Synthesis of acyl thiourea derivatives of chitosan and their antimicrobial activities in vitro

Exploring the latest trends in chemistry, structure, coordination, and diverse applications of 1-acyl-3-substituted thioureas: a comprehensive review

Acyl thioureas represent a privileged moiety with vast potential applicability across diverse fields, making them the subject of extensive research efforts. The inherent flexibility of thiourea facilitates the synthesis of a wide range of core structures with diverse functionalities and properties. The distinctive presence of hard and soft donor sites renders acyl thioureas inclined to act as versatile ligands, thereby engendering a diverse array of metal complexes incorporating acyl thiourea as a pivotal ligand. Extensive investigations into the synthesized acyl thioureas and their derivatives have culminated in the elucidation of their substantial potential across a spectrum of applications, spanning biological activities, materials chemistry, catalysis, and beyond. This literature review represents a continuation of our ongoing endeavor to compile comprehensive data on research endeavors concerning acyl thioureas over the past two years.

Design, Synthesis and Biological Activities of (Thio)Urea Benzothiazole Derivatives

(Thio)ureas ((T)Us) and benzothiazoles (BTs) each have demonstrated to have a great variety of biological activities. When these groups come together, the 2-(thio)ureabenzothizoles [(T)UBTs] are formed, improving the physicochemical as well as the biological properties, making these compounds very interesting in medicinal chemistry. Frentizole, bentaluron and methabenzthiazuron are examples of UBTs used for treatment of rheumatoid arthritis and as wood preservatives and herbicides in winter corn crops, respectively. With this antecedent, we recently reported a bibliographic review about the synthesis of this class of compounds, from the reaction of substituted 2-aminobenzothiazoles (ABTs) with iso(thio)cyanates, (thio)phosgenes, (thio)carbamoyl chlorides, 1,1'-(thio)carbonyldiimidazoles, and carbon disulfide. Herein, we prepared a bibliographic review about those features of design, chemical synthesis, and biological activities relating to (T)UBTs as potential therapeutic agents. This review is about synthetic methodologies generated from 1968 to the present day, highlighting the focus to transform (T)UBTs to compounds containing a range substituents, as illustrated with 37 schemes and 11 figures and concluded with 148 references. In this topic, the scientists dedicated to medicinal chemistry and pharmaceutical industry will find useful information for the design and synthesis of this interesting group of compounds with the aim of repurposing these compounds.

Anticandidal action of polyurethane foam: a new modifier with functionalized isothiouronium group

A novel sorbent of isothiouronium polyurethane foam, PUF-SC(NH2)2, was synthesized from low-cost raw materials (a commercial polyurethane foam). The prepared PUF-SC(NH2)2 was characterized with different tools, the infrared spectra and Boehm test demonstrated the presence of several active groups in the material matrices of PUF-SC(NH2)2. The diffraction analysis and images of the scanning electron microscope showed that the surface structure was amorphous, and Cu(II) salt crystals were embedded on its surface. The polyurethane foam, as a modifier, was applied to enhance antimicrobial activity, and its anticandidal action was studied against Candida albicans ATCC 10,231. Agar well-diffusion test showed a significantly biocidal action of PUF-SC(NH2)2. The anticandidal action was dependent on PUF-SC(NH2)2 dose, while the microbial inhibition increased with increases in PUF-SC(NH2)2 dose and the microbial growth stopped at 26 μg/mL. The PUF-SC(NH2)2-treated yeast was studied by transmission electron microscope (TEM). TEM micrographs showed severe morphological changes in the yeast cells including the disruption of the cell membrane structure and the appearance of large vacuoles as well as separation between cell membranes and cell walls. The results indicated that this green synergy of PUF-SC(NH2)2 may have a promising potential in antifungal therapy as an effective biomaterial and other biomedical applications.

Graphical Abstract

Synthesis and Biological Importance of 2-(thio)ureabenzothiazoles

The (thio)urea and benzothiazole (BT) derivatives have been shown to have a broad spectrum of biological activities. These groups, when bonded, result in the 2-(thio)ureabenzothizoles (TBT and UBT), which could favor the physicochemical and biological properties. UBTs and TBTs are compounds of great importance in medicinal chemistry. For instance, Frentizole is a UBT derivative used for the treatment of rheumatoid arthritis and systemic lupus erythematosus. The UBTs Bentaluron and Bethabenthiazuron are commercial fungicides used as wood preservatives and herbicides in winter corn crops. On these bases, we prepared this bibliography review, which covers chemical aspects of UBTs and TBTs as potential therapeutic agents as well as their studies on the mechanisms of a variety of pharmacological activities. This work covers synthetic methodologies from 1935 to nowadays, highlighting the most recent approaches to afford UBTs and TBTs with a variety of substituents as illustrated in 42 schemes and 13 figures and concluded with 187 references. In addition, this interesting review is designed on chemical reactions of 2-aminobenzothiazoles (2ABTs) with (thio)phosgenes, iso(thio)cyanates, 1,1′-(thio)carbonyldiimidazoles [(T)CDI]s, (thio)carbamoyl chlorides, and carbon disulfide. This topic will provide information of utility for medicinal chemists dedicated to the design and synthesis of this class of compounds to be tested with respect to their biological activities and be proposed as new pharmacophores.

