The antioxidant and antimicrobial activities of different phenolic acids grafted onto chitosan

Chitosan oligosaccharide-g-linalool polymer as inhibitor of hyaluronidase and collagenase activity

In this study, chitosan oligosaccharide (COS) was modified by grafting Linalool (Lin) on its backbone to improve its anti-inflammatory activity. By changing the molar ratios of COS to Lin, three different degrees of substitution COS-g-Lin1-3 were prepared. The degrees of substitution of derivatives were 0.65, 0.80 and 1.14 respectively. The structure of COS-g-Lin1-3 were characterized by UV-vis, FT-IR, ¹H NMR and elemental analysis in order to show the COS-g-Lin1-3 successfully synthesized. Besides, the thermal stability, solubility, pH stability as well as crystallinity were also investigated. The results revealed that the derivatives exhibited higher thermal stability and more remarkable anti-inflammatory property against hyaluronidase and collagenase than that of COS. The good biocompatibility made this novel material a promising and effective compound for anti-inflammatory applications.

Modification of Hydroxypropyltrimethyl Ammonium Chitosan with Organic Acid: Synthesis, Characterization, and Antioxidant Activity

A novel and green method for the preparation of chitosan derivatives bearing organic acids was reported in this paper. In order to improve the antioxidant activity of chitosan, eight different hydroxypropyltrimethyl ammonium chitosan derivatives were successfully designed and synthesized via introducing of organic acids onto chitosan by mild and non-toxic ion exchange. The data of Fourier Transform Infrared (FTIR), ¹³C Nuclear Magnetic Resonance (NMR), ¹H NMR, and elemental analysis for chitosan derivatives indicated the successful conjugation of organic acid salt with hydroxypropyltrimethyl ammonium chloride chitosan (HACC). Meanwhile, the antioxidant activity of the chitosan derivatives was evaluated in vitro. The results indicated that the chitosan derivatives possessed dramatic enhancements in DPPH-radical scavenging activity, superoxide-radical scavenging activity, hydroxyl radical scavenging ability, and reducing power. Furthermore, the cytotoxicity of the synthesized compounds was investigated in vitro on L929 cells and showed low cytotoxicity. Thus, the enhanced antioxidant property of all novel chitosan products might be a great advantage, while applied in a wide range of applications in the form of antioxidant in biomedical, food, and cosmetic industry.

A review on the synthesis of graft copolymers of chitosan and their potential applications

Chitosan is an antimicrobial, biodegradable and biocompatible natural polymer, commercially derived from the partial deacetylation of chitin. Currently modified chitosan has occupied a major part of scientific research. Modified chitosan has excellent biotic characteristics like biodegradation, antibacterial, immunological, metal-binding and metal adsorption capacity and wound-healing ability. Chitosan is an excellent candidate for drug delivery, food packaging and wastewater treatment and is also used as a supporting object for cell culture, gene delivery and tissue engineering. Modification of pure chitosan via grafting improves the native properties of chitosan. Chitosan grafted copolymers exhibit high significance and are extensively used in numerous fields. In this review, modifications of chitosan through several graft copolymerization techniques such as free radical, radiation, and enzymatic were reported and the properties of grafted chitosan were discussed. This review also discussed the applications of grafted chitosan in the fields of drug delivery, food packaging, antimicrobial, and metal adsorption as well as dye removal.

Impact of Gallic Acid on Gut Health: Focus on the Gut Microbiome, Immune Response, and Mechanisms of Action

Gallic acid (GA) is a naturally occurring polyphenol compound present in fruits, vegetables, and herbal medicines. According to previous studies, GA has many biological properties, including antioxidant, anticancer, anti-inflammatory, and antimicrobial properties. GA and its derivatives have multiple industrial uses, such as food supplements or additives. Additionally, recent studies have shown that GA and its derivatives not only enhance gut microbiome (GM) activities, but also modulate immune responses. Thus, GA has great potential to facilitate natural defense against microbial infections and modulate the immune response. However, the exact mechanisms of GA acts on the GM and immune system remain unclear. In this review, first the physicochemical properties, bioavailability, absorption, and metabolism of GA are introduced, and then we summarize recent findings concerning its roles in gastrointestinal health. Furthermore, the present review attempts to explain how GA influences the GM and modulates the immune response to maintain intestinal health.

Recent Advancement of Molecular Structure and Biomaterial Function of Chitosan from Marine Organisms for Pharmaceutical and Nutraceutical Application

Chitosan is an innate cationic biological polysaccharide polymer, naturally obtained from chitin deacetylation, that possesses broad-spectrum properties such as antibacterial, biodegradability, biocompatibility, non-toxic, non-immunogenicity, and so on. Chitosan can be easily modified owing to its molecular chain that contains abundant active amino and hydroxyl groups, through various modifications. Not only does it possess excellent properties but it also greatly accelerates its solubility and endows it with additional special properties. It can be developed into bioactive materials with innovative properties, functions, and multiple uses, especially in the biomedical fields. In this paper, the unique properties and the relationship between the molecular structure of chitosan and its derivatives are emphasized, an overview of various excellent biomedical properties of chitosan and its current progress in the pharmaceutical and nutraceutical field have prospected, to provide the theoretical basis for better development and utilization of new biomedical materials of chitosan and its derivatives.

