Production of chitooligosaccharides and their potential applications in medicine

Mechano-Enzymatic Degradation of the Chitin from Crustacea Shells for Efficient Production of N-acetylglucosamine (GlcNAc)

Chitin, the second richest polymer in nature, is composed of the monomer N-acetylglucosamine (GlcNAc), which has numerous functions and is widely applied in the medical, food, and chemical industries. However, due to the highly crystalline configuration and low accessibility in water of the chitin resources, such as shrimp and crab shells, the chitin is difficult utilize, and the traditional chemical method causes serious environment pollution and a waste of resources. In the present study, three genes encoding chitinolytic enzymes, including the N-acetylglucosaminidase from Ostrinia furnacalis (OfHex1), endo-chitinase from Trichoderma viride (TvChi1), and multifunctional chitinase from Chitinolyticbacter meiyuanensis (CmChi1), were expressed in the Pichia pastoris system, and the positive transformants with multiple copies were isolated by the PTVA (post-transformational vector amplification) method, respectively. The three recombinants OfHex1, TvChi1, and CmChi1 were induced by methanol and purified by the chitin affinity adsorption method. The purified recombinants OfHex1 and TvChi1 were characterized, and they were further used together for degrading chitin from shrimp and crab shells to produce GlcNAc through liquid-assisted grinding (LAG) under a water-less condition. The substrate chitin concentration reached up to 300 g/L, and the highest yield of the product GlcNAc reached up to 61.3 g/L using the mechano-enzymatic method. A yield rate of up to 102.2 g GlcNAc per 1 g enzyme was obtained.

Identification of Mucilaginibacter conchicola sp. nov., Mucilaginibacter achroorhodeus sp. nov. and Mucilaginibacter pallidiroseus sp. nov. and emended description of the genus Mucilaginibacter

Three chitinolytic, Gram-negative, light pink, capsule-forming, rod-shaped bacterial strains with gliding motion (MYSH2T, MJ1aT and dk17T) were isolated from seashells, soil and foxtail, respectively. Phylogenetic analysis of the 16S rRNA gene sequences and concatenated alignment of 92 core genes indicated that strains MYSH2T, MJ1aT and dk17T were novel species of the genus Mucilaginibacter and exhibited a high 16S rRNA sequence similarity (i.e. more than 97.2 %) among each other. These novel strains contained summed feature 3 (C16:1 ω7c and/or C16:1 ω6), iso-C15:0 and MK-7 as the predominant fatty acids and menaquinone. According to the CAZys coding gene of KAAS, MYSH2T and MJ1aT were interpreted as strains containing both GH18 and 19 family coding genes, except for dk17T, which shows only GH19 family genes. These strains likely degrade chitin to chitobiose or directly to N-acetyl-d-glucosamine, which may enhance their chitinolytic capacity, thus making these stains potentially useful for industrial chitin degradation. Based on distinct morphological, physiological, chemotaxonomic and phylogenetic differences from their closest phylogenetic neighbours, we propose that strains MYSH2T, MJ1aT and dk17T represent three novel species in the genus Mucilaginibacter , for which the names Mucilaginibacter conchicola sp. nov. (=KACC 19716T=JCM 32787T), Mucilaginibacter achroorhodeus sp. nov. (=KACC 19906T=NBRC 113667T) and Mucilaginibacter pallidiroseus sp. nov. (=KACC 19907T=NBRC 113666T) are proposed. An emended description of the genus Mucilaginibacter is proposed.

Peculiarities of the interaction of sodium dodecyl sulfate with chitosan in acidic and alkaline media

In this work, the interaction between the negatively charged surfactant sodium dodecyl sulfate (SDS) and partially N-reacetylated chitosan (RA-CHI), which is soluble at pH range up to pH 12, is studied in a wide pH range including alkaline media by light scattering (LS) and isothermic titration calorimetry (ITC). It is shown that in the weakly alkaline medium (pH 7.4), RA-CHI/SDS interaction is exothermic and cooperative. This interaction is found to be coupled with proton transfer from the buffer substance to chitosan as it is revealed by the dependence of the measured heat release on the ionization enthalpy of the buffer. At higher pH values (pH > 8), another mechanism of interaction is observed that include SDS micellization induced by hydrophobic interactions with polymer segments, so that no phase separation occurred in these mixtures. The results obtained can contribute to expand the knowledge about application of chitosan for preparation of pharmaceutical and cosmetic compositions containing anionic surfactants.

Purification, identification and characterization of Nag2 N-acetylglucosaminidase from Trichoderma virens strain mango

BACKGROUND

N-acetylglucosaminidase (NAGase) could liberate N-acetylglucosamine (GlcNAc) from GlcNAc-containing oligosaccharides. Trichoderma spp. is an important source of chitinase, particularly NAGase for industrial use. nag1 and nag2 genes encoding NAGase, are found in the genome in Trichoderma spp. The deduced Nag1 and Nag2 shares ~ 55% homology in Trichoderma virens. Most studies were focus on Nag1 and nag1 previously.

RESULTS

The native NAGase (TvmNAG2) was purified to homogeneity with molecular mass of ~ 68 kDa on SDS-PAGE analysis, and identified as Nag2 by MALDI/MS analysis from an isolate T. virens strain mango. RT-PCR analyses revealed that only nag2 gene was expressed in liquid culture of T. virens, while both of nag1 and nag2 were expressed in T. virens cultured on the plates. TvmNAG2 was thermally stable up to 60 °C for 2 h, and the optimal pH and temperature were 5.0 and 60-65 °C, respectively, using p-nitrophenyl-N-acetyl-β-D-glucosaminide (pNP-NAG) as substrate. The hydrolytic product of colloidal chitin by TvmNAG2 was suggested to be GlcNAc based on TLC analyses. Moreover, TvmNAG2 possesses antifungal activity, inhibiting the mycelium growth of Sclerotium rolfsii. And it was resistant to the proteolysis by papain and trypsin.

CONCLUSIONS

The native Nag2, TvmNAG2 was purified and identified from T. virens strain mango, as well as enzymatic properties. To our knowledge, it is the first report with the properties of native Trichoderma Nag2.

