Preparation of chitosan-rosmarinic acid derivatives with enhanced antioxidant and anti-inflammatory activities

Enhanced stabilization of multifunctional phenolic acids-grafted chitin nanofibers for Pickering emulsions

The objective of this study was to develop novel functional stabilizers for Pickering emulsions using phenolic acids-grafted chitin nanofibers (phenolic acids-g-ChNF), which were fabricated by grafting ferulic acid (FA), sinapic acid (SA) and caffeic acid (CA) onto ChNF via free radical-mediated method. The Fourier transform infrared spectrum and Proton nuclear magnetic resonance showed that graft copolymerization occurred between the amino groups of ChNF and the carbonyl of the phenolic acids. Further, it was revealed that CA-g-ChNF and SA-g-ChNF possessed stronger antioxidant and antibacterial properties than the original ChNF and FA-g-ChNF. Additionally, we applied phenolic acids-g-ChNF to develop Pickering emulsions and found that SA-g-ChNF- and CA-g-ChNF-stabilized emulsions displayed reduced droplet sizes compared to FA, the main reason for which was that SA and CA had a rather close bonding relationship with ChNF. Taken together, SA-g-ChNF and CA-g-ChNF as novel multi-functional particles can be employed for facilitating the stability of Pickering emulsions.

LC-ESI-QTOF-MS/MS Identification and Characterization of Phenolic Compounds from Leaves of Australian Myrtles and Their Antioxidant Activities

Phenolic compounds, present in plants, provide substantial health advantages, such as antioxidant and anti-inflammatory properties, which enhance cardiovascular and cognitive well-being. Australia is enriched with a wide range of plants with phytopharmacological potential, which needs to be fully elucidated. In this context, we analyzed leaves of aniseed myrtle (Syzygium anisatum), lemon myrtle (Backhousia citriodora), and cinnamon myrtle (Backhousia myrtifolia) for their complex phytochemical profile and antioxidant potential. LC-ESI-QTOF-MS/MS was applied for screening and characterizing these Australian myrtles' phenolic compounds and the structure-function relation of phenolic compounds. This study identified 145 and quantified/semi-quantified 27 phenolic compounds in these Australian myrtles. Furthermore, phenolic contents (total phenolic content (TPC), total condensed tannins (TCT), and total flavonoids (TFC)) and antioxidant potential of phenolic extracts from the leaves of Australian myrtles were quantified. Aniseed myrtle was quantified with the highest TPC (52.49 ± 3.55 mg GAE/g) and total antioxidant potential than other selected myrtles. Catechin, epicatechin, isovitexin, cinnamic acid, and quercetin were quantified as Australian myrtles' most abundant phenolic compounds. Moreover, chemometric analysis further validated the results. This study provides a new insight into the novel potent bioactive phenolic compounds from Australian myrtles that could be potentially useful for functional, nutraceutical, and therapeutic applications.

Recent Applications of Chitosan and Its Derivatives in Antibacterial, Anticancer, Wound Healing, and Tissue Engineering Fields

Chitosan, a versatile biopolymer derived from chitin, has garnered significant attention in various biomedical applications due to its unique properties, such as biocompatibility, biodegradability, and mucoadhesiveness. This review provides an overview of the diverse applications of chitosan and its derivatives in the antibacterial, anticancer, wound healing, and tissue engineering fields. In antibacterial applications, chitosan exhibits potent antimicrobial properties by disrupting microbial membranes and DNA, making it a promising natural preservative and agent against bacterial infections. Its role in cancer therapy involves the development of chitosan-based nanocarriers for targeted drug delivery, enhancing therapeutic efficacy while minimising side effects. Chitosan also plays a crucial role in wound healing by promoting cell proliferation, angiogenesis, and regulating inflammatory responses. Additionally, chitosan serves as a multifunctional scaffold in tissue engineering, facilitating the regeneration of diverse tissues such as cartilage, bone, and neural tissue by promoting cell adhesion and proliferation. The extensive range of applications for chitosan in pharmaceutical and biomedical sciences is not only highlighted by the comprehensive scope of this review, but it also establishes it as a fundamental component for forthcoming research in biomedicine.

