Preparation of chitosan oligomers and their antioxidant activity

Spray drying the Pickering emulsions stabilized by chitosan/ovalbumin polyelectrolyte complexes for the production of oxidation stable tuna oil microcapsules

The microencapsulation of polysaturated fatty acids by spray drying remains a challenge due to their susceptibility to oxidation. In this work, antioxidant Pickering emulsions were attempted as feeds to produce oxidation stable tuna oil microcapsules. The results indicated that the association between chitosan (CS) and ovalbumin (OVA) was a feasible way to fabricate antioxidant and wettable complexes and a high CS percentage favored these properties. The particles could yield tuna oil Pickering emulsions with enhanced oxidation stability through high-pressure homogenization, which were successfully spray dried to produce microcapsules with surface oil content of 8.84 % and microencapsulation efficiency of 76.65 %. The microcapsules exhibited significantly improved oxidation stability and their optimum peroxide values after storage at 50 °C, 85 % relative humidity, or natural light for 15 d were 48.67 %, 60.07 %, and 39.69 % respectively lower than the powder derived from the OVA-stabilized emulsion. Hence, Pickering emulsions stabilized by the CS/OVA polyelectrolyte complexes are potential in the production of oxidation stable polyunsaturated fatty acid microcapsules by spray drying.

O-carboxymethyl chitosan in biomedicine: A review

O-carboxymethyl chitosan (O-CMC) is a chitosan derivative produced through the substitution of hydroxyl (-OH) functional groups in glucosamine units with carboxymethyl (-CH2COOH) substituents, effectively addressing the inherent solubility issues of chitosan in aqueous solutions. O-CMC has garnered significant interest due to its enhanced solubility, elevated viscosity, minimal toxicity, and advantageous biocompatibility properties. Furthermore, O-CMC demonstrates antibacterial, antifungal, and antioxidant characteristics, rendering it a promising candidate for various biomedical uses such as wound healing, tissue engineering, anti-tumor therapies, biosensors, and bioimaging. Additionally, O-CMC is well-suited for the fabrication of nanoparticles, hydrogels, films, microcapsules, and tablets, offering opportunities for effective drug delivery systems. This review outlines the distinctive features of O-CMC, offers analyses of advancements and future potential based on current research, examines significant obstacles for clinical implementation, and foresees its ongoing significant impacts in the realm of biomedicine.

α-Chitosan and β-Oligochitosan Mixtures-Based Formula for In Vitro Assessment of Melanocyte Cells Response

Chitosan is a natural polymer with numerous biomedical applications. The cellular activity of chitosan has been studied in various types of cancer, including melanoma, and indicates that these molecules can open new perspectives on antiproliferative action and anticancer therapy. This study analyzes how different chitosan conformations, such as α-chitosan (CH) or β-oligochitosan (CO), with various degrees of deacetylation (DDA) and molar mass (MM), both in different concentrations and in CH-CO mixtures, influence the cellular processes of SK-MEL-28 melanocytes, to estimate the reactivity of these cells to the applied treatments. The in vitro evaluation was carried out, aiming at the cellular metabolism (MTT assay), cellular morphology, and chitinase-like glycoprotein YKL-40 expression. The in vitro effect of the CH-CO mixture application on melanocytes is obvious at low concentrations of α-chitosan/β-oligochitosan (1:2 ratio), with the cell's response supporting the hypothesis that β-oligo-chitosan amplifies the effect. This oligochitosan mixture, favored by the β conformation and its small size, penetrates faster into the cells, being more reactive when interacting with some cellular components. Morphological effects expressed by the loss of cell adhesion and the depletion of YKL-40 synthesis are significant responses of melanocytes. β-oligochitosan (1.5 kDa) induces an extension of cytophysiological effects and limits the cell viability compared to α-chitosan (400-900 kDa). Statistical analysis using multivariate techniques showed differences between the CH samples and CH-CO mixtures.

Physicochemical modifications in microwave-irradiated chitosan: biopharmaceutical and medical applications

Biopharmaceutical and biomedical applications of chitosan has evolved exponentially in the past decade, owing to its unique physicochemical properties. However, further applications can be garnered from modified chitosan, specifically, depolymerized chitosan, with potentially useful applications in drug delivery or biomedicine. The use of microwave irradiation in depolymerization of chitosan appears to be more consequential than other methods, and results in modification of key physicochemical properties of chitosan, including molecular weight, viscosity and degree of deacetylation. In-depth review of such microwave-depolymerized chitosan and subsequent potential biopharmaceutical or biomedical applications has not been presented before. Herein, we present a detailed review of key physicochemical changes in chitosan following various depolymerization approaches, with focus on microwave irradiation and how these changes impact relevant biopharmaceutical or biomedical applications.

Bee chitosan nanoparticles loaded with apitoxin as a novel approach to eradication of common human bacterial, fungal pathogens and treating cancer