Characterization of a New Multifunctional GH20 β-N-Acetylglucosaminidase From Chitinibacter sp. GC72 and Its Application in Converting Chitin Into N-Acetyl Glucosamine

In this study, a gene encoding β-N-acetylglucosaminidase, designated NAGaseA, was cloned from Chitinibacter sp. GC72 and subsequently functional expressed in Escherichia coli BL21 (DE3). NAGaseA contains a glycoside hydrolase family 20 catalytic domain that shows low identity with the corresponding domain of the well-characterized NAGases. The recombinant NAGaseA had a molecular mass of 92 kDa. Biochemical characterization of the purified NAGaseA revealed that the optimal reaction condition was at 40°C and pH 6.5, and exhibited great pH stability in the range of pH 6.5-9.5. The V ma x , K m, k cat, and k cat /K m of NAGaseA toward p-nitrophenyl-N-acetyl glucosaminide (pNP-GlcNAc) were 3333.33 μmol min-1 l-1, 39.99 μmol l-1, 4667.07 s-1, and 116.71 ml μmol-1 s-1, respectively. Analysis of the hydrolysis products of N-acetyl chitin oligosaccharides (N-Acetyl COSs) indicated that NAGaseA was capable of converting N-acetyl COSs ((GlcNAc)2-(GlcNAc)6) into GlcNAc with hydrolysis ability order: (GlcNAc)2 > (GlcNAc)3 > (GlcNAc)4 > (GlcNAc)5 > (GlcNAc)6. Moreover, NAGaseA could generate (GlcNAc)3-(GlcNAc)6 from (GlcNAc)2-(GlcNAc)5, respectively. These results showed that NAGaseA is a multifunctional NAGase with transglycosylation activity. In addition, significantly synergistic action was observed between NAGaseA and other sources of chitinases during hydrolysis of colloid chitin. Finally, 0.759, 0.481, and 0.986 g/l of GlcNAc with a purity of 96% were obtained using three different chitinase combinations, which were 1.61-, 2.36-, and 2.69-fold that of the GlcNAc production using the single chitinase. This observation indicated that NAGaseA could be a potential candidate enzyme in commercial GlcNAc production.

Chitosan-Based Biomaterial Scaffolds for the Repair of Infected Bone Defects

The treatment of infected bone defects includes infection control and repair of the bone defect. The development of biomaterials with anti-infection and osteogenic ability provides a promising strategy for the repair of infected bone defects. Owing to its antibacterial properties, chitosan (an emerging natural polymer) has been widely studied in bone tissue engineering. Moreover, it has been shown that chitosan promotes the adhesion and proliferation of osteoblast-related cells, and can serve as an ideal carrier for bone-promoting substances. In this review, the specific molecular mechanisms underlying the antibacterial effects of chitosan and its ability to promote bone repair are discussed. Furthermore, the properties of several kinds of functionalized chitosan are analyzed and compared with those of pure chitosan. The latest research on the combination of chitosan with different types of functionalized materials and biomolecules for the treatment of infected bone defects is also summarized. Finally, the current shortcomings of chitosan-based biomaterials for the treatment of infected bone defects and future research directions are discussed. This review provides a theoretical basis and advanced design strategies for the use of chitosan-based biomaterials in the treatment of infected bone defects.

Deproteinization of Shrimp Shell Waste by Kurthia gibsonii Mb126 immobilized chitinase

This work was aimed at immobilization, characterization, and utilization of chitinase from Kurthia gibsonii Mb126. Immobilization of Kurthia gibsonii Mb126 chitinase on glutaraldehyde treated chitosan was carried out with immobilization yield of 106%. The optimal factors of the immobilization technique such as concentration of glutaraldehyde, chitinase concentration, and immobilization time were evaluated. After optimizing process parameters of immobilization (Glutaraldehyde concentration 4%, chitinase conc. 60mg, immobilization time 30min.), the specific activity of immobilized chitinase improved to 4.3-fold compared to the free form of chitinase. Temperature and pH optima of the immobilized chitinase and free enzyme were same i.e., 7.5 and 40°C respectively. The relative activity of immobilized chitinase remained 90% at 40°C, at 50°C, and at 60°C for 120 min. In the pH range from 5.5 to 8, the immobilized chitinase retained 100% activity. The results confirmed that the pH stability and thermal stability of chitinase increased by immobilizing chitinase on chitosan. The immobilized enzyme system maintained 90% of its efficiency even after 16 successive reaction cycles. The immobilized chitinase maintained 78% of its activity even after 20 months. Fermentation of prawn shell waste with immobilized chitinase indicated a high level of deproteinization. Deproteinization experiments were carried out with 5mL (0.4 mg/mL ) of immobilized and free chitinase on 300 mg/mL of prawn shell waste for 20 days without any additional supplements at 40°C and 6.5 pH. Protein content was reduced from 38.4 to 0.8% with immobilized chitinase. Results suggests the possibility of using immobilized enzymes to remove the prawn shell waste from the environment. To the best of our knowledge there was no such study about the deproteinization of prawn shell waste using immobilized chitinase till the date.

Characterization of chitin and chitosan derived from Hermetia illucens, a further step in a circular economy process

Due to their properties and applications, the growing demand for chitin and chitosan has stimulated the market to find more sustainable alternatives to the current commercial source (crustaceans). Bioconverter insects, such as Hermetia illucens, are the appropriate candidates, as chitin is a side stream of insect farms for feed applications. This is the first report on production and characterization of chitin and chitosan from different biomasses derived from H. illucens, valorizing the overproduced larvae in feed applications, the pupal exuviae and the dead adults. Pupal exuviae are the best biomass, both for chitin and chitosan yields and for their abundance and easy supply from insect farms. Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscope analysis revealed the similarity of insect-derived polymers to commercial ones in terms of purity and structural morphology, and therefore their suitability for industrial and biomedical applications. Its fibrillary nature makes H. illucens chitin suitable for producing fibrous manufacts after conversion to chitin nanofibrils, particularly adults-derived chitin, because of its high crystallinity. A great versatility emerged from the evaluation of the physicochemical properties of chitosan obtained from H. illucens, which presented a lower viscosity-average molecular weight and a high deacetylation degree, fostering its putative antimicrobial properties.

Enhancing nonspecific enzymatic hydrolysis of chitin to oligosaccharides pretreated by acid and green solvents under simultaneous microwave-radiation

It is hard to degrade untreated highly crystalline chitin. In this study, two solvents pretreatment chitin (acid swollen chitin (AC), super fine chitin (FC)) and microwave-heating method were used to enhance nonspecific enzymatic hydrolysis (lysozyme and pepsin), which obviously improved the enzymolysis rates by at least 1.31 times. Characterizations of chitin substrates (M_v, SEM, XRD) showed that calcium solvent pretreatment (obtained FC) was milder but effective than phosphoric acid pretreatment (obtained AC). The highest yield of chitin oligosaccharides (37.58 mg/g) were obtained after hydrolyzing AC under five-hour simultaneous microwave radiation by pepsin, among them, the content of N-acetylglucosamine was 13.76 mg/g. While, more chitin oligosaccharides with DP (degree of polymerization) 3-4 and lower DA (degree of acetylation) were obtained when using lysozyme than pepsin. Significantly, the conversion rate of chitin to oligosaccharides went best only when microwave and enzymes acting together (simultaneous strategy), which were at least 35.59% higher than separately pretreatment enzymes and substrates by microwave. The damages of microwave radiation on lysozyme and chitin substrates were revealed, and the operating principle of the whole enzyme reaction system heated by microwave was preliminatively explored.

