Preparation and characterization of an extracellular polysaccharide produced by the deep-sea fungus Penicillium griseofulvum

Neuroprotection of low-molecular-weight galactan obtained from Cantharellus cibarius Fr. against Alzheimer's disease

The large molecular weight of polysaccharides limits their absorption and utilization by organisms, affecting their biological activities. In this study, we purified α-1,6-galactan from Cantharellus cibarius Fr. (chanterelle) and reduced its molecular weight from approximately 20 kDa to 5 kDa (named CCP) to increase its solubility and absorption. In APP/PS1 mice, CCP improved both spatial and non-spatial memory loss in Alzheimer's disease (AD) mice, as confirmed by the Morris water maze, step-down, step-through, and novel object recognition tests, and dampened the deposition of amyloid-β plaques, as assessed by immunohistochemical analysis. Proteomic analysis suggested that the neuroprotective effects of CCP are related to anti-neuroinflammation. Immunofluorescence analysis and western blotting confirmed that CCP attenuated AD-like symptoms partly by inhibiting neuroinflammation, which was related to the blocking of complement component 3. Our study provides theoretical support and experimental evidence for the future application of chanterelle-extracted polysaccharides in AD treatment, promoting the modern development of traditional medicines originating from natural polysaccharides.

Extraction, characterization and anti-oxidant activity of polysaccharide from red Panax ginseng and Ophiopogon japonicus waste

Red ginseng and Ophiopogon japonicus are both traditional Chinese medicines. They have also been used as food in China for thousands of years. These two herbs were frequently used in many traditional Chinese patent medicines. However, the carbohydrate compositions of these two herbs were not normally used during the production of said medicine, such as Shenmai injection, resulting in a large amount of waste composed of carbohydrates. In this study, the extraction conditions were optimized by response surface methodology. The Shenmai injection waste polysaccharide was extracted by using distilled water that was boiled under the optimized conditions. The Shenmai injection waste polysaccharide (SMP) was thereby obtained. SMP was further purified by anion exchange chromatography and gel filtration. With this method, a neutral polysaccharide fraction (SMP-NP) and an acidic polysaccharide fraction (SMP-AP) were obtained. The results of structure elucidation indicated that SMP-NP was a type of levan, and SMP-AP was a typical acidic polysaccharide. SMP-NP exhibited potential stimulation activity on the proliferation of five different Lactobacilli strains. Therefore, SMP-AP could promote the antioxidant defense of IPEC-J2 cells. These findings suggest that Shenmai injection waste could be used as a resource for prebiotics and antioxidants.

Structure and Anticoagulant Activity of a Galactofuranose-Containing Sulfated Polysaccharide from the Green Seaweed, Codium isthmocladum

A water-soluble sulfated polysaccharide, F2-1, was obtained from the marine green alga, Codium isthmocladum, using ion-exchange and size-exclusion chromatography. Structure analysis showed that the F2-1 was a sulfated arabinan comprising Ara, Rha, Man, Gal, and Xyl with an 18% sulfate content and a molecular weight of 100 kDa. Methylation analysis combined with desulfation, GC-MS, IR, and NMR spectroscopy showed that the backbone of F2-1 was →4)-β-L-Arap(1→ residue. Its 2-O and/or 3-O positions showed sulfate modification; additionally, the 2-O or 3-O position showed branch points. The side chains were composed of →5)-β-D-Galf, (1→2,6)-β-D-Galf(1→, (1→2)-β-L-Rhap4S, →4)-α-D-Glcp(1→, and terminal α-D-Galp(1→ and β-D-Xylp(1→. Polysaccharides containing β-D-galactofuranose are rarely found in seaweed. F2-1 exhibited significant anticoagulant activity in vitro. Our findings suggested that the green-tide alga, Codium isthmocladum, can be considered as a useful resource for bioactive polysaccharides.

