Sulfated chitosan oligosaccharides suppress LPS-induced NO production via JNK and NF-κB inactivation

The preparation, modification and hepatoprotective activity of chitooligosaccharides: A review

Chitooligosaccharides (COS) has attracted increasing attention due to the various promising bioactivities, tremendous potential in agricultural, environmental nutritional and functional food fields. COS as the major degradation product from chitosan or chitin is prepared via enzymatic, chemical and physical methods. Further obtained COS generally possesses different structural characteristics, such as molecular weight, degree of acetylation and degree of polymerization. Innovations into COS modification has also broadened application of COS in nutrition as well as in agricultural safety. Due to the affinity between structure and bioactivity, diversity of structural characteristics endows COS with various bioactivities like antitumor, antioxidant and anti-inflammatory effects, especially hepatoprotective activity. Therefore, the present review narrates the recent developments in COS physicochemical properties, while paying considerable attention to preparation strategies of COS and their advantages and disadvantages. Moreover, the modification of COS is also discussed including alkylation, quaternization and sulfation, herein the structure-activity relationship of COS was highlighted. Additionally, we summarize the latest research on hepatoprotective activity and mechanisms of COS. Eventually, the future directions of research on COS were discussed, which would provide a new appreciation for the future use of COS.

Chitosan-Based Hydrogels as Antibacterial/Antioxidant/Anti-Inflammation Multifunctional Dressings for Chronic Wound Healing

Due to repeated microbial infection, persistent inflammation, excessive oxidative stress, and cell dysfunction, chronic wounds are difficult to heal, posing a serious threat to public health. Therefore, developing multifunctional wound dressings that can regulate the complex microenvironment of chronic wounds and enhance cellular function holds great significance. Recently, chitosan has emerged as a promising biopolymer for wound healing due to its excellent biocompatibility, biodegradability, and versatile bioactivity. The aim of this review is to provide a comprehensive understanding of the mechanisms of delayed chronic wound healing and discuss the healing-promoting properties of chitosan and its derivatives, such as good biocompatibility, antibacterial activity, hemostatic capacity, and the ability to promote tissue regeneration. On this basis, the potential applications of chitosan-based hydrogels are summarized in chronic wound healing, including providing a suitable microenvironment, eliminating bacterial infections, promoting hemostasis, inhibiting chronic inflammation, alleviating oxidative stress, and promoting tissue regeneration. In addition, the concerns and perspectives for the clinical application of chitosan-based hydrogels are also discussed.

Advances in the preparation, characterization, and biological functions of chitosan oligosaccharide derivatives: A review

Chitosan oligosaccharide (COS), which represent the positively charged basic amino oligosaccharide in nature, is the deacetylated and degraded products of chitin. COS has become the focus of intensive scientific investigation, with a growing body of practical and clinical studies highlighting its remarkable health-enhancing benefits. These effects encompass a wide range of properties, including antibacterial, antioxidant, anti-inflammatory, and anti-tumor activities. With the rapid advancements in chemical modification technology for oligosaccharides, many COS derivatives have been synthesized and investigated. These newly developed derivatives possess more stable chemical structures, improved biological activities, and find applications across a broader spectrum of fields. Given the recent interest in the chemical modification of COS, this comprehensive review seeks to consolidate knowledge regarding the preparation methods for COS derivatives, alongside discussions on their structural characterization. Additionally, various biological activities of COS derivatives have been discussed in detail. Lastly, the potential applications of COS derivatives in biomedicine have been reviewed and presented.

Caffeic acid-grafted chitooligosaccharides downregulate MAPK and NF-kB in RAW264.7 cells

Chitooligosaccharide (COS) is a derivative of chitosan, which is a natural macromolecular compound. COS has been shown effects in an inflammatory response. Recent reports show that COS derivatives have enhanced anti-inflammatory activity by inhibiting intracellular signals. Evaluation of the anti-inflammatory effect of caffeic acid conjugated COS chain (CA-COS) was performed in this study. The effects of CA-COS on the inflammatory response were demonstrated in lipopolysaccharide-stimulated RAW264.7 macrophages. The results showed that CA-COS inhibited nitric oxide (NO) production and downregulated the gene expression of nitric oxide synthase (iNOS), and cytokines such as tumor necrosis factor-alpha (TNF-α), IL-1β, and IL-6 without cytotoxic effect. In addition, western blot analysis showed that CA-COS inhibits the protein expression of iNOS and nuclear factor kappa B (NF-kB), including p50 and p65, and mitogen-activated protein kinase (MAPK) signaling pathways. Collectively, these results provide clear evidence for the anti-inflammatory mechanism of CA-COS that show great potential as a novel agent for the prevention and therapy of inflammatory diseases.