Antimicrobial resistance is one of the largest medical challenges because of the rising frequency of opportunistic human microbial infections across the globe. This study aimed to extract chitosan from the exoskeletons of dead bees and load it with bee venom (commercially available as Apitoxin [Api]). Then, the ionotropic gelation method would be used to form nanoparticles that could be a novel drug-delivery system that might eradicate eight common human pathogens (i.e., two fungal and six bacteria strains). It might also be used to treat the human colon cancer cell line (Caco2 ATCC ATP-37) and human liver cancer cell line (HepG2ATCC HB-8065) cancer cell lines. The x-ray diffraction (XRD), Fourier transform infrared (FTIR), and dynamic light scattering (DLS) properties, ζ-potentials, and surface appearances of the nanoparticles were evaluated by transmission electron microscopy (TEM). FTIR and XRD validated that the Api was successfully encapsulated in the chitosan nanoparticles (ChB NPs). According to the TEM, the ChB NPs and the ChB NPs loaded with Apitoxin (Api@ChB NPs) had a spherical shape and uniform size distribution, with non-aggregation, for an average size of approximately 182 and 274 ± 3.8 nm, respectively, and their Zeta potential values were 37.8 ± 1.2 mV and - 10.9 mV, respectively. The Api@ChB NPs had the greatest inhibitory effect against all tested strains compared with the ChB NPs and Api alone. The minimum inhibitory concentrations (MICs) of the Api, ChB NPs, and Api@ChB NPs were evaluated against the offer mentioned colony forming units (CFU/mL), and their lowest MIC values were 30, 25, and 12.5 μg mL-1, respectively, against Enterococcus faecalis. Identifiable morphological features of apoptosis were observed by 3 T3 Phototox software after Api@ChB NPs had been used to treat the normal Vero ATCC CCL-81, Caco2 ATCC ATP-37, and HepG2 ATCC HB-8065 cancer cell lines for 24 h. The morphological changes were clear in a concentration-dependent manner, and the ability of the cells was 250 to 500 μg mL-1. These results revealed that Api@ChB NPs may be a promising natural nanotreatment for common human pathogens.

Impacts of chitosan and its nanoformulations on the metabolic syndromes: a review

A significant public health issue worldwide is metabolic syndrome, a cluster of metabolic illnesses that comprises insulin resistance, obesity, dyslipidemia, hyperglycemia, and hypertension. The creation of natural treatments and preventions for metabolic syndrome is crucial. Chitosan, along with its nanoformulations, is an oligomer of chitin, the second-most prevalent polymer in nature, which is created via deacetylation. Due to its plentiful biological actions in recent years, chitosan and its nanoformulations have drawn much interest. Recently, the chitosan nanoparticle-based delivery of CRISPR-Cas9 has been applied in treating metabolic syndromes. The benefits of chitosan and its nanoformulations on insulin resistance, obesity, diabetes mellitus, dyslipidemia, hyperglycemia, and hypertension will be outlined in the present review, highlighting potential mechanisms for the avoidance and medication of the metabolic syndromes by chitosan and its nanoformulations.

Sustainable functionalized chitosan based nano-composites for wound dressings applications: A review

Functionalized chitosan nanocomposites have been studied for wound dressing applications due to their excellent antibacterial and anti-fungal properties. Polysaccharides show excellent antibacterial and drug-release properties and can be utilized for wound healing. In this article, we comprise distinct approaches for chitosan functionalization, such as photosensitizers, dendrimers, graft copolymerization, quaternization, acylation, carboxyalkylation, phosphorylation, sulfation, and thiolation. The current review article has also discussed brief insights on chitosan nanoparticle processing for biomedical applications, including wound dressings. The chitosan nanoparticle preparation technologies have been discussed, focusing on wound dressings owing to their targeted and controlled drug release behavior. The future directions of chitosan research include; a) finding an effective solution for chronic wounds, which are unable to heal completely; b) providing effective wound healing solutions for diabetic wounds and venous leg ulcers; c) to better understanding the wound healing mechanism with such materials which can help provide the optimum solution for wound dressing; d) to provide an improved treatment option for wound healing.

Functional Properties of Chitosan Oligomers Obtained by Enzymatic Hydrolysis

The aims of this study were to obtain chitooligosaccharides (COS) from chitosan (CH) with improved functional properties and comparison of the use of two different enzymes: commercial cellulase (CL) and the dedicated enzyme chitosanase (CS). After enzymatic reaction, chitosan oligomers (NFs) were isolated by methanol into two fractions: precipitate (HMF) and supernatant (LMF). The occurrence of a hydrolysis reaction was confirmed by an increased reducing sugar content and viscosity reduction of chitosan oligomers. CPMAS 13C NMR analysis confirmed the dissimilar cleavage mechanism of the enzymes used. LMF and NF fractions were characterised by improved solubility in water (94.56%) compared to the HMF and CH samples (70.64%). Thermogravimetric analysis (TGA) showed that the HMF decomposed in two-stage process while CH, NF, and LMF decomposed in a three-stage process. The greatest mass loss of LMF samples (58.35%) suggests their sensitivity to high-temperature treatments. COS were a mixture of DP (degrees of polymerisation) from 3 to 18 hetero-chitooligomers, with an average Mw of <3 kDa. CL consisted of more low-DP products (DP 3-7) than COS made with CS. LMF characterised by DP~2 showed lower DPPH radical scavenging activity than HMF and NF with DP 3-7. The ability to reduce Escherichia coli increased in the given order: LMF > NF > HMF > CH.

The antioxidant activity of polysaccharides: A structure-function relationship overview

Over the last years, polysaccharides have been linked to antioxidant effects using both in vitro chemical and biological models. The reported structures, claimed to act as antioxidants, comprise chitosan, pectic polysaccharides, glucans, mannoproteins, alginates, fucoidans, and many others of all type of biological sources. The structural features linked to the antioxidant action include the polysaccharide charge, molecular weight, and the occurrence of non-carbohydrate substituents. The establishment of structure/function relationships can be, however, biased by secondary phenomena that tailor polysaccharides behavior in antioxidant systems. In this sense, this review confronts some basic concepts of polysaccharides chemistry with the current claim of carbohydrates as antioxidants. It critically discusses how the fine structure and properties of polysaccharides can define polysaccharides as antioxidants. Polysaccharides antioxidant action is highly dependent on their solubility, sugar ring structure, molecular weight, occurrence of positive or negatively charged groups, protein moieties and covalently linked phenolic compounds. However, the occurrence of phenolic compounds and protein as contaminants leads to misleading results in methodologies often used for screening and characterization purposes, as well as in vivo models. Despite falling in the concept of antioxidants, the role of polysaccharides must be well defined according with the matrices where they are involved.