Potential functions and applications of diverse microbial exopolysaccharides in marine environments

Exopolysaccharides (EPSs) from microorganisms are essential harmless natural biopolymers used in applications including medications, nutraceuticals and functional foods, cosmetics, and insecticides. Several microbes can synthesize and excrete EPSs with chemical properties and structures that make them suitable for several important applications. Microbes secrete EPSs outside their cell walls, as slime or as a "jelly" into the extracellular medium. These EPS-producing microbes are ubiquitous and can be isolated from aquatic and terrestrial environments, such as freshwater, marine water, wastewater, and soils. They have also been isolated from extreme niches like hot springs, cold waters, halophilic environments, and salt marshes. Recently, microbial EPSs have attracted interest for their applications such as environmental bio-flocculants because they are degradable and nontoxic. However, further efforts are required for the cost-effective and industrial-scale commercial production of microbial EPSs. This review focuses on the exopolysaccharides obtained from several extremophilic microorganisms, their synthesis, and manufacturing optimization for better cost and productivity. We also explored their role and applications in interactions between several organisms.

Galactofuranose side chains in galactomannans from Penicillium spp. modulate galectin-8-mediated bioactivity

Polysaccharides from fungi have many bioactivities. Previous studies showed that galactomannans from Penicillium oxalicum antagonize galectin-8-mediated activity. Here, two intracellular and two extracellular galactomannans were purified and their structures were comparatively characterized by NMR, partial acid hydrolysis and methylation. All four of them were identified to be galactomannans with similar mannan backbones having 1,2-/1,6-linkages (~3:1) and various amounts of galactofuranan side chains. The interaction of those polysaccharides with galectin-8 was assessed by hemagglutination and biolayer interferometry. These results show that side chains are important for the interaction, and the more the side chains, the stronger the interaction. But the side chains alone did not show act on galectin-8, which indicated that the cooperation between backbone and side chains is another necessary factor for this interaction. Our findings provide important information about structure-activity relationships and the galactofuranose-containing galactomannans might be as potential therapeutic of galectin-8 related diseases.

Research progress of the biosynthetic strains and pathways of bacterial cellulose

Bacterial cellulose is a glucose biopolymer produced by microorganisms and widely used as a natural renewable and sustainable resource in the world. However, few bacterial cellulose-producing strains and low yield of cellulose greatly limited the development of bacterial cellulose. In this review, we summarized the 30 cellulose-producing bacteria reported so far, including the physiological functions and the metabolic synthesis mechanism of bacterial cellulose, and the involved three kinds of cellulose synthases (type I, type II, and type III), which are expected to provide a reference for the exploration of new cellulose-producing microbes.

Purification, Characterization, and Self-Assembly of the Polysaccharide from Allium schoenoprasum

The major polysaccharide component from the stalk of Allium schoenoprasum (AssP) was extracted and purified. Gel filtration chromatography purified AssP exhibited a molecular weight of around 1.7 kDa, which was verified by MALDI-ToF-MS. The monosaccharide analysis revealed its composition as rhamnose: arabinose: galactose: glucose: mannose: fructose with a molar ratio of 0.03:2.46:3.71:3.35:1.00:9.93, respectively. The Congo-red assay indicated that there was no tertiary structure of this polysaccharide, however, it self-assembled into a homogenous nanoparticle with a diameter of ~600 nm as revealed by the dynamic light scattering measurement. The solution behavior of this polysaccharide was simulated. The association of this polysaccharide was both time dependent and concentration dependent. AssP forms spherical particles spontaneously as time passes by, and when the AssP concentration increased, the spherical particles increased their sizes and eventually merged into cylindrical micelles. The diversity of AssP hydrodynamic behavior endowed potential versatility in its future applications.