Preparation of biocompatibility coating on magnesium alloy surface by sodium alginate and carboxymethyl chitosan hydrogel

Magnesium alloy is an excellent material for biodegradable cerebrovascular stents. However, the rapid degradation rate of magnesium alloy will make stent unstable. To improve the biocompatibility of magnesium alloy, in this study, biodegradable sodium alginate and carboxymethyl chitosan (SA/CMCS) was used to coat onto hydrothermally treated the surface of magnesium alloy by a dipping coating method. The results show that the SA/CMCS coating facilitates the growth, proliferation, and migration of endothelial cells and promotes neovascularization. Moreover, the SA/CMCS coating suppresses macrophage activation while promoting their transformation into M2 type macrophages. Overall, the SA/CMCS coating demonstrates positive effects on the safety and biocompatibility of magnesium alloy after implantation, and provide a promising therapy for the treatment of intracranial atherosclerotic stenosis in the future.

A novel chitosan antioxidant bearing sulfhydryl group: Synthesis, characterization and activity assessment

To improve the antioxidant activity, sulfhydryl groups (-SH) were introduced into chitosan. Acylated chitosan derivatives, chitosan cationic salt derivatives, hydroxypropyl trimethylammonium chloride chitosan quaternary ammonium salt (HACC) derivatives and N,N,N-trimethyl chitosan iodine (TMC) derivatives were obtained. The chitosan derivatives were characterized by FTIR and 1H NMR to confirm the successful synthesis. Ellman's reagent was used to determine that the compound contained free sulfhydryl groups. The water solubility and thermal stability of chitosan and derivatives were evaluated. The antioxidant activities of the derivatives were verified, including DPPH radical scavenging activity, superoxide anion radical scavenging activity and reducing power activity. The novel chitosan derivatives showed excellent antioxidant activities. Toxicity assay used L929 cells proved that the derivatives had no significant toxic. The results showed that the chitosan derivatives bearing sulfhydryl groups described in this paper has a certain antioxidant effect, which provides a practical approach for further study of chitosan.

Marine-derived polysaccharides and their therapeutic potential in wound healing application - A review

Polysaccharides originating from marine sources have been studied as potential material for use in wound dressings because of their desirable characteristics of biocompatibility, biodegradability, and low toxicity. Marine-derived polysaccharides used as wound dressing, provide several benefits such as promoting wound healing by providing a moist environment that facilitates cell migration and proliferation. They can also act as a barrier against external contaminants and provide a protective layer to prevent further damage to the wound. Research studies have shown that marine-derived polysaccharides can be used to develop different types of wound dressings such as hydrogels, films, and fibres. These dressings can be personalised to meet specific requirements based on the type and severity of the wound. For instance, hydrogels can be used for deep wounds to provide a moist environment, while films can be used for superficial wounds to provide a protective barrier. Additionally, these polysaccharides can be modified to improve their properties, such as enhancing their mechanical strength or increasing their ability to release bioactive molecules that can promote wound healing. Overall, marine-derived polysaccharides show great promise for developing effective and safe wound dressings for various wound types.

Preparation and Antioxidant Activity of New Carboxymethyl Chitosan Derivatives Bearing Quinoline Groups

