Comparison Study on Polysaccharide Fractions from Laminaria japonica: Structural Characterization and Bile Acid Binding Capacity

Mechanism study on the enhancement of bile acid-binding capacity in corn by-product juice via Lactiplantibacillus plantarum HY127 fermentation

Hyperlipidemia is a common endocrine metabolic disease in humans. Long-term medications often have adverse effects, making the search for safer and more effective treatments crucial. This study aimed to explore the impacts and mechanisms of Lactiplantibacillus plantarum HY127 fermentation on enhancing bile acid-binding capacity (BABC). We fermented corn by-product juice (CBJ) by HY127 and investigated the BABC of HY127 bacterial cells and their metabolites. Our results indicated that HY127 cells (95.25 %) played a major role in enhancing BABC, with metabolites (31.50 %-66.41 %) also contributing. Compared to unfermented CBJ, the contents of phenolics, flavonoids, polysaccharides, and organic acids were significantly higher. Non-targeted metabolomics revealed upregulated amino acids, alkaloids, terpenoids, and other bioactive substances associated with BABC in the supernatant. This study confirmed that HY127 fermentation enhances the BABC of CBJ (increased by 32.02 %-78.76 %), providing a research foundation and technical reference for the development of LAB-fermented corn by-product beverages with hypolipidemic activities.

Anti-inflammatory mechanism of Houttuynia cordata polysaccharides against ulcerative colitis based on multi-omics conjoint analysis

The Houttuynia cordata polysaccharide (HCP) was extracted from the traditional Chinese medicine, Houttuynia cordata, known for its anti-inflammatory properties. It has an acidic heteropolysaccharide with a molecular weight of approximately 13.38 kDa, consisting of 7 monosaccharides such as galactose, galacturonic acid, and glucose. Mouse ulcerative colitis (UC) model experiments demonstrated its effective anti-inflammatory activity at concentrations of 100 mg/kg and 300 mg/kg respectively. The objective of this study was to investigate the mechanism of action underlying the therapeutic effects of HCP in UC through omics analysis method. A total of 724 different metabolites and 246 differential lipids were identified. Through metabolomic analysis, six metabolic pathways including the linoleic acid metabolic pathway, caffeine metabolic pathway, mannose and fructose metabolic pathways, methyl histidine metabolic pathway and fatty acid biosynthesis, which were significantly associated with colon-related diseases. Subsequently, lipidomics analysis revealed that the metabolic pathways of α-linolenic and linoleic acid, fatty acid biosynthesis, and glycerolipid metabolism exhibited significant associations with serum lipid metabolism. These findings suggested that HCP had potential therapeutic effects in treating UC.

Laoxianghuang polysaccharide promotes the anti-inflammatory cytokine interleukin-10 in colitis via gut microbial linoleic acid

BACKGROUND

Our previous study found that the polysaccharide from Laoxianghuang (LP), fermented fruit of bergamot (traditional Chinese medicine and food), can alter gut microbiota and regulate short-chain fatty acids (SCFAs) in vitro. Nevertheless, there is a paucity of reports on the impact of LP on gut microbiota in vivo.

PURPOSE

To analyze the structures of LP, investigate the influence of LP on the damaged intestinal barrier in DSS-induced colitis mice, and further explore its potential mechanisms.

METHODS

We analyzed the physicochemical properties of purified LP by HPLC, SEM, and FT-IR spectrum. Then, to assess the effect of LP in DSS-induced colitis mice, we observed the damage to the colon tissue, measured inflammatory cytokines and tight junction protein expression through RT-qPCR as well as immunofluorescent staining, and investigated the influence of LP on altering gut microbiota and metabolites using 16 s rRNA sequencing and HPLC-MS/MS. Ultimately, the impact of linoleic acid on inflammatory cytokines was confirmed by the LPS-induced RAW264.7 cells.

RESULTS

LP, mainly galactoglucan, could inhibit weight loss and colon shortening, decrease levels of tumor necrosis factor-α (TNF-α), increase levels of interleukin-10 (IL-10) and the intestinal acetic acid and butyric acid, and promote the expression of tight junction proteins ZO-1 and Claudin-1. Meanwhile, LP enhanced the abundance of beneficial bacteria including Romboutsia, Eubacterium_coprostanoligenes_group, and Akkermansia, and regulated linoleic acid metabolism to increase the linoleic acid level. In vitro cell experiment proved that linoleic acid could elevate the level of IL-10 and inhibit inflammatory responses.

CONCLUSIONS

Our results suggested that LP effectively alleviated colitis by promoting the anti-inflammatory cytokine interleukin-10 via gut microbiota-mediated linoleic acid metabolism.

Ultra-high pressure assisted extraction of polysaccharide from Bangia fusco-purpurea: Structure and in vitro hypolipidemic activity

The structure and in vitro hypolipidemic activity of Bangia fusco-purpurea polysaccharide (BFP) assisted extracted with ultra-high pressure (UHP) at 100-600 MPa were studied. Compared to native BFP, UHP assisted extracted BFP had a more loose network structure with higher total sugar and uronic acid contents while less molecular weight (p < 0.05). Moreover, UHP assisted extraction significantly improved the in vitro hypolipidemic and antioxidant activity of BFP. Especially at 400 MPa UHP, the cholesterol adsorption and antioxidant capacities of BFP were increased by approximately 38.02 % and 11.69 %-32.29 %, respectively. BFP with UHP assisted extraction could alleviate oleic acid-induced lipid accumulation and lipid oxidation in HepG2 cells more effectively by activating the AMPK signaling pathway as well as inhibiting PPARγ expression, which was much related with its reduced molecular weight and loose network structure. The findings indicated that UHP assisted extracted BFP has better potential to develop natural hypolipidemic agent.

Structural characterization, antioxidant and immunomodulatory activities of a polysaccharide from a traditional Chinese rice wine, Guangdong Hakka Huangjiu

Hakka Huangjiu, a traditional Chinese rice wine, boasts a rich history and is known for its immunomodulatory, antibacterial, anti-aging and anti-fatigue effects. However, there is limited research on the primary active components and molecular mechanism of the bioactivity of Hakka Huangjiu. To address this gap, this study assessed the structural characteristics, antioxidant, and immunomodulatory activities of the polysaccharide-1 of Guangdong Hakka Huangjiu (HP1). Structural analysis revealed that HP1 had a low molecular weight polysaccharide of 5550 Da, primarily consisting of glucose (93.2 %), with smaller amounts of xylose, mannuronic acid and galactose. Methylation and NMR analysis suggested that the main glycosidic linkages present in HP1 are α-D-Glcp-(1→, →4)-α-D-Glcp-(1 → and →6) -α-D-Glcp-(1→. Furthermore, HP1 exhibited dose-dependent DPPH·, ABTS+ and OH· scavenging activity. HP1 exhibited significant protection of HepG2 cells from H2O2 damage. Additionally, HP1 induced the release of NO, TNF-α, IL-6 and iNOS in RAW264.7 cells. HP1 treatment significantly increased mRNA expression of TNF-α, IL-6, iNOS, COX-2, IL-1β and TGF-β1. These results suggested that polysaccharides HP1 may have potential as a novel natural antioxidant and immunomodulatory product for use in nutraceuticals and functional foods.

Ultrasound-assisted enzymatic extraction of soluble dietary Fiber from Hericium erinaceus and its in vitro lipid-lowering effect

Dietary fiber (DF) is an important active polysaccharide in Hericium erinaceus. Obesity can lead to a wide range of diseases. In this work, we investigated the in vitro lipid-lowering effect of soluble dietary fiber (SDF) from H. erinaceus, aiming to provide a basis for the subsequent development of lipid-lowering products. Ultrasound-assisted enzymatic extraction (UAEE) of SDF from H. erinaceus was performed. The optimal extraction parameters determined via single-factor experiments and response surface methodology (RSM) were as follows: Lywallzyme concentration, 1.0%; complex protease concentration, 1.2%; ultrasonication time, 35 min; and ultrasonication power, 150 W. In vitro lipid-lowering experiments revealed that the adsorption amount of cholesterol micelles by H. erinaceus SDF was 11.91 mg/g. The binding amount and binding rate of sodium taurocholate were 3.73 mg/g and 42.47%, respectively, and those of sodium glycocholate were 3.43 mg/g and 39.12%, respectively. The pancreatic lipase inhibition rate reached 52.11%, and the type of inhibition was competitive. Therefore, H. erinaceus SDF has good in vitro lipid-lowering ability.