Synthesis, characterization, and biological activities of new conjugates of Guanosine grafted on polyvinyl alcohol, carbohydrate chitosan, and cellulose

Guanosine (GU) is a purine nucleoside that has different biological applications. This study aimed to synthesize, characterize, and enhance the biological activities of GU through its covalently grafting on polyvinyl alcohol (PVA), chitosan (CS), and cellulose (CL). In this regard, the conjugation was constructed by different linkers such as chloroacetyl chloride, 2-bromopropionyl bromide, and epichlorohydrin (EPCH). The resulted novel conjugates were characterized by FT-IR, 1H-NMR, GPC, and TGA techniques. FT-IR spectra revealed the main characteristic groups, O–H, N–H, C=O and C=N of GU moieties. Furthermore, 1H-NMR spectra showed the aromatic C–H, O–H, and N–H protons of the grafted GU moieties. Two decomposition stages of grated polymers with high thermal stability are illustrated by TGA. GU showed no antifungal activity against Aspergillus fumigatus and Candida albicans. However, its conjugates: P-1A, P-1B, P-2A, P-2B, P-3A, and P-3B displayed significant antifungal effect with inhibitory zones in the range 8–11 mm. As compared to GU group, most of GU-polymer conjugates showed significant in vivo antitumor activity against EAC-bearing mice via the reduction in total tumor volume. In summary, these conjugates are biologically active macromolecules and may act as candidate carrier systems for other applications such as drug delivery.

Adsorption for rhodamine b dye and biological activity of nano-porous chitosan from shrimp shells

The present work aims to evaluate the removal capacity of Rhodamine B dye (RhB) using nano-porous chitosan (NC) from shrimp shells. NC was characterized by XRD, SEM-EDS, N2 porosimetry, zeta potential (ZP), FTIR, DLS, and zero charge point (pHZCP). Compound central rotational design (CCRD) was used to determine the ideal condition and antimicrobial activity was evaluated against different strains. NC showed characteristic of semi-crystalline material with negative charge surface (around - 21.13 mV), and SBET = 1.12 m2 g-1, Vp = 0.0064 cm3 g-1, Dp = 32.09 nm and pHZCP ≈ 7.98. Kinetic adsorption showed the pseudo first-order model had the best fit, with adsorption capacity (q1) between 3.78 and 64.43 mg g-1 and pseudo first-order kinetic constant (k1) between 0.066 and 0.052 min-1. Sips model best described the equilibrium data, with a maximum adsorption capacity of 505.131 mg g-1. Antimicrobial activity was observed at 0.25 mg mL-1 for different strains. Therefore, NC has potential application in the removal of the dye, combining sustainable development associated with nanotechnology.

Structure and surface analyses of a newly synthesized acyl thiourea derivative along with its in silico and in vitro investigations for RNR, DNA binding, urease inhibition and radical scavenging activities

N-((4-Acetylphenyl)carbamothioyl)-2,4-dichlorobenzamide (4) was synthesized by the treatment of 2,4-dichlorobenzoyl chloride with potassium thiocyanate in a 1 : 1 molar ratio in dry acetone to afford the 2,4-dichlorobenzoyl isothiocyanate in situ which on reaction with acetyl aniline furnished (4) in good yield and high purity. The compound was confirmed by FTIR, ¹H-NMR, and ¹³C-NMR and single crystal X-ray diffraction studies. The planar rings were situated at a dihedral angle of 33.32(6)°. The molecules, forming S(6) ring motifs with the intramolecular N–H⋯O hydrogen bonds, were linked through intermolecular C–H⋯O and N–H⋯S hydrogen bonds, enclosing R₂²(8) ring motifs, into infinite double chains along [101]. C–H⋯π and π⋯π interactions with an inter-centroid distance of 3.694 (1) Å helped to consolidate a three-dimensional architecture. Hirshfeld surface (HS) analysis further indicated that the most important contributions for the crystal packing were from H⋯C/C⋯H (20.9%), H⋯H (20.5%), H⋯Cl/Cl⋯H (19.4%), H⋯O/O⋯H (13.8%) and H⋯S/S⋯H (8.9%) interactions. Thus C–H⋯π (ring), π⋯π, van der Waals interactions and hydrogen bonding played the major roles in the crystal packing. The electronic structure and computed DFT (density functional theory) parameters identified the reactivity profile of compound (4). In silico binding of (4) with RNA indicated the formation of a stable protein–ligand complex via hydrogen bonding, while DNA docking studies inferred (4) as a potent groove binder. The experimentally observed hypochromic change (57.2%) in the UV-visible spectrum of (4) in the presence of varying DNA concentrations together with the evaluated binding parameters (K_b; 7.9 × 10⁴ M⁻¹, ΔG; −28.42 kJ mol⁻¹) indicated spontaneous interaction of (4) with DNA via groove binding and hence supported the findings obtained through docking analysis. This compound also showed excellent urease inhibition activity in both in silico and vitro studies with an IC₅₀ value of 0.0389 ± 0.0017 μM. However, the radical scavenging efficiency of (4) was found to be modest in comparison to vitamin C.

