Effects of chitooligosaccharides on rabbit neutrophils in vitro

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.

Chitosan protects liver against ischemia-reperfusion injury via regulating Bcl-2/Bax, TNF-α and TGF-β expression

The study aimed to investigate the potential attenuation effect of chitosan in liver ischemia/reperfusion injury (I/R), and its relevant protective mechanisms. Chitosan (200 mg/kg) has been administered orally for 30 days, later animals underwent liver 45 min ischemia and reperfusion for 60 min. Following treatment with chitosan, the levels of serum aminotransferases and lactate dehydrogenase were significantly reduced. Similarly, hepatic (GSH, SOD, CAT, GST and GPx) were enhanced, and the level of tissue malondialdehyde (MDA) was decreased. In addition, inflammatory cytokinesis (TNF-α and TGF-β) have recorded a significant decrease in their mRNA expression and protein levels using qPCR and ELISA respectively. Marked reduction of apoptosis has been indicated by the elevation in BCL2, and decreasing in BAX, Caspace-3 and Cytochrome-c expression levels, which furthermore confirmed by DNA fragmentation assay. The enhancement of the previous parameters resulted in a marked improvement in the liver architectures after chitosan administration. In conclusion, chitosan has proved its efficiency as an anti-inflammatory and antioxidant agent through its inhibitory effect of cytokines and reducing ROS respectively. In addition, chitosan could modulate the changes in histological structure and alleviate apoptosis induced by liver I/R, which recommend it as an efficient agent for protection against liver I/R injury.

Bioconversion of Chitin to Bioactive Chitooligosaccharides: Amelioration and Coastal Pollution Reduction by Microbial Resources

Chitin-metabolizing products are of high industrial relevance in current scenario due to their wide biological applications, relatively lower cost, greater abundance, and sustainable supply. Chitooligosaccharides have remarkably wide spectrum of applications in therapeutics such as antitumor agents, immunomodulators, drug delivery, gene therapy, wound dressings, as chitinase inhibitors to prevent malaria. Hypocholesterolemic and antimicrobial activities of chitooligosaccharides make them a molecule of choice for food industry, and their functional profile depends on the physicochemical characteristics. Recently, chitin-based nanomaterials are also gaining tremendous importance in biomedical and agricultural applications. Crystallinity and insolubility of chitin imposes a major hurdle in the way of polymer utilization. Chemical production processes are known to produce chitooligosaccharides with variable degree of polymerization and properties along with ecological concerns. Biological production routes mainly involve chitinases, chitosanases, and chitin-binding proteins. Development of bio-catalytic production routes for chitin will not only enhance the production of commercially viable chitooligosaccharides with defined molecular properties but will also provide a means to combat marine pollution with value addition.

Enhancement of the water solubility and antioxidant activity of hesperidin by chitooligosaccharide

BACKGROUND

Hesperidin is a natural product and a strong antioxidant with potential applications in various food and pharmaceutical products. However, its poor water solubility greatly limits its applications.

RESULTS

In this study, chitooligosaccharide (COS) was applied to prepare a stable complex with hesperidin (Hesp-COS) via the spray-drying method at 100 °C for 20 min. The resultant complex was characterized by Fourier transformation infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and proton nuclear magnetic resonance spectroscopy. It was demonstrated that the aromatic rings of hesperidin interacted with COS through hydrogen bonding and formed Hesp-COS complex. As a result, both the water solubility and antioxidant activity of Hesp-COS were higher than that of the free hesperidin.

CONCLUSION

The preparation conditions of Hesp-COS in this study were efficient and produced an increment in both the water solubility and antioxidant activity of hesperidin. © 2017 Society of Chemical Industry.

Chitosan oligosaccharide: Biological activities and potential therapeutic applications

Chitosan oligosaccharide (COS) is an oligomer of β-(1➔4)-linked d-glucosamine. COS can be prepared from the deacetylation and hydrolysis of chitin, which is commonly found in the exoskeletons of arthropods and insects and the cell walls of fungi. COS is water soluble, non-cytotoxic, readily absorbed through the intestine and mainly excreted in the urine. Of particular importance, COS and its derivatives have been demonstrated to possess several biological activities including anti-inflammation, immunostimulation, anti-tumor, anti-obesity, anti-hypertension, anti-Alzheimer's disease, tissue regeneration promotion, drug and DNA delivery enhancement, anti-microbial, anti-oxidation and calcium-absorption enhancement. The mechanisms of actions of COS have been found to involve the modulation of several important pathways including the suppression of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPK) and the activation of AMP-activated protein kinase (AMPK). This review summarizes the current knowledge of the preparation methods, pharmacokinetic profiles, biological activities, potential therapeutic applications and safety profiles of COS and its derivatives. In addition, future research directions are discussed.