Fractionation and characterization of sodium carbonate-soluble fractions of cell wall pectic polysaccharides involved in the rapid mealiness of 'Hongjiangjun' apple fruit

Apple flesh tends to turn mealy and textural deterioration commonly occurs during storage. The comparative investigation of three sub-fractions separated from sodium carbonate-soluble pectin (SSP) of 'Hongjiangjun' apples between crisp and mealy stages was performed to unveil the textural alterations related to mealiness. In situ immunofluorescence labelling showed that galactans declined in parenchyma cell walls during the fruit mealiness. FTIR analysis, monosaccharide compositions and structural polymers configurated that loss of rhammogalacturonan-I (RG-I) from SSP sub-fragments (SC0.0-P and S-M0.0-P) might be closely involved in the mealiness. The NMR spectroscopy revealed that loss of the substituted galactans from α-Rhap residues repeat unit in SC0.0-P constituting RG-I in crisp stage that subsequently converted to S-M0.0-P in mealy stage might be closely associated with the modifications of pectin in cell walls during mealiness. These findings provided novel evidence for understanding the underlying modifications of SSP polymers during the mealiness of 'Hongjiangjun' apples.

Preparation and characterization of kelp polysaccharide and its research on anti-influenza a virus activity

The beneficial effects of kelp polysaccharide (KPS) have recently attracted attention. In this study, KPS was extracted from kelp using the enzyme hydrolysis combined with freeze-drying, namely, KPS-EF. The structural characterization showed that KPS-EF was a highly sulfated macromolecule with the Mw of 764.2 kDa and the sulfate content of 23.49 %. The antiviral activity of KPS-EF in vitro was verified, and the IC50 value of KPS against the PR8 virus was 0.58 mg/mL. Intranasal administration of KPS-EF significantly inhibited death and weight loss in IAV-infected mice and alleviated virus-induced pneumonia symptoms, meanwhile, KPS-EF (10 mg/kg/day) significantly decreased the production levels of chemokines (CXCL1, RANTES) and inflammatory cytokines (IL-6, TNF-α) in lungs (p < 0.05). KPS-EF could downregulate the activity of viral neuraminidase (NA) primarily in the late stage of viral adsorption with an IC50 value of 0.29 mg/mL. This study provides a theoretical basis for the using KPS as a supplement to NA inhibitors or anti-influenza drugs.

A comparative study of the hypolipidemic effects and mechanisms of action of Laminaria japonica- and Ascophyllum nodosum-derived fucoidans in apolipoprotein E-deficient mice

The structural characteristics of fucoidans exhibit species and regional diversity. Previous studies have demonstrated that Laminaria japonica- and Ascophyllum nodosum-derived fucoidans have type I and type II fucosyl chains, respectively. These chemical differences may contribute to distinct hypolipidemic effects and mechanisms of action. Chemical analysis demonstrated that the percentage contents of sulfate, glucuronic acid, and galactose were higher in L. japonica-derived fucoidans than those of A. nodosum-derived fucoidans. In hyperlipidemic apolipoprotein E-deficient mice, both A. nodosum- and L. japonica-derived fucoidans significantly decreased the plasma and hepatic levels of total cholesterol and triglyceride, leading to the reduction of atherosclerotic plaques. Western blotting experiments demonstrated that these fucoidans significantly enhanced the expression and levels of scavenger receptor B type 1, cholesterol 7 alpha-hydroxylase A1, and peroxisome proliferator-activated receptor (PPAR)-α, contributing to circulating lipoprotein clearance and fatty acid degradation, respectively. Differentially, L. japonica-derived fucoidan significantly increased the LXR/ATP-binding cassette G8 signaling pathway in the small intestine, as revealed by real-time quantitative PCR, which may lead to further cholesterol and other lipid excretion. Collectively, these data are useful for understanding the hypolipidemic mechanisms of action of seaweed-derived fucoidans, and their potential application for the prevention and/or treatment of atherosclerotic cardiovascular diseases.

Highly active probiotic hydrogels matrixed on bacterial EPS accelerate wound healing via maintaining stable skin microbiota and reducing inflammation

Skin microbiota plays an important role in wound healing, but skin injuries are highly susceptible to wound infections, leading to disruption of the skin microbiota. However, conventional antibacterial hydrogels eliminate both probiotics and pathogenic bacteria, disrupting the balance of the skin microbiota. Therefore, it is important to develop a wound dressing that can fend off foreign pathogenic bacteria while preserving skin microbiota stability. Inspired by live bacteria therapy, we designed a probiotic hydrogel (HAEPS@L.sei gel) with high viability for promoting wound healing. Lactobacillus paracasei TYM202 encapsulated in the hydrogel has the activity of promoting wound healing, and the hydrogel matrix EPS-M76 has the prebiotic activity that promotes the proliferation and metabolism of Lactobacillus paracasei TYM202. During the wound healing process, HAEPS@L.sei gel releases lactic acid and acetic acid to resist the growth of pathogenic bacteria while maintaining Firmicutes and Proteobacteria balance at the phylum level, thus preserving skin microbiota stability. Our results showed that live probiotic hydrogels reduce the incidence of inflammation during wound healing while promoting angiogenesis and increasing collagen deposition. This study provides new ideas for developing wound dressings predicated on live bacterial hydrogels.

Biomedical potency and mechanisms of marine polysaccharides and oligosaccharides: A review

Derived from bountiful marine organisms (predominantly algae, fauna, and microorganisms), marine polysaccharides and marine oligosaccharides are intricate macromolecules that play a significant role in the growth and development of marine life. Recently, considerable attention has been paid to marine polysaccharides and marine oligosaccharides as auspicious natural products due to their promising biological attributes. Herein, we provide an overview of recent advances in the miscellaneous biological activities of marine polysaccharides and marine oligosaccharides that encompasses their anti-cancer, anti-inflammatory, antibacterial, antiviral, antioxidant, anti-diabetes mellitus, and anticoagulant properties. Furthermore, we furnish a concise summary of the underlying mechanisms governing the behavior of these biological macromolecules. We hope that this review inspires research on marine polysaccharides and marine oligosaccharides in medicinal applications while offering fresh perspectives on their broader facets.

Skin healthcare protection with antioxidant and anti-melanogenesis activity of polysaccharide purification from Bletilla striata

In this study, we investigated the structural characterization and biological activities of Bletilla striata polysaccharides (BSPs) for their role as antioxidants and anti-melanogenesis agents in skin healthcare protection. Three neutral polysaccharides (BSP-1, BSP-2, and BSP-3) with molecular weights of 269.121 kDa, 57.389 kDa, and 28.153 kDa were extracted and purified. Their structural characteristics were analyzed by ion chromatography, GC-MS, and 1D/2D NMR. The results showed that BSP-1, which constitutes the major part of BSPs, was composed of α-D-Glcp, β-D-Glcp, β-D-Manp, and 2-O-acetyl-β-D-Manp, with the branched-chain accompanied by β-D-Galp and α-D-Glcp. BSP-1, BSP-2, and BSP-3 can enhance the total antioxidant capacity of skin fibroblasts with non-toxicity. Meanwhile, BSP-1, BSP-2, and BSP-3 could significantly inhibit the proliferative activity of melanoma cells. Among them, BSP-1 and BSP-2 showed more significance in anti-melanogenesis, tyrosinase inhibition activity, and cell migration inhibition. BSPs have effective antioxidant capacity and anti-melanogenesis effects, which should be further emphasized and developed as skin protection components.