Anti-COVID-19 Credentials of Chitosan Composites and Derivatives: Future Scope?

Chitosan derivatives and composites are the next generation polymers for biomedical applications. With their humble origins from the second most abundant naturally available polymer chitin, chitosan is currently one of the most promising polymer systems, with wide biological applications. This current review gives a bird's eye view of the antimicrobial applications of chitosan composites and derivatives. The antiviral activity and the mechanisms behind the inhibitory activity of these components have been reviewed. Specifically, the anti-COVID-19 aspects of chitosan composites and their derivatives have been compiled from the existing scattered reports and presented. Defeating COVID-19 is the battle of this century, and the chitosan derivative-based combat strategies naturally become very attractive. The challenges ahead and future recommendations have been addressed.

Chitosan and its derivatives as polymeric anti-viral therapeutics and potential anti-SARS-CoV-2 nanomedicine

The coronavirus pandemic, COVID-19 has a global impact on the lives and livelihoods of people. It is characterized by a widespread infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), where infected patients may develop serious medical complications or even face death. Development of therapeutic is essential to reduce the morbidity and mortality of infected patients. Chitosan is a versatile biomaterial in nanomedicine and exhibits anti-microbial, anti-cancer and immunomodulatory properties. This review highlights the progress in chitosan design and application pertaining to the anti-viral effects of chitosan and chitosan derivatives (hydroxypropyl trimethylammonium, sulfate, carboxymethyl, bromine, sialylglycopolymer, peptide and phosphonium conjugates) as a function of molecular weight, degree of deacetylation, type of substituents and their degree and site of substitution. The physicochemical attributes of these polymeric therapeutics are identified against the possibility of processing them into nanomedicine which can confer a higher level of anti-viral efficacy. The designs of chitosan for the purpose of targeting SARS-CoV-2, as well as the ever-evolving strains of viruses with a broad spectrum anti-viral activity to meet pandemic preparedness at the early stages of outbreak are discussed.

Chitosan and Chitooligosaccharide: The Promising Non-Plant-Derived Prebiotics with Multiple Biological Activities

Biodegradable chitin is the second-most abundant natural polysaccharide, widely existing in the exoskeletons of crabs, shrimps, insects, and the cell walls of fungi. Chitosan and chitooligosaccharide (COS, also named chitosan oligosaccharide) are the two most important deacetylated derivatives of chitin. Compared with chitin, chitosan and COS not only have more satisfactory physicochemical properties but also exhibit additional biological activities, which cause them to be widely applied in the fields of food, medicine, and agriculture. Additionally, due to their significant ability to improve gut microbiota, chitosan and COS are deemed prospective prebiotics. Here, we introduced the production, physicochemical properties, applications, and pharmacokinetic characteristics of chitosan and COS. Furthermore, we summarized the latest research on their antioxidant, anti-inflammatory, and antimicrobial activities. Research progress on the prebiotic functions of chitosan and COS is particularly reviewed. We creatively analyzed and discussed the mechanisms and correlations underlying these activities of chitosan and COS and their physicochemical properties. Our work enriched people's understanding of these non-plant-derived prebiotics. Based on this review, the future directions of research on chitosan and COS are explored. Collectively, optimizing the production technology of chitin derivatives and enriching understanding of their biological functions will shed more light on their capability to improve human health.

Chrysin-Loaded Chitosan Nanoparticle-Mediated Neuroprotection in Aβ1-42-Induced Neurodegenerative Conditions in Zebrafish

Amyloid β plaques and neurofibrillary tangles are the characteristic features of Alzheimer's disease (AD). Plaques of amyloid β play a pivotal role in affecting cognitive functions and memory. Alzheimer's disease is a progressive neurodegenerative disease and is one of the leading causes of dementia worldwide. Several treatment strategies focusing on the amyloid cascade have been implemented to treat AD. The blood-brain barrier (BBB) poses the main obstructive barrier by refraining drugs from penetrating the brain. Nanotechnology is a promising research field for brain drug delivery using nanosized particles. Zebrafish is emerging as a model of interest to elaborate on brain targeting and nanotechnology-based therapeutics for neurodegenerative diseases. In the current study, we have synthesized and characterized chrysin-loaded chitosan nanoparticles (Chr-Chi NPs) and evaluated them for neuroprotection against amyloid-β-induced toxicity. We find that treatment with Chr-Chi NPs helps to retain memory, cognition, and synaptic connections, which are otherwise compromised due to Aβ_1-42 toxicity. The NPs further help in reducing aggregates of amyloid β, thus decreasing neuronal death and generation of reactive oxygen species (ROS). Taken together, our study brings to light a novel strategy for treating AD by a combined action on the neurons and amyloid aggregates mediated by chrysin and chitosan, respectively. Chr-Chi NPs, therefore, have the potential to provide a beneficial combinatorial treatment strategy for AD.