Chitosan Nanoparticle/Simvastatin for Experimental Maxillary Bony Defect Healing: A Histological and Histomorphometrical Study

Biomaterials such as chitosan and simvastatin (Sim) have been introduced to accelerate the extensive and multicellular biological process of bone healing. The aim of this study was to evaluate the bone healing potential of chitosan and Sim, alone or combined. Forty-two male New Zealand rabbits were divided into three groups: chitosan nanoparticles (ChN), Sim and chitosan simvastatin nanoparticles (ChSimN). Two bony defects were created in the maxillary bone. The hole on the right side received one of the experimental materials, while the other side was assigned as the control and left to heal without any intervention. Bone specimens were collected at 2 and 4 weeks and then taken for histological and histomorphometrical analyses. The histological findings revealed that ChN possessed the highest number of osteoblasts and osteoclasts at weeks 2 and osteocytes after 4 weeks. There was a significant difference between the two healing periods regarding all bone parameters across all groups. ChN stood out as the only group that had a significant difference in the count of all bone cells between the two periods, thus having the best potential in promoting bone healing.

Chitosan Oligosaccharides Alleviate Heat-Stress-Induced Lipid Metabolism Disorders by Suppressing the Oxidative Stress and Inflammatory Response in the Liver of Broilers

Heat stress has been reported to induce hepatic oxidative stress and alter lipid metabolism and fat deposition in broilers. Chitosan oligosaccharides (COSs), a natural oligosaccharide, has anti-oxidant, anti-inflammatory, and lipid-lowering effects. This study is conducted to evaluate dietary COS supplementation on hepatic anti-oxidant capacity, inflammatory response, and lipid metabolism in heat-stressed broilers. The results indicate that heat-stress-induced poor (p < 0.05) growth performance and higher (p < 0.05) abdominal adiposity are alleviated by COS supplementation. Heat stress increases (p < 0.05) serum AST and ATL activity, serum and liver MDA, TG, TC, and LDL-C levels, and the expression of hepatic IL-1β, IL-6, SREBP-1c, ACC, and FAS, while it decreases (p < 0.05) serum SOD and CAT activity, liver GSH-Px and SOD activity, and the expression of hepatic Nrf2, GPX1, IL-10, MTTP, PPARα, and CPT1. Nevertheless, COS supplementation decreases (p < 0.05) serum AST and ATL activity, serum and liver MDA, TG, TC, and LDL-C levels, and the expression of hepatic IL-1β, IL-6, SREBP-1c, ACC, and FAS, while it increases (p < 0.05) serum SOD and CAT activity, liver GSH-Px activity, and the expression of hepatic Nrf2, CAT, IL-10, LPL, MTTP, PPARα, and CPT1. In conclusion, COS could alleviate heat-stress-induced lipid metabolism disorders by enhancing hepatic anti-oxidant and anti-inflammatory capacity.

Application of depolymerized chitosan in crop production: A review

Currently, chitosan (CHT) is well known for its uses, particularly in veterinary and agricultural fields. However, chitosan's uses suffer greatly due to its extremely solid crystalline structure, it is insoluble at pH levels above or equal to 7. This has sped up the process of derivatizing and depolymerizing it into low molecular weight chitosan (LMWCHT). As a result of its diverse physicochemical as well as biological features which include antibacterial activity, non-toxicity, and biodegradability, LMWCHT has evolved into new biomaterials with extremely complex functions. The most important physicochemical and biological property is antibacterial, which has some degree of industrialization today. CHT and LMWCHT have potential due to the antibacterial and plant resistance-inducing properties when applied in crop production. This study has highlighted the many advantages of chitosan derivatives as well as the most recent studies on low molecular weight chitosan applications in crop development.

Advances in Antiviral Delivery Systems and Chitosan-Based Polymeric and Nanoparticulate Antivirals and Antiviral Carriers

Current antiviral therapy research is focused on developing dosage forms that enable highly effective drug delivery, providing a selective effect in the organism, lower risk of adverse effects, a lower dose of active pharmaceutical ingredients, and minimal toxicity. In this article, antiviral drugs and the mechanisms of their action are summarized at the beginning as a prerequisite background to develop relevant drug delivery/carrier systems for them, classified and briefly discussed subsequently. Many of the recent studies aim at different types of synthetic, semisynthetic, and natural polymers serving as a favorable matrix for the antiviral drug carrier. Besides a wider view of different antiviral delivery systems, this review focuses on advances in antiviral drug delivery systems based on chitosan (CS) and derivatized CS carriers. CS and its derivatives are evaluated concerning methods of their preparation, their basic characteristics and properties, approaches to the incorporation of an antiviral drug in the CS polymer as well as CS nanoparticulate systems, and their recent biomedical applications in the context of actual antiviral therapy. The degree of development (i.e., research study, in vitro/ex vivo/in vivo preclinical testing), as well as benefits and limitations of CS polymer and CS nanoparticulate drug delivery systems, are reported for particular viral diseases and corresponding antivirotics.

Antidiabetic Properties of Chitosan and Its Derivatives

Diabetes mellitus is a chronic metabolic disorder. In addition to taking medication, adjusting the composition of the diet is also considered one of the effective methods to control the levels of blood glucose. Chitosan and its derivatives are natural and versatile biomaterials with health benefits. Chitosan has the potential to alleviate diabetic hyperglycemia by reducing hepatic gluconeogenesis and increasing skeletal muscle glucose uptake and utility. Scientists also focus on the glucose-lowering effect of chitosan oligosaccharide (COS). COS supplementation has the potential to alleviate abnormal glucose metabolism in diabetic rats by inhibiting gluconeogenesis and lipid peroxidation in the liver. Both high and low molecular weight chitosan feeding reduced insulin resistance by inhibiting lipid accumulation in the liver and adipose tissue and ameliorating chronic inflammation in diabetic rats. COS can reduce insulin resistance but has less ability to reduce hepatic lipids in diabetic rats. A clinical trial showed that a 3-month administration of chitosan increased insulin sensitivity and decreased body weight and triglycerides in obese patients. Chitosan and COS are considered Generally Recognized as Safe; however, they are still considered to be of safety concerns. This review highlights recent advances of chitosan and its derivatives in the glucose-lowering/antidiabetic effects and the safety.