Microwave-assisted synthesis of chitooligosaccharide guanidine and its effect on GLUT4-dependent glucose uptake through an Akt-activated protein kinase signaling pathway in L6 skeletal muscle cells

COSG was likely to be effective by increasing the phosphorylation level of Akt and promoting the membrane translocation of GLUT4, thereby increasing the glucose uptake of skeletal cells.

Immunomodulatory properties of shellfish derivatives associated with human health

Some vital components of marine shellfish are documented as an important source for both nutritional and pharmacological applications.

Dietary chitosan oligosaccharide supplementation improves foetal survival and reproductive performance in multiparous sows

Chitosan oligosaccharide (COS), a partially hydrolysed product of chitosan, has various important biological activities.

Chitosan-based vaccine adjuvants: incomplete characterization complicates preclinical and clinical evaluation

A number of preclinical and clinical studies with chitosan-adjuvanted antigen- and DNA-based vaccines have been carried out. Various chitosans and their modifications, in different forms (solutions, powders, gels and particles), have been evaluated with various antigens administered via different routes. Chitosan is a generic name for a wide array of glucosamine-based substances derived from biological sources, and standardization is necessary. However, in most of the studies published to date, molecular weight, viscosity, deacetylation degree and/or purity level (especially endotoxins) are not provided for the initial chitosan substance and/or final formulation and the preparation procedure is not detailed. Evaluation of adjuvant properties is challenging, given that the only available data are insufficient to demonstrate immunogenicity for chitosans with characteristics within certain intervals to elucidate mechanisms of action or to exclude impurities as the active substance. These and other issues of chitosan-based vaccine adjuvants are summarized and a step-by-step evaluation approach for chitosan-based vaccine adjuvants is outlined.

Chitosan oligosaccharides downregulate the expression of E-selectin and ICAM-1 induced by LPS in endothelial cells by inhibiting MAP kinase signaling

The expression of adhesion molecules in endothelial cells elicited by lipopolysaccharide (LPS) is involved in the adhesive interaction between endothelial cells and monocytes in inflammation. In this study, in order to characterize the anti-inflammatory effects of chitosan oligosaccharides (COS) on LPS‑induced inflammation and to elucidate the underlying mechanisms, the mRNA levels of E-selectin and intercellular adhesion molecule-1 (ICAM-1) were measured in porcine iliac artery endothelial cells (PIECs). When these cells were treated with COS, the LPS-induced mRNA expression of E-selectin and ICAM-1 was reduced through the inhibition of the signal transduction cascade, p38 mitogen‑activated protein kinase (MAPK)/extracellular regulated protein kinase 1/2 (ERK1/2) and nuclear factor-κB (NF-κB). Moreover, through the inhibition of p38 MAPK and ERK1/2, COS suppressed the LPS-induced NF-κB p65 translocation. We found that COS suppressed the phosphorylation of p38 MAPK and the translocation of NF-κB p65 into the nucleus in a dose-dependent manner, and inhibited the adhesion of U973 cells to PIECs. Based on these results, it can be concluded that COS downregulate the expression of E-selectin and ICAM-1 by inhibiting the phosphorylation of MAPKs and the activation of NF-κB in LPS-treated PIECs. Our study demonstrates the valuable anti-inflammatory properties of COS.

The antiviral activities and mechanisms of marine polysaccharides: an overview

Recently, the studies on the antiviral activities of marine natural products, especially marine polysaccharides, are attracting more and more attention all over the world. Marine-derived polysaccharides and their lower molecular weight oligosaccharide derivatives have been shown to possess a variety of antiviral activities. This paper will review the recent progress in research on the antiviral activities and the mechanisms of these polysaccharides obtained from marine organisms. In particular, it will provide an update on the antiviral actions of the sulfated polysaccharides derived from marine algae including carrageenans, alginates, and fucans, relating to their structure features and the structure-activity relationships. In addition, the recent findings on the different mechanisms of antiviral actions of marine polysaccharides and their potential for therapeutic application will also be summarized in detail.

Dietary administration of chitooligosaccharides to enhance growth, innate immune response and disease resistance of Trachinotus ovatus

The present study was conducted to investigate the effects of dietary chitooligosaccharides (COS) supplementation on the innate immune response and protection against Vibrio harveyi infection in Trachinotus ovatus. A basal diet was supplemented with 0.0 (control), 2.0, 4.0 and 6.0 g COS kg(-1) to formulate four experimental diets. Each diet was randomly allocated to triplicate groups of fish in floating sea cages (1.5 × 1.0 × 2.0 m), and each cage was stocked with 80 fish (initial average weight 10.8 ± 0.05 g). After 8 weeks of feeding trial, Both the final weight and specific growth rate (SGR) significantly increased with increasing dietary COS levels up to 4.0 g kg(-1), whereas there were no significant differences for COS levels from 4.0 to 6.0 g kg(-1). A decreased feed conversion ratio (FCR) was observed with increasing dietary COS levels. The total leukocyte counts (WBC), differential leukocyte counts, respiratory burst activity, lysozyme and superoxide dismutase (SOD) activity were significantly increased with the increased levels of dietary COS (P < 0.05), and reached a maximum at level of 4.0 g kg(-1) COS. There were no significant differences in those immunological parameters between 4.0 and 6.0 g kg(-1) COS. Moreover, the dietary COS supplementation groups also exhibited a decrease in the cumulative symptom rates compared to the controls when challenged with V. harveyi. These results indicated that dietary intake containing COS could enhance the immune responses of fish and improve its resistance to infection by V. harveyi. Especially supplementation with 4.0 g kg(-1) COS to the fish for 56 days showed considerable improvement in the growth, survival and immune response of the fish.