Comparative study on the structures of intra- and extra-cellular polysaccharides from Penicillium oxalicum and their inhibitory effects on galectins

Here, we compare the content and composition of polysaccharides derived from the mycelium (40.4 kDa intracellular polysaccharide, IPS) and culture (27.2 kDa extracellular polysaccharide, EPS) of Penicillium oxalicum. Their chemical structures investigated by IR, NMR, enzymolysis and methylation analysis indicate that both IPS and EPS are galactomannans composed of α-1,2- mannopyranose (Manp) and α-1,6-Manp in a backbone ratio of ~3:1, respectively, both decorated with β-l,5-galactofuranose (Galf) side chains. A few β-l,6-Galf residues were also detected in the IPS fraction. EPS and IPS have different molecular weights (Mw) and degrees of branching. IPS obtained by alkaline extraction of P. oxalicum have been reported to be galactofuranans, a composition different from our IPS. Up to now, there have been no reports on the fine structure of EPS. Our results of galectin-mediated hemagglutination demonstrate that IPS exhibits greater inhibitory effects on five galectins compared with EPS. In addition, we find that Galf, a five-membered ring form of galactose, can also inhibit galectins. IPS may provide a new source of galectin inhibitors. These results increase our understanding of structure-activity relationships of polysaccharides as galectin inhibitors.

Different techniques for concentration of extracellular biopolymers with herbicidal activity produced by Phoma sp

The natural ability of microorganisms to secrete high levels of bioactive compounds make them attractive hosts for producing novel compounds. Microbial biopolymers have potential applications in most of the sectors of the world economy. According to the physicochemical properties, they present some advantages, such as biodegradability, reproducibility, and stability. Based on this context, the objective of this work was to evaluate different methods for concentration and characterisation of extracellular biopolymers produced by Phoma sp. Extracellular biopolymers were produced by submerged fermentation and were concentrated by hollow fibre membranes and by adsorption. The structural characterisation of purified biopolymers was determined by Fourier Transform Infrared spectroscopy. Phytotoxic effects were assessed through absorption assays in detached leaves of Cucumis sativus and evaluated on the seventh day after application. The surface tension was evaluated for each sample. Hollow-fibre microfiltration membrane presented a higher purification factor than hollow-fibre ultrafiltration membrane. Extracellular biopolymers were identified in the permeate and retentate fractions, but in higher concentration in the retentate fractions. The adsorption process was efficient for recovering more than 88% of extracellular biopolymers from cell-free fermented broth. The best performance was obtained by using silica and activated carbon as adsorbent, with a recovery higher than 93%. The herbicidal activity was proportional to the concentration of biopolymers and the results are very promising for future applications because a concentrated solution of biopolymers can increase weed control. Membrane processes can be used to develop a liquid formulation of bioherbicide, whereas adsorption can be used to develop a solid formula.

A water-soluble selenium-enriched polysaccharide produced by Pleurotus ostreatus: Purification, characterization, antioxidant and antitumor activities in vitro

The development and application of new selenium-enriched polysaccharides has become a critical topic in recent years. In this study, a natural selenium-enriched polysaccharide fraction (Se-POP-21) produced by Pleurotus ostreatus was purified, characterized, and investigated the antioxidant and antitumor activities in vitro. The Se-POP-21 was mainly composed of mannose, glucose, galactose and arabinose, with a molar ratio of 18.01:2.40:26.15:7.34, of which molecular weight was 15,888 Da and the selenium content was 5.31 μg/g. Spectral analysis demonstrated that Se-POP-21 represented a non-triple helix pyranopolysaccharide and selenium occurred in the form of C-O-Se and SeO. Molecular size and morphology studies showed that Se-POP-21 exhibited a spherical shape with a particle size distribution between 100 and 200 nm, even though Se-POP-21 aggregates were also found with a size between 500 and 600 nm. In addition, Se-POP-21 showed strong scavenging capacity to DPPH and hydroxyl radical. More, cell experiments showed that Se-POP-21 could reduce viability of A549, SKOV3, HepG2 and MCF-7 cells, induce apoptosis and inhibit metastasis of A549 cells. A potential mechanism was that Se-POP-21 inhibited the epithelial-to-mesenchymal transition of cancer cells. Se-POP-21 featured no significant effect on normal cells. Se-POP-21 showed great potential to develop into a natural antioxidant or low-toxic antitumor drug.