Chitosan Nanoparticles: A Versatile Platform for Biomedical Applications

Chitosan is a biodegradable and biocompatible natural polymer that has been extensively explored in recent decades. The Food and Drug Administration has approved chitosan for wound treatment and nutritional use. Furthermore, chitosan has paved the way for advancements in different biomedical applications including as a nanocarrier and tissue-engineering scaffold. Its antibacterial, antioxidant, and haemostatic properties make it an excellent option for wound dressings. Because of its hydrophilic nature, chitosan is an ideal starting material for biocompatible and biodegradable hydrogels. To suit specific application demands, chitosan can be combined with fillers, such as hydroxyapatite, to modify the mechanical characteristics of pH-sensitive hydrogels. Furthermore, the cationic characteristics of chitosan have made it a popular choice for gene delivery and cancer therapy. Thus, the use of chitosan nanoparticles in developing novel drug delivery systems has received special attention. This review aims to provide an overview of chitosan-based nanoparticles, focusing on their versatile properties and different applications in biomedical sciences and engineering.

Multifunctional role of chitosan in farm animals: a comprehensive review

The deacetylation of chitin results in chitosan, a fibrous-like material. It may be produced in large quantities since the raw material (chitin) is plentiful in nature as a component of crustacean (shrimps and crabs) and insect hard outer skeletons, as well as the cell walls of some fungi. Chitosan is a nontoxic, biodegradable, and biocompatible polygluchitosanamine that contains two essential reactive functional groups, including amino and hydroxyl groups. This unique chemical structure confers chitosan with many biological functions and activities such as antimicrobial, anti-inflammatory, antioxidative, antitumor, immunostimulatory and hypocholesterolemic, when used as a feed additive for farm animals. Studies have indicated the beneficial effects of chitosan on animal health and performance, aside from its safer use as an antibiotic alternative. This review aimed to highlight the effects of chitosan on animal health and performance when used as a promising feed additive.

Anthocyanin Encapsulated Nanoparticles as a Pulmonary Delivery System

Anthocyanins are known for their therapeutic efficacy for many human diseases, including cancer. After ingestion, anthocyanins degrade due to oxidation and enzymatic breakdown, resulting in reduced therapeutic efficacy. Direct delivery to target tissues and entrapment of anthocyanins increases their stability, bioavailability, and therapeutic efficacy. The objective of the present study was to develop a direct delivery system of anthocyanins into pulmonary tissues via encapsulated nanocarriers. A cyanidin-3-O-glucoside (C3G)-rich anthocyanin extract was prepared from well-ripened haskap (Lonicera caerulea L.) berries (HB) and encapsulated in three different polymeric nanocarrier systems: polyethylene glycol-poly(lactide-co-glycolide), maltodextrin, and carboxymethyl chitosan (CMC). The anthocyanin encapsulation efficiency was significantly higher in CMC (10%) than in the other two polymers. The cytotoxicity and cytoprotective effect of HB anthocyanin-encapsulated CMC (HB-CMC, 4 μg of C3G equivalent anthocyanin in 2 mg/mL nanoparticle) and anthocyanin-free CMC (E-CMC, 2 mg/mL) were tested for cytotoxicity using human normal lung epithelial BEAS-2B cells. The CMC nanoparticles were not cytotoxic for BEAS-2B cells. The HB-CMC nanoparticles reduced carcinogen-induced oxidative stress in BEAS-2B cells and restored the expression of superoxide dismutase and glutathione peroxidase enzymes. The HB-CMC nanoparticles also reduced carcinogen-induced DNA single-strand breaks and alkaline-labile sites but not the double-strand breaks. The E-CMC, HB-CMC (28 μg C3G equivalent/mouse/day for six days), or the same dose of free HB anthocyanin was administered to A/JCr mice through a nose-only passive inhalation device. C3G and its metabolites, cyanidin, peonidin-3-O-glucoside, and cyanidin-3-O-glucuronide, were detected by UPLC/ESI/Q-TOF-MS in the lungs of mice after one hour of exposure. Therefore, the CMC could be a promising noncytotoxic candidate to encapsulate HB anthocyanin. Direct delivery of anthocyanin to lung tissues enhances tissue retention, slows phase 2 metabolism, and improves therapeutic efficacy.

A comprehensive review of food gels: formation mechanisms, functions, applications, and challenges

Gels refer to the soft and flexible macromolecular polymeric materials retaining a large amount of water or biofluids in their three-dimensional network structure. Gels have attracted increasing interest in the food discipline, especially proteins and polysaccharides, due to their good biocompatibility, biodegradability, nutritional properties, and edibility. With the advancement of living standards, people's demand for nutritious, safe, reliable, and functionally diverse food and even personalized food has increased. As a result, gels exhibiting unique advantages in food application will be of great significance. However, a comprehensive review of functional hydrogels as food gels is still lacking. Here, we comprehensively review the gel-forming mechanisms of food gels and systematically classify them. Moreover, the potential of hydrogels as functional foods in different types of food areas is summarized, with a special focus on their applications in food packaging, satiating gels, nutrient delivery systems, food coloring adsorption, and food safety monitoring. Additionally, the key scientific issues for future food gel research, with specific reference to future novel food designs, mechanisms between food components and matrices, food gel-human interactions, and food gel safety, are discussed. Finally, the future directions of hydrogels for food science and technology are summarized.