A new acyl thiourea derivative was explored for its binding interaction with RNR and DNA and for excellent urease inhibition activity.

Aspirin effect on bone remodeling and skeletal regeneration: Review article

Bone tissues are one of the most complex tissues in the body that regenerate and repair themselves spontaneously under the right physiological conditions. Within the limitations of treating bone defects, mimicking tissue engineering through the recruitment of scaffolds, cell sources and growth factors, is strongly recommended. Aspirin is one of the non-steroidal anti-inflammatory drugs (NSAIDs) and has been used in clinical studies for many years due to its anti-coagulant effect. On the other hand, aspirin and other NSAIDs activate cytokines and some mediators in osteoclasts, osteoblasts and their progenitor cells in a defect area, thereby promoting bone regeneration. It also stimulates angiogenesis by increasing migration of endothelial cells and the newly developed vessels are of emergency in bone fracture repair. This review covers the role of aspirin in bone tissue engineering and also, highlights its chemical reactions, mechanisms, dosages, anti-microbial and angiogenesis activities.

Co-crystals synthesis of 2- and 4-mercaptopyridine with thiourea and its analogue, trithiocyanuric acid

This article describes the synthesis of four new co-crystals obtained via cross-crystallisation of 2- and 4-mercaptopyridine with thiourea and trithiocyanuric acid, and examines their crystal structures. The resulting structures are...

Single-Crystal Investigation, Hirshfeld Surface Analysis, and DFT Study of Third-Order NLO Properties of Unsymmetrical Acyl Thiourea Derivatives

In the current research work, unsymmetrical acyl thiourea derivatives, 4-((3-benzoylthioureido)methyl)cyclohexane-1-carboxylic acid (BTCC) and methyl 2-(3-benzoylthioureido)benzoate (MBTB), have been synthesized efficiently. The structures of these crystalline thioureas were unambiguously confirmed by single-crystal diffractional analysis. The crystallographic investigation showed that the molecular configuration of both compounds is stabilized by intramolecular N-H···O bonding. The crystal packing of BTCC is stabilized by strong N-H···O bonding and comparatively weak O-H···S, C-H···O, C-H···π, and C-O···π interactions, whereas strong N-H···O bonding and comparatively weak C-H···O, C-H···S, and C-H···π interactions are responsible for the crystal packing of MBTB. The noncovalent interactions that are responsible for the crystal packing are explored by the Hirshfeld surface analysis for both compounds. The void analysis is performed to find the quantitative strength of crystal packing in both compounds. Additionally, state-of-the-art applied quantum chemical techniques are used to further explore the structure-property relationship in the above-entitled molecules. The optimization of molecular geometries showed a reasonably good correlation with their respective experimental structures. Third-order nonlinear optical (NLO) polarizability calculations were performed to see the advanced functional application of entitled compounds as efficient NLO materials. The average static γ amplitudes are found to be 27.30 × 10^-36 and 102.91 × 10^-36 esu for the compounds BTCC and MBTB, respectively. The γ amplitude of MBTB is calculated to be 3.77 times larger, which is probably due to better charge-transfer characteristics in MBTB. The quantum chemical analysis in the form of 3-D plots was also performed for their frontier molecular orbitals and molecular electrostatic potentials for understanding charge-transfer characteristics. We believe that the current investigation will not only report the new BTCC and MBTB compounds but also evoke the interest of the materials science community in their potential use in NLO applications.