Heterologous Expression of GH5 Chitosanase in Pichia pastoris and Antioxidant Biological Activity of Its Chitooligosacchride Hydrolysate

Chitosanase was widely used in the production of bioactive chitooligosacchride (CHOS) due to their safety, controllability, environmental protection, and biodegradability. Studies showed that the bioactivity of CHOS is closely related to its degree of polymerization. Therefore, the production of ideal polymerized CHOS becomes our primary goal. In this study, the glycosyl hydrolase (GH) family 5 chitosanase was successfully expressed heterologously in Pichia pastoris. After 96h of high-density fermentation, the chitosanase activity reached 90.62 U·mL^-1, the protein content reached 9.76mg·mL^-1. When 2% chitosan was hydrolyzed by crude enzyme (20U/mL), the hydrolysis rate reached 91.2% after 8h, producing a mixture of CHOS with 2-4 desirable degrees of polymerization (DP). Then, the antioxidant activity of CHOS mixture was investigated, and the results showed that the antioxidant effect was concentration-dependent and had great application potential in the field of nutrition.

Immobilized fungal enzymes: Innovations and potential applications in biodegradation and biosynthesis

Microbial enzymes catalyze various reactions inside and outside living cells. Among the widely studied enzymes, fungal enzymes have been used for some of the most diverse purposes, especially in bioremediation, biosynthesis, and many nature-inspired commercial applications. To improve their stability and catalytic ability, fungal enzymes are often immobilized on assorted materials, conventional as well as nanoscale. Recent advances in fungal enzyme immobilization provide effective and sustainable approaches to achieve improved environmental and commercial outcomes. This review aims to provide a comprehensive overview of commonly studied fungal enzymes and immobilization technologies. It also summarizes recent advances involving immobilized fungal enzymes for the degradation or assembly of compounds used in the manufacture of products, such as detergents, food additives, and fossil fuel alternatives. Furthermore, challenges and future directions are highlighted to offer new perspectives on improving existing technologies and addressing unexplored fields of applications.

Study of the Nanofibers Fabrication Conditions from the Mixture of Poly(vinyl alcohol) and Chitosan by Electrospinning Method

Nanofiber fabrication is attracting great attention from scientists and technologists due to its applications in many fields of life. In order to design a nanosized polymer-based drug delivery system, we studied the conditions for the fabrication of electrospun nanofibers from poly (vinyl alcohol) (PVA) and chitosan (CS), which are well-known as biocompatible, biodegradable and non-toxic polymers that are widely used in the medical field. Aiming to develop nanofibers that can directly target diseased cells for treatment, such as cancerous cells, the ideal choice would be a system that contains the highest CS content as well as high quality fibers. In the present manuscript, it is expected to become the basis for improving the low bioavailability of medicinal drugs limited by poor solubility and low permeability. PVA-CS nanofibers were obtained by electrospinning at a PVA:CS ratio of 5:5 in a 60% (w/w) acetic acid solution under the following parameters: voltage 30 kV, feed rate 0.2 mL/h, needle-collector distance 14 cm. The obtained fibers were relatively uniform, with a diameter range of 77-292 nm and average diameter of 153 nm. The nanofiber system holds promise as a potential material for the integration of therapeutic drugs.

Pharmacokinetics, bioavailability and tissue distribution of chitobiose and chitotriose in rats

Chitooligosaccharides (COSs) have various physiological activities and broad application prospects; however, their pharmacokinetics and tissue distribution remain unclear. In this study, a sensitive and selective ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) method for determining chitobiose (COS 2) and chitotriose (COS 3) in rat serum and tissues was developed. This method was successfully validated based on FDA guidelines in terms of selectivity, calibration curves (lower limit of quantification was 0.002 µg/mL for COS 2 and 0.02 µg/mL for COS 3), precision (intra-day relative standard deviation of 0.04%-3.55% and inter-day relative standard deviation of 1.94%-11.63%), accuracy (intra-day relative error of - 1.81%-11.06% and inter-day relative error of - 9.41%-8.63%), matrix effects, recovery (97.10%-101.29%), stability, dilution integrity, and carry-over effects. Then, the method was successfully applied to the pharmacokinetics and tissue distribution study of COS 2 and COS 3 after intragastric and intravenous administration. After intragastric administration, COS 2 and COS 3 were rapidly absorbed, reached peak concentrations in the serum after approximately 0.45 h, and showed rapid elimination with clearances greater than 18.82 L/h/kg and half-lives lower than 6 h. The absolute oral bioavailability of COS 2 and COS 3 was 0.32%-0.52%. COS 2 and COS 3 were widely distributed in Wistar rat tissues and could penetrated the blood-brain barrier without tissue accumulation.

Combinatorial pathway engineering of Bacillus subtilis for production of structurally defined and homogeneous chitooligosaccharides

Chitooligosaccharides (COSs) have a widespread range of biological functions and an incredible potential for various pharmaceutical and agricultural applications. Although several physical, chemical, and biological techniques have been reported for COSs production, it is still a challenge to obtain structurally defined COSs with defined polymerization (DP) and acetylation patterns, which hampers the specific characterization and application of COSs. Herein, we achieved the de novo production of structurally defined COSs using combinatorial pathway engineering in Bacillus subtilis. Specifically, the COSs synthase NodC from Azorhizobium caulinodans was overexpressed in B. subtilis, leading to 30 ± 0.86 mg/L of chitin oligosaccharides (CTOSs), the homo-oligomers of N-acetylglucosamine (GlcNAc) with a well-defined DP lower than 6. Then introduction of a GlcNAc synthesis module to promote the supply of the sugar acceptor GlcNAc, reduced CTOSs production, which suggested that the activity of COSs synthase NodC and the supply of sugar donor UDP-GlcNAc may be the limiting steps for CTOSs synthesis. Therefore, 6 exogenous COSs synthase candidates were examined, and the nodCM from Mesorhizobium loti yielded the highest CTOSs titer of 560 ± 16 mg/L. Finally, both the de novo pathway and the salvage pathway of UDP-GlcNAc were engineered to further promote the biosynthesis of CTOSs. The titer of CTOSs in 3-L fed-batch bioreactor reached 4.82 ± 0.11 g/L (85.6% CTOS5, 7.5% CTOS4, 5.3% CTOS3 and 1.6% CTOS2), which was the highest ever reported. This is the first report proving the feasibility of the de novo production of structurally defined CTOSs by synthetic biology, and provides a good starting point for further engineering to achieve the commercial production.