A total of 16 novel carboxymethyl chitosan derivatives bearing quinoline groups in four classes were prepared by different synthetic methods. Their chemical structures were confirmed by Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and elemental analysis. The antioxidant experiment results in vitro (including DPPH radical scavenging ability, superoxide anion radical scavenging ability, hydroxyl radical scavenging ability, and ferric reducing antioxidant power) demonstrated that adding quinoline groups to chitosan (CS) and carboxymethyl chitosan (CMCS) enhanced the radical scavenging ability of CS and CMCS. Among them, both N, O-CMCS derivatives and N-TM-O-CMCS derivatives showed DPPH radical scavenging over 70%. In addition, their scavenging of superoxide anion radicals reached more than 90% at the maximum tested concentration of 1.6 mg/mL. Moreover, the cytotoxicity assay was carried out on L929 cells by the MTT method, and the results indicated that all derivatives showed no cytotoxicity (cell viability > 75%) except O-CMCS derivative 1a, which showed low cytotoxicity at 1000 μg/mL (cell viability 50.77 ± 4.67%). In conclusion, the carboxymethyl chitosan derivatives bearing quinoline groups showed remarkable antioxidant ability and weak cytotoxicity, highlighting their potential use in food and medical applications.

An injectable conductive hydrogel with dual responsive release of rosmarinic acid improves cardiac function and promotes repair after myocardial infarction

Myocardial infarction (MI) causes irreversible damage to the heart muscle, seriously threatening the lives of patients. Injectable hydrogels have attracted extensive attention in the treatment of MI. By promoting the coupling of mechanical and electrical signals between cardiomyocytes, combined with synergistic therapeutic strategies targeting the pathological processes of inflammation, proliferation, and fibrotic remodeling after MI, it is expected to improve the therapeutic effect. In this study, a pH/ROS dual-responsive injectable hydrogel was developed by modifying xanthan gum and gelatin with reversible imine bond and boronic ester bond double crosslinking. By encapsulating polydopamine-rosmarinic acid nanoparticles to achieve on-demand drug release in response to the microenvironment of MI, thereby exerting anti-inflammatory, anti-apoptotic, and anti-fibrosis effects. By adding conductive composites to improve the conductivity and mechanical strength of the hydrogel, restore electrical signal transmission in the infarct area, promote synchronous contraction of cardiomyocytes, avoid induced arrhythmias, and induce angiogenesis. Furthermore, the multifunctional hydrogel promoted the expression of cardiac-specific markers to restore cardiac function after MI. The in vivo and in vitro results demonstrate the effectiveness of this synergistic comprehensive treatment strategy in MI treatment, showing great application potential to promote the repair of infarcted hearts.

Preparation of imidazole acids grafted chitosan with enhanced antioxidant, antibacterial and antitumor activities

Herein, imidazole acids grafted chitosan derivatives were synthesized, including HACC, HACC derivatives, TMC, TMC derivatives, amidated chitosan and amidated chitosan bearing imidazolium salts. The prepared chitosan derivatives were characterized by FT-IR and ¹H NMR. The tests evaluated the biological antioxidant, antibacterial, and cytotoxic activities of chitosan derivatives. The antioxidant capacity (DPPH radical, superoxide anion radical and hydroxyl radical) of chitosan derivatives was 2.4-8.3 times higher than that of chitosan. The antibacterial capacity against E. coli and S. aureus of cationic derivatives (HACC derivatives, TMC derivatives, and amidated chitosan bearing imidazolium salts) was more active than only imidazole-chitosan (amidated chitosan). In particular, the inhibition effect of HACC derivatives on E. coli was 15.625 μg/mL. Moreover, the series of chitosan derivatives bearing imidazole acids showed certain activity against MCF-7 and A549 cells. The present results suggest that the chitosan derivatives in this paper seem to be promising carrier materials for use in drug delivery systems.

Exploring the Traditional Uses of Thymbra capitata Infusion in Algarve (Portugal): Anti-Inflammatory, Wound Healing, and Anti-Aging