Design of Chitosan Sterilization Agents by a Structure Combination Strategy and Their Potential Application in Crop Protection

Chitosan is the only cationic polysaccharide in nature. It is a type of renewable resource and is abundant. It has good biocompatibility, biodegradability and biological activity. The amino and hydroxyl groups in its molecules can be modified, which enables chitosan to contain a variety of functional groups, giving it a variety of properties. In recent years, researchers have used different strategies to synthesize a variety of chitosan derivatives with novel structure and unique activity. Structure combination is one of the main strategies. Therefore, we will evaluate the synthesis and agricultural antimicrobial applications of the active chitosan derivatives structure combinations, which have not been well-summarized. In addition, the advantages, challenges and developmental prospects of agricultural antimicrobial chitosan derivatives will be discussed.

Efficacy of chitosan-based chewing gum on reducing salivary S. mutans counts and salivary pH: a randomised clinical trial

OBJECTIVE

To determine chitosan-based chewing gum role on reducing salivary S. mutans counts and salivary pH.

MATERIALS AND METHODS

The present double-blind randomised clinical trial with the trial registration number of IRCT20190724044319N1 was conducted on 36 dental students. The volunteers were, randomly, divided into two groups (n = 18) including: G1: intervention group (chitosan chewing gum) and G2: control group (placebo chewing gum). Each participant was given eight pieces of the chewing gum, and was asked to chew each gum piece for 5 min and this was repeated for eight times. Their Saliva was collected before and after chewing gums and the number of S. mutans colonies and salivary pH were determined. Data were analysed using SPSS (ver.21) and independent student t test. p Value less than .05 was set as significant.

RESULTS

There was significant difference between two groups for the number of salivary S. mutans colonies (3.31*105  in the intervention group compared to 13.94*105 in the Control group) (p < .001). The salivary pH evaluation showed that salivary pH mean value in intervention group was not significant in compared with control group (p = .17). However, the chitosan chewing gum led to an increase in salivary pH by 0.17, which was statistically significant (p = .01).

CONCLUSION

Results of this study showed that chitosan chewing gum has a positive effect on the reduction of numbers of salivary S. mutans colonies but had no considerable effect on the increase of salivary pH.

Design, synthesis, characterization, and biological evaluation of nicotinoyl thioureas as antimicrobial and antioxidant agents

Addressed herein a series of thioureas starting from various amines and nicotinic acid have been synthesized. Notably, thiourea based scaffolds are increasingly employed in medicinal chemistry owing to their tunable physicochemical and structural properties. As well-known from the literature, the pyridine ring contains various biological properties, especially antimicrobial activity. Therefore, we performed the synthesis of biologically important thiourea derivatives containing pyridine ring. The structures of the synthesized compounds were characterized by ¹H NMR, ¹³C NMR and FT-IR. In the second part of the study, newly synthesized compounds were also tested in order to demonstrate their antimicrobial and antioxidant properties. All compounds exhibited moderate activity against all tested bacteria known to cause nosocomial infections, which have acquired resistance to many antibiotics, as compared to the standard antibiotics and also strong antioxidant properties. Therefore, they can be evaluated as possible seeds of agents in the treatment of bacterial infections and many health problems related to aging such as cancer, and neurodegenerative diseases.

Investigation of applying chitosan coating on antibacterial and biocompatibility properties of bredigite/titanium dioxide composite scaffolds

In this study by considering the advantages of bredigite (Br) and titanium dioxide (TiO2) bioceramics, composite scaffolds of bredigite/titanium dioxide were prepared by the gelcasting method, then, to improve the mechanical, biological and antibacterial properties, scaffolds were coated with chitosan (Ch) polymer phase. The phase structure, fundamental groups, chemical composition, and elemental distribution analysis, morphology and the form of porosity were respectively characterized by XRD, FTIR, EDS, and SEM. Mechanical properties and porosity percentage of scaffolds were also measured by the compressive strength test and Archimedean method, respectively. In order to verify the cell compatibility, MG63 bone marrow cells were cultured on the surface of the specimens. The results showed that the addition of titanium dioxide to the scaffold of bredigite resulted in decrease of porosity and increase of compressive strength of scaffolds from 0.299 to 0.687 MPa. Furthermore, the coated scaffold with chitosan polymer reduced porosity from 83 to 63 percent and a remarkable improvement in compressive strength from 0.585 to 2.339 MPa. The results of the antibacterial test showed that in composite scaffolds, The diameter of the inhibition zone is 22 and 29 mm, in the culture media of Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive), respectively. On the other hand, the results of cell compatibility and cell adhesion tests showed that the scaffolds had no toxicity and the growth, proliferation, and adhesion of MG63 bone cells adjacent to the scaffolds was desirable. Therefore, the scaffold in this study can be used as an ideal scaffold for use in bone tissue engineering.