Biological function and molecular properties of Pyrenaican SF-1 as biological macromolecule extracted from Daldinia pyrenaica

Molecular properties and biological functions of Pyrenaican SF-1 as a novel biological macromolecule extracted from a fungal isolate were studied. The isolate was identified as Daldinia pyrenaica on the basis of 5.8S rDNA sequencing. Pyrenaican SF-1 was obtained from the culture filtrate of the fungal isolate. The partial characterization of biochemical structure of Pyrenaican SF-1 was conducted. The fungal extract was also tested for the treatment of AGS, MDA and HeLa cell lines to assess cells proliferation, cells cycle and apoptosis. Furthermore, Pyrenaican SF-1 extract was tested for its antibacterial and antioxidant activity. Initial chemical analysis revealed that Pyrenaican SF-1 extract was composed of various monosaccharides such as d-glucose, D- mannitol, D-arabinose and β-D-ribopyranose. In vitro study indicated that Pyrenaican SF-1 could effectively elevate percentage of apoptosis and necrosis of cancer cells and block cell cycle phase of the control group. The fungal extract could inhibit proliferation of Hela and MDA cell up to 67% and 56%, respectively. Moreover, Pyrenaican SF-1 represented a strong antioxidant activity compared to that one obtained from vitamin C. On the other hand, Pyrenaican SF-1 exhibited growth inhibitory effects against different Gram-negative and Gram-positive bacterial strains. Pyrenaican SF-1 can be considered as a bioactive macromolecule with promising application in pharmaceutical and medical sectors.

Structural characterization of a polysaccharide from dry mycelium of Penicillium chrysogenum that induces resistance to Tobacco mosaic virus in tobacco plants

Polysaccharides are essential macromolecules that are present in all living organisms. They have a range of biological activities, such as antiviral, antioxidant, immunity-enhancing, and anticancer activities. In this study, a polysaccharide (PCPS) was separated and extracted from dry mycelium of Penicillium chrysogenum by a boiling water step and gel-filtration chromatography. Its structure was characterized by high performance gel-permeation chromatography, chemical derivative, and nuclear magnetic resonance analyses. The results showed that PCPS is a neutral galactomannan with an apparent molecular weight of 19.5 kDa. We evaluated the antiviral activity of PCPS. In half-leaf assays of tobacco plants, the protective effect of PCPS against Tobacco mosaic virus (TMV) was stronger than the protective effects of ningnanmycin and oligosaccharins. Electron microscopy analyses showed that PCPS can directly inactivate viral particles. The mechanism of the antiviral activity of PCPS was explored in a preliminary study. PCPS induced the production of NO and H2O2 to initiate an early defense response. Treatment with PCPS resulted in increased transcript levels of the genes PAL, 4CL, LPO, and increased activities of phenylalanine lyase and peroxidase, which improved the TMV resistance of Nicotiana glutinosa. Expression of the PR-1b gene was also activated during the defense response.

Structure and immunostimulating activity of a galactofuranose-rich polysaccharide from the bamboo parasite medicinal fungus Shiraia bambusicola

ETHNOPHARMACOLOGICAL RELEVANCE

Shiraia bambusicola is a parasitic fungus on the twigs of bamboos. Its relatively large stroma has high medicinal value and can treat a variety of diseases such as rheumatoid arthritis, cold stomach pain, sciatica, injuries, chronic bronchitis, and infantile. It is widely distributed in many provinces in Southern China and also is also found in Japan.

AIM OF THE STUDY

Medicinal fungi were important resources for bioactive polysaccharides. To explore bioactive polysaccharides from Shiraia bambusicola, a heteropolysaccharide SB2-1 was purified and obtained from S. bambusicola and its immunostimulating activity was researched.

MATERIALS AND METHODS

The polysaccharide from S. bambusicola was extracted and purified using enzyme assisted extraction, ethanol precipitation, anion-exchange and size-exclusion chromatography. Molecular weight of polysaccharide was estimated by high performance gel permeation chromatography. Monosaccharide compositions were determined by high performance liquid chromatography after pre-column derivatization and UV detection. Structure information was elucidated by IR spectrum, GC-MS analysis after methylation and gradual acid hydrolysis of the polysaccharide. The RAW264.7 cells were used to study the immunostimulating activity in vitro.