Dietary chitooligosaccharide supplementation alleviates intestinal barrier damage, and oxidative and immunological stress in lipopolysaccharide-challenged laying hens

This study aimed to investigate the effects of chitooligosaccharide (COS) on intestinal barrier, antioxidant capacity, and immunity of lipopolysaccharide (LPS)-challenged laying hens. A total of 360 Hy-line Brown laying hens (80-wk-old) were randomly divided into 5 groups with 6 replicates of 12 birds. Hens were fed a corn-soybean meal basal diet supplemented with different COS levels (0; 5; 10; 15; 20 mg/kg) for 8 wk. The results showed that 15 mg/kg COS administration elevated albumen height and Haugh unit (P < 0.05), and numerically optimized productive performance (P > 0.05), therefore, the dosage of 15 mg/kg was chosen for the subsequent experiment. Thereafter, 12 birds from non-supplemented group were randomly selected and assigned into 2 groups, and birds in each group were administered (1.5 mg/kg BW, i.p.) with saline (control group) or LPS (challenge group). Another 6 hens from 15 mg/kg COS-supplemented group were selected and injected with LPS in the same way. Compared with the control group, LPS-challenged birds exhibited elevated circulating diamine oxidase activity, and reduced jejunal villus height and ratio of villus height to crypt depth, and these indices were reversed to control levels by COS (P < 0.05). Also, LPS increased malondialdehyde accumulation and reduced several antioxidant enzyme activities in the intestinal mucosa (P < 0.05). Additionally, LPS increased jejunal secretory IgA and interferon-γ (IFN-γ), and ileal secretory IgA, IgM, and interleukin-1β (IL-1β) concentrations, whereas COS reduced jejunal IFN-γ and IL-1β, and ileal IgM levels (P < 0.05). Moreover, LPS down-regulated mRNA abundance of jejunal occludin and claudin 2, and upregulated expression of jejunal nuclear factor erythroid-2 related factor 2, superoxide dismutase 1, and IFN-γ as well as ileal IL-1β (P < 0.05). Besides, COS increased jejunal occludin and ileal claudin 2, nuclear factor erythroid-2 related factor 2, and heme oxygenase-1 expression, and decreased jejunal IFN-γ and IL-1β abundance (P < 0.05). These results suggested that COS could alleviate LPS-induced intestinal barrier impairment, and oxidative and immunological stress in laying hens.

Deciphering the ChitoCode: fungal chitins and chitosans as functional biopolymers

Chitins and chitosans are among the most widespread and versatile functional biopolymers, with interesting biological activities and superior material properties. While chitins are evolutionary ancient and present in many eukaryotes except for higher plants and mammals, the natural distribution of chitosans, i.e. extensively deacetylated derivatives of chitin, is more limited. Unequivocal evidence for its presence is only available for fungi where chitosans are produced from chitin by the action of chitin deacetylases. However, neither the structural details such as fraction and pattern of acetylation nor the physiological roles of natural chitosans are known at present. We hypothesise that the chitin deacetylases are generating chitins and chitosans with specific acetylation patterns and that these provide information for the interaction with specific chitin- and chitosan-binding proteins. These may be structural proteins involved in the assembly of the complex chitin- and chitosan-containing matrices such as fungal cell walls and insect cuticles, chitin- and chitosan-modifying and -degrading enzymes such as chitin deacetylases, chitinases, and chitosanases, but also chitin- and chitosan-recognising receptors of the innate immune systems of plants, animals, and humans. The acetylation pattern, thus, may constitute a kind of 'ChitoCode', and we are convinced that new in silico, in vitro, and in situ analytical tools as well as new synthetic methods of enzyme biotechnology and organic synthesis are currently offering an unprecedented opportunity to decipher this code. We anticipate a deeper understanding of the biology of chitin- and chitosan-containing matrices, including their synthesis, assembly, mineralisation, degradation, and perception. This in turn will improve chitin and chitosan biotechnology and the development of reliable chitin- and chitosan-based products and applications, e.g. in medicine and agriculture, food and feed sciences, as well as cosmetics and material sciences.

Anti-anaphylactic potential of benzoylpaeoniflorin through inhibiting HDC and MAPKs from Paeonia lactiflora

Guided by cell-based anti-anaphylactic assay, eighteen cage-like monoterpenoid glycosides (1-18) were obtained from the bioactive fraction of P. lactiflora extract. Among these, compounds 1, 5, 6, 11, 12, 15, and 17 significantly reduced the release rate of β-HEX and HIS without or with less cytotoxicity. Furthermore, the most potent inhibitor benzoylpaeoniflorin (5) was selected as the prioritized compound for the study of action of mechanism, and its anti-anaphylactic activity was medicated by dual-inhibiting HDC and MAPK signal pathway. Moreover, molecular docking simulation explained that benzoylpaeoniflorin (5) blocked the conversion of L-histidine to HIS by occupying the HDC active site. Finally, in vivo on PCA using BALB/c mice, benzoylpaeoniflorin (5) suppressed the IgE-mediated PCA reaction in antigen-challenged mice. These findings indicated that cage-like monoterpenoid glycosides, especially benzoylpaeoniflorin (5), mainly contribute to the anti-anaphylactic activity of P. lactiflora by dual-inhibiting HDC and MAPK signal pathway. Therefore, benzoylpaeoniflorin (5) may be considered as a novel drug candidate for the treatment of anaphylactic diseases.

The protective effects of chitosan oligosaccharide (COS) on cadmium-induced neurotoxicity in Wistar rats

The aim of the study was to investigate the influence of chitosan oligosaccharide (COS) on some antioxidant and cytokine levels in the rat hippocampus as well as synaptophysin (SYP) immunoreactivity in the cerebral cortex of the cadmium (Cd) exposed rats. Thirty-two male albino Wistar rats were divided randomly into four equal groups as control (C; n = 8), Cd (n = 8), COS (n = 8), and Cd + COS (CdCOS; n = 8). The rats in the Cd and CdCOS groups received Cd chloride (CdCl₂) (2 mg/kg/d) orally by gastric gavage three times a week for 4 weeks. Besides, COS (200 mg/kg/d) was administered to COS and CdCOS groups five times a week for 4 weeks. Then, they were decapitated and hippocampal/cerebral cortex tissue samples were taken for measurement of GSH levels, CAT and SOD activities, MDA values, TNF-α, IL-6, and IL-10 levels as well as SYP immunoreactivity. Although tissue GSH levels were determined the lowest in the Cd group, these values were attenuated with COS treatment in the CdCOS group (p < .01). In addition, TNF-α levels were alleviated by COS treatment in the CdCOS group when compared to Cd (p < .01). SYP-positive cells were investigated in the cerebral cortex and found mild in the CdCOS group. COS exhibits potential protective effects on Cd-induced neurotoxicity in rats.