Antimicrobial Effect of a Novel Chitosan Derivative and Its Synergistic Effect with Antibiotics

Cationic polymers are promising antibacterial agents because bacteria have a low propensity to develop resistance against them, but they usually have low biocompatibility because of their hydrophobic moieties. Herein, we report a new biodegradable and biocompatible chitosan-derived cationic antibacterial polymer, 2,6-diamino chitosan (2,6-DAC). 2,6-DAC shows excellent broad-spectrum antimicrobial activity with minimum inhibitory concentrations (MICs) of 8-32 μg/mL against clinically relevant and multidrug-resistant (MDR) bacteria including Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. Furthermore, 2,6-DAC shows an excellent synergistic effect with various clinically relevant antibiotics proved by decreasing the MICs of the antibiotics against MDR A. baumannii and methicillin-resistant Staphylococcus aureus to <1 μg/mL. In vivo biocompatibility of 2,6-DAC is proved by a dosage of 100 mg/kg compound via oral administration and 25 mg/kg compound via intraperitoneal injection to mice; 2,6-DAC does not cause any weight loss and any significant change in liver and kidney biomarkers or the important blood electrolytes. The combinations of 2,6-DAC together with novobiocin and rifampicin show >2.4 log10 reduction of A. baumannii in murine intraperitoneal and lung infection models. The novel chitosan derivative, 2,6-DAC, can be utilized as a biocompatible broad-spectrum cationic antimicrobial agent alone or in synergistic combination with various antibiotics.

Antibacterial Activity of Chitosan Nanoparticles: A Review

In recent years, nanotechnology has attracted attention in many fields because it has several up-and-coming novel uses. Many researchers have suggested that chitosan nanoparticles (CS-NPs) and their derivatives are one of the best nanomaterials for delivering antibacterial activity. CS-NPs have a broad spectrum of antibacterial activity, but they manifest different inhibitory efficacy against gram-negative (G−) and gram-positive (G+) bacterial species. The mechanism of antibacterial action is an intricate process that varies between G− and G+ bacteria as a result of the differences in cell wall and cell membrane chemistry. In previous studies, greater antibacterial activity was more evident against G− bacteria than G+ bacteria, whereas in some studies G+ bacteria were more sensitive. Researchers predicted that the varied responses of bacteria are caused by the mixed hydrophilicity and negative charge distribution on the bacterial surface. Moreover, its activity depends on a number of variables including bacterial target (i.e., G− or G+ bacteria) and bacterial growth, as well as its concentration, pH, zeta-potential, molecular weight, and degree of acetylation. Therefore, this review examines current research on the mechanisms and factors affecting antibacterial activity, and application of CS-NPs specifically against animal and plant pathogenic bacteria.

Effect of chitosan-essential oil, a surface mold inhibitor, on microbiological and physicochemical characteristics of semidried fermented sausages

Mold growth on sausage casing during processing is an important problem in fermented sausages. In this work, sausages were dipped into 1% chitosan (C), 1% thyme essential oil in 1% chitosan (CT), 1% rosemary essential oil in 1% chitosan (CR), 20% potassium sorbate (PS) as chemical antifungal, and 1% acetic acid solution (AA) as chitosan solver, or distilled water (DW) as control after fermentation (at day 4). The changes in microbiological (total viable count, lactic acid bacteria [LAB], Micrococcaceae, Enterobacteriaceae, and mold and yeast counts) and physicochemical attributes of the sausages during 12 days of processing were monitored. As expected, LAB were the most dominant microbiota in fermented sausages and the dipping process did not have any negative effect. Additionally, the treatment with C, CT, and CR suppressed the growth of spoilage microorganisms, which resulted in a significant reduction (P < 0.01) of about 1.4 to 1.6 log CFU/g in Enterobacteriaceae counts at day 12. The C, CT, and CR similarly suppressed the growth of fungi in the interior of the sausages, and the antifungal treatment significantly reduced (P < 0.01) the load of fungi on the casing. Throughout the study, approximately log counts of 3 and 4 in lower molds and yeasts in the casings treated with PS and CR were found, respectively, as compared to DW. Finally, the microbial quality of the end product was notably improved. PRACTICAL APPLICATION: Processing conditions such as high humidity and O₂ in the ripening chamber result in undesirable fungal growth on the casings of the sausages. Fermented sausages are usually treated with weak acids such as sorbic or benzoic acids or their salts to inhibit mold growth during the drying process. However, increasing consumer demand to reduce the use of chemicals encourages the applications of natural antifungals.