RESULTS

Physicochemical and structural analyses showed that SB2-1 was a neutral heteropolysaccharide with molecular weight at 22.2 kDa and consisted of glucose, galactose and mannose at a ratio of 2.0:1.5:1.0. The structure of SB2-1 was a branched polysaccharides composed of a mannan core and side chains consisted of glucose and galactose. The mannan core was composed of (1→2)-Manp as the main chain. Glucose with (1→4)-D-Glcp, (1→2)-D-Glcp and (1→6)-D-Glcp at different degrees of polymerization were linked at C-6 and C-3 of the (1→2)-Manp as the side chains. The galactose with the linages of (1→6)-D-Galf, →2)-D-Galf(1→ and terminal D-Galf(1→ also existed in the side chain. The study on the immunostimulating activities of SB2-1 and its core structure P-2 were investigated on RAW264.7 macrophages. The results showed that SB2-1 could activate RAW264.7 macrophage and significantly improve its phagocytic ability by neutral red uptake experiment. Meanwhile, SB2-1 increased significantly higher inducible nitric oxide synthase (iNOS) production and the productions of IL-1, IL-6, IL-12 and TNF-α. The effect of SB2-1 was better than its core structure P-2 produced by gradual acid hydrolysis, which meant the side chains played an important role in the immunostimulating activities.

CONCLUSIONS

The investigation demonstrated that the galactofuranose-containing mannogalactoglucan was characteristic polysaccharides in S. bambusicola and could enhance the activation of macrophages.

Bioactive exopolysaccharide from Neopestalotiopsis sp. strain SKE15: Production, characterization and optimization

Fungal exopolysaccharides are powerful resources of medicinal applications. Neopestalotiopsis sp. SKE15 was isolated and identified according to phenotypical and genotypical analyses (GenBank Accession No. MG649986). The exopolysaccharide (EPS) was produced by cultivation of mycelia in broth culture and extracted. The production was optimized to 2.02 g/l after selection of agitation, temperature, FeSO₄ and K₂HPO₄ concentrations as the most influencing factors using Placket-Burman design and then by applying response surface methodology. Analytical Tools showed that the EPS is composed of a polysaccharide (1.5-2.1 × 10⁶ Da) and its probable low molecular weight derivatives, in a wide range of chain lengths, among them an oligosaccharide of about 1970 Da was dominant. GC-MS (Gas chromatography-mass spectrometry) analysis revealed the EPS was mainly constructed from d-glucose, sorbitol and D-galactose. The EPS showed antibacterial activity against Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633 and Pseudomonas aeruginosa ATCC 27853. DPPH (1,1-diphenyl-2-picryl-hydrazyl) and hydroxyl radical scavenging activity assays showed strong antioxidant activity of the EPS. A challenge with three different cancerous cell lines showed cytotoxic activity of the EPS at final concentration of 100 and 200 μg/ml. Further investigation on medicinal applications of the biopolymer is promising.

Development of sugarcane resource for efficient fermentation of exopolysaccharide by using a novel strain of Kosakonia cowanii LT-1

This work focuses on the development of non-food fermentation for the cost-effective biosynthesis of exopolysaccharide (EPS) by using a new strain of Kosakonia cowanii LT-1. This novel strain more efficiently utilizes sucrose for EPS production than other glycosyl donors. Comparative transcriptomic analysis is used to understand EPS synthesis promotion and the effects of sucrose on EPS biosynthesis. We speculate that ATP-binding cassette transporter, phosphotransferase, and two-component systems may be the most essential factors for EPS biosynthesis. The enhanced oxidative phosphorylation increases the synthesis rate of ATP to satisfy the energy demands for EPS production with sucrose as the substrate. Sugarcane juice, a cheap raw material, could improve the EPS yield in batch fermentation and achieve approximately 29.66% cost savings for substrate. Our work presents a promising non-food fermentation approach for the synthesis of high-value industrial products.