Resolving the Mutually Exclusive Immune Responses of Chitosan with Nanomechanics and Immunological Assays

Multifaceted functions displayed by both pro- and anti-inflammatory properties of chitosan hinder its effective development as an immunomodulatory agent. Herein, the contributions of the bending stiffness of chitosan with regard to its immune regulatory properties toward inflammation are investigated. The anti-inflammatory properties of chitosan molecular weight (MW) with a shorter (≈1 kDa) or longer (≈15 kDa) than the persistent length (L_P ) are compared using immunological assays and nanomechanics-based experiments on the surface forces apparatus (SFA). Interestingly, 1 kDa chitosan significantly enhances the generation of anti-inflammatory regulatory T cells (Tregs) through the Dectin-1-dependent pattern recognition receptor (PRR) on antigen-presenting cells. SFA analyses also show a similar trend of interaction forces between chitosan and diverse PRRs depending on their MW. The results obtained in the immunological and nanomechanical experiments are consistent and imply that the binding features of PRRs vary depending on the MW of chitosan, which may alter immune activity. In accordance, in vivo administration of only 1 kDa represses inflammatory responses and suppresses the progression of experimental colitis. This study elucidates a previously unexplored bending stiffness-dependent immune regulatory property of chitosan and suggests the applicability of low MW (rod-like) chitosan as a pharmaceutical ingredient to treat diverse inflammatory disorders.

The Microstructure, Antibacterial and Antitumor Activities of Chitosan Oligosaccharides and Derivatives

Chitosan obtained from abundant marine resources has been proven to have a variety of biological activities. However, due to its poor water solubility, chitosan application is limited, and the degradation products of chitosan oligosaccharides are better than chitosan regarding performance. Chitosan oligosaccharides have two kinds of active groups, amino and hydroxyl groups, which can form a variety of derivatives, and the properties of these derivatives can be further improved. In this review, the key structures of chitosan oligosaccharides and recent studies on chitosan oligosaccharide derivatives, including their synthesis methods, are described. Finally, the antimicrobial and antitumor applications of chitosan oligosaccharides and their derivatives are discussed.

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.

The potential roles of chitosan oligosaccharide in prevention of kidney injury in obese and diabetic conditions

Obesity is closely associated with insulin resistance (IR). The most likely links between the two are obesity-mediated systemic low-grade chronic inflammation, endoplasmic reticulum stress and mitochondrial dysfunction, which are all known to contribute to the development of type 2 diabetes (T2DM) and eventually diabetic nephropathy (DN). Chitosan oligosaccharide (COS) is an oligomer of chitosan prepared by the deacetylation of chitin commonly found in exoskeletons of crustaceans such as shrimp and crab as well as the cell walls of fungi. COS has various biological effects including lipid lowering, anti-inflammation, anti-diabetes, and anti-oxidant effects. Therefore, COS is a potential new therapeutic agent for treatment of the obesity-induced DN condition. It is an abundant natural polymer and therefore freely available. This review includes information regarding the relationship between obesity, IR, T2DM, and DN as well as the potential usefulness of COS in controlling lipid and cholesterol metabolism, T2DM and kidney injury models in both in vivo and in vitro studies. However, evidence is limited regarding the effect of COS on the DN model. Further studies, especially in obesity-induced DN, are needed to support the mechanisms proposed in this review.

Use of Biodegradable, Chitosan-Based Nanoparticles in the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that affects more than 24 million people worldwide and represents an immense medical, social and economic burden. While a vast array of active pharmaceutical ingredients (API) is available for the prevention and possibly treatment of AD, applicability is limited by the selective nature of the blood-brain barrier (BBB) as well as by their severe peripheral side effects. A promising solution to these problems is the incorporation of anti-Alzheimer drugs in polymeric nanoparticles (NPs). However, while several polymeric NPs are nontoxic and biocompatible, many of them are not biodegradable and thus not appropriate for CNS-targeting. Among polymeric nanocarriers, chitosan-based NPs emerge as biodegradable yet stable vehicles for the delivery of CNS medications. Furthermore, due to their mucoadhesive character and intrinsic bioactivity, chitosan NPs can not only promote brain penetration of drugs via the olfactory route, but also act as anti-Alzheimer therapeutics themselves. Here we review how chitosan-based NPs could be used to address current challenges in the treatment of AD; with a specific focus on the enhancement of blood-brain barrier penetration of anti-Alzheimer drugs and on the reduction of their peripheral side effects.