Mouse Acidic Chitinase Effectively Degrades Random-Type Chitosan to Chitooligosaccharides of Variable Lengths under Stomach and Lung Tissue pH Conditions

Chitooligosaccharides exhibit several biomedical activities, such as inflammation and tumorigenesis reduction in mammals. The mechanism of the chitooligosaccharides’ formation in vivo has been, however, poorly understood. Here we report that mouse acidic chitinase (Chia), which is widely expressed in mouse tissues, can produce chitooligosaccharides from deacetylated chitin (chitosan) at pH levels corresponding to stomach and lung tissues. Chia degraded chitin to produce N-acetyl-d-glucosamine (GlcNAc) dimers. The block-type chitosan (heterogenous deacetylation) is soluble at pH 2.0 (optimal condition for mouse Chia) and was degraded into chitooligosaccharides with various sizes ranging from di- to nonamers. The random-type chitosan (homogenous deacetylation) is soluble in water that enables us to examine its degradation at pH 2.0, 5.0, and 7.0. Incubation of these substrates with Chia resulted in the more efficient production of chitooligosaccharides with more variable sizes was from random-type chitosan than from the block-type form of the molecule. The data presented here indicate that Chia digests chitosan acquired by homogenous deacetylation of chitin in vitro and in vivo. The degradation products may then influence different physiological or pathological processes. Our results also suggest that bioactive chitooligosaccharides can be obtained conveniently using homogenously deacetylated chitosan and Chia for various biomedical applications.

Reprint of: Advanced glycosidases as ingenious biosynthetic instruments

Until recently, glycosidases, naturally hydrolyzing carbohydrate-active enzymes, have found few synthetic applications in industry, being primarily used for cleaving unwanted carbohydrates. With the establishment of glycosynthase and transglycosidase technology by genetic engineering, the view of glycosidases as industrial biotechnology tools has started to change. Their easy production, affordability, robustness, and substrate versatility, added to the possibility of controlling undesired side hydrolysis by enzyme engineering, have made glycosidases competitive synthetic tools. Current promising applications of engineered glycosidases include the production of well-defined chitooligomers, precious galactooligosaccharides or specialty chemicals such as glycosylated flavonoids. Other synthetic pathways leading to human milk oligosaccharides or remodeled antibodies are on the horizon. This work provides an overview of the synthetic achievements to date for glycosidases, emphasizing the latest trends and outlining possible developments in the field.

Chitosan as possible inhibitory agents and delivery systems in leukemia

Leukemia is a lethal cancer in which white blood cells undergo proliferation and immature white blood cells are seen in the bloodstream. Without diagnosis and management in early stages, this type of cancer can be fatal. Changes in protooncogenic genes and microRNA genes are the most important factors involved in development of leukemia. At present, leukemia risk factors are not accurately identified, but some studies have pointed out factors that predispose to leukemia. Studies show that in the absence of genetic risk factors, leukemia can be prevented by reducing the exposure to risk factors of leukemia, including smoking, exposure to benzene compounds and high-dose radioactive or ionizing radiation. One of the most important treatments for leukemia is chemotherapy which has devastating side effects. Chemotherapy and medications used during treatment do not have a specific effect and destroy healthy cells besides leukemia cells. Despite the suppressing effect of chemotherapy against leukemia, patients undergoing chemotherapy have poor quality of life. So today, researchers are focusing on finding more safe and effective natural compounds and treatments for cancer, especially leukemia. Chitosan is a valuable natural compound that is biocompatible and non-toxic to healthy cells. Anticancer, antibacterial, antifungal and antioxidant effects are examples of chitosan biopolymer properties. The US Food and Drug Administration has approved the use of this compound in medical treatments and the pharmaceutical industry. In this article, we take a look at the latest advances in the use of chitosan in the treatment and improvement of leukemia.

Chitosan: An Overview of Its Properties and Applications

Chitosan has garnered much interest due to its properties and possible applications. Every year the number of publications and patents based on this polymer increase. Chitosan exhibits poor solubility in neutral and basic media, limiting its use in such conditions. Another serious obstacle is directly related to its natural origin. Chitosan is not a single polymer with a defined structure but a family of molecules with differences in their composition, size, and monomer distribution. These properties have a fundamental effect on the biological and technological performance of the polymer. Moreover, some of the biological properties claimed are discrete. In this review, we discuss how chitosan chemistry can solve the problems related to its poor solubility and can boost the polymer properties. We focus on some of the main biological properties of chitosan and the relationship with the physicochemical properties of the polymer. Then, we review two polymer applications related to green processes: the use of chitosan in the green synthesis of metallic nanoparticles and its use as support for biocatalysts. Finally, we briefly describe how making use of the technological properties of chitosan makes it possible to develop a variety of systems for drug delivery.

Mechanotransducive Biomimetic Systems for Chondrogenic Differentiation In Vitro

Osteoarthritis (OA) is a long-term chronic joint disease characterized by the deterioration of bones and cartilage, which results in rubbing of bones which causes joint stiffness, pain, and restriction of movement. Tissue engineering strategies for repairing damaged and diseased cartilage tissue have been widely studied with various types of stem cells, chondrocytes, and extracellular matrices being on the lead of new discoveries. The application of natural or synthetic compound-based scaffolds for the improvement of chondrogenic differentiation efficiency and cartilage tissue engineering is of great interest in regenerative medicine. However, the properties of such constructs under conditions of mechanical load, which is one of the most important factors for the successful cartilage regeneration and functioning in vivo is poorly understood. In this review, we have primarily focused on natural compounds, particularly extracellular matrix macromolecule-based scaffolds and their combinations for the chondrogenic differentiation of stem cells and chondrocytes. We also discuss different mechanical forces and compression models that are used for In Vitro studies to improve chondrogenic differentiation. Summary of provided mechanical stimulation models In Vitro reviews the current state of the cartilage tissue regeneration technologies and to the potential for more efficient application of cell- and scaffold-based technologies for osteoarthritis or other cartilage disorders.