Chitin Nanocrystals Provide Antioxidant Activity to Polylactic Acid Films

About 1/3rd of produced food goes to waste, and amongst others, advanced packaging concepts need to be developed to prevent this from happening. Here, we target the antioxidative functionality of food packaging to thus address food oxidation without the need for the addition of antioxidants to the food product, which is not desirable from a consumer point of view. Chitin nanocrystals (ChNC) have been shown to be promising bio-fillers for improving the mechanical strength of biodegradable plastics, but their potential as active components in plastic films is rather unexplored. In the current study, we investigate the antioxidant activity of chitin nanocrystals as such and as part of polylactic acid (PLA) films. This investigation was conducted using DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity. Chitin nanocrystals produced via acid hydrolysis showed five times higher activity compared to crude chitin powder. When using these crystals as part of a polylactic acid film (either inside or on top), in both scenarios, antioxidant activity was found, but the effect was considerably greater when the particles were at the surface of the film. This is an important proof of the principle that it is possible to create biodegradable plastics with additional functionality through the addition of ChNC.

Newly synthesized chitosan-nanoparticles attenuate carbendazim hepatorenal toxicity in rats via activation of Nrf2/HO1 signalling pathway

Widespread application of carbendazim (CBZ) is a major environmental impact because of its residues that caused multi-organ dysfunction. Recently, Chitosan nanoparticles (CS-NPs) are extensively used as nanocarriers due to their non-toxic and biodegradable nature. Therefore, the current study aimed to investigate the possible mechanistic pathway of modified CS-NPs to reduce the hepatic and nephrotoxicity of CBZ in rats. CS-NPs were synthesized by the ionic gelation method by using ascorbic acid instead of acetic acid to increase its antioxidant efficiency. Twenty-adult male Wistar rats were grouped (n = 5) as follows: Group (1) negative control, group (2) received CS-NPs, group (3) received CBZ, and group (4) co-administered CS-NPs with CBZ. Rats received the aforementioned materials daily by oral gavage for 28 days and weighed weekly. The results revealed that CBZ receiving group showed severe histopathological alterations in the liver and kidney sections including cellular necrosis and interstitial inflammation confirmed by immunostaining and showed marked immunopositivity of iNOS and caspase-3 protein. There were marked elevations in the serum levels of ALT, AST, urea, and creatinine with a significant increase in MDA levels and decrease in TAC levels. Upregulation of the Keap1 gene and down-regulation of Nrf2 and HO-1 genes were also observed. Co-treatment of rats by CS-NPs with CBZ markedly improved all the above-mentioned toxicological parameters and return liver and kidney tissues to normal histological architecture. We concluded that CBZ caused hepatorenal toxicity via oxidative stress and the Nrf2/HO-1 pathway and CS-NPs could reduce CBZ toxicity via their antioxidant, anti-apoptotic, and anti-inflammatory effects.

Dietary Chitosan Supplementation Improved Egg Production and Antioxidative Function in Laying Breeders

Simple Summary

Chitosan is a natural, non-toxic and biodegradable compound, which has antibacterial, antioxidant and anti-tumor properties. Several studies have shown that chitosan also improve the antioxidant capacity of poultry. Recent research showed that chitosan decreased oxidative damage by activating the nuclear factor erythroid-2 related factor 2 pathway, then elevated the meat quality of broilers. Egg breeders are susceptible to oxidative stress during peak egg production, which increase their susceptibility to diseases and lead performance decline. In addition, previous reports on the effect of chitosan on poultry production performance were inconsistent. Based on above reports, this study explored whether chitosan could promote the production performance, and antioxidant defense of laying hens by affecting the nuclear factor erythroid-2 related factor 2 pathway. The results showed that addition chitosan to layer hen diet could increase egg production and feed conversion ratio, and the effect was better at the level of 250~500 mg/kg; as well as, chitosan promoted the antioxidant status in serum, liver and duodenum tissues and the effect was better at the level of 500 mg/kg. Chitosan was likely to increase antioxidant enzyme activities by enhancing the expression of nuclear factor erythroid-2 related factor 2, thereby improving the antioxidant capacity of laying breeders.

Abstract

This study was conducted to explore the dietary effect of chitosan on the production performance, and antioxidative enzyme activities and corresponding gene expression in the liver and duodenum of laying breeders. A total of 450 laying breeders (92.44% ± 0.030% of hen-day egg production) were randomly assigned to five dietary treatments fed 8 weeks: maize-soybean meal as the basal control diet and the basal diet containing 250, 500, 1000 and 2000 mg/kg of chitosan, respectively. Each treatment was randomly divided into 6 equal replicates, with 15 laying breeders in each replicate. The results showed that dietary chitosan could increase hen-day egg production and feed conversion ratio, especially at the level of 250~500 mg/kg; however, chitosan had no prominent effect on feed intake and average egg weight. Dietary chitosan could dose-dependently promote the antioxidant status in serum, liver and duodenum of layer breeders. It has a better promotion effect at the level of 500 mg/kg; however, the effect was weakened at the level of 2000 mg/kg. Chitosan was likely to enhance the gene expression and activities of Nrf2-mediated phase II detoxification enzyme by up-regulating the expression of Nrf2, thereby improving the antioxidant capacity of laying breeder hens.