Fully bio-based coating from chitosan and phytate for fire-safety and antibacterial cotton fabrics

In this study, a fully bio-based coating was constructed by layer-by-layer deposition of chitosan (CS) and ammonium phytate (AP), to obtain fire-safety and antibacterial cotton fabrics. With about 8% weight gains of CS/AP coatings, the treated cotton fabrics self-extinguished in the vertical burning test. The data obtained from cone calorimetry showed CS/AP/cotton had much lower smoke and heat production, which indicated the fire safety of the fabrics was significantly improved for the presence of CS/AP coatings. The flame-retardant mechanism of this system was finally proposed according to the analysis of gaseous products and char residues. What is more, CS/AP coatings had higher antibacterial activity in Gram-negative bacteria and did improve the tensile strength of cotton fabrics compared with AP coating. With its ease of operation and use of non-toxic chemicals, this fully bio-based coating can further offer a feasible flame-retardant and antibacterial solution of the inflammable natural fabrics.

Synthesis, characterization, antimicrobial, antioxidant and computational evaluation of N-acyl-morpholine-4-carbothioamides

The present research paper reports the convenient synthesis, successful characterization, in vitro antibacterial, antifungal, antioxidant potency and biocompatibility of N-acyl-morpholine-4-carbothioamides (5a-5j). The biocompatible derivatives were found to be highly active against the tested bacterial and fungal strains. Moreover, some of the screened N-acyl-morpholine-4-carbothioamides exhibited excellent antioxidant potential. Docking simulation provided additional information about possibilities of their inhibitory potential against RNA. It has been predicted by in silico investigation of the binding pattern that compounds 5a and 5j can serve as the potential surrogate for design of novel and potent antibacterial agents. The results for the in vitro bioassays were promising with the identification of compounds 5a and 5j as the lead and selective candidate for RNA inhibition. Results of the docking computations further ascertained the inhibitory potential of compound 5a. Based on the in silico studies, it can be suggested that compounds 5a and 5j can serve as a structural model for the design of antibacterial agents with better inhibitory potential. Binding mode of compound 5j inside the active site of RNA in 3D space. 5j displayed highest antibacterial potential than the reference drug ampicillin with ZOI 10.50 mm against Staphylococcus aureus. 5j also displayed highest antifungal potential than the reference drug amphotericin B with ZOI 18.20 mm against Fusarium solani.

C—Br...S halogen bonds in novel thioureaN-oxide cocrystals: analysis of energetic and QTAIM parameters

Cocrystals of thiourea with 4-nitropyridineN-oxide, C5H4N2O3·2CH4N2S, (I), and 3-bromopyridineN-oxide, C5H4BrNO·CH4N2S, (II), crystallize in the monoclinic space groupP21/c. In the crystals, molecules of both components are linked by N—H...O hydrogen bonds, creatingR21(6) synthons. The bromine substituent of theN-oxide component in (II) is a centre for C—Br...S halogen bonding to the thiourea molecule. Computations based on quantum chemistry methods (quantum theory of atoms in molecules, QTAIM) and atoms in molecules (AIM) theory were performed for a more detailed description of the observed type of halogen-bonding interaction.

Wound healing and antimicrobial effect of active secondary metabolites in chitosan-based wound dressings: A review

Wound healing can lead to complex clinical problems, hence finding an efficient approach to enhance the healing process is necessary. An ideal wound dressing should treat wounds at reasonable costs, with minimal inconveniences for the patient. Chitosan is one of the most investigated biopolymers for wound healing applications due to its biocompatibility, biodegradability, non-toxicity, and antimicrobial activity. Moreover, chitosan and its derivative have attracted numerous attentions because of the accelerating wound healing, and easy processability into different forms (gels, foams, membranes, and beads). All these properties make chitosan-based materials particularly versatile and promising for wound dressings. Besides, secondary natural metabolites could potentially act like the antimicrobial and anti-inflammatory agents and accelerate the healing process. This review collected almost all studies regarding natural compounds applications in wound healing by focusing on the chitosan-based bioactive wound dressing systems. An accurate analysis of different chitosan formulations and the influence of bioactive compounds on their wound healing properties are reported.

Design, Synthesis, and Docking Study of Acyl Thiourea Derivatives as Possible Histone Deacetylase Inhibitors with a Novel Zinc Binding Group

Histone deacetylase inhibitors with zinc binding groups often exhibit drawbacks like non-selectivity or toxic effects. Thus, there are continuous efforts to modify the currently available inhibitors or to discover new derivatives to overcome these problems. One approach is to synthesize new compounds with novel zinc binding groups. The present study describes the utilization of acyl thiourea functionality, known to possess the ability to complex with metals, to be a novel zinc binding group incorporated into the designed histone deacetylase inhibitors. N-adipoyl monoanilide thiourea (4) and N-pimeloyl monoanilide thiourea (5) have been synthesized and characterized successfully. They showed inhibition of growth of human colon adenocarcinoma and mouse hepatoblastoma cells with low cytotoxic effect against normal human breast cells. Their binding mode to the active site of several histone deacetylases has been studied by docking and the results gave a preliminary indication that they could be successful histone deacetylase inhibitors.

