oligosaccharides Ameliorate DSS-Induced Colitis through Modulation of AMPK/NF-κB Pathway and Intestinal Microbiota

Alginate oligosaccharides (AOS) are shown to have various biological activities of great value to medicine, food, and agriculture. However, little information is available about their beneficial effects and mechanisms on ulcerative colitis. In this study, AOS with a polymerization degree between 2 and 4 were found to possess anti-inflammatory effects in vitro and in vivo. AOS could decrease the levels of nitric oxide (NO), IL-1β, IL-6, and TNFα, and upregulate the levels of IL-10 in both RAW 264.7 and bone-marrow-derived macrophage (BMDM) cells under lipopolysaccharide (LPS) stimulation. Additionally, oral AOS administration could significantly prevent bodyweight loss, colonic shortening, and rectal bleeding in dextran sodium sulfate (DSS)-induced colitis mice. AOS pretreatment could also reduce disease activity index scores and histopathologic scores and downregulate proinflammatory cytokine levels. Importantly, AOS administration could reverse DSS-induced AMPK deactivation and NF-κB activation in colonic tissues, as evidenced by enhanced AMPK phosphorylation and p65 phosphorylation inhibition. AOS could also upregulate AMPK phosphorylation and inhibit NF-κB activation in vitro. Moreover, 16S rRNA gene sequencing of gut microbiota indicated that supplemental doses of AOS could affect overall gut microbiota structure to a varying extent and specifically change the abundance of some bacteria. Medium-dose AOS could be superior to low- or high-dose AOS in maintaining remission in DSS-induced colitis mice. In conclusion, AOS can play a protective role in colitis through modulation of gut microbiota and the AMPK/NF-kB pathway.

The role of functional oligosaccharides as prebiotics in ulcerative colitis

The incidence rate of ulcerative colitis (UC) has increased significantly over the past decades and it places an increasing burden on health and social systems. The current studies on UC implicate a strong correlation between host gut microbiota immunity and the pathogenesis of UC. Meanwhile, more and more functional oligosaccharides have been reported as prebiotics to alleviate UC, since many of them can be metabolized by gut microbiota to produce short-chain fatty acids (SCFAs). The present review is focused on the structure, sources and specific applications of various functional oligosaccharides related to the prevention and treatment of UC. The available evidence for the usage of functional oligosaccharides in UC treatment are summarized, including fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), chito-oligosaccharides (COS), alginate-oligosaccharides (AOS), xylooligosaccharides (XOS), stachyose and inulin.

The risk of carrageenan-induced colitis is exacerbated under high-sucrose/high-salt diet

As a common used food additive, the threat of carrageenan to colon health is controversial, and is inseparable from personal eating habits. However, no detailed descriptions are available concerning the influence of different dietary patterns on the risk of carrageenan-induced colitis. In this study, we explored the risk of κ-carrageenan-induced colitis under high-sucrose or high-salt diet in mice. Intervention with carrageenan under high-sucrose diet significantly reduced colon length and induced more serious deepening of the crypts. In addition, the intake of carrageenan under high-sucrose/high-salt diet induced more serious goblet cell reduction and increased intestinal permeability. 16S rRNA sequencing and LC-MS based metabonomic approaches were conducted to explore the changes of gut microbiota and metabolites. It was found that the intake of carrageenan under high-sucrose/high-salt diet significantly reduced the abundance of anti-inflammatory bacterium and increased the abundance of harmful bacterium, which was significantly related to the decrease of anti-inflammatory metabolites in colon, such as methyl caffeate, spermine, oleanolic acid and senecionine. Overall, high-sucrose or high-salt diet increased the risk of carrageenan-induced colitis. This reminds us to maintain good eating habits, do not prefer high-sugar or high-salt foods, and try not to consume large amounts of carrageenan continuously to maintain gut health.