Chitosan-hydroxycinnamic acid conjugates: Optimization of the synthesis and investigation of the structure activity relationship

A new synthesis method was developed and optimized by a full factorial design for conjugating hydroxycinnamic acids (HCA-s) to chitosan. Cinnamic acid and tert-butyldimethylsilyl protected HCA-s were converted to their corresponding acyl chlorides and reacted with 3,6-di-O-tert-butyldimethylsilyl-chitosan to selectively form amide linkages, resulting in water-soluble conjugates after deprotection. Nineteen conjugates were obtained with various degrees of substitution (DS) ranging from 3% to 60%. The conjugates were found to be bactericidal against Staphylococcus aureus and Escherichia coli, with their activities equal to chitosan at low DS but an increase in the DS correlated with reduced activity. DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging assay was performed to determine the EC₅₀ values. Chitosan only exhibited low antioxidant activity, whereas the HCA-chitosan conjugates exhibited higher antioxidant activities correlating with the DS. One caffeic acid conjugate (21%) was 4000 times more active than chitosan and more active than free caffeic acid.

Protective Effect of Chitosan Oligosaccharide against Hydrogen Peroxide-Mediated Oxidative Damage and Cell Apoptosis via Activating Nrf2/ARE Signaling Pathway

Chitosan oligosaccharide (COS), hydrolyzed and deacetylated from chitosan, has been reported to possess varieties of biological activities. Alzheimer's disease (AD) is a multifactorial progressive neurodegenerative disorder characterized by cognitive decline and memory loss, where oxidative stress was reported to be an overwhelming cause of the occurrence of AD. We have previously reported that COS could significantly decrease cell death, ROS generation, and lipid peroxidation, though the potential mechanism was yet to be determined. This study was designed to investigate the neuroprotective effect of COS against hydrogen peroxide (H2O2)-induced oxidative stress and apoptosis in neuronal SH-SY5Y cells. Our results indicated that COS could dose-dependently scavenge H2O2 in the cell-free systems. Accordingly, COS markedly decreased H2O2-induced cell apoptosis and intracellular ROS generation, while increased antioxidant capacity in SH-SY5Y cells. Further, COS significantly reduced the expression of Bax and upregulated Bcl-2. The mRNA and protein expression levels of nuclear Nrf2, heme oxygenase 1 (HO-1), and NAD(P)H: quinone oxidoreductase 1 (NQO1) were significantly increased upon COS treatment. Moreover, Nrf2-siRNA evidently reversed the promotive effect of COS on expression levels of HO-1 and NQO1, and ARE-driven transcriptional activity as determined by double-luciferase reporter gene assay. Besides, COS reversed H2O2-mediated increased phosphorylation of ERK1/2 and p38 MAPK. In conclusion, our findings indicate that COS could protect SH-SY5Y cells from oxidative damage and apoptosis via regulating Nrf2/ARE signaling pathway, which may provide new applications for the prevention and treatment of AD.

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.

Evaluating the Anticarcinogenic Activity of Surface Modified/Functionalized Nanochitosan: The Emerging Trends and Endeavors

Chitosan begins its humble journey from marine food shell wastes and ends up as a versatile nutraceutical. This review focuses on briefly discussing the antioxidant activity of chitosan and retrospecting the accomplishments of chitosan nanoparticles as an anticarcinogen. The various modified/functionalized/encapsulated chitosan nanoparticles and nanoforms have been listed and their biomedical deliverables presented. The anticancer accomplishments of chitosan and its modified composites have been reviewed and presented. The future of surface modified chitosan and the lacunae in the current research focus have been discussed as future perspective. This review puts forth the urge to expand the scientific curiosity towards attempting a variety of functionalization and surface modifications to chitosan. There are few well known modifications and functionalization that benefit biomedical applications that have been proven for other systems. Being a biodegradable, biocompatible polymer, chitosan-based nanomaterials are an attractive option for medical applications. Therefore, maximizing expansion of its bioactive properties are explored. The need for applying the ideal functionalization that will significantly promote the anticancer contributions of chitosan nanomaterials has also been stressed.

Characterizations and Antibacterial Efficacy of Chitosan Oligomers Synthesized by Microwave-Assisted Hydrogen Peroxide Oxidative Depolymerization Method for Infectious Wound Applications

The use of naturally occurring materials with antibacterial properties has gained a great interest in infected wound management. Despite being an abundant resource in Vietnam, chitosan and its derivatives have not yet been intensively explored for their potential in such application. Here, we utilized a local chitosan source to synthesize chitosan oligomers (OCS) using hydrogen peroxide (H2O2) oxidation under the microwave irradiation method. The effects of H2O2 concentration on the physicochemical properties of OCS were investigated through molecular weight, degree of deacetylation, and heavy metal contamination for optimization of OCS formulation. Then, the antibacterial inhibition was examined; the minimum inhibitory concentration and minimum bactericidal concentration (MIC and MBC) of OCS-based materials were determined against common skin-inhabitant pathogens. The results show that the local Vietnamese chitosan and its derivative OCS possessed high-yield purification while the molecular weight of OCS was inversely proportional and proportional to the concentration of H2O2, respectively. Further, the MIC and MBC of OCS ranged from 3.75 to less than 15 mg/mL and 7.5-15 mg/mL, respectively. Thus, OCS-based materials induce excellent antimicrobial properties and can be attractive for wound dressings and require further investigation.

Role of ethylene and light in chitosan-induced local and systemic defence responses of tomato plants

Plant defence responses can be triggered by the application of elicitors for example chitosan (β-1,4-linked glucosamine; CHT). It is well-known that CHT induces rapid, local production of reactive oxygen species (ROS) and nitric oxide (NO) resulting in fast stomatal closure. Systemic defence responses are based primarily on phytohormones such as ethylene (ET) and salicylic acid (SA), moreover on the expression of hormone-mediated defence genes and proteins. At the same time, these responses can be dependent also on external factors, such as light but its role was less-investigated. Based on our result in intact tomato plants (Solanum lycopersicum L.), CHT treatment not only induced significant ET emission and stomatal closure locally but also promoted significant production of superoxide which was also detectable in the distal, systemic leaves. However, these changes in ET and superoxide accumulation were detected only in wild type (WT) plants kept in light and were inhibited under darkness as well as in ET receptor Never ripe (Nr) mutants suggesting pivotal importance of ET and light in inducing resistance both locally and systemically upon CHT. Interestingly, CHT-induced NO production was mostly independent of ET or light. At the same time, expression of Pathogenesis-related 3 (PR3) was increased locally in both genotypes in the light and in WT leaves under darkness. This was also observed in distal leaves of WT plants. The CHT-induced endoplasmic reticulum (ER) stress, as well as unfolded protein response (UPR) were examined for the first time, via analysis of the lumenal binding protein (BiP). Whereas local expression of BiP was not dependent on the availability of light or ET, systemically it was mediated by ET.