Immunostimulatory effect of N-2-hydroxypropyltrimethyl ammonium chloride chitosan-sulfate chitosan complex nanoparticles on dendritic cells

In this study, we synthesized negatively charged chitosan sulfate and positively charged hydroxypropyltrimethyl ammonium chloride chitosan (HACC), and then prepared chitosan derivatives with positive and negative ions as nanoparticles (NPs) by ovalbumin encapsulation using the polyelectrolyte method. NPs with different substitution sites and molecular weights (MW) were prepared by varying conditions. We then determined the zeta potential average, diameter, encapsulation effect, and their immunostimulatory effects on dendritic cells (DCs). The results showed that chitosan-derivative NPs ranged in size from 153.33 to 320.90 nm; all NPs were positive, with charges ranging from 17.10 to 39.30 mV and the encapsulation rates of 65 %-75 %. Three NPs greatly promoted the expression and secretion of interleukin-6 (IL-6), tumor necrosis factor (TNF-α), and interleukin-1β (IL-1β) in DC cells: C2,3,6 chitosan sulfate-HACC (C2,3,6-HACC; 200 kDa), C3,6 chitosan sulfate-HACC (C3,6-HACC; 200 kDa) and C6 chitosan sulfate-HACC (C6-HACC; 50 kDa). We also found that 200-kDa C2,3,6-HACC and 50-kDa C6-HACC NPs greatly increased secretion of the major histocompatibility complex-II (MHC-II), CD40, CD80, and CD86, indicating that these NPs promote effective antigen presentation, further increasing immunity effects. Finally, we applied laser confocal photography and determined that NPs entered the cell to promote the regulation of cellular immune activity; this discovery lays a foundation for further research on their mechanism of their action. Therefore, C2,3,6-HACC and C6-HACC NPs have the potential as immunological adjuvants.

In Situ Mannosylated Nanotrinity-Mediated Macrophage Remodeling Combats Candida albicans Infection

Deep Candida albicans infection is one of the major causes of death in immunosuppressed hosts. Remodeling macrophages to phenotype M1 can decrease fungus burden and facilitate combating C. albicans under an immunosuppressive state. In this study, a nanotrinity was exploited to direct fungicidal macrophage polarization by leveraging the regulation pathways in macrophage redifferentiation. Conventional chemotherapeutic imatinib, which can abrogate M2 macrophage polarization via "shutting off" the STAT6 phosphorylation pathway, was encapsulated in biodegradable polymeric nanoparticles. In house-customized dual functional mannosylated chitosan oligosaccharides were then coated on the surface of the imatinib-laden nanoparticles, and thus, a mannosylated nanotrinity was achieved with ternary functions for macrophage remodeling: (i) imatinib-blocked STAT6 phosphorylation pathway for decreasing M2 macrophage population; (ii) chitosan oligosaccharides-mediated TLR-4 pathway activation that could promote macrophage redifferentiation to M1 phenotype; (iii) mannose motif-enhanced macrophage targeting. After physiochemical characterization, regulatory effects of the mannosylated nanotrinity on macrophages and the anti-C. albicans efficacy were evaluated at the cellular level and animal level, respectively. The results demonstrated that our mannosylated nanotrinity could efficiently induce macrophage polarization toward the M1 phenotype, decrease M2 phenotype production, and markedly lessen fungus burden and increased the median survival time of mice infected with C. albicans. Therefore, the mannosylated nanotrinity developed in this study could significantly induce macrophage remodeling in situ by the two-pronged process, "turning on" M1 phenotype polarization meanwhile "shutting off" M2 phenotype polarization, and thus allowed to eradicate C. albicans infection.

