Extracellular polysaccharide with novel structure and antioxidant property produced by the deep-sea fungus Aspergillus versicolor N 2 bc

Advances in Research on Marine-Derived Lipid-Lowering Active Substances and Their Molecular Mechanisms

Hyperlipidemia (HLP) is a metabolic disorder caused by abnormal lipid metabolism. Recently, the prevalence of HLP caused by poor dietary habits in the population has been increasing year by year. In addition, lipid-lowering drugs currently in clinical use have shown significant improvement in blood lipid levels, but are accompanied by certain side effects. However, bioactive marine substances have been shown to possess a variety of physiological activities such as hypoglycemic, antioxidant, antithrombotic and effects on blood pressure. Therefore, the hypolipidemic efficacy of marine bioactive substances with complex and diverse structures has also attracted attention. This paper focuses on the therapeutic role of marine-derived polysaccharides, unsaturated fatty acids, and bioactive peptides in HLP, and briefly discusses the main mechanisms by which these substances exert their hypolipidemic activity in vivo.

A New Exopolysaccharide of Marine Coral-Associated Aspergillus pseudoglaucus SCAU265: Structural Characterization and Immunomodulatory Activity

Recent studies have found that many marine microbial polysaccharides exhibit distinct immune activity. However, there is a relative scarcity of research on the immunomodulatory activity of marine fungal exopolysaccharides. A novel water-soluble fungal exopolysaccharide ASP-1 was isolated from the fermentation broths of marine coral-associated fungus Aspergillus pseudoglaucus SCAU265, and purified by Diethylaminoethyl-Sepharose-52 (DEAE-52) Fast Flow and Sephadex G-75. Structural analysis revealed that ASP-1 had an average molecular weight of 36.07 kDa and was mainly composed of (1→4)-linked α-D-glucopyranosyl residues, along with highly branched heteropolysaccharide regions containing 1,4,6-glucopyranosyl, 1,3,4-glucopyranosyl, 1,4,6-galactopyranosyl, T(terminal)-glucopyranosyl, T-mannopyranosyl, and T-galactopyranosyl residues. ASP-1 demonstrated significant effects on the proliferation, nitric oxide levels, and the secretion of cytokines TNF-α and IL-6 in macrophage RAW264.7 cells. Metabolomic analysis provided insights into the potential mechanisms of the immune regulation of ASP-1, suggesting its involvement in regulating immune function by modulating amino acid anabolism, particularly arginine synthesis and metabolism. These findings provide fundamental scientific data for further research on its accurate molecular mechanism of immunomodulatory activity.

Marine Microbial Polysaccharides: An Untapped Resource for Biotechnological Applications

As the largest habitat on Earth, the marine environment harbors various microorganisms of biotechnological potential. Indeed, microbial compounds, especially polysaccharides from marine species, have been attracting much attention for their applications within the medical, pharmaceutical, food, and other industries, with such interest largely stemming from the extensive structural and functional diversity displayed by these natural polymers. At the same time, the extreme conditions within the aquatic ecosystem (e.g., temperature, pH, salinity) may not only induce microorganisms to develop a unique metabolism but may also increase the likelihood of isolating novel polysaccharides with previously unreported characteristics. However, despite their potential, only a few microbial polysaccharides have actually reached the market, with even fewer being of marine origin. Through a synthesis of relevant literature, this review seeks to provide an overview of marine microbial polysaccharides, including their unique characteristics. In particular, their suitability for specific biotechnological applications and recent progress made will be highlighted before discussing the challenges that currently limit their study as well as their potential for wider applications. It is expected that this review will help to guide future research in the field of microbial polysaccharides, especially those of marine origin.