Basic study for acyl chitosan isothiocyanates synthesis by model experiments using glucosamine derivatives

Affecting factors to the acyl chitosan isothiocyanate synthesis by N-phenylthiocarbamoylation and the following acylation was investigated using octyl 2-amino-2-deoxy-β-D-glucopyranoside as a model compound. It was found from the acetylation of N-phenylthiocarbamoyl glucosamine derivative with acetic anhydride/pyridine that the glucosamine isothiocyanate was formed via N,N-(acetyl)phenylthiocarbamoyl glucosamine derivative and the conversion of N,N-(acetyl)phenylthiocarbamoyl glucosamine derivative to the glucosamine isothiocyanate proceeded mainly by thermal degradation of N,N-(acetyl)phenylthiocarbamoyl groups. The reaction temperature was an important factor to the isothiocyanate synthesis. On the other hand, it was found from the acetylation of N-ethylthiocarbamoyl derivative (or N-allylthiocarbamoyl derivative) with acetic anhydride/pyridine that the glucosamine isothiocyanate was also prepared from N-ethylthiocarbamoyl glucoamine derivative (or N-allylthiocarbamoyl glucosamine derivative), but that N-phenylthiocarbamoylation was more preferable to the isothiocyanate synthesis than N-ethylthiocarbamoylation and N-allylthiocarbamoylation. Then, acylation products of N-phenylthiocarbamoyl chitosan (N,N-(hexanoyl)phenylthiocarbamoyl chitosan hexanoate or hexanoyl chitosan isothiocynate) could be controlled by the reaction temperature and reaction system.

Design, Synthesis, Antimicrobial, and Anticancer Activities of Acridine Thiosemicarbazides Derivatives

Background: Acridine and thiourea derivatives are important compounds in medicinal chemistry due to their diverse biological properties including anticancer and antimicrobial effects. However, literature reveals some side effects associated with use of acridines. It is suggested that hybrid molecules may reduce the side effects and enhance the beneficial properties due to synergistic activity. The objectives of the present study are to synthesize and evaluate the anticancer and antimicrobial properties of new hybrids of acridine thiosemicarbazides derivatives. Results: The structures of the synthesized compounds 4a-4e were elucidated by MS and NMR spectra. In antimicrobial assay, Compound 4c exhibited potent antimicrobial activity compared to the other four compounds. In anticancer studies, we observed that compounds 4a, 4b, 4d and 4e exhibited high cytotoxicity against the MT-4 cell line, with IC50 values of 18.42 ± 1.18, 15.73 ± 0.90, 10.96 ± 0.62 and 11.63 ± 0.11 μM, respectively. The evaluation of anticancer effects, and the associated mechanism reveals that, the anticancer activities may be related to Topo I inhibitory activity, apoptosis and cell-cycle. Molecular docking studies revealed that the presence of planar naphtho-fused rings and a flexible thiourea group together, could improve DNA-intercalation and inhibition of DNA-Topo I activity. Conclusions: The results of this study demonstrate that the rational design of target derivatives as novel antimicrobial or antitumor leads is feasible.

Synthesis and Anticancer Activity of [RuCl2(η6-arene)(aroylthiourea)] Complexes-High Activity against the Human Neuroblastoma (IMR-32) Cancer Cell Line

Eight new organometallic Ru(II)-arene complexes of the type [RuCl₂(η⁶-arene)(η¹-S-aroylthiourea)] (arene = p-cymene or benzene) were synthesized in order to evaluate the effect of the arene moiety and the substituent of the aroylthiourea ligand on the cytotoxicity of the complexes. The ligands (L1 and L2) and complexes (1-8) were characterized using analytical and spectroscopic (UV-visible, infrared, ¹H NMR, ¹³C NMR, and mass) methods. The structure of the ligands (L1 and L2) and complexes (1 and 3-6) was obtained from single-crystal X-ray diffraction studies. The cytotoxicity of the complexes was evaluated against four different cancer cell lines: MCF-7 (breast), COLO 205 (colon), A549 (lung), and IMR-32 (neuroblastoma). All the complexes showed good cytotoxicity and the highest was in the IMR-32 cell line, which articulates the specificity of these complexes toward the IMR-32 cancer cell line. The complexes 5, 7, and 8 exhibited remarkable cytotoxicity in the entire cancer cell lines tested, which was comparable with the standard drug, cisplatin. The anticancer mechanism of the complexes 3 and 7 in IMR-32 cells was evaluated by bright-field microscopy, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), DNA damage, and caspase-3 analyses. The cells treated with the complexes showed upregulated caspase-3 compared to the control, and it was found that ROS and MMP were dose-dependent on analysis. Also, bright-field microscopy and 4',6-diamidino-2-phenylindole (DAPI) staining have correspondingly shown cellular membrane blebbing and DNA damage, which were morphological hallmarks of apoptosis. The study concluded that the complexes promoted the oxidative stress-mediated apoptotic death of the cancer cells through the generation of intracellular ROS, depletion of MMP, and damage of the nuclear material.