Genomic characterization of a potentially novel Streptococcus species producing exopolysaccharide

Human oral streptococci, particularly the mitis group, often dwell in the upper respiratory tracts, oral mucosa, and tooth surfaces of healthy individuals. In this work, an α-hemolytic strain, designated LQJ-218, was isolated from the human oral cavity and evaluated for its ability to produce exopolysaccharides. Phylogenetic analysis based on 16S rRNA gene sequences showed that this strain is a potentially novel species belonging to the mitis group streptococci. Whole-genome sequence-based analysis indicated that the genome sequence of Streptococcus sp. LQJ-218 was 1,935,194 bp in length, with a mol% G + C content of 40.0, and contained 1897 coding DNA sequences and 91 RNA genes. Furthermore, four biosynthetic gene clusters relevant to exopolysaccharide production were identified in the genome. Both digital DNA-DNA hybridization (yielding a value of 56.60% between strain LQJ-218 and its nearest relative S. mitis) and average nucleotide identity analysis (revealing 91.29% identity of LQJ-218 with its nearest relative S. mitis) suggested that strain LQJ-218 should be classified as a novel Streptococcus species. This potentially novel strain may possess great potential for contributing to the development of new exopolysaccharides. The present study provides valuable genetic information that may be useful in comparative genomics and biotechnological applications.

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.

Extracellular polysaccharides from Ascomycota and Basidiomycota: production conditions, biochemical characteristics, and biological properties

Fungal polysaccharides (PSs) are the subject of research in many fields of science and industry. Many properties of PSs have already been confirmed and the list of postulated functions continues to grow. Fungal PSs are classified into different groups according to systematic affinity, structure (linear and branched), sugar composition (homo- and heteropolysaccharides), type of bonds between the monomers (β-(1 → 3), β-(1 → 6), and α-(1 → 3)) and their location in the cell (cell wall PSs, exoPSs, and endoPSs). Exopolysaccharides (EPSs) are most frequently studied fungal PSs but their definition, classification, and origin are still not clear and should be explained. Ascomycota and Basidiomycota fungi producing EPS have different ecological positions (saprotrophic and endophytic, pathogenic or symbiotic-mycorrhizae fungi); therefore, EPSs play different biological functions, for example in the protection against environmental stress factors and in interactions with other organisms. EPSs obtained from Ascomycota and Basidiomycota fungal cultures are known for their antioxidant, immunostimulating, antitumor, and antimicrobial properties. The major objective of the presented review article was to provide a detailed description of the state-of-the-art knowledge of the effectiveness of EPS production by filamentous and yeast Ascomycota and Basidiomycota fungi and techniques of derivation of EPSs, their biochemical characteristics, and biological properties allowing comprehensive analysis as well as indication of similarities and differences between these fungal groups. Understanding the role of EPSs in a variety of processes and their application in food or pharmaceutical industries requires improvement of the techniques of their derivation, purification, and characterization. The detailed analyses of data concerning the derivation and application of Ascomycota and Basidiomycota EPSs can facilitate development and trace the direction of application of these EPSs in different branches of industry, agriculture, and medicine.

An exopolysaccharide isolated from a coral-associated fungus and its sulfated derivative activates macrophages

A coral-associated fungus Penicillium sp.gxwz446 that produced exopolysaccharde was isolated from the coral Echinogorgia flora in South China. Two neutral exopolysaccharides GX1-1 and GX2-1 were obtained from the fermented broth of the fungus and purified by anion-exchange and gel-permeation chromatography. Chemical and spectroscopic analyses showed that GX1-1 was a glucan, primarily composed of glucose, with a molecular weight of 5.0 kDa. GX1-1 mainly consists of (1→4)-linked α-d-glucopyranose units as the backbone, substituted at C-2 with a single α-d-glucopyranose on every sixth sugar residues. GX2-1 was a galactofuranose-containing mannogalactoglucan with a molecular weight of 9.5 kDa. The main linkages were composed of (1→4)-β-d-Glcp, (1→5)-β-d-Galf, (1→3,5)-β-d-Galf, (1→6)-α-d-Manp and (1→2, 6)-α-d-Manp. GX1-1 showed RAW264.7 macrophage activation activity. After subjecting GX1-1 to sulfated modification, there was about one sulfate substitution on every sugar ring, primarily at O-6. The sulfated derivative of GX1-1 exhibited a more significant ability to promote the pinocytic activity of RAW264.7 cells and induce the production of NO.