Alginate oligosaccharides: The structure-function relationships and the directional preparation for application

Alginate oligosaccharides (AOS) are degradation products of alginate extracted from brown algae. With low molecular weight, high water solubility, and good biological activity, AOS present anti-inflammatory, antimicrobial, antioxidant, and antitumor properties. They also exert growth-promoting effects in animals and plants. Three types of AOS, mannuronate oligosaccharides (MAOS), guluronate oligosaccharides (GAOS), and heterozygous mannuronate and guluronate oligosaccharides (HAOS), can be produced from alginate by enzymatic hydrolysis. Thus far, most studies on the applications and biological activities of AOS have been based mainly on a hybrid form of HAOS. To improve the directional production of AOS for practical applications, systematic studies on the structures and related biological activities of AOS are needed. This review provides a summary of current understanding of structure-function relationships and advances in the production of AOS. The current challenges and opportunities in the application of AOS is suggested to guide the precise application of AOS in practice.

Preparation and potential applications of alginate oligosaccharides

Alginate, a linear polymer consisting of β-D-mannuronic acid (M) and α-L-guluronic acid (G) with 1,4-glycosidic linkages and comprising 40% of the dry weight of algae, possesses various applications in the food and nutraceutical industries. However, the potential applications of alginate are restricted in some fields because of its low water solubility and high solution viscosity. Alginate oligosaccharides (AOS) on the other hand, have low molecular weight which result in better water solubility. Hence, it becomes a more popular target to be researched in recent years for its use in foods and nutraceuticals. AOS can be obtained by multiple degradation methods, including enzymatic degradation, from alginate or alginate-derived poly G and poly M. AOS have unique bioactivity and can bring human health benefits, which render them potentials to be developed/incorporated into functional food. This review comprehensively covers methods of the preparation and analysis of AOS, and discussed the potential applications of AOS in foods and nutraceuticals.

Alginate Oligosaccharide Alleviated Cisplatin-Induced Kidney Oxidative Stress via Lactobacillus Genus-FAHFAs-Nrf2 Axis in Mice

Alginate oligosaccharide is the depolymerized product of alginate, a natural extract of brown algae, which is associated with beneficial health effects. Here, we aimed to investigate the mechanism via which alginate oligosaccharides improve kidney oxidative damage and liver inflammation induced by cisplatin chemotherapy via the gut microbiota. C57BL/6J mice were treated with cisplatin were administered alginate oligosaccharide via gavage for 3 weeks. Compared to that observed in the cisplatin chemotherapy group without intragastric administration of alginate oligosaccharide, liver inflammation improved in the alginate oligosaccharide group, indicated by reduction in lipopolysaccharide and interleukin-1β (IL-1β) levels. This was accompanied by improvement in the oxidative stress of mice kidneys, indicated by the increase in the levels of superoxide dismutase (SOD), catalase (CAT) and nuclear NF-E2-related factor 2 (Nrf2) in renal tissue, and reduction in the levels of malondialdehyde (MDA) in renal tissue and serum creatinine (Cr) to the levels of the normal control group. Alginate oligosaccharide intervention increased the concentration of fatty acid esters of hydroxy fatty acids (FAHFAs). Alginate oligosaccharide regulated the composition of the intestinal microbial community and promoted Lactobacillus stains, such as Lactobacillus johnsonii and Lactobacillus reuteri. Spearman analysis showed that 5 members of FAHFAs concentrations were positively correlated with Lactobacillus johnsonii and Lactobacillus reuteri abundance. We observed that alginate oligosaccharide increased FAHFAs producing-related bacterial abundance and FAHFAs levels, enhanced the levels of SOD and CAT in kidney tissue, and reduced the levels of MDA via activating Nrf2, thereby ameliorating the renal redox injury caused by cisplatin chemotherapy.