Inflammation plays a pivotal role in the resolution of infection or tissue damage. In addition, inflammation is considered a hallmark of aging, which in turn compromises wound healing. Thymbra capitata is an aromatic plant, whose infusion is traditionally used as an anti-inflammatory and wound-healing agent. In this study, a T. capitata infusion was prepared and characterized by HPLC-PDA-ESI-MSn and its safety profile determined by the resazurin metabolic assay. The anti-inflammatory potential was revealed in lipopolysaccharide (LPS)-stimulated macrophages by assessing nitric oxide (NO) release and levels of inducible nitric oxide synthase (iNOS) and the interleukin-1β pro-form (pro-IL-1β). Wound-healing capacity was determined using the scratch assay. The activity of senescence-associated β-galactosidase was used to unveil the anti-senescent potential, along with the nuclear accumulation of yH2AX and p21 levels. The antiradical potential was assessed by DPPH and ABTS scavenging assays. The infusion contains predominantly rosmarinic acid and salvianolic acids. The extract decreased NO, iNOS, and pro-IL-1β levels. Interestingly, the extract promoted wound healing and decreased β-galactosidase activity, as well as yH2AX and p21 levels. The present work highlights strong antiradical, anti-inflammatory, and wound healing capacities, corroborating the traditional uses ascribed to this plant. We have described, for the first time for this extract, anti-senescent properties.

Antibacterial and antioxidant properties of phenolic acid grafted chitosan and its application in food preservation: A review

Chitosan is a bio-renewable natural polymeric material. The antibacterial and antioxidant activity of chitosan can be enhanced by grafting with phenolic acids to further expand its application in food. Therefore, this paper focuses on reviewing the structure, antimicrobial and antioxidant activities and their mechanisms with phenolic acid-g-CS, evaluating its cytotoxicity, and describing its application in various food preservation. In general, different reaction mechanisms of phenolic acid-g-CS synthesis lead to different product structures. Compared to chitosan, phenolic acid-g-chitosan exhibited enhanced antibacterial and antioxidant activities. The toxicity assessment showed that phenolic acid-g-CS is not cytotoxic. Moreover, phenolic acid-g-CS has been applied to a variety of food products such as fruits, vegetables and meat with good results. Overall, this review provides a certain reference for subsequent researchers to design phenolic acid-g-CS more rationally and for the subsequent development of phenolic acid-g-CS in food preservation.

Dextran-Chitosan Composites: Antioxidant and Anti-Inflammatory Properties

This study presents the development of new formulations consisting of dextran (Dex) and chitosan (Ch) matrices, with fillings such as chitosan stearate (MCh), citric acid, salicylic acid, or ginger extract. These materials were characterized using Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and mechanical tests, and evaluated for antioxidant properties, including scavenging activities, metal chelation, and ferric ion reducing power, as well as anti-inflammatory properties, measuring the binding affinity between serum albumin and the bioactive substances, which can influence their bioavailability, transport, and overall anti-inflammatory effect. Compounds in ginger such as 6-gingerol reduce inflammation by inhibiting the production of inflammatory substances, such as prostaglandin, cytokines, interleukin-1β, and pro-inflammatory transcription factor (NF-κB) and, alongside citric and salicylic acids, combat oxidative stress, stabilizes cell membranes, and promote membrane fluidity, thereby preserving membrane integrity and function. Incorporating chitosan stearate in chitosan:dextran samples created a dense, stiff film with an elastic modulus approximately seventeen times higher than for the chitosan:dextran matrix. The Dex:Ch:MCh sample exhibited low compressibility at 48.74 ± 1.64 kPa, whereas the Dex:Ch:MCh:citric acid:salicylic acid composite had a compact network, allowing for 70.61 ± 3.9% compression at 109.30 kPa. The lipid peroxidation inhibitory assay revealed that Dex:Ch:MCh:citric acid had the highest inhibition value with 83 ± 0.577% at 24 h. The study highlights that adding active substances like ginger extract and citric acid to Dex:Ch composites enhances antioxidant properties, while modified chitosan improves mechanical properties. These composites may have potential medical applications in repairing cell membranes and regulating antioxidant enzyme activities.