Preparation and Antioxidant Activity of Chitosan Dimers with Different Sequences

As a popular marine saccharide, chitooligosaccharides (COS) has been proven to have good antioxidant activity. Its antioxidant effect is closely related to its degree of polymerization, degree of acetylation and sequence. However, the specific structure-activity relationship remains unclear. In this study, three chitosan dimers with different sequences were obtained by the separation and enzymatic method, and the antioxidant activity of all four chitosan dimers were studied. The effect of COS sequence on its antioxidant activity was revealed for the first time. The amino group at the reducing end plays a vital role in scavenging superoxide radicals and in the reducing power of the chitosan dimer. At the same time, we found that the fully deacetylated chitosan dimer DD showed the strongest DPPH scavenging activity. When the amino groups of the chitosan dimer were acetylated, it showed better activity in scavenging hydroxyl radicals. Research on COS sequences opens up a new path for the study of COS, and is more conducive to the investigation of its mechanism.

One pot synthesis of new cross-linked chitosan-Schiff' base: Characterization, and anti-proliferative activities

Four novel chitosan hydrogels were successfully synthesized through the cross-linking reaction of chitosan with different concentrations of ethyl 5-(3,5-dihydroxy-1,4-dioxan-2-yl)-2-methylfuran-3-carboxylate. Their structures were confirmed by Fourier transform infrared spectroscopy (FT-IR), ¹³C Cross polarization magic angle spinning nuclear magnetic resonance spectroscopy (CP/MAS ¹³C NMR), ultraviolet-visible spectroscopy, thermogravimetric analysis (TGA, DTA), and X-ray diffraction (XRD). Cytotoxicity on hepatocellular carcinoma (HepG-2) cell line and a normal African green monkey kidney (Vero) cell line were studied using the MTT assay. The resultant hydrogels showed a good inhibitory effect comparing to the un-modified parent; the hydrogels with the lowest degree cross-linking (0.125 and 0.25 mol cross-linker per one chitosan residue) showed potent anticancer activity in the HepG2 cells with IC₅₀ of 57.9 and 80.9 μg/ml, respectively. These results show that the newly synthesized cross-linked chitosan derivatives demonstrated more selectivity to the HepG2 than the Vero cells, indicating its potential for Investigation in the cure of hepatocellular carcinoma.

Recent Advances in Chemically-Modified and Hybrid Carrageenan-Based Platforms for Drug Delivery, Wound Healing, and Tissue Engineering

Recently, many studies have focused on carrageenan-based hydrogels for biomedical applications thanks to their intrinsic properties, including biodegradability, biocompatibility, resembling native glycosaminoglycans, antioxidants, antitumor, immunomodulatory, and anticoagulant properties. They can easily change to three-dimensional hydrogels using a simple ionic crosslinking process. However, there are some limitations, including the uncontrollable exchange of ions and the formation of a brittle hydrogel, which can be overcome via simple chemical modifications of polymer networks to form chemically crosslinked hydrogels with significant mechanical properties and a controlled degradation rate. Additionally, the incorporation of various types of nanoparticles and polymer networks into carrageenan hydrogels has resulted in the formation of hybrid platforms with significant mechanical, chemical and biological properties, making them suitable biomaterials for drug delivery (DD), tissue engineering (TE), and wound healing applications. Herein, we aim to overview the recent advances in various chemical modification approaches and hybrid carrageenan-based platforms for tissue engineering and drug delivery applications.

Crustacean Waste-Derived Chitosan: Antioxidant Properties and Future Perspective

Chitosan is obtained from chitin that in turn is recovered from marine crustacean wastes. The recovery methods and their varying types and the advantages of the recovery methods are briefly discussed. The bioactive properties of chitosan, which emphasize the unequivocal deliverables contained by this biopolymer, have been concisely presented. The variations of chitosan and its derivatives and their unique properties are discussed. The antioxidant properties of chitosan have been presented and the need for more work targeted towards harnessing the antioxidant property of chitosan has been emphasized. Some portions of the crustacean waste are being converted to chitosan; the possibility that all of the waste can be used for harnessing this versatile multifaceted product chitosan is projected in this review. The future of chitosan recovery from marine crustacean wastes and the need to improve in this area of research, through the inclusion of nanotechnological inputs have been listed under future perspective.

Relevance and perspectives of the use of chitosan in winemaking: a review

Chitosan is a natural polymer that has quite recently been approved as an aid for microbial control, metal chelation, clarification, and reduction of contaminants in enology. In foods other than wine, chitosan has also been evidenced to have some other activities such as antioxidant and antiradical properties. Nevertheless, the actual extent of its activities in must and wines has not been fully established. This review aimed to gather and discuss the available scientific information on the efficacy of chitosan as a multifaceted aid in winemaking, including antimicrobial, chelating, clarifying and antioxidant activities, while summarizing the chemical mechanisms underlying its action. Attention has been specifically paid to those data obtained by using unmodified chitosan in wine or in conditions pertinent to its production, intentionally excluding functionalized polymers, not admitted in enology. Unconventional utilizations together with future perspectives and research needs targeting, for example, the use of chitosan from distinct sources, production strategies to increase its efficacy or the potential sensory impact of this polysaccharide, have also been outlined.