Chitosan oligosaccharides suppress LPS-induced IL-8 expression in human umbilical vein endothelial cells through blockade of p38 and Akt protein kinases

AIM

To investigate whether and how COS inhibited IL-8 production in LPS-induced human umbilical vein endothelial cells (HUVECs).

METHODS

RT-PCR, enzyme-linked immunosorbent assays (ELISA) and Western blotting were used to study IL-8 expression and related signaling pathway. Wound healing migration assays and monocytic cell adhesion analysis were used to explore the chemotactic and adhesive activities of HUVECs.

RESULTS

COS 50-200 μg/mL exerted a significant inhibitory effect on LPS 100 ng/mL-induced IL-8 expression in HUVECs at both the transcriptional and translational levels. In addition, COS 50-200 μg/mL inhibited LPS-induced HUVEC migration and U937 monocyte adhesion to HUVECs in a concentration-dependent manner. Signal transduction studies suggest that COS blocked LPS-induced activation of nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) as well as phosphorylation of p38 mitogen-activated protein kinase (MAPK) and phosphokinase Akt. Further, the over-expression of LPS-induced IL-8 mRNA in HUVECs was suppressed by a p38 MAPK inhibitor (SB203580, 25 μmol/L) or a phosphatidylinositol 3-kinase (PI3K) inhibitor (LY294002, 50 μmol/L).

CONCLUSION

COS inhibited LPS-induced IL-8 expression in HUVECs through the blockade of the p38 MAPK and PI3K/Akt signaling pathways.

Potential anti-HIV agents from marine resources: an overview

Human immunodeficiency virus (HIV) infection causes acquired immune deficiency syndrome (AIDS) and is a global public health issue. Anti-HIV therapy involving chemical drugs has improved the life quality of HIV/AIDS patients. However, emergence of HIV drug resistance, side effects and the necessity for long-term anti-HIV treatment are the main reasons for failure of anti-HIV therapy. Therefore, it is essential to isolate novel anti-HIV therapeutics from natural resources. Recently, a great deal of interest has been expressed regarding marine-derived anti-HIV agents such as phlorotannins, sulfated chitooligosaccharides, sulfated polysaccharides, lectins and bioactive peptides. This contribution presents an overview of anti-HIV therapeutics derived from marine resources and their potential application in HIV therapy.

Angiotensin-I-converting enzyme (ACE) inhibitors from marine resources: prospects in the pharmaceutical industry

Hypertension or high blood pressure is one of the major independent risk factors for cardiovascular diseases. Angiotensin-I-converting enzyme (EC 3.4.15.1; ACE) plays an important physiological role in regulation of blood pressure by converting angiotensin I to angiotensin II, a potent vasoconstrictor. Therefore, the inhibition of ACE activity is a major target in the prevention of hypertension. Recently, the search for natural ACE inhibitors as alternatives to synthetic drugs is of great interest to prevent several side effects and a number of novel compounds such as bioactive peptides, chitooligosaccharide derivatives (COS) and phlorotannins have been derived from marine organisms as potential ACE inhibitors. These inhibitory derivatives can be developed as nutraceuticals and pharmaceuticals with potential to prevent hypertension. Hence, the aim of this review is to discuss the marine-derived ACE inhibitors and their future prospects as novel therapeutic drug candidates for treat hypertension.

Advance in chitosan hydrolysis by non-specific cellulases

Besides the specific chitinase, chitosanase and lysozyme, chitosan also could be hydrolyzed by some non-specific enzymes such as cellulase, protease, lipase and pepsin, especially cellulase, which show high activity on chitosan. Almost all the cellulases produced by different kinds of microorganisms could degrade chitosan to chitooligomers. The existence of bifunctional enzymes with cellulase and chitosanase activity is one of the reasons for cellulase on chitosan hydrolysis. The bifunctional cellulase-chitosanases mainly belong to glycoside hydrolase family 8 (GH-8), few belong to GH-5 and GH-7, according to the homogeneity analysis of amino acids sequences. Their three dimensional structures however have not been clearly determined. This paper may serve as a guide for a further study on the relationship between structure and function of chitosanolytic cellulases.