Effect of Thymbra capitata (L.) Cav. on Inflammation, Senescence and Cell Migration

Aromatic plants are reported to display pharmacological properties, including anti-aging. This work aims to disclose the anti-aging effect of the essential oil (EO) of Thymbra capitata (L.) Cav., an aromatic and medicinal plant widely used as a spice, as well as of the hydrodistillation residual water (HRW), a discarded by-product of EO hydrodistillation. The phytochemical characterization of EO and HRW was assessed by GC-MS and HPLC-PDA-ESI-MSⁿ, respectively. The DPPH, ABTS, and FRAP assays were used to disclose the antioxidant properties. The anti-inflammatory potential was evaluated using lipopolysaccharide-stimulated macrophages by assessing NO production, iNOS, and pro-IL-1β protein levels. Cell migration was evaluated using the scratch wound assay, and the etoposide-induced senescence was used to assess the modulation of senescence. The EO is mainly characterized by carvacrol, while the HRW is predominantly characterized by rosmarinic acid. The HRW exerts a stronger antioxidant effect in the DPPH and FRAP assays, whereas the EO was the most active sample in the ABTS assay. Both extracts reduce NO, iNOS, and pro-IL-1β. The EO has no effect on cell migration and presents anti-senescence effects. In opposition, HRW reduces cell migration and induces cellular senescence. Overall, our study highlights interesting pharmacological properties for both extracts, EO being of interest as an anti-aging ingredient and HRW relevant in cancer therapy.

A novel water-soluble chitosan grafted with nerol: Synthesis, characterization and biological activity

In order to improve the antibacterial activity of chitosan and change its solubility, a novel water-soluble chitosan (CS)-nerol (N) derivative (CS-N) was prepared via Schiff base reaction and grafting reaction. FT-IR, NMR, XRD, TGA and SEM were used to characterize the structure and physicochemical properties, and in vitro antibacterial, antioxidant, and cellular assays were used to test for bioactivity and safety. The results revealed that the C6 hydroxyl group of CS was substituted with N, with a degree of substitution of 38 % for CS-N. Furthermore, compared to CS, CS-N demonstrated superior antibacterial activity against Escherichia coli and Staphylococcus aureus, as well as significant DPPH and ABTS free radical scavenging activity. Most importantly, CS-N did not harm HaCaT cells. In conclusion, this study provides a promising strategy for the design of chitosan derivatives with significant potential for application in pharmaceutical, food and cosmetic applications.

Enhancing the Antioxidant, Antibacterial, and Wound Healing Effects of Melaleuca alternifolia Oil by Microencapsulating It in Chitosan-Sodium Alginate Microspheres

In this study, antibacterial and antioxidant molecules-rich Melaleuca alternifolia oil (tea tree oil (TTO)) loaded chitosan (CS) based nanoemulsions (NEMs) were prepared and encapsulated by sodium alginate (SA) microsphere for antibacterial wound dressing. CS-TTO NEMs were prepared by oil-in-water emulsion technique, and the nanoparticle tracking analysis (NTA) confirmed that the CS-TTO NEMs had an average particle size of 89.5 nm. Further, the SA-CS-TTO microsphere was confirmed through SEM analysis with an average particle size of 0.76 ± 0.10 µm. The existence of TTO in CS NEMs and SA encapsulation was evidenced through FTIR analysis. The XRD spectrum proved the load of TTO and SA encapsulation with CS significantly decreased the crystalline properties of the CS-TTO and SA-CS-TTO microsphere. The stability of TTO was increased by the copolymer complex, as confirmed through thermal gravimetric analysis (TGA). Furthermore, TTO was released from the CS-SA complex in a sustained manner and significantly inhibited the bacterial pathogens observed under confocal laser scanning microscopy (CLSM). In addition, CS-TTO (100 µg/mL) showed antioxidant potential (>80%), thereby increasing the DPPH and ABTS free radicals scavenging ability of SA-CS-TTO microspheres. Moreover, CS and SA-CS-TTO microsphere exhibited negligible cytotoxicity and augmented the NIH3T3 cell proliferation confirmed in the in vitro scratch assay. This study concluded that the SA-CS-TTO microsphere could be an antibacterial and antioxidant wound dressing.