Polysaccharide isolated from wax apple suppresses ethyl carbamate-induced oxidative damage in human hepatocytes

Wax apple (Syzygium samarangense) has received growing research interest for its high nutritional and medicinal value due to its constituents such as polysaccharide, organic acids, flavonoids, minerals, and other substances. In this study, wax apple polysaccharide (WAP) was isolated from this plant and its protective effect against ethyl carbamate (EC)‍-induced oxidative damage was evaluated in human hepatocytes (L02 cells). Firstly, a series of analyses such as high-performance liquid chromatography (HPLC), high-performance gel permeation chromatography (HPGPC), Fourier transform infrared spectroscopy (FT-IR), gas chromatography/mass spectrometry (GC/MS), and 1H and 13C nuclear magnetic resonance (NMR) were conducted to identify the structure of WAP. Thereafter, in vitro cell experiments were performed to verify the protective effects of WAP against EC-induced cytotoxicity, genotoxicity, and oxidative damage in L02 cells. Our results revealed that WAP is composed of mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, arabinose, and fucose in a molar ratio of 2.20:‍3.94:‍4.45:‍8.56:‍8.86:‍30.82:‍39.78:‍1.48. Using a combination of methylation and NMR spectroscopic analysis, the primary structure of WAP was identified as Araf-(1→, Glcp-(1→, →2)‍-Araf-(1→, →3)‍-Galp-(1→, →3)‍-Araf-‍(1→, and →6)‍-Galp-‍(1→. Cell experiments indicated that WAP exhibited significant protective effects on EC-treated L02 cells via suppressing cytotoxicity and genotoxicity, reducing reactive oxygen species (ROS) and O2•- formation, as well as improving mitochondrial membrane potential (MMP) and glutathione (GSH). In a nutshell, WAP has the potential as an important therapeutic agent or supplement for hepatic oxidative damage. Meanwhile, further studies are needed to prove the above effects in vivo at the biological and clinical levels.

Anti-Diabetic Activity of a Novel Exopolysaccharide Produced by the Mangrove Endophytic Fungus Penicillium janthinellum N29

Marine microorganisms often produce exopolysaccharides with novel structures and diverse biological activities due to their specific marine environment. The novel active exopolysaccharides from marine microorganisms have become an important research area in new drug discovery, and show enormous development prospects. In the present study, a homogeneous exopolysaccharide from the fermented broth of the mangrove endophytic fungus Penicillium janthinellum N29, designated as PJ1-1, was obtained. The results of chemical and spectroscopic analyses showed that PJ1-1 was a novel galactomannan with a molecular weight of about 10.24 kDa. The backbone of PJ1-1 was composed of →2)-α-d-Manp-(1→, →4)-α-d-Manp-(1→, →3)-β-d-Galf-(1→ and →2)-β-d-Galf-(1→ units with partial glycosylation at C-3 of →2)-β-d-Galf-(1→ unit. PJ1-1 had a strong hypoglycemic activity in vitro, evaluated using the assay of α-glucosidase inhibition. The anti-diabetic effect of PJ1-1 in vivo was further investigated using mice with type 2 diabetes mellitus induced by a high-fat diet and streptozotocin. The results indicated that PJ1-1 markedly reduced blood glucose level and improved glucose tolerance. Notably, PJ1-1 increased insulin sensitivity and ameliorated insulin resistance. Moreover, PJ1-1 significantly decreased the levels of serum total cholesterol, triglyceride and low-density lipoprotein cholesterol, enhanced the level of serum high-density lipoprotein cholesterol and alleviated dyslipidemia. These results revealed that PJ1-1 could be a potential source of anti-diabetic agent.

Structural characterization and immunomodulatory activity of an exopolysaccharide from marine-derived Aspergillus versicolor SCAU141

Until now, relatively little is known about marine-derived fungal polysaccharides and their activities. Exopolysaccharide AVP141-A was isolated from the broth of marine-derived fungus Aspergillus versicolor SCAU141 and purified by Diethylaminoethyl-Sepharose Fast Flow and Sephadex G-100. The structural characteristics of AVP141-A was studied by chemical analysis together with high-performance gel permeation chromatography, ion chromatography, Fourier-transform infrared spectroscopy, gas chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy. The results showed that AVP141-A with the molecular weight of 5.10 kDa was mainly composed of →4)-α-D-Glcp-(1→, branched by α-D-Glcp-(1→ and →6)-α-D-Glcp-(1→ at C-6 positions of the glucan backbone. In particular, sulfate ester (approximately 3.62 %) was found in AVP141-A, which was frequently considered to occur in marine-derived microbial polysaccharides rather than other microbial polysaccharides. Furthermore, AVP141-A significantly enhanced the activity of the inflammatory factors NO, COX-2 and TNF-α in RAW264.7 macrophages by activating the MAPK/p38 and NF-κB/p65 pathways. In addition, metabolomic analysis revealed that most of the pathways with significant changes in RAW264.7 macrophages treated with AVP141-A were amino acid-related pathways, and arginine was the characteristic metabolite. In conclusion, this study identified AVP141-A as a marine fungus-derived sulfated exopolysaccharide with potential for development as an immune activator.