Effects of cage versus floor rearing system on goose intestinal histomorphology and cecal microbial composition

Due to the demand for modern goose production and the pressure of environmental protection, the rearing systems of geese are changing from traditional waterside rearing to intensive rearing systems such as floor rearing (FR) and cage rearing (CR) systems. However, little is known about the effects of different rearing systems on goose intestinal functions and cecal microbial composition. Therefore, this study aimed to compare intestinal histomorphology and cecal microbial composition differences in geese reared under CR and FR at 270 d of age. Histomorphological analysis showed that the ileal villus height (VH) to crypt depth (CD) ratio was significantly greater in CR than in FR (P < 0.001). Taxonomic analysis showed that the dominant bacteria of cecal microorganisms in both rearing systems were roughly similar, with Bacteroidota, Firmicutes, Fusobacteriota, and Proteobacteria being the dominant phyla while Bacteroides, Fusobacterium, and uncultured_bacterium_o_Bacteroidales being the dominant genera. Differentially abundant taxa between CR and FR were also identified using Linear Discriminant Analysis Effect Size (LEfSe) analysis (P < 0.05, LDA score > 3.5). Megamonas and Anaerobiospirillum were significantly enriched in the CR group at the genus level, while uncultured_bacterium_f_Rikenellaceae and Sutterella were significantly enriched in the FR group. Notably, we found that the relative abundance of uncultured_bacterium_f_Rikenellaceae was significantly negatively correlated with the ileal VH and VH/CD (P < 0.05). The relative abundance of Megamonas and Anaerobiospirillum were significantly negatively correlated with abdominal fat weight and relative abdominal fat weight (P < 0.01), whereas that of Sutterella was significantly positively correlated with abdominal fat weight and relative abdominal fat weight (P < 0.01). Furthermore, PICRUSt2 analysis indicated that the lipid metabolism pathways of cecal microorganisms were lower enriched in CR than in FR. In conclusion, compared with FR, the CR significantly changed goose ileal histomorphological characteristics and cecal microbial composition, thereby affecting goose physiological functions and production performance.

Anti-Diabetic Effects of Ethanol Extract from Sanghuangporous vaninii in High-Fat/Sucrose Diet and Streptozotocin-Induced Diabetic Mice by Modulating Gut Microbiota

Type 2 diabetes mellitus (T2DM) may lead to abnormally elevated blood glucose, lipid metabolism disorder, and low-grade inflammation. Besides, the development of T2DM is always accompanied by gut microbiota dysbiosis and metabolic dysfunction. In this study, the T2DM mice model was established by feeding a high-fat/sucrose diet combined with injecting a low dose of streptozotocin. Additionally, the effects of oral administration of ethanol extract from Sanghuangporous vaninii (SVE) on T2DM and its complications (including hypoglycemia, hyperlipidemia, inflammation, and gut microbiota dysbiosis) were investigated. The results showed SVE could improve body weight, glycolipid metabolism, and inflammation-related parameters. Besides, SVE intervention effectively ameliorated the diabetes-induced pancreas and jejunum injury. Furthermore, SVE intervention significantly increased the relative abundances of Akkermansia, Dubosiella, Bacteroides, and Parabacteroides, and decreased the levels of Lactobacillus, Flavonifractor, Odoribacter, and Desulfovibrio compared to the model group (LDA > 3.0, p < 0.05). Metabolic function prediction of the intestinal microbiota by PICRUSt revealed that glycerolipid metabolism, insulin signaling pathway, PI3K-Akt signaling pathway, and fatty acid degradation were enriched in the diabetic mice treated with SVE. Moreover, the integrative analysis indicated that the key intestinal microbial phylotypes in response to SVE intervention were strongly correlated with glucose and lipid metabolism-associated biochemical parameters. These findings demonstrated that SVE has the potential to alleviate T2DM and its complications by modulating the gut microbiota imbalance.

A Randomized Placebo-Controlled Trial of Combination Therapy With Post-triple-antibiotic-therapy Fecal Microbiota Transplantation and Alginate for Ulcerative Colitis: Protocol

Background

Fecal microbiota transplantation (FMT) has been widely performed for ulcerative colitis (UC) treatment at the clinical trial stage. Previous reports have used multiple FMT methods to enhance the colonization of healthy donor microbiota in the recipient's intestines. FMT following triple antibiotic therapy with amoxicillin, fosfomycin, and metronidazole (A-FMT) is not only effective but also requires only one FMT, which improves dysbiosis caused by reduced Bacteroidetes diversity in patients with UC. Alginate and its derivatives have the potential to induce the growth of intestinal bacteria including Bacteroides members and produce short-chain fatty acids (SCFAs), which are beneficial in regulating overactive autoimmunity. Our trial aims to investigate whether post-intervention with alginate, which can improve the intestinal environment, will enhance the therapeutic effect of A-FMT in UC and increase the long-term remission rate.