The Prebiotic Activity of a Novel Polysaccharide Extracted from Huangshui by Fecal Fermentation In Vitro

A novel polysaccharide, HSP80-2, with an average molecular weight of 13.8 kDa, was successfully isolated by the gradient ethanol precipitation (GEP) method from Huangshui (HS), the by-product of Chinese Baijiu. It was mainly composed of arabinose, xylose, and glucose with a molar ratio of 4.0:3.1:2.4, which was completely different from the previous reported HS polysaccharides (HSPs). Morphological observations indicated that HSP80-2 exhibited a smooth but uneven fragmented structure. Moreover, HSP80-2 exerted prebiotic activity evaluated by in vitro fermentation. Specifically, HSP80-2 was utilized by gut microbiota, and significantly regulated the composition and abundance of beneficial microbiota such as Phascolarctobacterium, Parabacteroides, and Bacteroides. Notably, KEGG pathway enrichment analysis illustrated that HSP80-2 enriched the pathways of amino sugar and nucleotide sugar metabolism (Ko00520), galactose metabolism (ko00052), and the citrate cycle (TCA cycle) (ko00020). Meanwhile, the contents of short-chain fatty acids (SCFAs) mainly including acetic acid, propionic acid, and butyric acid in the HSP80-2 group were remarkably increased, which was closely associated with the growth of Lachnoclostridium and Parabacteroides. These results showed that HSP80-2 might be used as a potential functional factor to promote human gut health, which further extended the high value utilization of HS.

Bioengineered Wheat Arabinoxylan - Fostering Next-Generation Prebiotics Targeting Health-Related Gut Microbes

Dietary prebiotic fibers play an important role in modulating gut microbiota by enhancing the abundance of beneficial microorganisms and their bioactive metabolites. However, dietary fibers are a structurally heterogeneous class of polysaccharides, varying in molar mass, branching patterns, and monosaccharide composition, which could influence their utilization by various gut microorganisms. The present study aimed to investigate the effects of molar mass and chemical structure of wheat arabinoxylan fiber (AX) on the growth and metabolism of two key gut resident bacteria (Faecalibacterium prausnitzii and Lacticaseibacillus rhamnosus LGG), which are linked to human health. For this purpose, low, medium, and high molar masses of AX (LAX, MAX, and HAX, respectively) were modified with specific α-arabinofuranosidases to leave only singly substituted, only doubly substituted, or unsubstituted xylose units. Almost all the modified AX samples showed a better prebiotic score than unmodified AX for different molar masses. The modified LAX exhibited a better prebiotic effect than HAX and MAX. In addition, LAX, with doubly substituted xylose units, exhibited the highest prebiotic potential and SCFA production by both microorganisms. Furthermore, AX, either singly or doubly substituted, had a consistent impact on L. rhamnosus growth, whereas AX, with all arabinose residues removed, had a greater impact on F. prausnitzii. These findings support the potential of bioengineered AX as next-generation prebiotics targeting health-related gut microbes.

Natural polysaccharides protect against diet-induced obesity by improving lipid metabolism and regulating the immune system

Unhealthy dietary patterns-induced obesity and obesity-related complications pose a great threat to human health all over the world. Accumulating evidence suggests that the pathophysiology of obesity and obesity-associated metabolic disorders is closely associated with dysregulation of lipid and energy metabolism, and metabolic inflammation. In this review, three potential anti-obesity mechanisms of natural polysaccharides are introduced. Firstly, natural polysaccharides protect against diet-induced obesity directly by improving lipid and cholesterol metabolism. Since the immunity also affects lipid and energy metabolism, natural polysaccharides improve lipid and energy metabolism by regulating host immunity. Moreover, diet-induced mitochondrial dysfunction, prolonged endoplasmic reticulum stress, defective autophagy and microbial dysbiosis can disrupt lipid and/or energy metabolism in a direct and/or inflammation-induced manner. Therefore, natural polysaccharides also improve lipid and energy metabolism and suppress inflammation by alleviating mitochondrial dysfunction and endoplasmic reticulum stress, promoting autophagy and regulating gut microbiota composition. Specifically, this review comprehensively summarizes underlying anti-obesity mechanisms of natural polysaccharides and provides a theoretical basis for the development of functional foods. For the first time, this review elucidates anti-obesity mechanisms of natural polysaccharides from the perspectives of their hypolipidemic, energy-regulating and immune-regulating mechanisms.

Structural and spectroscopic details of polysaccharide-bile acid composites from molecular dynamics simulations

Interactions of a prototypical bile acid (cholic acid, 'Ch') and its corresponding sodium salt (sodium cholate, 'NaCh') with a standard dietary β-glucan (β-G), bearing β-D-glucopyranose units having mixed 1-4/1-3 glycosidic linkages are studied using molecular dynamics simulation and density functional theory (DFT) calculations. Self-aggregation of the biliary components and their interaction with fifteen strands of the decameric mixed linkage β-glucan is elucidated by estimating varieties of physical properties like the coordination number, moment of inertia and shape anisotropy of the biggest cluster formed at different time instants. Small angle scattering profiles indicate formation of compact spheroidal aggregates. The simulated results of small angle scattering and 1H NMR chemical shifts are compared to spectroscopic data, wherever available. Density functional theory calculations and estimation of the 1H NMR chemical shifts of Ch-protons lying close to the β-G chains reveal change in chemical shift values from that in absence of the polysaccharide. Hydrogen bonding and non-bonding interactions, primarily short range van der Waals interactions and some extent of inter-molecular charge transfer are found to play significant role in stabilizing the complex soft assemblies of bile acid aggregates and β-G.Communicated by Ramaswamy H. Sarma.

Preparation, structures, and biological functions of rhamnan sulfate from green seaweed of the genus Monostroma: A review

Rhamnan sulfate, a rhamnose-rich sulfated polysaccharide, is present in the cell walls of green seaweed belonging to the genus Monostroma. This macromolecule demonstrates promising therapeutic properties, including anti-coagulant, thrombolytic, anti-viral, anti-obesity, and anti-inflammatory activities, which hold potential applications in food and medical industries. However, rhamnan sulfate has not garnered as much attention from researchers as other seaweed polysaccharides, including alginate, carrageenan, and fucoidan. This review discusses the extraction and purification techniques of rhamnan sulfate, delves into its chemical structures and related elucidation approaches, and provides an overview of its biological functions. Future research should focus on the structure-activity relationship of rhamnan sulfate and the industrial preparation of rhamnan sulfate with a specific homogeneous structure to facilitate its practical applications.

Fucogalactan Sulfate (FS) from Laminaria japonica Regulates Lipid Metabolism in Diet-Induced Humanized Dyslipidemia Mice via an Intestinal FXR-FGF19-CYP7A1/CYP8B1 Pathway

Our previous study found that fucogalactan sulfate (FS) from Laminaria japonica exhibited significant hypolipidemic effects. To further elucidate the mechanism, we first constructed a dyslipidemia mouse model with humanized gut microbiota and proved the main differential metabolic pathway involved bile acid metabolism. Then, we evaluated the beneficial effects of FS on dyslipidemia in this model mice, which revealed that oral FS administration reduced serum cholesterol levels and mitigated liver fat accumulation. Gut microbiota and microbiome analysis showed FS increased the abundance of Ruminococcaceae_NK4A214_group, GCA-900066755, and Eubacterium, which were positively associated with the fecal DCA, β-MCA, and HDCA. Further investigation demonstrated that FS inhibited the hepatic farnesoid X receptor (FXR), while activating the intestinal FXR-FGF19 pathway, leading to suppression of CYP7A1 and CYP8B1, as well as potentially reduced bile acid synthesis and lipid absorption. Overall, FS regulated lipid metabolism in diet-induced humanized dyslipidemia mice via the bile acid-mediated intestinal FXR-FGF19-CYP7A1/CYP8B1 pathway.

