Antioxidant properties of some different molecular weight chitosans

Films based on TEMPO-oxidized chitosan nanoparticles: Obtaining and potential application as wound dressings

A series of novel films based on TEMPO-oxidized chitosan nanoparticles were prepared by casting method. Fourier transform infrared spectroscopy (FTIR) was employed to ascertain the chemical structure of TEMPO-oxidized chitosan. The surface morphology of the TEMPO-oxidized chitosan nanoparticles was analyzed by atomic force microscopy (AFM). The physicochemical (area density, thickness, iodine sorption, roughness), functional (moisture sorption, liquid absorption capacity, weight loss upon contact with the liquid, and water vapor transmission rate), antibacterial, and antioxidant properties of films based on TEMPO-oxidized chitosan nanoparticles were also investigated. The physicochemical properties of the films varied widely: area density ranged from 77.83 ± 0.06 to184.46 ± 0.05 mg/cm2, thickness varied between 80.5 ± 1.6 and 200.5 ± 1.6 μm, iodine sorption spanned from 333.7 ± 2.1 to166.4 ± 2.2 mg I2/g, and roughness ranged from 4.1 ± 0.2 to 5.6 ± 0.3 nm. Similarly, the functional properties also varied significantly: moisture sorption ranged from 4.76 ± 0.03 to 9.62 ± 0.11 %, liquid absorption capacity was between 129.04 ± 0.24 and 159.33 ± 0.73 % after 24 h, weight loss upon contact with the liquid varied between 31.06 ± 0.35 and 45.88 ± 0.58 % after 24 h and water vapor transmission rate ranged from 1220.10 ± 2.91to1407.77 ± 5.22 g/m2 day. Despite the wide variations in physicochemical and functional properties, all films showed maximum bacterial reduction of Staphylococcus aureus and Escherichia coli, although they exhibited low antioxidant activity. The results suggest that the films could be effectively utilized as antibacterial wound dressings.

The relationship between polysaccharide structure and its antioxidant activity needs to be systematically elucidated

Polysaccharides have a wide range of applications due to their excellent antioxidant activity. However, the low purity and unclear structure of polysaccharides have led some researchers to be skeptical about the antioxidant activity of polysaccharides. The current reports on the structure-activity relationship of polysaccharides are sporadic, so there is an urgent need to systematically summarize the antioxidant effects of polysaccharides with clear structures and the relationships between the structures to provide a scientific basis for the development and application of polysaccharides. This paper will systematically elucidate the structure-activity relationship of antioxidant polysaccharides, including the molecular weight, monosaccharide composition, glycosidic linkage, degree of branching, advanced conformation and chemical modification. For the first time, the antioxidant activity of polysaccharides is related to their chemical structure through histogram and radar map, and further studies using principal component analysis and cluster analysis. We critically discussed how the source, chemical structure and chemically modified groups of polysaccharides significantly contribute to their antioxidant activity and summarized the current research status and shortcomings of the structure-activity relationship of antioxidant polysaccharides. This review provides a theoretical basis and new perspective for further research on the structure-activity relationship of antioxidant polysaccharides and the development of natural antioxidants.

Effect of Chitosan and Its Water-Soluble Derivatives on Antioxidant Activity

The antioxidant activity of chitosan (CS) and three water-soluble derivatives was analyzed comparatively by in vitro and in vivo experiments, including hydroxypropyl chitosan (HPCS), quaternary ammonium salt of chitosan (HACC), and carboxymethyl chitosan (CMCS). The results show that chitosan and its water-soluble derivatives have a scavenging ability on DPPH radicals, superoxide radicals, and hydroxyl radicals, and a reducing ability. A remarkable difference (p < 0.05) was found for HACC and HPCS compared with CS on DPPH radicals, hydroxyl radicals, and reducing ability. The antioxidant ability of the four chitosan samples was in the order of HPCS > HACC > CMCS > CS. Furthermore, antioxidant activity of all samples increased gradually in a concentration-dependent manner. The in vivo result indicates that oral CS and its derivatives samples result in a decrease in lipid peroxides (LPO) and free fatty acids (FFA) levels in serum with an increase in superoxide dismutase (SOD) activity. Especially for the HPCS and HACC groups, the LPO, FFA, and SOD activity in serum was different significantly in comparison with the high-fat controlgroup (HF) (p < 0.05). These results indicate that chitosan and its derivatives can be used as good antioxidants, and the antioxidant activity might be related to the molecular structure of chitosan derivatives.