Recent Updates in Pharmacological Properties of Chitooligosaccharides

Chemical structures derived from marine foods are highly diverse and pharmacologically promising. In particular, chitooligosaccharides (COS) present a safe pharmacokinetic profile and a great source of new bioactive polymers. This review describes the antioxidant, anti-inflammatory, and antidiabetic properties of COS from recent publications. Thus, COS constitute an effective agent against oxidative stress, cellular damage, and inflammatory pathogenesis. The mechanisms of action and targeted therapeutic pathways of COS are summarized and discussed. COS may act as antioxidants via their radical scavenging activity and by decreasing oxidative stress markers. The mechanism of COS antidiabetic effect is characterized by an acceleration of pancreatic islets proliferation, an increase in insulin secretion and sensitivity, a reduction of postprandial glucose, and an improvement of glucose uptake. COS upregulate the GLUT2 and inhibit digestive enzyme and glucose transporters. Furthermore, they resulted in reduction of gluconeogenesis and promotion of glucose conversion. On the other hand, the COS decrease inflammatory mediators, suppress the activation of NF-κB, increase the phosphorylation of kinase, and stimulate the proliferation of lymphocytes. Overall, this review brings evidence from experimental data about protective effect of COS.

Immunomodulatory Effects and Induction of Apoptosis by Different Molecular Weight Chitosan Oligosaccharides in Head Kidney Macrophages From Blunt Snout Bream (Megalobrama amblycephala)

Prophylactic administration of immunopotentiators has been tested and practiced as one of the most promising disease prevention methods in aquaculture. Chitosan oligosaccharide (COS), as an ideal immunopotentiator, is mainly used as feed additives in aquaculture, and the antimicrobial and immune enhancement effects are highly correlated with molecular weight (MW), but little is known about the mechanisms in teleost. Here, we isolated and purified macrophages in head kidney from blunt snout bream (Megalobrama amblycephala), stimulated them with three different MW (~500 Da, ~1000 Da and 2000~3000 Da) COSs, performed RNA-sequencing, global transcriptional analyses, and verification by quantitative real-time PCR (qRT-PCR) and immunofluorescent staining methods. Differential expression gene (DEG) analysis indicated that gene expression patterns are different and the proportion of unique genes are relatively high in different treatment groups. Biological process and gene set enrichment analysis (GSEA) demonstrated that all three COSs activate resting macrophages, but the degrees are different. Weighted gene co-expression network analysis (WGCNA) reflected gene modules correlated to MW, the module hub genes and top GO terms showed the activation of macrophage was positively correlated with the MW, and larger MW COS activated cell death associated GO terms. Further use of the screening and enrichment functions of STRING and Pfam databases discovered that apoptosis-related pathways and protein families were activated, such as the P53 pathway and caspase protein family. qRT-PCR results showed that as the stimulation time extends, the innate immune-related and P53 pathways are gradually activated, and the degree of activation is positively correlated with the stimulation time. In addition, apoptosis was detected by immunofluorescent staining in three groups. Therefore, the use of COS has two sides—it can activate the immune system against pathogen invasion, but with the increase in stimulation time and MW, macrophage apoptosis is induced, which may be caused by abnormal replication of DNA and excessive inflammation. This study provides a theoretical basis for the rational use of COS as an immunopotentiator in aquaculture.

Anti-inflammatory effects of newly synthesized α-galacto-oligosaccharides on dextran sulfate sodium-induced colitis in C57BL/6J mice

α-Galacto-oligosaccharides have been reported to have beneficial health effects. The purpose of this study was to investigate the preventive effects of a newly synthesized α-galacto-oligosaccharide mixture (α-GOSg), as well as raffinose family oligosaccharides (RFOs), on dextran sulfate sodium (DSS)-induced colitis in mice. When administered in drinking water at 0.5% for 15 days, both α-GOSg and RFOs significantly decreased fecal hemoglobin content, partially prevented colon length shortening, reduced the severity of colon inflammation, and attenuated DSS-induced upregulation of cyclooxygenase-2. In addition, the activation of the inflammatory regulator nuclear factor-kappa B was slightly inhibited by α-GOSg. The results showed that the newly synthesized α-GOSg preparation has similar anti-inflammatory activities as RFOs in this colitis model. The anti-inflammatory activity of α-GOSg in humans remains to be investigated.