Synergistic Antifungal Activity of Chito-Oligosaccharides and Commercial Antifungals on Biofilms of Clinical Candida Isolates

The development of yeast biofilms is a major problem due to their increased antifungal resistance, which leads to persistent infections with severe clinical implications. The high antifungal activity of well-characterized chitosan polymers makes them potential alternatives for treating yeast biofilms. The activity of a chito-oligosaccharide with a depolymerization degree (DPn) of 32 (C32) and a fraction of acetylation (FA) of 0.15 on Candida sp. biofilms was studied. The results showed a concentration-dependent reduction in the number of viable cells present in C. albicans, C. glabrata, and C. guillermondii preformed biofilms in the presence of C32, especially on intermediate and mature biofilms. A significant decrease in the metabolic activity of yeast biofilms treated with C32 was also observed. The antifungals fluconazole (Flu) and miconazole (Mcz) decreased the number of viable cells in preformed early biofilms, but not in the intermediate or mature biofilms. Contrary to Flu or Mcz, C32 also reduced the formation of new biofilms. Interestingly, a synergistic effect on yeast biofilm was observed when C32 and Flu/Mcz were used in combination. C32 has the potential to become an alternative therapeutic agent against Candida biofilms alone or in combination with antifungal drugs and this will reduce the use of antifungals and decrease antifungal resistance.

The Role of Chitosan Oligosaccharide in Metabolic Syndrome: A Review of Possible Mechanisms

Metabolic syndrome, a cluster of metabolic disorders including central obesity, insulin resistance, hyperglycemia, dyslipidemia, and hypertension, has become a major public health problem worldwide. It is of great significance to develop natural products to prevent and treat metabolic syndrome. Chitosan oligosaccharide (COS) is an oligomer of chitosan prepared by the deacetylation of chitin, which is the second most abundant polymer in nature. In recent years, COS has received widespread attention due to its various biological activities. The present review will summarize the evidence from both in vitro and in vivo studies of the beneficial effects of COS on obesity, dyslipidemia, diabetes mellitus, hyperglycemia, and hypertension, and focus attention on possible mechanisms of the prevention and treatment of metabolic syndrome by COS.

Structures and functions of carbohydrate-active enzymes of chitinolytic bacteria Paenibacillus sp. str. FPU-7

Chitin and its derivatives have valuable potential applications in various fields that include medicine, agriculture, and food industries. Paenibacillus sp. str. FPU-7 is one of the most potent chitin-degrading bacteria identified. This review introduces the chitin degradation system of P. str. FPU-7. In addition to extracellular chitinases, P. str. FPU-7 uses a unique multimodular chitinase (ChiW) to hydrolyze chitin to oligosaccharides on the cell surface. Chitin oligosaccharides are converted to N-acetyl-d-glucosamine by β-N-acetylhexosaminidase (PsNagA) in the cytosol. The functions and structures of ChiW and PsNagA are also summarized. The genome sequence of P. str. FPU-7 provides opportunities to acquire novel enzymes. Genome mining has identified a novel alginate lyase, PsAly. The functions and structure of PsAly are reviewed. These findings will inform further improvement of the sustainable conversion of polysaccharides to functional materials.

Enzymatic Synthesis and Structural Confirmation of Novel Oligosaccharide, D-Fructofuranose-linked Chitin Oligosaccharide

Utilizing transglycosylation reaction catalyzed by β- N -acetylhexosaminidase of Stenotrophomonas maltophilia , β-D-fructofuranosyl-(2↔1)-α- N , N ´diacetylchitobioside (GlcNAc ₂ -Fru) was synthesized from N -acetylsucrosamine and N , N ´-diacetylchitobiose (GlcNAc ₂ ), and β-D-fructofuranosyl-(2↔1)-α- N , N ´, N ´´-triacetylchitotrioside (GlcNAc ₃ -Fru) was synthesized from GlcNAc ₂ -Fru and GlcNAc ₂ . Through purification by charcoal column chromatography, pure GlcNAc ₂ -Fru and GlcNAc ₃ -Fru were obtained in molar yields of 33.0 % and 11.7 % from GlcNAc ₂ , respectively. The structures of these oligosaccharides were confirmed by comparing instrumental analysis data of fragments obtained by enzymatic hydrolysis and acid hydrolysis of them with known data of these fragments.

Progress and challenges in the synthesis of sequence controlled polysaccharides

The sequence, length and substitution of a polysaccharide influence its physical and biological properties. Thus, sequence controlled polysaccharides are important targets to establish structure-properties correlations. Polymerization techniques and enzymatic methods have been optimized to obtain samples with well-defined substitution patterns and narrow molecular weight distribution. Chemical synthesis has granted access to polysaccharides with full control over the length. Here, we review the progress towards the synthesis of well-defined polysaccharides. For each class of polysaccharides, we discuss the available synthetic approaches and their current limitations.

Enzymatic approaches in the bioprocessing of shellfish wastes

Several tonnes of shellfish wastes are generated globally due to the mass consumption of shellfish meat from crustaceans like prawn, shrimp, lobster, crab, Antarctic krill, etc. These shellfish wastes are a reservoir of valuable by-products like chitin, protein, calcium carbonate, and pigments. In the present scenario, these wastes are treated chemically to recover chitin by the chitin and chitosan industries, using hazardous chemicals like HCl and NaOH. Although this process is efficient in removing proteins and minerals, the unscientific dumping of harmful effluents is hazardous to the ecosystem. Stringent environmental laws and regulations on waste disposal have encouraged researchers to look for alternate strategies to produce near-zero wastes on shellfish degradation. The role of enzymes in degrading shellfish wastes is advantageous yet has not been explored much, although it produces bioactive rich protein hydrolysates with good quality chitin. The main objective of the review is to discuss the potential of various enzymes involved in shellfish degradation and their opportunities and challenges over chemical processes in chitin recovery.

Microbial chitinases: properties, enhancement and potential applications

Chitinases are a category of hydrolytic enzymes that catalyze chitin and are formed by a wide variety of microorganisms. In nature, microbial chitinases are primarily responsible for chitin decomposition and play a vital role in the balance of carbon and nitrogen ratio in the ecosystem. The physicochemical attributes and the source of chitinase are the main bases that determine their functional characteristics and hydrolyzed products. Several chitinases have been reported and characterized, and they obtain a wider consideration for their utilization in a large number of uses such as in agriculture, food, environment, medicine and pharmaceutical companies. The antifungal and insecticidal impacts of several chitinases have been extensively studied, aiming to protect crops from phytopathogenic fungi and insects. Chitooligosaccharides synthesized by chitin degradation have been shown to improve human health through their antimicrobial, antioxidant, anti-inflammatory and antitumor properties. This review aims at investigating chitinase production, properties and their potential applications in various biotechnological fields.