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.

Engineering Antioxidant Surfaces for Titanium-Based Metallic Biomaterials

Prolonged inflammation induced by orthopedic metallic implants can critically affect the success rates, which can even lead to aseptic loosening and consequent implant failure. In the case of adverse clinical conditions involving osteoporosis, orthopedic trauma and implant corrosion-wear in peri-implant region, the reactive oxygen species (ROS) activity is enhanced which leads to increased oxidative stress. Metallic implant materials (such as titanium and its alloys) can induce increased amount of ROS, thereby critically influencing the healing process. This will consequently affect the bone remodeling process and increase healing time. The current review explores the ROS generation aspects associated with Ti-based metallic biomaterials and the various surface modification strategies developed specifically to improve antioxidant aspects of Ti surfaces. The initial part of this review explores the ROS generation associated with Ti implant materials and the associated ROS metabolism resulting in the formation of superoxide anion, hydroxyl radical and hydrogen peroxide radicals. This is followed by a comprehensive overview of various organic and inorganic coatings/materials for effective antioxidant surfaces and outlook in this research direction. Overall, this review highlights the critical need to consider the aspects of ROS generation as well as oxidative stress while designing an implant material and its effective surface engineering.

Design of a water-soluble chitosan-based polymer with antioxidant and chelating properties for labile iron extraction

Loosely bound iron, due to its contribution to oxidative stress and inflammation, has become an important therapeutic target for many diseases. A water-soluble chitosan-based polymer exhibiting both antioxidant and chelating properties due to the dual functionalization with DOTAGA and DFO has been developed to extract this iron therefore preventing its catalytic production of reactive oxygen species. This functionalized chitosan was shown to have stronger antioxidant properties compared to conventional chitosan, improved iron chelating properties compared to the clinical therapy, deferiprone, and provided promising results for its application and improved metal extraction within a conventional 4 h hemodialysis session with bovine plasma.

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.

Application of functionalized chitosan in food: A review

Environmental and sustainability issues have received increasing attention in recent years. As a natural biopolymer, chitosan has been developed as a sustainable alternative to traditional chemicals such as food preservation, food processing, food packaging, and food additives due to its abundant functional groups and excellent biological functions. This review analyzes and summarizes the unique properties of chitosan, with a particular focus on the mechanism of action for its antibacterial and antioxidant properties. This provides a lot of information for the preparation and application of chitosan-based antibacterial and antioxidant composites. In addition, chitosan is modified by physical, chemical and biological modifications to obtain a variety of functionalized chitosan-based materials. The modification not only improves the physicochemical properties of chitosan, but also enables it to have different functions and effects, showing promising applications in multifunctional fields such as food processing, food packaging, and food ingredients. In the current review, applications, challenges, and future perspectives of functionalized chitosan in food will be discussed.

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.

Potential Medical Applications of Chitooligosaccharides

Chitooligosaccharides, also known as chitosan oligomers or chitooligomers, are made up of chitosan with a degree of polymerization (DP) that is less than 20 and an average molecular weight (MW) that is lower than 3.9 kDa. COS can be produced through enzymatic conversions using chitinases, physical and chemical applications, or a combination of these strategies. COS is of significant interest for pharmacological and medical applications due to its increased water solubility and non-toxicity, with a wide range of bioactivities, including antibacterial, anti-inflammatory, anti-obesity, neuroprotective, anticancer, and antioxidant effects. This review aims to outline the recent advances and potential applications of COS in various diseases and conditions based on the available literature, mainly from preclinical research. The prospects of further in vivo studies and translational research on COS in the medical field are highlighted.