Polysaccharide-based biosorbents for cholesterol and bile salts in gastric-intestinal passage: Advances and future trends

Cholesterol is one of the hazard elements for many cardiovascular diseases, but many cholesterol-lowering drugs are expensive and unhealthy. Therefore, it is necessary to develop edible and safe biosorbents to reduce excess cholesterol and bile salts in the gastric-intestinal passage. Polysaccharide-based biosorbents offer a feasible strategy for decreasing them. This review summarized polysaccharide-based biosorbents that have been developed for adsorbing cholesterol and bile salts from the gastric-intestinal passage and analyzed common modification methods for these adsorbents. Finally, the adsorption models were also elucidated. Polysaccharides, including β-cyclodextrin, pectin, chitin/chitosan, dietary fiber extract, and cellulose, have been proposed for adsorbing cholesterol and bile salts in the gastric-intestinal passage as biosorbents. This is mainly due to the retention of pores, the capture of the viscosity network, and the help of hydrophobic interactions. In spite of this, the adsorption capacity of polysaccharides is still limited. Therefore, the modifications for them became the most popular areas in the recent studies of in vitro cholesterol adsorption. Chemical approaches namely grafting, (1) acetylation, (2) hydroxypropylation, (3) carboxymethylation, and (4) amination are considered to modify the polysaccharides for higher adsorption ability. Moreover, ultrasonic/microwave/pressure treatment and micron technology (microfluidization, micronization, and ball milling) are effective physical modification methods, while the biological approach mainly refers to enzymatic hydrolysis and microbial fermentation. The adsorption models are generally explained by two adsorption isotherms and two adsorption kinetics. In sum, it is reckoned that further food applications will follow soon.

Structural elucidation of hemicelluloses from oil-tea camellia fruit shell

Oil-tea camellia fruit shell (CFS) is a very abundant waste lignocellulosic resource. The current treatments of CFS, i.e. composting and burning, pose a severe threat on environment. Up to 50 % of the dry mass of CFS is composed of hemicelluloses. However, chemical structures of the hemicelluloses in CFS have not been extensively studied, which limits their high-value utilization. In this study, different types of hemicelluloses were isolated from CFS through alkali fractionation with the assistance of Ba(OH)2 and H3BO3. Xylan, galacto-glucomannan and xyloglucan were found to be the major hemicelluloses in CFS. Through methylation, HSQC and HMBC analyses, we have found that the xylan in CFS is composed of →4)-β-D-Xylp-(1→ and →3,4)-β-D-Xylp-(1→ linked by (1→4)-β glycosidic bond as the main chain; the side chains are α-L-Fucp-(1→, →5)-α-L-Araf-(1→, β-D-Xylp-(1→, α-L-Rhap-(1→ and 4-O-Me-α-D-GlcpA-(1→, connected to the main chain through (1→3) glycosidic bond. The main chain of galacto-glucomannan in CFS consists of →6)-β-D-Glcp-(1→, →4)-β-D-Glcp-(1→, →4,6)-β-D-Glcp-(1→ and →4)-β-D-Manp-(1→; the side chains are β-D-Glcp-(1→, →2)-β-D-Galp-(1→, β-D-Manp-(1→ and →6)-β-D-Galp-(1→ connected to the main chain through (1→6) glycosidic bonds. Moreover, galactose residues are connected by α-L-Fucp-(1→. The main chain of xyloglucan is composed of →4)-β-D-Glcp-(1→, →4,6)-β-D-Glcp-(1→ and →6)-β-D-Glcp-(1→; the side groups, i.e. β-D-Xylp-(1→ and →4)-β-D-Xylp-(1→, are connected to the main chain by (1→6) glycosidic bond; →2)-β-D-Galp-(1→ and α-L-Fucp-(1→ can also connect to →4)-β-D-Xylp-(1→ forming di- or trisaccharide side chains.

Hypolipidemic Activity and Mechanism of Action of Sargassum fusiforme Polysaccharides

Sargassum fusiforme polysaccharide (SFP) is a kind of biologically active macromolecule with biological functions. In this study, oxidative stress and high-fat HepG2 cell models were established to investigate its lipid-lowering activity and mechanism of action. It was found that SFP and its two isolated fractions had antioxidant effects on the cells. It was also found the polysaccharides decreased the content of total cholesterol and total triglyceride in the high-fat cells. RT-qPCR assays revealed that the three polysaccharides down-regulated the mRNA expression level of ACC, PPARγ, and SREBP-2. It could be concluded that the hypolipidemic effect of SFPs is achieved via multiple pathways, including the regulation on the expression level of lipid metabolism-related key enzymes and factors, and binding with bile acids. The hypolipidemic effect of SFPs could be partially due to their antioxidant activity. SFPs developed in the present work have potential as ingredients of functional foods with hypolipidemic effect.

The fate of mamaku gum in the gut: effect on in vitro gastrointestinal function and colon fermentation by human faecal microbiota

Mamaku is a fern indigenous to the Pacific Islands with a long history of use for therapeutic benefits such as to combat skin conditions and manage gastrointestinal discomfort; however, the scientific understanding is limited. In this study, we examined the effect of mamaku gum, extracted from different age fronds of the New Zealand Black tree fern (Cyathea medullaris, Mamaku) (stage 1: young, stage 2: fully grown and stage 3: old), on gut function using in vitro models of static digestion, enzyme activity and static colonic fermentation. Under simulated gastric and small intestinal conditions, mamaku polysaccharide (MP) was indigestible as there was no decrease in the molecular weight (Mw) of the polymer. Mamaku gum could reduce the activity of digestive enzymes (α-amylase, pepsin and lipase) in a concentration-dependent manner, with the stage 1 sample showing the highest inhibition and stage 3 the lowest. All three mamaku gum samples could also equally bind bile acids during intestinal digestion. During fermentation, human faecal microbiota utilised the mamaku gum and significantly increased the production of total short-chain fatty acids (SCFAs) and reduced the pH when compared with the blank. However, changes in SCFAs and pH for mamaku groups were less prominent than for inulin and guar gum control groups, suggesting lower fermentability of mamaku gum compared to the latter two. Furthermore, mamaku gum altered the composition of colonic microbiota, specifically reducing the ratio of Firmicutes to Bacteroidetes and increasing the relative abundance of Bacteroides, Enterococcus, Paraprevotella and Parabacteroides genera. No obvious difference between mamaku gum samples from stage 1, 2 and 3 was observed during fermentation. Collectively, these results suggest that mamaku gum may modulate the functionality of the host gut by reducing enzyme activity, binding bile acids, altering the colonic microbial composition and producing SCFAs.

Structural characterization of a fucoidan from Ascophyllum nodosum and comparison of its protective effect against cellular oxidative stress with its analogues

In the present study, a fucoidan fraction (ANP-3) was isolated from Ascophyllum nodosum, and the combined application of desulfation, methylation, HPGPC, HPLC-MSn, FT-IR, GC-MS, NMR, and Congo red test elucidated ANP-3 (124.5 kDa) as a triple-helical sulfated polysaccharide constituted by →2)-α-Fucp3S-(1→, →3)-α-Fucp2S4S-(1→, →3,6)-β-Galp4S-(1→, →3,6)-β-Manp4S-(1→, →3,6)-β-Galp4S-(1→，→6)-β-Manp-(1→, →3)-β-Galp-(1→, α-Fucp-(1→, and α-GlcAp-(1→ residues. To better understand the relationship between the fucoidan structure of A. nodosum and protective effects against oxidative stress, two fractions ANP-6 and ANP-7 were used as contrast. ANP-6 (63.2 kDa) exhibited no protective effect against H2O2-induced oxidative stress. However, ANP-3 and ANP-7 with the same molecular weight of 124.5 kDa could protect against oxidative stress by down-regulating reactive oxygen species (ROS) and malondialdehyde (MDA) levels and up-regulating total antioxidant capability (T-AOC), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities. Then metabolites analysis indicated that arginine biosynthesis and phenylalanine, tyrosine, and tryptophan biosynthesis metabolic pathways and metabolic biomarkers such as betaine were involved in the effects of ANP-3 and ANP-7. The better protective effect of ANP-7 compared to that of ANP-3 could be attributed to its relatively higher molecular weight, sulfate substitution and →6)-β-Galp-(1→ content, and lower uronic acid content.