Characteristics of exopolysaccharides produced by isolates from natural bioflocculant of Ruditapes philippinarum conglutination mud

Three novel types of exopolysaccharides (EPS) EPS-S8, EPS-S5, and EPS-F10 were extracted and purified from bacterial isolates Bacillus sp. GHS8, Pseudoalteromonas sp. GHS5 and Psychrobacter sp. GHF10, which were originated from natural bioflocculant of Ruditapes philippinarum conglutination mud (RPM), respectively. The EPS had similar function groups C-H, N-H, C-O, and C = O. The EPS were composed of different monosaccharides (EPS-F10, Man: GlcN: GlcUA: GalUA = 1:0.66:5.75:0.51; EPS-S5, Man: Gal: GlcN: Rib = 1: 0.50: 2.94: 0.26; EPS-S8, Man: Gal: GlcN = 1:1.54:7.69). The molecular weights (Mw) of EPS were ordered as 51.4 kDa (EPS-S5) > 9.15 kDa (EPS-S8) > 4.41 kDa (EPS-F10). Three types of EPS all showed higher peak flocculation activities than the reported crude EPS from the RPM. Besides, the EPS also exhibited efficient decoloration and antioxidation activities, especially for EPS-S8, which might be due to the low Mw and specific monosaccharide composition.

Structural features of biologically active extracellular polysaccharide produced by green microalgae Dictyosphaerium chlorelloides

Ion-exchange chromatography of the biologically active extracellular biopolymer produced by D. chlorelloides yielded ten fractions differing in yield, protein content, monosaccharide composition and molecular weight distribution. Their sugar compositional analyses showed rhamnogalactans, substituted to different extent by mannose and glucose, as a dominant EPS component in all fractions (91 %) except one containing arabinogalactan (7 %). In highly branched rhamnogalactans the quantity of linear (1,3-; 1,4- and 1,6-linked) and branched β-D-galactose units (1,3,6-, 1,4,6- and 1,3,4,6-linked) was nearly equal. From various α-L-rhamnose linkages the 1,2,4-linkage was dominant. Data indicate a rhamnogalactan backbone of EPS, branched by terminal mannose and glucose units, and a lot of O-methylated derivatives of galactose residues (2-O-methyl, 2,3-O-dimethyl, 3-O-methyl and 6-O-methyl). In individual fractions their content and type varied. Detail study of the arabinogalactan showed that its backbone consists of 1,3-linked β-D-Galp units; some of them are branched through O-4 by 6-OMe-α-D-Galp- (1 → 2) -α-L-Araf side chain, other through O-6 by 3-OMe-β-D-Galp, 6-OMe-β-D-Galp, β-D-Galp and β-D-Galf.

Structural characterization and biological activities of a new polysaccharide isolated from Morchella Sextelata

Morchella is the famous medicinal fungi in the ascomycetes. In this study, a new water-soluble polysaccharide (MSP-3-1) with an average molecular weight of 2.35 × 10⁷ Da was extracted and purified from fruiting bodies of cultivated M. Sextelata. The structural characterization and biological activities of purified polysaccharide was further investigated. The results indicated that MSP-3-1 was mainly a α-glucan, mainly consisting of mannose (Man), glucose (Glc) and galactose (Gal) in a ratio of 5.10: 91.39: 3.51. Its surface morphology exhibited irregular lamellar structures with small voids. And the particle size analysis showed that MSP-3-1 was the homogeneous nanoparticle in water solution. Furthermore, the antioxidant activity analysis showed that MSP-3-1 possessed certain scavenging activity against hydroxyl radicals, DPPH radicals and ABTS radicals in a dose-dependent manner. Immunological tests suggested that MSP-3-1 could significantly promote the proliferation, phagocytosis and nitric oxide (NO) production of macrophage RAW264.7. Thus, our results will provide a theoretical basis for the development and utilization of Morchella Sextelata polysaccharides as an immunmodulatory component in functional foods.