Preparation and Properties of Blended Composite Film Manufactured Using Walnut-Peptide-Chitosan-Sodium Alginate

In this study, layer-by-layer assembly was performed to prepare sodium alginate (SA) layer and walnut-peptide-chitosan (CS) bilayer composite films. Genipin was adopted to crosslink CS and walnut peptide. The properties of walnut peptide-CS-SA composite film were determined, and the influence of material ratio on the performance of composite film was explored. According to the results, the mechanical tensile property, oil absorption property, and water vapor barrier property of the composite film were improved with the presence of genipin. Moreover, the proportion of CS and walnut peptide had significant effects on color, transmittance, mechanical properties, barrier properties, and antioxidant properties of the composite films. Among them, the composite film containing 1% (w/v) CS, 1% (w/v) walnut peptide, and 0.01% (w/v) genipin showed the best performance, with a tensile strength of 3.65 MPa, elongation at break of 30.82%, water vapor permeability of 0.60 g·mm·m^-2·h^-1·kPa^-1, oil absorption of 0.85%, and the three-phase electrochemistry of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging rate of 25.59%. Under this condition, the tensile property, barrier property, and oxidation resistance of the composite film are good, which can provide a good preservation effect for food, and has great application potential.

Application of chitosan nanoparticles in skin wound healing

The rising prevalence of impaired wound healing and the consequential healthcare burdens have gained increased attention over recent years. This has prompted research into the development of novel wound dressings with augmented wound healing functions. Nanoparticle (NP)-based delivery systems have become attractive candidates in constructing such wound dressings due to their various favourable attributes. The non-toxicity, biocompatibility and bioactivity of chitosan (CS)-based NPs make them ideal candidates for wound applications. This review focusses on the application of CS-based NP systems for use in wound treatment. An overview of the wound healing process was presented, followed by discussion on the properties and suitability of CS and its NPs in wound healing. The wound healing mechanisms exerted by CS-based NPs were then critically analysed and discussed in sections, namely haemostasis, infection prevention, inflammatory response, oxidative stress, angiogenesis, collagen deposition, and wound closure time. The results of the studies were thoroughly reviewed, and contradicting findings were identified and discussed. Based on the literature, the gap in research and future prospects in this research area were identified and highlighted. Current evidence shows that CS-based NPs possess superior wound healing effects either used on their own, or as drug delivery vehicles to encapsulate wound healing agents. It is concluded that great opportunities and potentials exist surrounding the use of CSNPs in wound healing.

Investigation of the Antioxidant Properties of the Quaternized Chitosan Modified with a Gallic Acid Residue Using Peroxidase that Produces Reactive Oxygen Species

Chitosan modified with a (2-hydroxy-3-trimethylammonium) propyl group and gallic acid residue, or quaternized chitosan with gallic acid (QCG), was synthesized. Antioxidant properties of the produced QCG have been investigated. Peroxidase in combination with NADH and salicyl hydroxamate (SHAM) caused consumption of oxygen and production of H2O2 in aqueous solution as a result of O2 reduction in the peroxidase-oxidase reactions. The rates of O2 consumption and H2O2 generation were reduced in the presence of QCG. The antioxidant propyl gallate (PG) and superoxide dismutase (SOD) had the same effect, but not the quaternized chitosan (QC) without gallic acid. The effect of chitosan derivatives on the production of reactive oxygen species (ROS) in the cells of pea leaf epidermis and on the cell death detected by the destruction of cell nuclei, was investigated. QCG, QC, and SOD had no effect, while PG decreased the rate of ROS generation in the cells of the epidermis, which was induced by NADH with SHAM or by menadione. QCG and QC prevented destruction of the guard cell nuclei in the pea leaf epidermis that was caused by NADH with SHAM or by KCN. SOD had no effect on the destruction of nuclei, while the effect of PG depended on the inducer of the cell death. Suppression of the destruction of guard cell nuclei by chitosan derivatives was associated not with their antioxidant effect, but with the disruption of the plasma membrane of the cells. The results obtained have shown that QCG exhibits antioxidant properties in solutions, but does not prevent generation of ROS in the plant cells. The mechanism of antioxidant effect of QCG is similar to that of PG and SOD.

Recent advances in extraction, modification, and application of chitosan in packaging industry

Current environmental concerns fostered a strong interest in extracting polymers from renewable feedstocks. Chitosan, a second most abundant polysaccharide after cellulose, may prove to be a promising green material owing to its renewability, inherent biodegradablity, natural availability, non-toxicity, and ease of modification. This review is intended to comprehensively overview the recent developments on the isolation of chitosan from chitin, its modification and applications as a reinforcing candidate for food packaging materials, emphasizing the scientific underpinnings arising from its physicochemical properties, antimicrobial, antioxidant, and antifungal activities. We review various chitosan-reinforced composites reported in the literature and comprehensively present intriguing mechanical and other functional properties. We highlight the contribution of these mechanically robust and responsive materials to extend the shelf-life and maintain the qualities of a wide range of food commodities. Finally, we assess critical challenges and highlight future opportunities towards understanding the versatile applications of chitosan nanocomposites.