Methods and Analysis

This trial is a double-blinded, randomized, placebo-controlled, parallel assignment trial. Patients with UC and fecal donation candidates will undergo strict screening before being involved in the trial. Eligible patients are randomly divided into two groups: one group will drink one bottle of alginate twice a day for 8 consecutive weeks after A-FMT, while the other group will take a placebo instead of the alginate drink. The primary endpoints are the changes in the Total Mayo Score at 8 weeks after study initiation and A-FMT from baseline. The secondary endpoint is the comparison of clinical features, microbiota, and metabolomic analysis before and after 8 weeks of study food intake. Changes at 6, 12, 18, and 24 months after A-FMT will be assessed. Finally, a subpopulation analysis of the relationship between patients and donors is an exploratory endpoint.

Discussion

The FMT post-treatment used in this study is an oral alginate drink that is easily accepted by patients. If the regimen achieves the desired results, it can further improve the A-FMT regimen and provide evidence for clinical practice guidelines for UC.

Clinical Trial Registration

https://jrct.niph.go.jp/latest-detail/jRCTs031200103, identifier: jRCTs031200103.

Enzymatic Preparation of Low-Molecular-Weight Laminaria japonica Polysaccharides and Evaluation of Its Effect on Modulating Intestinal Microbiota in High-Fat-Diet-Fed Mice

Recent studies have shown that seaweed polysaccharides can ameliorate high-fat-diet (HFD)-induced metabolic syndromes associated with the regulatory function of gut microbiota. However, kelp, a natural source of seaweed polysaccharides, is highly viscous, making it difficult to prepare dietary fiber by simple degradation. Therefore, we developed a novel method of preparing low-molecular-weight polysaccharides from Laminaria japonica by combining high-pressure pretreatment and composite enzymatic degradation and evaluated the obesity prevention activity of these polysaccharides. Seaweed L. japonica polysaccharides (SJP) were rapidly utilized by the human fecal microbiota in vitro, resulting in the generation of short-chain fatty acids (SCFAs), specifically acetate and propionate. The in vivo effects of SJP on the intestinal microbiota were also investigated using HFD-fed C57BL/6J mice. SJP reduced weight gain and fat deposition in HFD-fed mice and increased the concentration of total SCFAs, including acetate, propionate, and butyrate in the feces. SJP ameliorated HFD-induced gut microbiota dysbiosis, resulting in increased abundance of Faecalibaculum, Romboutsia, and Clostridium sensu stricto 1 and decreased abundance of Blautia and Lactobacillus. Further, SJP enhanced the abundance of Akkermansia muciniphila in mice provided with HFD and normal chow. Single-strain culture experiments also revealed that SJP promoted the growth of A. muciniphila. This study highlights the potential use of SJP, prepared using composite enzymatic degradation (cellulase and recombinant alginate lyase), in preventing obesity and restoring intestinal homeostasis in obese individuals.

Alginate oligosaccharides protect against fumonisin B1-induced intestinal damage via promoting gut microbiota homeostasis

Fumonisin B1 (FB1), one of the most common mycotoxins contaminating feed and food, has been shown to induce intestinal barrier degradation. However, its role on gut microbiota in this process is still unclear. Alginate oligosaccharides (AOS) have been reported to exert their anti-inflammatory and anti-apoptotic function partially via modulation the gut microbiota. However, little is known about the beneficial effect of AOS on gut microbiota upon FB1 exposure. Results show that FB1 degraded intestinal epithelial barrier function as evidenced by increased pathological epithelial cell shedding, reduced the number of goblet cells, and promoted intestinal cell apoptosis. Markedly, FB1 disturbed the cecal and fecal microbiota composition. FB1 increased the level of Lactobacillus and decreased the relative abundance of beneficial microbes. FB1 largely inhibited the production of short chain fatty acids (SCFAs). AOS greatly ameliorated FB1-induced intestinal damage, inflammation, and oxidative stress (eg., T-SOD and MDA). AOS alleviated gut microbial dysbiosis by promoting the growth of beneficial microbes such as Roseburia, Bifidobacterium, and Akkermansia, and increasing SCFAs production upon FB1 exposure. Moreover, the correlation analysis showed that FB1- and AOS-treated gut microbiota alteration is closely associated with the change of intestinal phenotype. We have thus provided a novel insight into the protective role of AOS on FB1-induced gut microbial dysbiosis.