Structural Characterization and In Vitro Antioxidant, Hypoglycemic and Hypolipemic Activities of a Natural Polysaccharide from Liupao Tea

This study extracted and purified a natural polysaccharide (TPS-5) that has a molecular weight of 48.289 kDa from Liupao tea, a typical dark tea with many benefits to human health. TPS-5 was characterized as a pectin-type acidic polysaccharide. It has a backbone composed of → 2,4)- α- L-Rhap-(1) → 4)- α- D-GalAp-(1) →, with a branch composed of → 5)- α- L-Ara-(1 → 5,3)- α- L-Ara-(1 → 3)- β- D-Gal-(1 → 3,6)- β- D-Galp-(1) →. The in vitro biological activity evaluation illustrated that TPS-5 has free radical scavenging, ferric-ion-reducing, digestive enzyme inhibitory, and bile-salt-binding abilities. These results suggest that TPS-5 from Liupao tea has potential applications in functional foods or medicinal products.

Laminaria Japonica Polysaccharide Improved the Productivities and Systemic Health of Ducks by Mediating the Gut Microbiota and Metabolome

This study investigated the beneficial effects of a Laminaria japonica polysaccharide (LJPS) on the systemic health of ducks by modulating the gut microbiome and metabolome. Our findings demonstrated that the LJPS supplementation enhanced the overall growth performance and physiological immune and antioxidant index of ducks. In addition, the LJPS-fed group significantly increased abundances of intestinal Bacteroides and Prevotellaceae with decreased α-diversity than that in the control group. Among the total of 1840 intestinal metabolites, 186 metabolites were identified to be differentially regulated by LJPS feeding (upregulated 143 metabolites and downregulated 43 metabolites), which is closely associated with some of the growth-related metabolic pathways. Lastly, the correlation analysis recapitulates that the beneficial effects of LJPS underlie the alterations in intestinal microbiota and metabolites. Taken together, LJPS supplementation improved the physiological parameters and richness of some beneficial microbes and upregulated certain metabolic pathways, which facilitated better productivities and systemic health of ducks.

In vitro effects of two polysaccharide fractions from Laminaria japonica on gut microbiota and metabolome

To investigate the prebiotic potential of two Laminaria japonica polysaccharide (LJP) fractions with different molecular weights and structures, we conducted in vitro simulated digestion and fermentation with hyperlipidemia-associated human gut microbiota. The results indicated that the LJP fraction with higher molecular weight (HLJP) appeared to have a more complex monosaccharide composition and microstructure than did the LJP fraction with lower molecular weight (LLJP), and both fractions could not be digested by in vitro simulated digestion. After in vitro fermentation, HLJP generated more short-chain fatty acids (SCFAs) and showed stronger ability to regulate core metabolites. Intriguingly, LLJP is better at promoting the proliferation of Akkermansiaceae, while HLJP is more effective in reducing the Firmicutes/Bacteroidetes ratio and increasing the content of Bacteroidaceae and Tannerellaceae. The present study indicates that LLJP and HLJP may have probiotic effects through different approaches and these differences may be related to the molecular weight and structure of the polysaccharides.

Releasing Bioactive Compounds from Brown Seaweed with Novel Cold-Adapted Alginate Lyase and Alcalase

Seaweeds are considered to be third-generation renewable biomasses, the comprehensive utilization of which has drawn increasing attention in recent years. A novel cold-active alginate lyase (VfAly7) was identified from Vibrio fortis and biochemically characterized for brown seaweed utilization. The alginate lyase gene was high-level expressed in Pichia pastoris, with an enzyme yield of 560 U/mL and a protein content of 9.8 mg/mL by high-cell density fermentation. The recombinant enzyme was most active at 30 °C and pH 7.5, respectively. VfAly7 was a bifunctional alginate lyase with both poly-guluronate and poly-mannuronate hydrolysis activities. On the basis of VfAly7, a bioconversion strategy for the utilization of brown seaweed (Undaria pinnatifida) was developed. The obtained AOSs showed stronger prebiotic activity towards tested probiotics when compared to that of commercial fructooligosaccharides (FOSs), while the obtained protein hydrolysates displayed strong xanthine oxidase inhibitory activity with IC50 of 3.3 mg/mL. This study provided a novel alginate lyase tool as well as a biotransformation route for the utilization of seaweeds.

Metagenomic Insights into the Anti-Obesity Effect of a Polysaccharide from Saccharina japonica

Saccharina japonica polysaccharides exhibit great potential to be developed as anti-obesity and prebiotic health products, but the underlying mechanism has not been adequately addressed. In this study, we investigated the potential mechanism of a S. japonica polysaccharide fraction (SjC) in preventing high-fat-diet (HFD)-induced obesity in mice using 16S rRNA gene and shotgun metagenomic sequencing analysis. SjC was characterized as a 756 kDa sulfated polysaccharide and 16 weeks of SjC supplementation significantly alleviated HFD-induced obesity, insulin resistance, and glucose metabolism disorders. The 16S rRNA and metagenomic sequencing analysis demonstrated that SjC supplementation prevented gut microbiota dysbiosis mainly by regulating the relative abundance of Desulfovibrio and Akkermansia. Metagenomic functional profiling demonstrated that SjC treatment predominantly suppressed the amino acid metabolism of gut microbiota. Linking of 16S rRNA genes with metagenome-assembled genomes indicated that SjC enriched at least 22 gut bacterial species with fucoidan-degrading potential including Desulfovibrio and Akkermansia, which showed significant correlations with bodyweight. In conclusion, our results suggest that SjC exhibits a promising potential as an anti-obesity health product and the interaction between SjC and fucoidan-degrading bacteria may be associated with its anti-obesity effect.

Effect of physiological pH on the molecular characteristics, rheological behavior, and molecular dynamics of κ-carrageenan/casein

Introduction

During gastrointestinal digestion, κ-carrageenan (κ-CGN) undergoes physicochemical changes, which associated with the risk of colitis.

Methods

To understand the effect of physiological pH on the conformational transition and binding stability of κ-CGN and κ-carrageenan/casein (κ-CC), we conducted experiments at pH 3.0 (gastric environment) and pH 7.0 (intestinal environment). We evaluated zeta potential, free sulfate group content, Fourier transform infrared spectroscopy, thermodynamic properties, microstructure, and molecular mechanism.

Results and Discussion

Our results revealed that the helical conformation of κ-CGN and κ-CC were more ordered and stable, and sulfate group exposure both lower in the intestinal environment (pH 7.0). However, in gastric environment (pH 3.0), the charge density of κ-CGN decreased, accompanied by random curling conformation and free sulfate group content increased. In contrast, the intermolecular interactions between κ-CGN and casein increased in gastric acid environments due to casein flocculation and secondary structure folding, and significantly reduced the exposure of free sulfate groups of κ-CGN. Our research results provide an important theoretical basis for elucidating the molecular mechanism and structure-activity relationship of κ-CGN under casein matrix to protect the mucosal barrier and inhibit colitis, and are of great significance for guiding and expanding the safe application of κ-CGN, thus assisting food nutrition to be absorbed.