Chitosan as an Underrated Polymer in Modern Tissue Engineering

Chitosan is one of the most well-known and characterized materials applied in tissue engineering. Due to its unique chemical, biological and physical properties chitosan is frequently used as the main component in a variety of biomaterials such as membranes, scaffolds, drug carriers, hydrogels and, lastly, as a component of bio-ink dedicated to medical applications. Chitosan's chemical structure and presence of active chemical groups allow for modification for tailoring material to meet specific requirements according to intended use such as adequate endurance, mechanical properties or biodegradability time. Chitosan can be blended with natural (gelatin, hyaluronic acid, collagen, silk, alginate, agarose, starch, cellulose, carbon nanotubes, natural rubber latex, κ-carrageenan) and synthetic (PVA, PEO, PVP, PNIPPAm PCL, PLA, PLLA, PAA) polymers as well as with other promising materials such as aloe vera, silica, MMt and many more. Chitosan has several derivates: carboxymethylated, acylated, quaternary ammonium, thiolated, and grafted chitosan. Its versatility and comprehensiveness are confirming by further chitosan utilization as a leading constituent of innovative bio-inks applied for tissue engineering. This review examines all the aspects described above, as well as is focusing on a novel application of chitosan and its modifications, including the 3D bioprinting technique which shows great potential among other techniques applied to biomaterials fabrication.

Foliage application of chitosan alleviates the adverse effects of cadmium stress in wheat seedlings (Triticum aestivum L.)

Excessive cadmium (Cd) causes toxic effects on crops. The effects of chitosan (CTS) with different molecular weight (MW) (5 kDa, 3 kDa, and 1 kDa) on the growth and biochemical parameters, as well as Cd concentrations in Cd-treated wheat plants were examined in a pot experiment. The results demonstrated that foliar spraying with CTS significantly improve the wheat growth, reduce malondialdehyde content and reactive oxygen species accumulation in leaves and decrease Cd concentrations in roots and shoots of wheat seedling under Cd stress. The alleviation of Cd toxicity by CTS is probably related with the activity of antioxidant enzymes, osmotic adjustment matter and root morphology. The application of CTS enhanced the activities of superoxide dismutase, peroxidase, and catalase in Cd-stressed wheat seedling leaves by 6.6%-13.1%, 17.2%-33.0%, and 19.6%-25.5%, respectively. Besides, exogenously applied CTS also increased the soluble protein and soluble sugar contents by 17.6%-33.8% and 30.1%-36.1% in the leaves of wheat under Cd stress. Furthermore, CTS with a molecular weight of 1 kDa was the most effective in mitigating Cd toxicity in wheat seedlings, which indicates that the activity of CTS is dependent on its molecular weight. It can be concluded that the use of foliar spraying, especially with 1 kDa CTS, could have potential in reducing the damage of Cd stress.

Fabrication of chitosan-gallic acid conjugate for improvement of physicochemical stability of β-carotene nanoemulsion: Impact of Mw of chitosan

In this research, three various Mw of chitosan (CS)-gallic acid (GA) conjugates were synthesized, characterized, and used for improvement of physicochemical stability of β-carotene (BC) nanoemulsion (NE) by layer-by-layer technique. GA conjugation degrees were in the following order: HCS (125.6 mg/g) > MCS (102.3 mg/g) > LCS (74.6 mg/g) at GA:CS mass ratio of 0.5:1. Three varying Mw of CS-GA conjugates exhibited pronouncedly higher antioxidant abilities than native CS. For native CS, antioxidant abilities increased with the decrease of Mw. However, HCS-GA conjugate showed the highest antioxidant activity, due to the higher GA conjugation degrees and decreased intramolecular hydrogen bonds and crystallinity in HCS-GA conjugate. CS-GA conjugates substantially improved BC chemical stability in NE than CS and BC retentions were in the following order: HCS-GA (76.8%) > MCS-GA (68.3%) > LCS-GA (53.4%) after 30 days storage. The results obtained may provide some useful information for the applications of CS-GA conjugates for nutraceuticals stabilization in food systems.