Synthesis, characterization, and the antioxidant activity of the acetylated chitosan derivatives containing sulfonium salts

In this study, a new class of chitosan derivatives possessing sulfonium salts was synthesized, and characterized by FT-IR, ¹H NMR, ¹³C NMR, and elemental analyses. IR spectra, ¹H NMR and ¹³C NMR of the structural units of these polymers validated the designed chitosan derivatives were successfully synthesized. In addition, the antioxidant potential of chitosan and chitosan derivatives was assessed in vitro, screened by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, hydroxyl radical scavenging, and superoxide radical scavenging, respectively. Results revealed that designed chitosan derivatives could effectively scavenge DPPH radical, hydroxyl radical, and superoxide radical with inhibition rate of more than 90% at 1.6 mg/mL, higher than chitosan. Moreover, in the cytotoxicity assay, no cytotoxicity was observed for the L929 cells with chitosan and its derivatives at all the testing concentrations. These results indicated that the acetylated chitosan derivatives containing sulfonium salts may be a promising natural antioxidant for the pharmaceutics, food, cosmetics and agriculture management.

Chitosan-Functionalized Mg0.5Co0.5Fe2O4 Magnetic Nanoparticles Enhance Delivery of 5-Fluorouracil In Vitro

Magnetic nanoparticles (MNPs) have been widely investigated as a strategy to improve the delivery efficiency of therapeutic and diagnostic agents. Substituted iron oxides or ferrite nanoparticles (NPs) such as CoFe2O4 represent an interesting and novel class of MNPs, although they are under-researched in the field of biomedicine. In this study, chitosan-functionalized Mg0.5Co0.5Fe2O4 NPs were loaded with the anti-cancer 5-fluorouracil (5-FU) drug to yield CS-Mg0.5Co0.5Fe2O4-5FU. Transmission electron microscopy (TEM), Fourier Transform infra-red (FTIR) spectroscopy and nanoparticle tracking analysis (NTA) were employed to determine the physiochemical properties of the NPs. Physico-chemical characterizations confirmed spherical NPs with particle sizes of approximately 20.39 nm. Improved colloidal stability was observed, as determined by a zeta potential of approximately −20 mV for the drug-loaded CS-Mg0.5Co0.5Fe2O4 NPs. Drug encapsulation efficiencies of >60% were attained, showing a pH-dependent release of 5-FU. Cell viabilities investigated using the 3-[(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] (MTT) and sulforodhamine B (SRB) assays in human embryonic kidney (HEK293), human breast adenocarcinoma (MCF-7) and human cervical cancer (HeLa) cells showed that these drug-loaded NPs exhibited more targeted tumor-specific cytotoxicities compared to free drugs. CS-Mg0.5Co0.5Fe2O4-5-FU NPs displayed significant targeted delivery potential to the investigated cancer cell lines. Conclusively, these results suggest that the CS-Mg0.5Co0.5Fe2O4-5-FU NPs are promising therapeutic delivery systems in anti-cancer treatment.

Antimicrobial Chitosan Conjugates: Current Synthetic Strategies and Potential Applications

As a natural polysaccharide, chitosan possesses good biocompatibility, biodegradability and biosafety. Its hydroxyl and amino groups make it an ideal carrier material in the construction of polymer-drug conjugates. In recent years, various synthetic strategies have been used to couple chitosan with active substances to obtain conjugates with diverse structures and unique functions. In particular, chitosan conjugates with antimicrobial activity have shown great application prospects in the fields of medicine, food, and agriculture in recent years. Hence, we will place substantial emphasis on the synthetic approaches for preparing chitosan conjugates and their antimicrobial applications, which are not well summarized. Meanwhile, the challenges, limitations, and prospects of antimicrobial chitosan conjugates are described and discussed.

Synthesis and molecular characterization of chitosan/starch blends based polyurethanes

Starch/chitosan modified polyurethanes (PUs) were synthesized by step growth polymerization reaction between -NCO terminated prepolymer and chain extenders (1,4-Butanediol/starch/chitosan). Isophorone diisocyanate (IPDI) was reacted with hydroxyl-terminated polybutadiene (HTPB) to synthesize prepolymer and was further reacted with different moles ratio of starch/chitosan to produced five samples of polyurethane (PU). These samples were characterized by Fourier transformed infrared (FTIR) and Proton nuclear magnetic resonance (¹H NMR) spectroscopy. The surface characterizations of PUs were done by scanning electron microscope (SEM). Thermogravimetric analysis showed that the thermal stability of PUs was higher when the mixture of both natural materials was used at equal amounts. It is concluded that combination of both starch and chitosan are efficient for the synthesis of PUs.

Synthesis, Characterization, and the Antioxidant Activity of Carboxymethyl Chitosan Derivatives Containing Thiourea Salts

A new class of chitosan derivatives possessing thiourea salts were synthesized to improve the solubility and the antioxidant activity of chitosan. Firstly, chitosan was modified to carboxymethyl chitosan, combining carboxymethyl chitosan with thiourea salts that have different structures to form new chitosan derivatives. The chitosan and chitosan derivatives were characterized by FT-IR, ¹³C NMR, TGA, and elemental analyses. The new peaks of thiourea salts could be clearly observed at about 1240 cm^-1 in the IR spectra, and the peak of C=S was clearly observed at around 180 ppm in the ¹³C NMR. IR spectra and ¹³C NMR of the structural units of these polymers validated the chitosan derivatives possessing thiourea salts were successfully synthesized. Their antioxidant properties were tested, including DPPH-radical scavenging ability, superoxide-radical scavenging ability, and hydroxyl-radical scavenging ability. Our results suggested the increase of thiourea salt groups in chitosan derivatives promotes the scavenging effect. The scavenging activity of 4TMCMCS, TMCMCS. 4,4DCMCS, and 4ACMCS against DPPH-radical and superoxide-radical were more than 90% at 1.6 mg/mL, respectively. In the cytotoxicity assay, no cytotoxicity was observed for the L929 cells with chitosan and its derivatives at all testing concentrations. These results demonstrated that the combination of chitosan and thiourea salt groups improved the antioxidant activity of chitosan, and the antioxidants or free radical scavengers based on natural polymers and thiourea salts showed potential applications.