Antioxidant and anti-aging activities of Laminaria japonica polysaccharide in Caenorhabditis elegans based on metabonomic analysis

In this study, Laminaria japonica polysaccharide (LJP) was measured in vitro against three antioxidant indicators: DPPH, ABTS, and hydroxyl. In vivo, LJP investigated thermal tolerance, H2O2-induced oxidative stress tolerance, and lipofuscin in Caenorhabditis elegans (C. elegans). Following that, after LJP treatment, the effects and underlying mechanisms were investigated at the mRNA and metabolite levels. We discovered the free radical scavenging activity of LJP. The thermal tolerance of C. elegans improved significantly, lowering levels of malondialdehyde, lipofuscin, and reactive oxygen species. Upregulation of Glp-1, Daf-16, Skn-1, and Sod-3 expression and downregulation of Age-1 and Daf-2 expression increased the ability to resist oxidative stress. Metabolomic analysis revealed that LJP promoted alanine, aspartate, and glutamate metabolism, the TCA cycle, butanoate metabolism, and the FOXO signaling pathway expression, resulting in significant changes in (R)-3-hydroxybutyric acid, palmitic acid, L-glutamic acid, L-malic acid, and oleic acid. The present study shows that LJP, as a functional food, has the potential to boost antioxidant capacity and delay aging.

Two Polysaccharides from Liupao Tea Exert Beneficial Effects in Simulated Digestion and Fermentation Model In Vitro

Liupao tea is an important dark tea, but few studies on purified Liupao tea polysaccharide (TPS) are reported in the literature. In this study, two TPSs, named TPS2 and TPS5, with molecular weights of 70.5 and 133.9 kDa, respectively, were purified from Liupao tea. TPS2 contained total sugar content (53.73% ± 1.55%) and uronic acid content (35.18% ± 0.96%), while TPS5 was made up of total sugar (51.71% ± 1.1%), uronic acid (40.95% ± 3.12%), polyphenols (0.43% ± 0.03%), and proteins (0.11% ± 0.07%). TPS2 and TPS5 were composed of Man, Rha, GlcA, Glc, Gal, and Ara in the molar ratios of 0.12:0.69:0.20:0.088:1.60:0.37 and 0.090:0.36:0.42:0.07:1.10:0.16, respectively. The effects of TPS2 and TPS5 on digestion and regulation of gut microbiota in hyperlipidemic rats were compared. In simulated digestion, TPS5 was degraded and had good antioxidant effect, whereas TPS2 was not affected. The bile acids binding capacities of TPS2 and TPS5 were 42.79% ± 1.56% and 33.78% ± 0.45%, respectively. During in vitro fermentation, TPS2 could more effectively reduce pH, promote the production of acetic acid and propionic acid, and reduce the ratio of Firmicutes to Bacteroidetes. TPS5 could more effectively promote the production of butyric acid and increase the abundance of genus Bacteroides. Results indicate that polysaccharides without polyphenols and proteins have better antidigestibility and bile acid binding. Meanwhile, polysaccharides with polyphenols and proteins have a better antioxidant property. Both have different effects on the gut microbiota.

Research Progress on the Protective Effect of Brown Algae-Derived Polysaccharides on Metabolic Diseases and Intestinal Barrier Injury

In the human body, the intestine is the largest digestive and immune organ, where nutrients are digested and absorbed, and this organ plays a key role in host immunity. In recent years, intestinal health issues have gained attention and many studies have shown that oxidative stress, inflammation, intestinal barrier damage, and an imbalance of intestinal microbiota may cause a range of intestinal diseases, as well as other problems. Brown algae polysaccharides, mainly including alginate, fucoidan, and laminaran, are food-derived natural products that have received wide attention from scholars owing to their good biological activity and low toxic side effects. It has been found that brown algae polysaccharides can repair intestinal physical, chemical, immune and biological barrier damage. Principally, this review describes the protective effects and mechanisms of brown algae-derived polysaccharides on intestinal health, as indicated by the ability of polysaccharides to maintain intestinal barrier integrity, inhibit lipid peroxidation-associated damage, and suppress inflammatory cytokines. Furthermore, our review aims to provide new ideas on the prevention and treatment of intestinal diseases and act as a reference for the development of fucoidan as a functional product for intestinal protection.

Polymeric Compounds of Lingonberry Waste: Characterization of Antioxidant and Hypolipidemic Polysaccharides and Polyphenol-Polysaccharide Conjugates from Vaccinium vitis-idaea Press Cake

Lingonberry (Vaccinium vitis-idaea L.) fruits are important Ericaceous berries to include in a healthy diet of the Northern Hemisphere as a source of bioactive phenolics. The waste generated by the V. vitis-idaea processing industry is hard-skinned press cake that can be a potential source of dietary fiber and has not been studied thus far. In this study, water-soluble polysaccharides of V. vitis-idaea press cake were isolated, separated, and purified by ion-exchange and size-exclusion chromatography. The results of elemental composition, monosaccharide analysis, ultraviolet–visible and Fourier-transform infrared spectroscopy, molecular weight determination, linkage analysis, and alkaline destruction allowed us to characterize two polyphenol–polysaccharide conjugates (PPC) as neutral arabinogalactans cross-linked with monomeric and dimeric hydroxycinnamate residues with molecular weights of 108 and 157 kDa and two non-esterified galacturonans with molecular weights of 258 and 318 kDa. A combination of in vitro and in vivo assays confirmed that expressed antioxidant activity of PPC was due to phenolic-scavenged free radicals, nitrogen oxide, hydrogen peroxide, and chelate ferrous ions. Additionally, marked hypolipidemic potential of both PPC and acidic polymers bind bile acids, cholesterol, and fat, inhibit pancreatic lipase in the in vitro study, reduce body weight, serum level of cholesterol, triglycerides, low/high-density lipoprotein–cholesterol, and malondialdehyde, and increase the enzymatic activity of superoxide dismutase, glutathione peroxidase, and catalase in the livers of hamsters with a 1% cholesterol diet. Polysaccharides and PPC of V. vitis-idaea fruit press cake can be regarded as new antioxidants and hypolipidemic agents that can be potentially used to cure hyperlipidemic metabolic disorders.

Two Laminaria japonica polysaccharides with distinct structure characterization affect gut microbiota and metabolites in hyperlipidemic mice differently

Our previous study found dietary mannogluconic acid (MA) and fucogalactan sulfate (FS) from Laminaria japonica have distinct structure characterization and potential hypolipidemic effects in vitro. Herein, we compared the benefits of MA and FS on hyperlipidemia. The result showed only FS treatment decreased body weight and serum cholesterol levels. Compared with MA, FS was more effective in mitigating hepatic fat accumulation, promoting GSH-Px activity, reducing the MDA formation, and lowering the level of TNF-α in liver. Gut microbiota and metabolism analysis revealed that FS increased the relative abundance of beneficial bacteria and boosted the level of short chain fatty acids. Particularly, taurine and 3α,7α,12α-trihydroxy-24-oxo-5-β-cholestanoyl CoA were upregulated by FS, which might attribute to the increased Oscillibacter and thus affect the enterohepatic circulation of bile acids and serum TC level. Therefore, FS with more branches and sulfate ester groups could be a good lipid-lowering dietary supplement.

Saccharina japonica fucan suppresses high fat diet-induced obesity and enriches fucoidan-degrading gut bacteria

Low molecular weight seaweed polysaccharides exhibit promising potential as novel therapeutics for the prevention of obesity and gut microbiota dysbiosis. The interplay between polysaccharides and gut microbiota may play crucial roles in their anti-obesity effects, but is largely unknown, including the impact of polysaccharides on the composition of the gut microbiota with polysaccharide-degrading capacity. The primary structure of a 5.1 kDa fucan (J2H) from Saccharina japonica was characterized and oral administration of J2H effectively suppressed high-fat diet-induced obesity, blood glucose metabolic dysfunction, dyslipidemia, and gut microbiota dysbiosis. Furthermore, the Jensen-Shannon divergence analysis demonstrated that J2H enriched at least four gut bacterial species with fucoidan-degrading potential, including Bacteroides sartorii and Bacteroides acidifaciens. Our findings suggest that the low molecular weight S. japonica fucan, J2H, is a promising potential agent for obesity prevention and its enrichment of gut bacteria with fucoidan-degrading potential may play a vital role in the anti-obesity effects.