Antioxidative Potency of Dolphin Serum Albumin Is Stronger Than That of Human Serum Albumin Irrespective of Substitution of 34Cysteine With Serine

Serum albumin (SA), the most abundant protein in circulation, functions as a carrier protein, osmoregulator, and antioxidant. Generally, SA exerts its antioxidative effects by scavenging reactive oxygen species. Because marine mammals are superior divers, they are intermittently exposed to oxidative stress induced by rapid reperfusion of oxygen to ischemic tissues after the dive. Although several antioxidants in marine mammals have been described, SA activity remains largely uncharacterized. In this study, we investigated the antioxidative activity of SA in marine mammals by comparing features of the primary and steric structures, biochemical properties, and antioxidative activities of common bottlenose dolphin SA (DSA) and human SA (HSA). Our results revealed that DSA lacked free cysteine at position 34 that is important for the antioxidative activity of HSA; however, the antioxidative capacity and thiol activity of DSA were stronger than those of HSA. Circular dichroism spectra showed different patterns in DSA and HSA. Ultraviolet fluorescence intensities of DSA were higher than those of HSA, suggesting lower surface hydrophobicity of DSA. Additionally, DSA showed higher excess heat capacity than HSA. We then compared a homology model of DSA with a 3D model of HSA. Our results indicate that DSA was more unstable than HSA at least in the body-temperature range, probably due to the mode of molecules involved in the disulfide bonds and/or the lower surface hydrophobicity, and it may be related to the equivalent or stronger antioxidant potency of DSA. These data show that DSA is an effective antioxidant in the circulation of the dolphin.

Antibacterial performance of fully biobased chitosan-grafted-polybenzoxazine films: Elaboration and properties of released material

A fully biobased benzoxazine monomer, V-fa (using vanillin and furfurylamine) was grafted onto chitosan (CS) at different weight ratios (C_XV_Y) using "grafting to" benign Schiff base chemistry. Incorporation of V-fa onto CS increased the tensile strength and improved chemical resistance of the CS-graft-V-fa films. Reversible labile linkages, expansion of CS galleries and leaching out of phenolic species from biobased polymer films led to an improved antibacterial activity against Staphylococcus aureus, which is ∼125 times higher than the bare CS film, V-fa and oligomeric V-fa. The leached out species from films were analyzed extensively by NMR, FTIR, GPC, ABTS and HRMS analysis. Oxidative-stress seems to be responsible for antibacterial activity. Current work illustrates an attractive synthetic approach and the improved antibacterial performance of biobased CS-graft-poly(V-fa) films which may hold as a potential alternative for wound-healing and implant applications in future.

Effects of chitosan and oligochitosans on the phosphatidylinositol 3-kinase-AKT pathway in cancer therapy

Phosphatidylinositol 3-kinase (PI3K)-AKT pathway is one of the most important kinase signaling networks in the context of cancer development and treatment. Aberrant activation of AKT, the central mediator of this pathway, has been implicated in numerous malignancies including endometrial, hepatocellular, breast, colorectal, prostate, and, cervical cancer. Thus regulation and blockage of this kinase and its key target nodes is an attractive approach in cancer therapy and diverse efforts have been done to achieve this aim. Chitosan is a carbohydrate with multiple interesting applications in cancer diagnosis and treatment strategies. This bioactive polymer and its derivative oligomers commonly used in drug/DNA delivery methods due to their functional properties which improve efficiency of delivery systems. Further, these compounds exert anti-tumor roles through the stimulation of apoptosis, immune enhancing potency, anti-oxidative features and anti-angiogenic roles. Due to the importance of PI3K-AKT signaling in cancer targeting and treatment resistance, this review discusses the involvement of chitosan, oligochitosaccharides and carriers based on these chemicals in the regulation of this pathway in different tumors.