Immunostimulatory effects of sulfated chitosans on RAW 264.7 mouse macrophages via the activation of PI3K/Akt signaling pathway

To investigate the immunostimulatory effects of chitosan sulfates, we prepared α- and β-chitosan sulfates with different molecular weights and compared their immunostimulatory activities in RAW 264.7 macrophages. Results suggest that β-chitosan sulfates were more active than α-chitosan in promoting nitric oxide (NO) production. Further study show that β-chitosan sulfate significantly promoted the production of NO, prostaglandin E₂, tumor necrosis factor (TNF)-α, interleukin-6 and interleukin-1β at the levels of transcription and translation. Moreover, Western blots revealed that it induced the phosphorylation of p85 and Akt, and the nuclear translocation of p50/p65 and c-Fos/c-Jun. The luciferase activity of cells pretreated with β-chitosan sulfate further confirmed the nuclear translocation of p50/p65 and c-Fos/c-Jun. Determination of Toll-like receptor (TLR) 4 expression suggested that β-chitosan sulfate at least partly bound to TLR4. In conclusion, β-chitosan sulfates activate RAW 264.7 cells through the PI3K-Akt pathway, which is dependent on activator protein-1 and nuclear factor-κB activation.

Application of Chitosan, Chitooligosaccharide, and Their Derivatives in the Treatment of Alzheimer's Disease

Classic hypotheses of Alzheimer's disease (AD) include cholinergic neuron death, acetylcholine (ACh) deficiency, metal ion dynamic equilibrium disorder, and deposition of amyloid and tau. Increased evidence suggests neuroinflammation and oxidative stress may cause AD. However, none of these factors induces AD independently, but they are all associated with the formation of Aβ and tau proteins. Current clinical treatments based on ACh deficiency can only temporarily relieve symptoms, accompanied with many side-effects. Hence, searching for natural neuroprotective agents, which can significantly improve the major symptoms and reverse disease progress, have received great attention. Currently, several bioactive marine products have shown neuroprotective activities, immunomodulatory and anti-inflammatory effects with low toxicity and mild side effects in laboratory studies. Recently, chitosan (CTS), chitooligosaccharide (COS) and their derivatives from exoskeletons of crustaceans and cell walls of fungi have shown neuroprotective and antioxidative effects, matrix metalloproteinase inhibition, anti-HIV and anti-inflammatory properties. With regards to the hypotheses of AD, the neuroprotective effect of CTS, COS, and their derivatives on AD-like changes in several models have been reported. CTS and COS exert beneficial effects on cognitive impairments via inhibiting oxidative stress and neuroinflammation. They are also a new type of non-toxic β-secretase and AChE inhibitor. As neuroprotective agents, they could reduce the cell membrane damage caused by copper ions and decrease the content of reactive oxygen species. This review will focus on their anti-neuroinflammation, antioxidants and their inhibition of β-amyloid, acetylcholinesterase and copper ions adsorption. Finally, the limitations and future work will be discussed.

Regulatory effects and molecular mechanism of Trigonostemon reidioides on lipopolysaccharide‑induced inflammatory responses in RAW264.7 cells

Trigonostemon reidioides (Kurz) Craib has been traditionally used for the treatment of vomiting and asthma in Cambodia. However, the underlying molecular mechanisms of the anti‑inflammatory effect of T. reidioides extract remains unknown. The present study investigated the anti‑inflammatory activity and molecular action of an ethanol extract of T. reidioides (ETR) in lipopolysaccharide (LPS)‑induced RAW264.7 macrophage cells. Nitric oxide assays, ELISA, reverse transcription‑quantitative polymerase chain reaction and western blot analysis were used. ETR treatment inhibited the production of nitric oxide by downregulating inducible nitric oxide synthase expression, while exhibiting no significant cytotoxicity compared with macrophages treated with LPS‑alone. Consequently, ETR decreased the production of certain proinflammatory cytokines, including interleukin (IL)‑1β, IL‑6 and tumor necrosis factor‑α. Additionally, ETR inhibited the activation of mitogen‑activated protein kinases (MAPKs), including extracellular signal‑regulated kinase, c‑Jun N‑terminal kinase and p38 MAPK, as well as the phosphatidylinositol 3‑kinase (PI3K)/Akt signaling pathway. These effects were mediated by inhibition of the nuclear localization of nuclear factor κ‑B (NF‑κB). Taken together, the results of the present study demonstrate that ETR may exert an anti‑inflammatory effect by inhibiting the expression of inflammatory mediators and cytokines via downregulation of the NF‑κB, PI3K/Akt and the MAPK signaling pathways in LPS‑stimulated macrophages. Based on these results, we hypothesize that ETR may be a potential therapeutic agent for the treatment of inflammatory disorders.