Two Ascophyllum nodosum Fucoidans with Different Molecular Weights Inhibit Inflammation via Blocking of TLR/NF-κB Signaling Pathway Discriminately

The present study aimed to clarify the potential mechanism of fucoidans found in Ascophyllum nodosum on anti-inflammation and to further explore the relationship between their structures and anti-inflammation. Two novel fucoidans named ANP-6 and ANP-7 and found in A. nodosum, were separated and purified and their structures were elucidated by HPGPC, HPLC, GC-MS, FT-IR, NMR, and by the Congo red test. They both possessed a backbone constructed of →2)-α-L-Fucp4S-(1→, →3)-α-L-Fucp2S4S-(1→, →6)-β-D-Galp-(1→, and →3,6)-β-D-Galp4S-(1→ with branches of →2)-α-L-Fucp4S-(1→ and →3)-β-D-Galp-(1→. Moreover, ANP-6 and ANP-7 could prevent the inflammation of the LPS-stimulated macrophages by suppressing the NO production and by regulating the expressions of iNOS, COX-2, TNF-α, IL-1β, IL-6, and IL-10. Their inhibitory effects on the TLR-2 and TLR-4 levels suggest that they inhibit the inflammation process via the blocking of the TLR/NF-κB signal transduction. In addition, ANP-6, with a molecular weight (63.2 kDa), exhibited stronger anti-inflammatory capabilities than ANP-7 (124.5 kDa), thereby indicating that the molecular weight has an influence on the anti-inflammatory effects of fucoidans.

Studies on the partial characterization of extracted glycosaminoglycans from fish waste and its potentiality in modulating obesity through in-vitro and in-vivo

Glycosaminoglycans (GAGs) are bioactive polysaccharides or glycoconjugates found in the fish waste having significant health impacts. In the present study it has been attempted to extract GAGs from mackerel fish waste through chemical and enzymatic methods. Further, the extracted GAGs (e-GAGs) were analyzed for their composition (uronic acid, total sugar & sulfate), chemical characterization was carried out through techniques of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) & Proton NMR. Further, probable major GAGs present was identified by enzymatic digestion. The biological potential of the extracted glycoconjugate was assessed further through in-vitro and in-vivo studies. In-vitro biological activity showed good lipase inhibition (IC₅₀, 2.6 mg/mL) and bile acid binding properties (dose-dependent). Lipid accumulation lowered in the e-GAGs differentiated 3T3L1 preadipocyte cells have also been observed. The high fat fed animal (in-vivo) study showed ameliorative effect via reducing blood sugar∼1.28↓, lipid profile↓, plasma insulin∼3.5↓, improved glucose tolerance, and homeostatic model assessment for insulin resistance (HOMA-IR, ∼3.0↓). Furthermore, elimination of bile acid (BA) due to GAG-BA binding properties resultant in removal of elevated fecal triglyceride and cholesterol suggesting its lipid lowering activity. Regulation of various proteins linked to carbohydrate and lipid metabolism including fatty acid synthase (FAS), low density lipoproteins receptor (LDL-R), 7α-hydroxylase, glucose transporter-4 (GLUT4) and Peroxisome proliferator- activated receptor gamma (PPAR-γ) were significant (p < 0.05) with e-GAGs treatment when compared to HFD group. Thus, the e-GAGs showed potential hypolipidemic activity through elimination of bile acid binding property together with regulating the specific protein related to obesity and its associated complications.

Structural characterization and anti-inflammatory activity of a pectin polysaccharide HBHP-3 from Houttuynia cordata

In this study, a hot buffer soluble Houttuynia cordata polysaccharide (HBHP-3) with a molecular weight of 397.4 kDa was isolated from H. cordata. HBHP-3 was composed of rhamnose, arabinose, glucose, galactose and galacturonic acid with molar ratio of 16.0:12.6:4.6:18.1:15.6. Structural analysis showed that the main chain of HBHP-3 was composed of →2)-α-L-Rhap-(1→, →4)-α-D-GalpA-(1→ and →4)-β-D-Galp-(1→. There were branched chains of α-L-Araf-(1→, →5)-α-L-Araf-(1→, →4)-α-D-Glcp-(1→, →6)-β-D-Galp-(1→, β-D-Galp-(1→ connected to the O-4 positions of →2)-α-L-Rhap-(1→. HBHP-3 effectively inhibited the secretion of NO and the mRNA expression of pro-inflammatory cytokines in a dose-dependent manner in macrophages. HBHP-3 inhibited the phosphorylation of p65 and IκBα proteins as well, illustrating that HBHP-3 exerted its anti-inflammatory activity by inhibiting the activation of NF-κB pathway.

Nutritional and Chemical Composition of Sargassum zhangii and the Physical and Chemical Characterization, Binding Bile Acid, and Cholesterol-Lowering Activity in HepG2 Cells of Its Fucoidans

Fucoidan is a marine sulfated polysaccharide that is rich in Sargassum and has a wide range of biological activities. In this study, the chemical composition and bile acid binding ability of six crude fucoidans were compared, the nutrition and chemical composition of Sargassum zhangii were analyzed, and fucoidan from Sargassum zhangii was extracted and purified. The purified fractions (ZF1, ZF2, and ZF3) were analyzed by physicochemical characterization, and the ability of binding bile acid and cholesterol lowering in HepG2 cells were evaluated. The results showed that the contents of sulfate in crude fucoidan from Sargassum Zhangii (ZF) was as high as13.63%. Its ability of binding bile acid was better than other five crude fucoidans. Sargassum zhangii was a kind of brown seaweed with high carbohydrate, and low fat and rich in minerals. The sulfate content of ZF1, ZF2, and ZF3 was 3.29%, 19.39%, and 18.89% respectively, and the molecular weight (Mw) was 4.026 × 10⁵, 2.893 × 10⁵, and 3.368 × 10⁵, respectively. Three fucoidans all contained the characteristic absorption bands of polysaccharides and sulfate groups and were rich in fucose. Three fucoidans can bind to bile acid, and ZF2 showed the best binding capability. In vitro experiments showed that ZF1, ZF2, and ZF3 could reduce intracellular total cholesterol (TC) content in HepG2 cells without affecting their viability. ZF2 showed the best ability to reduce TC.

Dietary Macroalgae Saccharina japonica Ameliorates Liver Injury Induced by a High-Carbohydrate Diet in Swamp Eel (Monopterus albus)

A high-carbohydrate diet lowers the rearing cost and decreases the ammonia emission into the environment, whereas it can induce liver injury, which can reduce harvest yields and generate economic losses in reared fish species. Macroalgae Saccharina japonica (SJ) has been reported to improve anti-diabetic, but the protective mechanism of dietary SJ against liver injury in fish fed a high-carbohydrate diet has not been studied. Therefore, a 56-day nutritional trial was designed for swamp eel Monopterus albus, which was fed with the normal diet [20% carbohydrate, normal carbohydrate (NC)], a high carbohydrate diet (32% carbohydrate, HC), and a HC diet supplemented with 2.5% SJ (HC-S). The HC diet promoted growth and lowered feed coefficient (FC), whereas it increased hepatosomatic index (HSI) when compared with the NC diet in this study. However, SJ supplementation increased iodine contents in muscle, reduced HSI, and improved liver injury, such as the decrease of glucose (GLU), total bile acid (TBA), and alanine aminotransferase (ALT) in serum, and glycogen and TBA in the liver. Consistently, histological analysis showed that SJ reduced the area of lipid droplet, glycogen, and collagen fiber in the liver (p < 0.05). Thoroughly, the underlying protective mechanisms of SJ supplementation against HC-induced liver injury were studied by liver transcriptome sequencing coupled with pathway analysis. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the differentially expressed genes (DEGs), such as the acetyl-coenzyme A synthetase (acss1), alcohol dehydrogenase (adh), interferon-induced protein with tetratricopeptide repeats 1 (ifit1), aldo-keto reductase family 1 member D1 (akr1d1), cholesterol 7-alpha-monooxygenase (cyp7a1), and UDP-glucuronosyltransferase (ugt), indicated that the pathway of glycolysis/gluconeogenesis was the main metabolic pathway altered in the HC group compared with the NC group. Meanwhile, hepatitis C, primary BA biosynthesis, and drug metabolism-cytochrome P450 were the three main metabolic pathways altered by SJ supplementation when compared with the HC group. Moreover, the BA-targeted metabolomic analysis of the serum BA found that SJ supplementation decreased the contents of taurohyocholic acid (THCA), taurochenodeoxycholic acid (TCDCA), taurolithocholic acid (TLCA), nordeoxycholic acid (NorDCA), and increased the contents of ursocholic acid (UCA), allocholic acid (ACA), and chenodeoxycholic acid (CDCA). In particular, the higher contents of UCA, ACA, and CDCA regulated by SJ were associated with lower liver injury. Overall, these results indicate that the 2.5% supplementation of SJ can be recommended as a functional feed additive for the alleviation of liver injury in swamp eel-fed high-carbohydrate diets.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Gut Microbiota of Individuals Could Be Balanced by a 14-Day Supplementation With Laminaria japonica and Differed in Metabolizing Alginate and Galactofucan