Chitin/Chitosan and Its Derivatives: Fundamental Problems and Practical Approaches

In this review, we present the data on the natural occurrence of chitin and its partially or fully deacetylated derivative chitosan, as well as their properties, methods of modification, and potential applications of derivatives with bactericidal, fungicidal, and antioxidant activities. The structure and physicochemical characteristics of the polymers, their functions, and features of chitin microbial synthesis and degradation, including the processes occurring in nature, are described. New data on the hydrolytic microorganisms capable of chitin degradation under extreme conditions are presented. Special attention is focused on the effect of physicochemical characteristics of chitosan, including molecular weight, degree of deacetylation, polydispersity index, and number of amino group derivatives (quaternized, succinyl, etc.) on the antimicrobial and antioxidant properties of modified polymers that can be of particular interest for biotechnology, medicine, and agriculture. Analysis of the available literature data confirms the importance of fundamental research to broaden our knowledge on the occurrence of chitin and chitosan in nature, their role in global biosphere cycles, and prospects of applied research aimed at using chitin, chitosan, and their derivatives in various aspects of human activity.

Treatment of hepatotoxicity induced by γ-radiation using platelet-rich plasma and/or low molecular weight chitosan in experimental rats

Background and aim: Platelet-rich plasma (PRP) is rich in growth factors and plays an important role in tissue healing and cytoprotection. Also, it has been proved that low molecular weight chitosan (LMC) possesses many outstanding health benefits. The aim of this study was to assess the possibility of using PRP and/or fungal LMC to treat hepatotoxicity induced by γ-radiation in albino rats.Materials and methods: Forty-eight adult male albino rats were randomly divided into eight groups. Group I (control), Group II (PRP alone), Group III (LMC alone), Group IV (PRP + LMC), Group V (γ-irradiated alone), Group VI (γ-irradiated + PRP), Group VII (γ-irradiated + LMC), and Group VIII (γ-irradiated + PRP + LMC). The irradiated rats were whole body exposed to γ-radiation (8 Gy) as fractionated doses (2 Gy) twice a week for 2 consecutive weeks. The treated groups received PRP (0.5 mL/kg body weight, s.c.) and/or LMC (10 mg/kg body weight, s.c.) 2 days a week 1 h after every dose of γ-radiation and continued for another week after the last dose of radiation. Serum alanine transaminase (ALT) and aspartate transaminase (AST) activities, as well as reduced glutathione (GSH) content, malondialdehyde (MDA), total antioxidant capacity (TAC), and nuclear factor erythroid 2-related factor 2 (Nrf2) levels in the liver tissue and relative expression of microRNA-21 (miR-21) in serum were measured, in addition to histopathological examination.Results: Exposure of rats to γ-radiation resulted in a significant increase in serum ALT and AST activities, hepatic MDA levels, and serum miR-21 relative expression, along with a significant decrease in hepatic GSH content, TAC, and Nrf2 levels. Treatment with PRP and/or fungal LMC after exposure to γ-radiation ameliorated these parameters and improved the histopathological changes induced by γ-radiation.Conclusions: The results demonstrated that PRP and/or LMC inhibited γ-radiation-induced hepatotoxicity and using both of them together seems more effective. They can be a candidate to be studied toward the development of a therapeutic strategy for liver diseases.

Chitooligosaccharides from squid pen prepared using different enzymes: characteristics and the effect on quality of surimi gel during refrigerated storage

Abstract

Chitooligosaccharides (COS) from squid pen produced using amylase, lipase and pepsin were characterized. COS produced by 8% (w/w) lipase (COS-L) showed the maximum FRAP and ABTS radical scavenging activity than those prepared using other two enzymes. COS-L had the average molecular weight (MW) of 79 kDa, intrinsic viscosity of 0.41 dL/g and water solubility of 49%. DPPH, ABTS radical scavenging activities, FRAP and ORAC of COS-L were 5.68, 322.68, 5.66 and 42.20 μmol TE/g sample, respectively. Metal chelating activity was 2.58 μmol EE/g sample. For antibacterial activity, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of COS-L against the targeted bacteria were in the range of 0.31–4.91 mg/mL and 0.62–4.91 mg/mL, respectively. Sardine surimi gel added with 1% (w/w) COS-L showed the lower PV, TBARS and microbial growth during 10 days of storage at 4 °C. COS-L from squid pen could inhibit lipid oxidation and extend the shelf-life of refrigerated sardine surimi gel.