Chitosan-based delivery systems for plants: A brief overview of recent advances and future directions

Chitosan has been termed as the most well-known among biopolymers, receiving widespread attention from researchers in various fields mainly, agriculture, food, and health. Chitosan is a deacetylated derivative of chitin, mainly isolated from waste shells of the phylum Arthropoda after their consumption as food. Chitosan molecules can be easily modified for adsorption and slow release of plant growth regulators, herbicides, pesticides, and fertilizers, etc. Chitosan as a carrier and control release matrix that offers many benefits including; protection of biomolecules from harsh environmental conditions such as pH, light, temperatures and prolonged release of active ingredients from its matrix consequently protecting the plant's cells from the hazardous effects of burst release. In the current review, tends to discuss the recent advances in the area of chitosan application as a control release system. Also, future recommendations will be made in light of current advancements and major gaps.

Inhibitory activity of biofunctionalized silver-capped N-methylated water-soluble chitosan thiomer for microbial and biofilm infections

One of the most important self-defense strategies employed by bacteria to resist the action of antibiotics is a biofilm formation upon the infected surface. Thus, there is an urgent need to explore novel candidates that have potent antibacterial and anti-biofilm effects to tackle this challenge. In this endeavor, we have transformed shrimp shell wastes to N-methylated water-soluble chitosan thiomer (MWSCT) which was used as either a chelating agent or bio-reductant and capping agent for Ag(I) ions in the preparation of a Ag(I)MWSCT complex or silver nanocomposite (Ag(0)MWSCT), for targeting antibacterial and anti-biofilm applications. The antibacterial and anti-biofilm performance of the new methylated chitosan thiomer (MWSCT) and its silver architectures (Ag(I)MWSCT, Ag(0)MWSCT) were assessed in vitro against E. coli and S. aureus. These new materials have significant capacities to synergistically inhibit the proliferation of the targeted bacterial cells and biofilm formation, in a structure- and species-dependent manner. Ag(0)MWSCT emerged as the most potent compound in inhibiting the growth of bacterial strains (MIC_{E. coli}/ MIC_{S. aureus} = 0.05/ 0.34 μg/mL, 1.6-/ 2.5-times lower than that recorded for the clinical drug (ciprofloxacin, Cipro). Also, this nanocomposite showed the highest anti-biofilm effects (only 1.7% E. coli biofilm growth; 11.8% staphylococcal biofilm growth).

In Vitro Antifungal Activity of Chitosan-Polyphenol Conjugates against Phytophthora cinnamomi

Phytophthora cinnamomi is responsible for radical rot in a wide range of hosts, resulting in large economic and ecological losses worldwide. In Spain, it is responsible for diseases such as the oak decline or the chestnut blight. In this study, different polyphenol-stevioside inclusion compounds dispersed in a hydroalcoholic solution of chitosan oligomers have been investigated, with a view to their application as natural bioactive complexes to replace conventional systemic fungicides against this fungus. The polyphenols tested in vitro were curcumin, ferulic acid, gallic acid and silymarin. Three concentrations (125, 250 and 500 µg·mL−1) were assayed, with and without silver nanoparticles (AgNPs), and notable differences were found in the inhibition of mycelium growth, with EC50 and EC90 values ranging from 171 to 373.6 µg·mL−1, and from 446.2 to 963.7 µg·mL−1, respectively. The results obtained showed that the addition of AgNPs, despite their antimicrobial activity, did not always lead to synergies. In the case of P. cinnamomi, an unexpected antagonistic behavior was found for two of the polyphenols (curcumin and silymarin), while an additive behavior for ferulic acid and a synergistic behavior for gallic acid were attained. In view of their inhibitory power, the preparations based on ferulic acid with AgNPs and on silymarin without AgNPs are proposed for applications in crop and forests protection against P. cinnamomi.

Conversion of Chitin to Defined Chitosan Oligomers: Current Status and Future Prospects

Chitin is an abundant polysaccharide primarily produced as an industrial waste stream during the processing of crustaceans. Despite the limited applications of chitin, there is interest from the medical, agrochemical, food and cosmetic industries because it can be converted into chitosan and partially acetylated chitosan oligomers (COS). These molecules have various useful properties, including antimicrobial and anti-inflammatory activities. The chemical production of COS is environmentally hazardous and it is difficult to control the degree of polymerization and acetylation. These issues can be addressed by using specific enzymes, particularly chitinases, chitosanases and chitin deacetylases, which yield better-defined chitosan and COS mixtures. In this review, we summarize recent chemical and enzymatic approaches for the production of chitosan and COS. We also discuss a design-of-experiments approach for process optimization that could help to enhance enzymatic processes in terms of product yield and product characteristics. This may allow the production of novel COS structures with unique functional properties to further expand the applications of these diverse bioactive molecules.

Synergistic antioxidant activity of size controllable chitosan-templated Prussian blue nanoparticle

Aim: Prussian blue nanoparticles (PB NPs) have been reported as excellent antioxidant agents owing to their ability to scavenge reactive oxygen species. However, their poor stability in vivo limits their use in biomedical applications. Materials & methods: In this study, we developed chitosan-templated PB NPs using water-soluble chitosan samples with molecular weights ranging from 3 to 100 kDa, which stabilized the PB NPs and improved their antioxidant activity. Results & conclusion: The chitosan-templated PB NPs coordinated with the optimal chitosan molecular weight had uniform sphere-like particles, improved stability and effective scavenging activity of in vitro reactive oxygen species generation in murine fibroblast cells stimulated by oxidative stress agents without any cytotoxicity, implying that they could be promising antioxidant agents.