Structural characterization and immunomodulatory activity of mycelium polysaccharide from liquid fermentation of Monascus purpureus (Hong Qu)

Alkaline extracted endopolysaccharides (MPS) from Monascus purpureus (Hong Qu) mycelium were successfully separated into four sub-fractions, namely MPS-1 (18.0 %), MPS-2 (27.1 %), MPS-3 (12.6 %) and MPS-4 (14.7 %), by DEAE-Cellulose column chromatography. By combining monosaccharide composition analysis, methylation analysis and 1D & 2D NMR, the structure of sub-fractions was systematically characterized. Both MPS-1 and MPS-2 were comprised of mannose, glucose and galactose in the molar ratio of 1.5:1.6:1.0 and 10.6:1.0:13.8, respectively. The backbone of them both consisted of 2-α-Manp with several different branched chains. However, MPS-1 contained glucose based sugar residues such as 3-Glcp and 4-Glcp which were not shown on MPS-2. The proposed structures of MPS-3 and MPS-4 were not obtained due to the fairly complex molecular structure and relatively low yield. Moreover, based on the RAW 264.7 cells model, MPS-2 could significantly promote cytokines secretion including IL-6, TNF-α, and IL-10 and improve expression levels of the related mRNA.

Quantification of schizophyllan directly from the fermented broth by ATR-FTIR and PLS regression

Non-destructive methods that allow the quantification of bioproducts in a simple and quick manner during fermentation are extremely desirable from a practical point of view. Therefore, a 9 day fermentation experiment with Schizophyllum commune was carried out to investigate the possibility of using ATR-FTIR to quantify the schizophyllan biopolymer (SPG) directly from the culture medium. On each day, aliquots of the fermentation were taken, and the cell-free supernatant was analyzed by ATR-FTIR. The main objective of this step was to evaluate whether FTIR would be able to detect the appearance of specific peaks related to the production of SPG. The results of the PCA analysis showed that there was a reasonable separation of the days through the FTIR spectra. Then PCA-LDA was applied to the same dataset, which confirmed the formation of groups for each day of fermentation, after which, a calibration and test set was developed. Through a matrix generated by an experimental design with 2 factors and 5 levels, 25 samples were created with variations in the concentration of the culture medium and SPG. The ATR-FTIR spectra of this data set were modeled using PLS regression with backward selection of predictors. The results revealed that the amount of SPG produced can be quantified directly in the culture medium with excellent precision with R²CV = 0.951, R²P = 0.970, RMECV = 0.205 g, RMSEP = 0.170 g, RPDcv = 4.53 and RPDp = 5.88. The traditional method to quantify SPG is time consuming, requires several steps and uses solvents. In contrast, the method proposed in this work is a viable, faster, and a simpler alternative, which does not use reagents and does not require extensive pre-treatment of the samples.

Antioxidant Molecules from Marine Fungi: Methodologies and Perspectives

The marine environment represents a prosperous existing resource for bioprospecting, covering 70% of the planet earth, and hosting a huge biodiversity. Advances in the research are progressively uncovering the presence of unknown microorganisms, which have evolved unique metabolic and genetic pathways for the production of uncommon secondary metabolites. Fungi have a leading role in marine bioprospecting since they represent a prolific source of structurally diverse bioactive metabolites. Several bioactive compounds from marine fungi have already been characterized including antibiotics, anticancer, antioxidants and antivirals. Nowadays, the search for natural antioxidant molecules capable of replacing those synthetic currently used, is an aspect that is receiving significant attention. Antioxidants can inactivate reactive oxygen and nitrogen species, preventing the insurgence of several degenerative diseases including cancer, autoimmune disorders, cardiovascular and neurodegenerative diseases. Moreover, they also find applications in different fields, including food preservation, healthcare and cosmetics. This review focuses on the production of antioxidants from marine fungi. We begin by proposing a survey of the available tools suitable for the evaluation of antioxidants, followed by the description of various classes of marine fungi antioxidants together with their extraction strategies. In addition, a view of the future perspectives and trends of these natural products within the "blue economy" is also presented.