Genomic and Proteomic Study of Andreprevotia ripae Isolated from an Anthill Reveals an Extensive Repertoire of Chitinolytic Enzymes

Chitin is an abundant natural polysaccharide that is hard to degrade because of its crystalline nature and because it is embedded in robust co-polymeric materials containing other polysaccharides, proteins, and minerals. Thus, it is of interest to study the enzymatic machineries of specialized microbes found in chitin-rich environments. We describe a genomic and proteomic analysis of Andreprevotia ripae, a chitinolytic Gram-negative bacterium isolated from an anthill. The genome of A. ripae encodes four secreted family GH19 chitinases of which two were detected and upregulated during growth on chitin. In addition, the genome encodes as many as 25 secreted GH18 chitinases, of which 17 were detected and 12 were upregulated during growth on chitin. Finally, the single lytic polysaccharide monooxygenase (LPMO) was strongly upregulated during growth on chitin. Whereas 66% of the 29 secreted chitinases contained two carbohydrate-binding modules (CBMs), this fraction was 93% (13 out of 14) for the upregulated chitinases, suggesting an important role for these CBMs. Next to an unprecedented multiplicity of upregulated chitinases, this study reveals several chitin-induced proteins that contain chitin-binding CBMs but lack a known catalytic function. These proteins are interesting targets for discovery of enzymes used by nature to convert chitin-rich biomass. The MS proteomic data have been deposited in the PRIDE database with accession number PXD025087.

Efficacy of a Chitin-Based Water-Soluble Derivative in Inducing Purpureocillium lilacinum against Nematode Disease (Meloidogyne incognita)

Plant-parasitic nematodes cause severe economic losses annually which has been a persistent problem worldwide. As current nematicides are highly toxic, prone to drug resistance, and have poor stability, there is an urgent need to develop safe, efficient, and green strategies. Natural active polysaccharides such as chitin and chitosan with good biocompatibility and biodegradability and inducing plant disease resistance have attracted much attention, but their application is limited due to their poor solubility. Here, we prepared 6-oxychitin with good water solubility by introducing carboxylic acid groups based on retaining the original skeleton of chitin and evaluated its potential for nematode control. The results showed that 6-oxychitin is a better promoter of the nematicidal potential of Purpureocillium lilacinum than other water-soluble chitin derivatives. After treatment, the movement of J2s and egg hatching were obviously inhibited. Further plant experiments found that it can destroy the accumulation and invasion of nematodes, and has a growth-promoting effect. Therefore, 6-oxychitin has great application potential in the nematode control area.

CaCO3-Chitosan Composites Granules for Instant Hemostasis and Wound Healing

Excessive bleeding induces a high risk of death and is a leading cause of deaths that result from traffic accidents and military conflict. In this paper, we developed a novel porous chitosan-CaCO3 (CS-CaCO3) composite material and investigated its hemostatic properties and wound healing performance. The CS-CaCO3 composites material was prepared via a wet-granulation method. Granulation increases the infiltrating ability of the CS-CaCO3 composites material. The improved water absorption ability was enhanced to 460% for the CS-CaCO3 composites material compared to the CaCO3 or chitosan with only one single component. The coagulation studies in vivo illustrated that the blood clotting time was greatly reduced from 31 s for CaCO3 to 16 s for the CS-CaCO3 composite material. According to the results of the wound healing experiments in rats, it was found that the CS-CaCO3 composite material can promote wound healing. The CS-CaCO3 composite material could accelerate wound healing to a rate of 9 days, compared with 12 days for the CaCO3. The hemostatic activity, biocompatibility, and low cost of CS-CaCO3 composite material make it a potential agent for effective hemostatic and wound healing materials.

Structural characterization of two solute-binding proteins for N,N'-diacetylchitobiose/N,N',N''-triacetylchitotoriose of the gram-positive bacterium, Paenibacillus sp. str. FPU-7

The chitinolytic bacterium Paenibacillus sp. str. FPU-7 efficiently degrades chitin into oligosaccharides such as N-acetyl-D-glucosamine (GlcNAc) and disaccharides (GlcNAc)2 through multiple secretory chitinases. Transport of these oligosaccharides by P. str. FPU-7 has not yet been clarified. In this study, we identified nagB1, predicted to encode a sugar solute-binding protein (SBP), which is a component of the ABC transport system. However, the genes next to nagB1 were predicted to encode two-component regulatory system proteins rather than transmembrane domains (TMDs). We also identified nagB2, which is highly homologous to nagB1. Adjacent to nagB2, two genes were predicted to encode TMDs. Binding experiments of the recombinant NagB1 and NagB2 to several oligosaccharides using differential scanning fluorimetry and surface plasmon resonance confirmed that both proteins are SBPs of (GlcNAc)2 and (GlcNAc)3. We determined their crystal structures complexed with and without chitin oligosaccharides at a resolution of 1.2 to 2.0 Å. The structures shared typical SBP structural folds and were classified as subcluster D-I. Large domain motions were observed in the structures, suggesting that they were induced by ligand binding via the "Venus flytrap" mechanism. These structures also revealed chitin oligosaccharide recognition mechanisms. In conclusion, our study provides insight into the recognition and transport of chitin oligosaccharides in bacteria.

Recent advances in biotechnology for marine enzymes and molecules

The marine environment is the most biologically and chemically diverse habitat on Earth, and provides numerous marine-derived products, including enzymes and molecules, for industrial and pharmaceutical applications. Marine biotechnology provides important biological resources from marine habitat conservation to applied science. In recent years, advances in techniques in interdisciplinary research fields, including metabolic engineering and synthetic biology have significantly improved the production of marine-derived commodities. In this review, we outline the recent progress in the use or marine enzymes and molecules in biotechnology, including newly discovered products, function optimization of enzymes, and production improvement of small molecules.

Waste-Derived NPK Nanofertilizer Enhances Growth and Productivity of Capsicum annuum L

Waste generation is a global issue that necessitates effective management for both human and animal health as well as environment. There are several ways to reduce waste, but recycling appears to be the best choice. By recycling, not only will the problem of pollution be resolved, but valuable compounds could be generated to be used as nutrients for plants. In this study, eco-friendly methods were established to produce α- and β-chitosan (CS) (as a source of nitrogen) with different degrees of deacetylation from shrimp shells and squid pin waste, phosphorous through degreasing and calcination of bovine bone and potassium from evaporation of banana peels Kolakhar. The waste bulk products were physically characterized and dry-milled into nano-powders. Different concentrations of the produced nano-NPK fertilizer (10%, 25%, 50% and 100%) were foliar-applied to Capsicum annum L. cv. Cordoba plants and compared to commercial chemical fertilizer and untreated control plants. The obtained results revealed that the nano-composite NPK with 25% concentration significantly promoted growth, yield and harvest of C. annuum as compared with the control and chemical fertilizer-treated plants. This study demonstrated that the use of an eco-friendly preparation of waste NPK composites, with a low concentration, could be applied as foliar fertilizer over chemical fertilizer to enhance the growth and productivity of Capsicum.