Laminaria japonica is rich in alginate (Alg) and galactofucan (GF) which have both been reported to regulate gut microbiota composition. To reveal the effect of L. japonica on human gut microbiota, the fecal microbiota of 12 volunteers before and after 14-day L. japonica intake was sequenced and compared, and the capabilities of the gut microbiota to utilize Alg and GF were also investigated. The 16S rRNA gene sequencing results demonstrated that Firmicutes/Bacteroidetes ratio could be balanced by L. japonica supplementation. The ability of gut microbiota to utilize Alg was significantly enhanced by L. japonica supplementation. Furthermore, the multiple linear regression analysis suggested that bacteria from Bacteroidaceae and Ruminococcaceae were positively correlated with Alg utilization while those from Erysipelotrichaceae, Bacteroidaceae, and Prevotellaceae participated in GF degradation. Moreover, the production of acetic acid and the total short-chain fatty acids (SCFAs) in fermentation were consistent with the consumption of Alg or GF, and propionic acid content was positively correlated with Alg consumption. In addition, the percentage of monosaccharides in the consumed GF after the fermentation suggested that gut microbiota from individuals could consume GF with different monosaccharide preferences. These findings shed a light on the impacts of dietary L. japonica on human health.

Physicochemical Properties and Anticoagulant Activity of Purified Heteropolysaccharides from Laminaria japonica

Laminaria japonica is widely consumed as a key food and medicine. Polysaccharides are one of the most plentiful constituents of this marine plant. In this study, several polysaccharide fractions with different charge numbers were obtained. Their physicochemical properties and anticoagulant activities were determined by chemical and instrumental methods. The chemical analysis showed that Laminaria japonica polysaccharides (LJPs) and the purified fractions LJP0, LJP04, LJP06, and LJP08 mainly consisted of mannose, glucuronic acid, galactose, and fucose in different mole ratios. LJP04 and LJP06 also contained minor amounts of xylose. The polysaccharide fractions eluted by higher concentration of NaCl solutions showed higher contents of uronic acid and sulfate group. Biological activity assays showed that LJPs LJP06 and LJP08 could obviously prolong the activated partial thromboplastin time (APTT), indicating that they had strong anticoagulant activity. Furthermore, we found that LJP06 exerted this activity by inhibiting intrinsic factor Xase with higher selectivity than other fractions, which may have negligible bleeding risk. The sulfate group may play an important role in the anticoagulant activity. In addition, the carboxyl group and surface morphology of these fractions may affect their anticoagulant activities. The results provide information for applications of L. japonica polysaccharides, especially LJP06 as anticoagulants in functional foods and therapeutic agents.

Structural Characteristics and Immunomodulatory Effects of a Long-Chain Polysaccharide From Laminaria japonica

Polysaccharides derived from Laminaria japonica (LJPS) have shown a variety of beneficial effects on improving human health; however, the structural features and bioactivities of long-chain LJPS remain unclear. This study aimed to investigate the structural characteristics and bioactivities of a novel long-chain LJPS. Results showed that the LJPS was composed of Fuc, Rha, Ara, Gal, Glc, Xyl, Man, Fru, Rib, GalA, GluA, GlcA, and ManA, with a molar ratio of 35.71:1.48:0.28:13.16:0.55:2.97:6.92:0.58:0.41:0.14:3.16:15.84:18.79. Of these, Fuc, Gal, Man, GlcA, and ManA were the predominant components with an accumulated proportion of 93.6%. The LJPS was found to consist of seven types of the monomer residues, and the main interchain glycosidic linkages were β -D-(1 → 2), α -D-(1 → 3), (1 → 4), and (1 → 6), and the molecular mass was 5.79 × 10⁴ g/mol. Regarding the molecular conformation, LJPS was a multi-branched, long-chain macromolecule, and appeared in a denser crosslinking network with highly branched and helix domains in the terms of morphology. Additionally, the LJPS had no toxicity to mouse macrophage cells and exhibited biphasic immuno-modulating capacity. The present findings suggested that the long-chain LJPS might be an attractive candidate as an immunopotentiating and anti-inflammatory functional food, and this study also provides a feasible approach to decipher the structural characteristics and spatial conformations of plant-derived polysaccharides.

Bile Acid Sequestrants for Hypercholesterolemia Treatment Using Sustainable Biopolymers: Recent Advances and Future Perspectives

Bile acids, the endogenous steroid nucleus containing signaling molecules, are responsible for the regulation of multiple metabolic processes, including lipoprotein and glucose metabolism to maintain homeostasis. Within our body, they are directly produced from their immediate precursors, cholesterol C (low-density lipoprotein C, LDL-C), through the enzymatic catabolic process mediated by 7-α-hydroxylase (CYP7A1). Bile acid sequestrants (BASs) or amphiphilic resins that are nonabsorbable to the human body (being complex high molecular weight polymers/electrolytes) are one of the classes of drugs used to treat hypercholesterolemia (a high plasma cholesterol level) or dyslipidemia (lipid abnormalities in the body); thus, they have been used clinically for more than 50 years with strong safety profiles as demonstrated by the Lipid Research Council-Cardiovascular Primary Prevention Trial (LRC-CPPT). They reduce plasma LDL-C and can slightly increase high-density lipoprotein C (HDL-C) levels, whereas many of the recent clinical studies have demonstrated that they can reduce glucose levels in patients with type 2 diabetes mellitus (T2DM). However, due to higher daily dosage requirements, lower efficacy in LDL-C reduction, and concomitant drug malabsorption, research to develop an "ideal" BAS from sustainable or natural sources with better LDL-C lowering efficacy and glucose regulations and lower side effects is being pursued. This Review discusses some recent developments and their corresponding efficacies as bile removal or LDL-C reduction of natural biopolymer (polysaccharide)-based compounds.

Protective Effects of Natural Polysaccharides on Intestinal Barrier Injury: A Review

Owing to their minimal side effects and effective protection from oxidative stress, inflammation, and malignant growth, natural polysaccharides (NPs) are a potential adjuvant therapy for several diseases caused by intestinal barrier injury (IBI). More studies are accumulating on the protective effects of NPs with respect to IBI, but the underlying mechanisms remain unclear. Thus, this review aims to represent current studies that investigate the protective effects of NPs on IBI by directly maintaining intestinal epithelial barrier integrity (inhibiting oxidative stress, regulating inflammatory cytokine expression, and increasing tight junction protein expression) and indirectly regulating intestinal immunity and microbiota. Furthermore, the mechanisms underlying IBI development are briefly introduced, and the structure-activity relationships of polysaccharides with intestinal barrier protection effects are discussed. Potential developments and challenges associated with NPs exhibiting protective effects against IBI have also been highlighted to guide the application of NPs in the treatment of intestinal diseases caused by IBI.