Graphical abstract

Recent Developments in the Reduction of Oxidative Stress through Antioxidant Polymeric Formulations

Reactive oxygen and nitrogen species (RONS) are produced endogenously in our body, or introduced through external factors, such as pollution, cigarette smoke, and excessive sunlight exposure. In normal conditions, there is a physiological balance between pro-oxidant species and antioxidant molecules that are able to counteract the detrimental effect of the former. Nevertheless, when this homeostasis is disrupted, the resulting oxidative stress can lead to several pathological conditions, from inflammation to cancer and neurodegenerative diseases. In this review, we report on the recent developments of different polymeric formulations that are able to reduce the oxidative stress, from natural extracts, to films and hydrogels, and finally to nanoparticles (NPs).

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.

Anti-Oxidant Activity and Dust-Proof Effect of Chitosan with Different Molecular Weights

High molecular weight chitosan (HMWC) was degraded to prepare chitosan with different molecular weight based on the fenton reaction, which can produce aggressive OH-radicals produced from hydrogen peroxide in the presence of catalytic metal ions. The relative molecular weight, anti-oxidant activity, and fine dust removal effect of chitosan hydrolysates were elucidated to define their molecular weight and their potent biological activity. Our results demonstrate that chitosan hydrolysates derived from the hydrolysis of HMWC may possess significant free-radical scavenging activity as good anti-oxidants against the radical scavenging activity of DPPH and ABTS, respectively. Furthermore, chitosan hydrolysates can effectively eliminate fine dust, which may contain some particulate matter (PM) and unknown species of microorganisms from the air, suggesting that our data provide important information for producing air filters, dust-proof masks and skin cleaner for the purpose of human healthcare and well-being.

Modification of different molecular weights of chitosan by p-Coumaric acid: Preparation, characterization and effect of molecular weight on its water solubility and antioxidant property

In this study, we modified three different molecular weights of chitosan by using p-Coumaric acid (p-CA) for enhancing their water solubility and antioxidant property. The chemical and physical properties of all native chitosan and its modified products were determined by Fourier transform spectroscopy (FTIR), ninhydrin assay, Folin-Ciocalteu reagent procedure, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), high performance of liquid chromatography (HPLC), X-ray diffraction (XRD), water solubility and antioxidant property (both DPPH assay and reducing power assay). Results showed that the water solubility and antioxidant property of modified product decreases, when molecular weight of corresponding native chitosan increases. The obtained modified product had good solubility over a wide range of pH. Thermal analysis (TGA and DSC) showed the lower thermal stability of the modified product than that of corresponding native chitosan. XRD pattern revealed that the crystallinity was less in modified product than that of respective chitosan. The enhanced partially water solubility and antioxidant property of all modified chitosan products might be a great advantage, while applied in a wide range of applications in the form antioxidant property in food, biomedical and cosmetic industry.

Antimicrobial Nanoparticles Incorporated in Edible Coatings and Films for the Preservation of Fruits and Vegetables

Edible coatings and films (ECF) are employed as matrixes for incorporating antimicrobial nanoparticles (NPs), and then they are applied on the fruits and vegetables to prolong shelf life and enhance storage quality. This paper provides a comprehensive review on the preparation, antimicrobial properties and mechanisms, surface and physical qualities of ECF containing antimicrobial NPs, and its efficient application to vegetables and fruits as well. Following an introduction on the properties of the main edible coating materials, the preparation technologies of ECF with NPs are summarized. The antimicrobial activity of ECF with NPs against the tested microorganism was observed by many researchers. This might be mainly due to the electrostatic interaction between the cationic polymer or free metal ions and the charged cell membrane, the photocatalytic reaction of NPs, the detachment of free metal ion, and partly due to the antimicrobial activity of edible materials. Moreover, their physical, mechanical and releasing properties are discussed in detail, which might be influenced by the concentration of NPs. The preservation potential on the quality of fruits and vegetables indicates that various ECF with NPs might be used as the ideal materials for food application. Following the introduction on these characteristics, an attempt is made to predict future trends in this field.