Effect of the structural characterization of the fungal polysaccharides on their immunomodulatory activity

The immunomodulatory effects of the four extracellular polysaccharides, namely WPA, WPB, AP2A, and TP1A, which were isolated from the fermented broth of Aspergillus aculeatus, A. terreus and Trichoderma sp. KK19L1, were investigated in vitro. WPA, WPB, AP2A, and TP1A were not toxic to RAW264.7 cells. These polysaccharides enhanced cell viability. WPA, WPB, AP2A, and TP1A showed increased immunomodulatory effect by strengthening the phagocytic activity and enhancing the release of NO, TNF-α and IL-6 from RAW264.7 cells. WPA, WPB, AP2A, and TP1A exhibited different immunomodulatory activity in vitro due to their different structural characterizations, and their immunoregulatory effects decreased successively in the following order: WPA, WPB, AP2A, and TP1A. The extracellular polysaccharides WPA, WPB, AP2A, and TP1A had potent immunomodulatory effects and could be used as potential immunomodulatory agents in the fields of functional food and medicine.

Chlorella vulgaris α-L-arabino-α-L-rhamno-α,β-D-galactan structure and mechanisms of its anti-inflammatory and anti-remodelling effects

Microalgal exopolysaccharides (EPSs) are given great attention due to their potential biotechnology applications. Purified C. vulgaris EPS was subjected to compositional and sugar linkage analyses, and partial acid hydrolysis. Hydrolysate separation by gel chromatography afforded oligosaccharide fractions. Both, EPS and oligomers were studied by NMR spectroscopy. Data suggest very complex highly branched α-L-arabino-α-L-rhamno-α,β-D-galactan structure. Backbone repeating unit is formed by →2)-α-L-Rha (1 → 3)-α-L-Rha(1 → sequence, highly branched by long 1,6-linked α-D-Galp side chains, further branched at C2, C3 or C4 by α-L-Araf, α-D-Galf and β-D-Galf residues. α-L-Araf form longer 1,2-linked chains branched at C3, C4 or C5. Galf residues are localized as terminal units predominantly in the β configuration, while α-D-Galp and α-L-Araf may be partially O-methylated. Ex vivo biological assays showed increased interleukin-12 (IL-12) and interferon-gamma (INF-γ) levels corresponding to transforming growth factor beta (TGF-β) decrease in guinea pig model experimental asthma. These facts point to the anti-remodelling effect of Chlorella EPS and suggest its possible application in the treatment of asthma and chronic obstructive pulmonary disorder.

The Antioxidant Activity of Polysaccharides Derived from Marine Organisms: An Overview

Marine-derived antioxidant polysaccharides have aroused extensive attention because of their potential nutritional and therapeutic benefits. However, the comprehensive comparison of identified marine-derived antioxidant polysaccharides is still inaccessible, which would facilitate the discovery of more efficient antioxidants from marine organisms. Thus, this review summarizes the sources, chemical composition, structural characteristics, and antioxidant capacity of marine antioxidant polysaccharides, as well as their protective in vivo effects mediated by antioxidative stress reported in the last few years (2013-2019), and especially highlights the dominant role of marine algae as antioxidant polysaccharide source. In addition, the relationships between the chemical composition and structural characteristics of marine antioxidant polysaccharides with their antioxidant capacity were also discussed. The antioxidant activity was found to be determined by multiple factors, including molecular weight, monosaccharide composition, sulfate position and its degree.

Antioxidant activity of exo-metabolites produced by Fusarium oxysporum: An endophytic fungus isolated from leaves of Otoba gracilipes

Tropical ecosystems hold an extremely diverse array of endophytic fungi, but their potential use still remains to be explored. In this study, we isolated an endophytic fungus from the leaves of Otoba gracilipes, a medicinal tree from a tropical rainforest in Colombia. Following isolation and cultivation, we evaluated its extracellular crude extract for antioxidant activity. Using traditional and molecular methods (ITS1, NL1 regions), the endophyte was identified as Fusarium oxysporum. Fresh spores from the fungal isolate were inoculated in liquid media (potato dextrose broth [PDB] and potato dextrose-yeast extract broth [PDYB]) and centrifuged for recovering extracellular polysaccharides from the exhausted medium after 30 days of cultivation. Crude extracts were recovered, purified, lyophilized, and evaluated for their ability to inactivate the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). The extracts obtained from PDB culture media had a 51.5% of scavenging effect on DPPH after 5 min of reaction compared with the extracts from PDBY (26.4%), which suggests a high antioxidant potential of these fungal extracts. Thus, our results suggest other fungi from tropical ecosystems should be explored as potential sources of novel enzymes and other metabolites with bioactivity.