Enzymatic Depolimerization of Chitosan for the Preparation of Functional Membranes

This work reports the study of chitosan depolymerization through the synergy of the Celuzyme® XB enzyme complex; it is composed of cellulase, xylanase, andβ-glucanase. The optimal conditions of temperature, pH, and concentration were determined to verify the depolymerization reaction. The specificity of the enzymes at theβ(1-4) glycosidic link site was checked. Low molecular weight chitosan (64 × 103 g·mol−1) with degree of acetylation 15% was obtained. The depolymerized chitosan products were characterized by infrared spectroscopy, the degree of acetylation was obtained by UV-Vis spectroscopy, and the determination of the molecular weight was obtained by capillary viscosimetry. With the depolymerized chitosan, membranes were formed and their antioxidant and antimicrobial functionality was determined; results show that these properties are dependent on the molecular weight and on the acetylation degree of chitosan.

Evaluation of electrospun poly (vinyl alcohol)-based nanofiber mats incorporated with Zataria multiflora essential oil as potential wound dressing

Infections, especially those caused by multi-drug resistant pathogens, result in serious problems in wound healing process. In this study, Zataria multiflora (ZM) essential oil, as a strong natural antimicrobial agent, is incorporated into poly (vinyl alcohol)-based nanofiber mats to fabricate a novel wound dressing. Different amounts of ZM essential oil (0, 2, 5 and 10% (v/v)) were incorporated into chitosan/poly(vinyl alcohol)/gelatin (CS/PVA/Gel) solutions and then were successfully electrospun into beadless and uniform fibers with 95 ± 14, 154 ± 27, 187 ± 40 and 218 ± 58 nm in diameters, respectively. The produced nanofiber mats (CS/PVA/Gel/ZM) were chemically crosslinked by glutaraldehyde vapor. The chemical compositions of ZM essential oil and nanofiber mats were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS) and Fourier Transform Infrared Spectroscopy (FTIR), respectively. The antimicrobial activity of the CS/PVA/Gel/ZM nanofiber mats was determined by the AATCC100 method. The nanofiber mat loaded with 10% of ZM essential oil completely inhibited the growth of Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans after 24 h of incubation. Swelling investigations showed that the produced nanofibers have a substantial ability to take up water, in the range of 400-900%. Mechanical properties of the nanofiber mats were studied by tensile testing. Furthermore, they were found to be non-toxic by biocompatibility assays on mouse fibroblast (L929) cells. The obtained results have demonstrated that CS/PVA/Gel nanofiber mats, loaded with ZM essential oil, are promising alternatives to conventional wound dressings.

Competitive Biological Activities of Chitosan and Its Derivatives: Antimicrobial, Antioxidant, Anticancer, and Anti-Inflammatory Activities

Chitosan is obtained from alkaline deacetylation of chitin, and acetamide groups are transformed into primary amino groups during the deacetylation. The diverse biological activities of chitosan and its derivatives are extensively studied that allows to widening the application fields in various sectors especially in biomedical science. The biological properties of chitosan are strongly depending on the solubility in water and other solvents. Deacetylation degree (DDA) and molecular weight (MW) are the most decisive parameters on the bioactivities since the primary amino groups are the key functional groups of chitosan where permits to interact with other molecules. Higher DDA and lower MW of chitosan and chitosan derivatives demonstrated higher antimicrobial, antioxidant, and anticancer capacities. Therefore, the chitosan oligosaccharides (COS) with a low polymerization degree are receiving a great attention in medical and pharmaceutical applications as they have higher water solubility and lower viscosity than chitosan. In this review articles, the antimicrobial, antioxidant, anticancer, anti-inflammatory activities of chitosan and its derivatives are highlighted. The influences of physicochemical parameters of chitosan like DDA and MW on bioactivities are also described.