Algal polysaccharides and derivatives as potential therapeutics for obesity and related metabolic diseases

The potential and challenges of algal polysaccharides and their derivatives as potential therapeutic agents for obesity and its related metabolic diseases.

The gut microbiota and its products: Establishing causal relationships with obesity related outcomes

Gut microorganisms not only participate in the metabolism of carbohydrate, lipids, protein, and polypeptides in the intestine but also directly affect the metabolic phenotypes of the host. Although many studies have described the apparent effects of gut microbiota on human health, the development of metagenomics and culturomics in the past decade has generated a large amount of evidence suggesting a causal relationship between gut microbiota and obesity. The interaction between the gut microbiota and host is realized by microbial metabolites with multiple biological functions. We concentrated here on several representative beneficial species connected with obesity as well as the mechanisms, with particular emphasis on microbiota-dependent metabolites. Finally, we consider the potential clinical significance of these relationships to fuel the conception and realization of novel therapeutic and preventive strategies.

Algae-derived hydrocolloids in foods: applications and health-related issues

Hydrocolloids are a class of food additives with broad applications in the food industry to develop structure in food ingredients. Hydrocolloids can be synthetic, plant-based, or animal-based. Increasing consumer awareness has led to the use of natural food ingredients derived from natural sources, making algae-derived hydrocolloids more appealing nowadays. Algae-derived hydrocolloids such as carrageenan, agar, and alginate are widely used in the food industry as thickening, gelling, and emulsifying agents. Carrageenans are sulfated polysaccharides with diverse structural specificities. The safety of carrageenan use in the food industry has been widely debated recently due to the reported pro-inflammatory activities of carrageenan and the probable digestion of carrageenan by the gut microbiota to generate pro-inflammatory oligosaccharides. In contrast, both agar and alginate are primarily nontoxic, and generally no dispute regarding the use of the same in food ingredients. This review provides an overview of the algae industry, the food additives, the algae-derived hydrocolloids, the applications of algae-derived hydrocolloids in food industries, health-related studies, and other sectors, along with future perspectives. Even though differences of opinion exist in the use of carrageenan, it is continued to be used by the food industry and will be used until suitable alternatives are available. In summary, algal hydrocolloids are 'label-friendly' and considered a safe option against synthetic additives.

A Novel PTP1B Inhibitor-Phosphate of Polymannuronic Acid Ameliorates Insulin Resistance by Regulating IRS-1/Akt Signaling

Protein tyrosine phosphatase 1B (PTP1B) is a critical negative modulator of insulin signaling and has attracted considerable attention in treating type 2 diabetes mellitus (T2DM). Low-molecular-weight polymannuronic acid phosphate (LPMP) was found to be a selective PTP1B inhibitor with an IC₅₀ of 1.02 ± 0.17 μM. Cellular glucose consumption was significantly elevated in insulin-resistant HepG2 cells after LPMP treatment. LPMP could alleviate oxidative stress and endoplasmic reticulum stress, which are associated with the development of insulin resistance. Western blot and polymerase chain reaction (PCR) analysis demonstrated that LPMP could enhance insulin sensitivity through the PTP1B/IRS/Akt transduction pathway. Furthermore, animal study confirmed that LPMP could decrease blood glucose, alleviate insulin resistance, and exert hepatoprotective effects in diabetic mice. Taken together, LPMP can effectively inhibit insulin resistance and has high potential as an anti-diabetic drug candidate to be further developed.