AD, Agastian P, Choi KC. Isolation and characterization of Aspergillus sp. for the production of extracellular polysaccharides by response surface methodology

In this study, Aspergillus sp. was isolated for the production of extracellular polysaccharide. The process parameters were initially optimized by traditional methods. The cheap substrate, wheat bran was used for the production of extracellular polysaccharide in solid state fermentation. Supplementation of (1%, w/w) maltose, gelatin enhanced EPS production (5.36 mg/g). The salts such as, Cu²⁺ (4.9 mg/g), Ca²⁺ (3.5 mg/g), Zn²⁺ (2.9 mg/g), Mn²⁺ (3.4 mg/g) and Mg²⁺ (1.8 mg/g) stimulated EPS production. In two level full factorial experimental designs, the EPS yield varied from 3.18 to 11.65 mg/g wheat bran substrate with various combinations of the components supplemented with wheat bran substrate. Among these selected factors in central composite design, maltose significantly influenced on extracellular polysaccharide production.

Structure Characterization and Otoprotective Effects of a New Endophytic Exopolysaccharide from Saffron

Saffron, a kind of rare medicinal herb with antioxidant, antitumor, and anti-inflammatory activities, is the dry stigma of Crocus sativus L. A new water-soluble endophytic exopolysaccharide (EPS-2) was isolated from saffron by anion exchange chromatography and gel filtration. The chemical structure was characterized by FT-IR, GC-MS, and 1D and 2D-NMR spectra, indicating that EPS-2 has a main backbone of (1→2)-linked α-d-Manp, (1→2, 4)-linked α-d-Manp, (1→4)-linked α-d-Xylp, (1→2, 3, 5)-linked β-d-Araf, (1→6)- linked α-d-Glcp with α-d-Glcp-(1→ and α-d-Galp-(1→ as sidegroups. Furthermore, EPS-2 significantly attenuated gentamicin-induced cell damage in cultured HEI-OC1 cells and increased cell survival in zebrafish model. The results suggested that EPS-2 could protect cochlear hair cells from ototoxicity exposure. This study could provide new insights for studies on the pharmacological mechanisms of endophytic exopolysaccharides from saffron as otoprotective agents.

Structural characterization and anti-inflammatory effect in hepatocytes of a galactoglucan from Antrodia camphorata mycelium

The galactoglucan ACP2 was isolated from cultured Antrodia camphorata mycelium through anion-exchange column chromatography and Sephadex G-100 chromatography and shown to exhibit hepatoprotective function in L02 cells. Based on monosaccharide composition analysis, ACP2 was mainly composed of glucose, galactose, and 6-deoxyglucose in a molar ratio of 5 : 2 : 1. The average molecular weight of ACP2 was 1.93 × 10⁴ Da. The primary structure of ACP2 was elucidated with Fourier-transform infrared spectroscopy, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectroscopy. The results indicated the following composition: →6)-linked-β-d-Galp-(1→, →6)-linked-α-d-Glcp-(1→, →3)-linked-α-d-Glcp-(1→, and →2,4)-linked-β-d-Glcp-(1→, with terminal 6-deoxy-α-d-Glcp and α-d-Glcp. ACP2 alleviated lipopolysaccharide-induced hepatocyte inflammation by down-regulating the expressions of COX-2, IL-1β, TNF-α and IL-6. The decreased expressions of TLR4, MyD88, NF-κB, and phosphorylated p38 in ACP2-treated L02 cells indicated that ACP2 might ameliorate inflammation through the TLR4 and p38/NF-κB signaling pathways.

A previously undescribed polysaccharide ACP2 was isolated from Antrodia camphorata mycelium. ACP2 ameliorated hepatocyte inflammation through TLR4 and p38/NF-κB signal pathway.