Preparation and characterization of a novel extracellular polysaccharide with antioxidant activity, from the mangrove-associated fungus Fusarium oxysporum

Marine fungi are recognized as an abundant source of extracellular polysaccharides with novel structures. Mangrove fungi constitute the second largest ecological group of the marine fungi, and many of them are new or inadequately described species and may produce extracellular polysaccharides with novel functions and structures that could be explored as a source of useful polymers. The mangrove-associated fungus Fusarium oxysporum produces an extracellular polysaccharide, Fw-1, when grown in potato dextrose-agar medium. The homogeneous Fw-1 was isolated from the fermented broth by a combination of ethanol precipitation, ion-exchange, and gel filtration chromatography. Chemical and spectroscopic analyses, including one- and two-dimensional nuclear magnetic resonance spectroscopies showed that Fw-1 consisted of galactose, glucose, and mannose in a molar ratio of 1.33:1.33:1.00, and its molecular weight was about 61.2 kDa. The structure of Fw-1 contains a backbone of (1 → 6)-linked β-D-galactofuranose residues with multiple side chains. The branches consist of terminal α-D-glucopyranose residues, or short chains containing (1 → 2)-linked α-D-glucopyranose, (1 → 2)-linked β-D-mannopyranose, and terminal β-D-mannopyranose residues. The side chains are connected to C-2 of galactofuranose residues of backbone. The antioxidant activity of Fw-1 was evaluated with the scavenging abilities on hydroxyl, superoxide, and 1,1-diphenyl-2-picrylhydrazyl radicals in vitro, and the results indicated that Fw-1 possessed good antioxidant activity, especially the scavenging ability on hydroxyl radicals. The investigation demonstrated that Fw-1 is a novel galactofuranose-containing polysaccharide with different structural characteristics from extracellular polysaccharides from other marine microorganisms and could be a potential source of antioxidant.

Carboxymethylation of an exopolysaccharide from Lachnum and effect of its derivatives on experimental chronic renal failure

Carboxymethylated polysaccharide CLEP-1b was prepared from a single component (LEP-1b) of Lachnum YM281 exopolysaccharides by molecular modification with a degree of substitution (DS) of 0.286. Infrared result proved that the carboxymethylation of LEP-1b succeeded and (13)C NMR result showed that the carboxymethyl group (CH2COOH) was chemically linked to an oxygen (O) atom of the hydroxyl on C-3 of LEP-1b. LEP-1b could improve the histopathological status of kidney and significantly reduce the contents of serum creatinine (Scr) and blood urea nitrogen (BUN), and increase the contents of total protein and albumin. It could also enhance the activity of SOD, GSH-PX, CAT, GSH and decrease MDA contents in the nephridial and hepatic tissues. What's more, CLEP-1b showed more significant effects than LEP-1b at the same dosage. The research indicated that LEP-1b and CLEP-1b could mitigate the chronic renal failure of mice and the effects were closely associated with antioxidant activity.

Nine new and five known polyketides derived from a deep sea-sourced Aspergillus sp. 16-02-1

Nine new C₉ polyketides, named aspiketolactonol (1), aspilactonols A–F (2–7), aspyronol (9) and epiaspinonediol (11), were isolated together with five known polyketides, (S)-2-(2′-hydroxyethyl)-4-methyl-γ-butyrolactone (8), dihydroaspyrone (10), aspinotriol A (12), aspinotriol B (13) and chaetoquadrin F (14), from the secondary metabolites of an Aspergillus sp. 16-02-1 that was isolated from a deep-sea sediment sample. Structures of the new compounds, including their absolute configurations, were determined by spectroscopic methods, especially the 2D NMR, circular dichroism (CD), Mo₂-induced CD and Mosher’s ¹H NMR analyses. Compound 8 was isolated from natural sources for the first time, and the possible biosynthetic pathways for 1–14 were also proposed and discussed. Compounds 1–14 inhibited human cancer cell lines, K562, HL-60, HeLa and BGC-823, to varying extents.