Eburicoic acid from Laetiporus sulphureus (Bull.:Fr.) Murrill attenuates inflammatory responses through inhibiting LPS-induced activation of PI3K/Akt/mTOR/NF-κB pathways in RAW264.7 cells

Excessive activation of macrophages has been implicated in various types of inflammatory injury. Suppression of macrophage activation would have therapeutic benefits, leading to the alleviation of the progression of inflammatory diseases. Eburicoic acid (EA) is one of main bioactive components isolated from Laetiporus sulphureus (Bull.:Fr.) Murrill. In our previous study, we found that EA possessed anti-inflammatory activities. However, the cellular and molecular mechanisms underlying its anti-inflammatory activities remain to be poorly understood. The present study aimed to further evaluate its effect on lipopolysaccharide (LPS)-induced inflammatory responses in RAW264.7 macrophage cells. We investigated the anti-inflammatory effect by modulating LPS-induced activation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/nuclear transcription factor-κB (NF-κB) pathway in RAW264.7 cells. The results showed that EA caused no obvious cytotoxicity, and its suitable concentrations on RAW264.7 cells were in the range from 0.02 to 0.08 μM. EA significantly inhibited the releases of inflammatory mediators, nitrite oxide (NO) and prostaglandin E2 (PGE₂); suppressed mRNA and protein expression levels of inducible nitrite oxide synthase (iNOS) and cyclooxygenase-2 COX-2 and pro-inflammatory cytokine TNF-α, IL-6, and IL-1β; and reduced levels of phosphorylated PI3K, Akt, mTOR, and NF-κBp65 in LPS-induced RAW264.7 cells in dose- and time-dependent manners. These aforementioned results indicated that EA executed anti-inflammatory effect on LPS-induced RAW264.7 cells, and this effect might be achieved via suppressing the PI3K/Akt/mTOR/NF-κB signaling pathway and inhibiting the LPS-induced productions of inflammatory mediators and pro-inflammatory cytokines.

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.

Evaluation of cytotoxicity and inflammatory activity of wastewater collected from a textile factory before and after treatment by coagulation-flocculation methods

Effective treatment of textile effluent prior to discharge is necessary in order to avert the associated adverse health impacts on human and aquatic life. In the present investigation, coagulation/flocculation processes were evaluated for the effectiveness of the individual treatment. Effectiveness of the treatment was evaluated based on the physicochemical characteristics. The quality of the pre-treated and post-flocculation treated effluent was further evaluated by determination of cytotoxicity and inflammatory activity using RAW264.7 cell cultures. Cytotoxicity was determined using WST-1 assay. Nitric oxide (NO) and interleukin 6 (IL-6) were used as biomarkers of inflammation. NO was determined in cell culture supernatant using the Griess reaction assay. The IL-6 secretion was determined using double antibody sandwich enzyme linked immunoassay (DAS ELISA). Cytotoxicity results show that raw effluent reduced the cell viability significantly (P < 0.001) compared to the negative control. All effluent samples treated by coagulation/flocculation processes at 1 in 100 dilutions had no cytotoxic effects on RAW264.7 cells. The results on inflammatory activities show that the raw effluent and effluent treated with 1.6 g/L of Fe-Mn oxide induced significantly (P < 0.001) higher NO production than the negative control. The inflammatory results further show that the raw effluent induced significantly (P < 0.001) higher production of IL-6 than the negative control. Among the coagulants/flocculants evaluated Al2(SO4)3.14H2O at a dosage of 1.6 g/L was the most effective to remove both toxic and inflammatory pollutants. In conclusion, the inflammatory responses in RAW264.7 cells can be used as sensitive biomarkers for monitoring the effectiveness of coagulation/flocculation processes used for textile effluent treatment.

Engineered hybrid cardiac patches with multifunctional electronics for online monitoring and regulation of tissue function

In cardiac tissue engineering approaches to treat myocardial infarction, cardiac cells are seeded within three-dimensional porous scaffolds to create functional cardiac patches. However, current cardiac patches do not allow for online monitoring and reporting of engineered-tissue performance, and do not interfere to deliver signals for patch activation or to enable its integration with the host. Here, we report an engineered cardiac patch that integrates cardiac cells with flexible, freestanding electronics and a 3D nanocomposite scaffold. The patch exhibited robust electronic properties, enabling the recording of cellular electrical activities and the on-demand provision of electrical stimulation for synchronizing cell contraction. We also show that electroactive polymers containing biological factors can be deposited on designated electrodes to release drugs in the patch microenvironment on demand. We expect that the integration of complex electronics within cardiac patches will eventually provide therapeutic control and regulation of cardiac function.