Advances in the preparation and assessment of the biological activities of chitosan oligosaccharides with different structural characteristics

Chitosan oligosaccharides (COSs) are widely used biopolymers that have been studied in relation to a variety of abnormal biological activities in the food and biomedical fields. Since different COS preparation technologies produce COS compounds with different structural characteristics, it has not yet been possible to determine whether one or more chito-oligomers are primarily responsible for the bioactivity of COSs. The inherent biocompatibility, mucosal adhesion and nontoxic nature of COSs are well documented, as is the fact that they are readily absorbed from the intestinal tract, but their structure-activity relationship requires further investigation. This review summarizes the methods used for COS preparation, and the research findings with regard to the antioxidant, anti-inflammatory, anti-obesity, bacteriostatic and antitumour activity of COSs with different structural characteristics. The correlation between the molecular structure and bioactivities of COSs is described, and new insights into their structure-activity relationship are provided.

Optimizing Chitin Depolymerization by Lysozyme to Long-Chain Oligosaccharides

Chitin oligosaccharides (COs) hold high promise as organic fertilizers in the ongoing agro-ecological transition. Short- and long-chain COs can contribute to the establishment of symbiotic associations between plants and microorganisms, facilitating the uptake of soil nutrients by host plants. Long-chain COs trigger plant innate immunity. A fine investigation of these different signaling pathways requires improving the access to high-purity COs. Here, we used the response surface methodology to optimize the production of COs by enzymatic hydrolysis of water-soluble chitin (WSC) with hen egg-white lysozyme. The influence of WSC concentration, its acetylation degree, and the reaction time course were modelled using a Box–Behnken design. Under optimized conditions, water-soluble COs up to the nonasaccharide were formed in 51% yield and purified to homogeneity. This straightforward approach opens new avenues to determine the complex roles of COs in plants.

A Novel GH Family 20 β-N-acetylhexosaminidase With Both Chitosanase and Chitinase Activity From Aspergillus oryzae

Aminooligosaccharides possess various biological activities and can exploit wide applications in food, pharmaceutical and cosmetic industries. Commercial aminooligosaccharides are often prepared by the hydrolysis of chitin and chitosan. In this study, a novel GH family 20 β-N-acetylhexosaminidases gene named AoNagase was cloned from Aspergillus oryzae and expressed in Pichia pastoris. The purified AoNagase had maximal activity at pH 5.5 and 65°C. It exhibited good pH stability in the range of pH 6.0–7.5 and at temperatures below 50°C. AoNagase was capable of hydrolyzing not only colloidal chitosan (508.26 U/mg) but also chitin (29.78 U/mg). The kinetic parameters (K_m and V_max) of AoNagase were 1.51 mM, 1106.02 U/mg for chitosan and 0.41 mM, 40.31 U/mg for colloidal chitin. To our knowledge, AoNagase is the first GH family 20 β-N-acetylhexosaminidase capable of hydrolyzing both chitosan and chitin. AoNagase is an endo-type β-N-acetylhexosaminidases and can potentially be used for the manufacturing of aminooligosaccharides.

Alginate gels crosslinked with chitosan oligomers - a systematic investigation into alginate block structure and chitosan oligomer interaction

Three alginates with fundamentally different block structures, poly-M, poly-G, and poly-MG, have been investigated upon ionic crosslinking with chitosan oligosaccharides (CHOS), using circular dichroism (CD), rheology, and computer simulations, supporting the previously proposed gelling principle of poly-M forming zipper-like junction zones with chitosan (match in charge distance along the two polyelectrolytes) and revealing a unique high gel strength poly-MG chitosan gelling system. CD spectroscopy revealed an increased chiroptical activity exclusively for the poly-M chitosan gelling system, indicative of induced conformational changes and higher ordered structures. Rheological measurement revealed gel strengths (G' < 900 Pa) for poly-MG (1%) CHOS (0.3%) hydrogels, magnitudes of order greater than displayed by its poly-M analogue. Furthermore, the ionically crosslinked poly-MG chitosan hydrogel increased in gel strength upon the addition of salt (G' < 1600 at 50 mM NaCl), suggesting a stabilization of the junction zones through hydrophobic interactions and/or a phase separation. Molecular dynamics simulations have been used to further investigate these findings, comparing interaction energies, charge distances and chain alignments. These alginates are displaying high gel strengths, are known to be fully biocompatible and have revealed a broad range of tolerance to salt concentrations present in biological systems, proving high relevance for biomedical applications.

Exploring Effects of Chitosan Oligosaccharides on the DSS-Induced Intestinal Barrier Impairment In Vitro and In Vivo

Intestinal barrier dysfunction is an essential pathological change in inflammatory bowel disease (IBD). The mucus layer and the intestinal epithelial tight junction act together to maintain barrier integrity. Studies showed that chitosan oligosaccharide (COS) had a positive effect on gut health, effectively protecting the intestinal barrier in IBD. However, these studies usually focused on its impact on the intestinal epithelial tight junction. The influence of COS on the intestinal mucus layer is still poorly understood. In this study, we explored the effect of COS on intestinal mucus in vitro using human colonic mucus-secreted HT-29 cells. COS relieved DSS (dextran sulfate sodium)-induced mucus defects. Additionally, the structural characteristics of COS greatly influenced this activity. Finally, we evaluated the protective effect of COS on intestinal barrier function in mice with DSS-induced colitis. The results indicated that COS could manipulate intestinal mucus production, which likely contributed to its intestinal protective effects.

Advanced glycosidases as ingenious biosynthetic instruments

Until recently, glycosidases, naturally hydrolyzing carbohydrate-active enzymes, have found few synthetic applications in industry, being primarily used for cleaving unwanted carbohydrates. With the establishment of glycosynthase and transglycosidase technology by genetic engineering, the view of glycosidases as industrial biotechnology tools has started to change. Their easy production, affordability, robustness, and substrate versatility, added to the possibility of controlling undesired side hydrolysis by enzyme engineering, have made glycosidases competitive synthetic tools. Current promising applications of engineered glycosidases include the production of well-defined chitooligomers, precious galactooligosaccharides or specialty chemicals such as glycosylated flavonoids. Other synthetic pathways leading to human milk oligosaccharides or remodeled antibodies are on the horizon. This work provides an overview of the synthetic achievements to date for glycosidases, emphasizing the latest trends and outlining possible developments in the field.