Functional Nanostructured Oligochitosan⁻Silica/ Carboxymethyl Cellulose Hybrid Materials: Synthesis and Investigation of Their Antifungal Abilities

Functional hybrid materials were successfully synthesized from low-cost waste products, such as oligochitosan (OCS) obtained from chitosan (one of the main components in crab shells) and nanosilica (nSiO₂) obtained from rice husk, in a 1:1 ratio (w/w), and their dispersion in the presence of carboxymethyl cellulose at pH 7 was stable for over one month without aggregation. The molecular weights, chemical structures, morphologies, and crystallinities of the obtained materials were characterized by GPC, FTIR, TEM, and XRD, respectively. The antifungal effects of OCS, nSiO₂, and the OCS/nSiO₂ hybrid materials were investigated via a disk-diffusion method. The results showed that the nanohybrid materials had better resistance to Phytophthora infestans fungus than the individual components, and a concentration of the OCS2/nSiO₂ hybrid material of 800 mg L⁻¹ was the lowest concentration where the material completely inhibited Phytophthora infestans growth, as measured via an agar dilution method. This study not only creates a novel environmentally friendly material with unique synergistic effects that can replace current toxic agrochemicals but also can be considered a new platform for further research in green agricultural applications.

Scavenging of reactive oxygen species by phenolic compound-modified maghemite nanoparticles

Maghemite (γ-Fe₂O₃) nanoparticles obtained through co-precipitation and oxidation were coated with heparin (Hep) to yield γ-Fe₂O₃@Hep, and subsequently with chitosan that was modified with different phenolic compounds, including gallic acid (CS-G), hydroquinone (CS-H), and phloroglucinol (CS-P), to yield γ-Fe₂O₃@Hep-CS-G, γ-Fe₂O₃@Hep-CS-H, and γ-Fe₂O₃@Hep-CS-P particles, respectively. Surface modification of the particles was analyzed by transmission electron microscopy, dynamic light scattering, attenuated total reflection Fourier transform infrared spectroscopy, and thermogravimetric analysis. Magnetic measurements indicated that the polymer coating does not affect the superparamagnetic character of the iron oxide core. However, magnetic saturation decreased with increasing thickness of the polymer coating. The antioxidant properties of the nanoparticles were analyzed using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Cellular uptake and intracellular antioxidant activity of the particles were evaluated by an iron assay and flow cytometry, respectively, using L-929 and LN-229 cells. Compared to the control, the phenolic modification significantly reduced intracellular reactive oxygen species (ROS) levels to 35-56%, which was associated with a 6-8-times higher cellular uptake in L-929 cells and a 21-31-times higher cellular uptake in LN-229 cells. In contrast, γ-Fe₂O₃@Hep particles induced a 3.8-times and 14.9-times higher cellular uptake without inducing antioxidant activity. In conclusion, the high cellular uptake and the antioxidant properties associated with the phenolic moieties in the modified particles allow for a potential application in biomedical areas.

Biological Activity of Native and Low Molecular Weight Chitosan obtained by Steam Explosion Process

BACKGROUND AND OBJECTIVE

Low molecular weight chitosan (LWCS) was interestingly used because of it's solubility and has good functional properties like antioxidant and antibacterial activity. This study aimed to evaluate antioxidant and antibacterial activity of chitosan and low molecular weight chitosan.

MATERIALS AND METHODS

Low molecular weight chitosan was obtained by physical and chemical hydrolysis using steam explosion process with steam pressure at 6 bar, temperature at 160°C and concentration of phosphotungstic acid at 0.1% w/v. The antioxidant activity was confirmed by radical DPPH scavenging activity, chelating metal ion value, inhibitory lipid peroxidation and antibacterial activity was confirmed by diffusion methods.

RESULTS

LWCS had antioxidant activity higher than native chitosan on radical scavenging, chelating ion value and inhibition of lipid peroxidation. LWCS had higher inhibitory effect as antibacterial than native chitosan against tested bacteria, there were Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Streptococcus aureus and Bacillus subtilis.

CONCLUSION

It was concluded that LWCS had more powerful antioxidant and antibacterial activity than native chitosan.

Involvement of FAK-mediated BMP-2/Smad pathway in mediating osteoblast adhesion and differentiation on nano-HA/chitosan composite coated titanium implant under diabetic conditions

Nanophase HA/CS composite coated porous titanium implant exhibited superior biological performance under diabetic conditions compared to pure Ti.