Enhanced expression of glucose-regulated protein 78 correlates with malondialdehyde levels during the formation of liver cirrhosis in rats

The aim of the present study was to explore the role of glucose-regulated protein 78 (GRP78) in the development of liver cirrhosis promoted by intestinal endotoxemia in rats. Fifty-one male Wistar rats were randomly divided into the liver cirrhosis 4-week, 6-week and 8-week groups and the normal control group at each time point. Liver cirrhosis was induced by employing multiple pathogenic factors in the rats. Blood and liver tissues were collected. The levels of alanine aminotransferase (ALT), homocysteine, endotoxin and tumor necrosis factor-α (TNF-α) in the plasma, and TNF-α, malondialdehyde (MDA) and procollagen type III peptide (PIIIP) in the liver tissues were determined. The mRNA and protein expression levels of GRP78 in the liver were detected using reverse transcription-quantitative polymerase chain reaction and immunohistochemistry. Morphological changes were observed through hematoxylin and eosin and van Gieson staining of the liver. Liver cirrhosis caused marked histopathological changes to the livers of the rats. Following significant increases in the levels of ALT, homocysteine, endotoxin and TNF-α in the plasma, and TNF-α, MDA and PIIIP in the liver tissues of all experimental groups with the progression of liver cirrhosis, the mRNA and protein expression levels of GRP78 also gradually increased. In addition, correlation analysis indicated that the enhanced expression of GRP78 correlated with the MDA levels of the rats during the formation of liver cirrhosis.

The assessment of inflammatory activity and toxicity of treated sewage using RAW264.7 cells

Toxicity and inflammatory activity of wastewater samples were evaluated using RAW264.7 cells as a bioassay model. The RAW264.7 cell cultures were exposed to sterile filtered wastewater samples collected from a sewage treatment plant. Cell viability was evaluated using WST-1 and XTT assays. Inflammatory effects of samples were assessed by determination of nitric oxide (NO) and interleukin 6 (IL-6). The NO was estimated using the Griess reaction and IL-6 was measured by enzyme-linked immunoassay. All samples had no toxicity effects to RAW264.7 cells, however they significantly (P < 0.001) induced NO and IL-6 production. The highest NO (12.5 ± 0.38 μM) and IL-6 (25383.84 ± 2327 pg/mL) production was induced by postbiofiltration sample. Final effluent induced the lowest inflammatory response, which indicates effective sewage treatment. In conclusion, wastewater samples can induce inflammatory activities in RAW264.7 cells. The RAW264.7 cells, therefore, can be used as a model for monitoring the quality of treated sewage.

The potential of chitosan and its derivatives in prevention and treatment of age-related diseases

Age-related, diet-related and protein conformational diseases, such as atherosclerosis, diabetes mellitus, cancer, hypercholesterolemia, cardiovascular and neurodegenerative diseases are common in the elderly population. The potential of chitosan, chitooligosaccharides and their derivatives in prevention and treatment of age-related dysfunctions is reviewed and discussed in this paper. The influence of oxidative stress, low density lipoprotein oxidation, increase of tissue stiffness, protein conformational changes, aging-associated chronic inflammation and their pathobiological significance have been considered. The chitosan-based functional food also has been reviewed.

Anti-inflammatory effect of resveratrol through the suppression of NF-κB and JAK/STAT signaling pathways

Resveratrol, the most important ingredient extracted from Polygonum cuspidatum, exerts cytoprotective effects via anti-inflammatory actions in vitro. In this study, we investigated this effect of resveratrol on the lipopolysaccharide (LPS)-induced inflammatory response and its underlying molecular mechanism of action in RAW264.7 murine macrophages. Results showed that resveratrol down-regulated the expression of inducible nitric oxide synthase (iNOS) and interleukin-6 (IL-6), therefore, suppressed the production of nitric oxide and the secretion of IL-6 in LPS-stimulated RAW264.7 cells in a dose-dependent manner. Resveratrol also inhibited the translocation of high-mobility group box 1 (HMGB1) from the nucleus to the cytoplasm and of nuclear transcription factor kappa-B (NF-κB) p65 from the cytoplasm to the nucleus; it suppressed the phosphorylation of IκBα. Furthermore, these actions were mediated by suppressing the phosphorylation of signal transducer and activator of transcription (STAT)-1 and -3. In conclusion, these data indicate that resveratrol exerts anti-inflammatory effects, at least in part by reducing the release of HMGB1 and modulating the NF-κB and Janus kinase/STAT signaling pathways. Resveratrol could potentially be developed as a useful agent for the chemoprevention of inflammatory diseases.