Thiazoles: having diverse biological activities

Single Continuous Near-Infrared Laser-Triggered Photodynamic and Photothermal Ablation of Antibiotic-Resistant Bacteria Using Effective Targeted Copper Sulfide Nanoclusters

The emergence of antibiotic-resistant bacterial strains has made conventional antibiotic therapies less efficient. The development of a novel nanoantibiotic approach for efficiently ablating such bacterial infections is becoming crucial. Herein, a collection of poly(5-(2-ethyl acrylate)-4-methylthiazole-g-butyl)/copper sulfide nanoclusters (PATA-C4@CuS) was synthesized for efficient capture and effective ablation of levofloxacin-resistant Gram-negative and Gram-positive bacteria upon tissue-penetrable near-infrared (NIR) laser irradiation. In this work, we took advantage of the excellent photothermal and photodynamic properties of copper sulfide nanoparticles (CuSNPs) upon NIR laser irradiation and thiazole derivative as a membrane-targeting cationic ligand toward bacteria. The conjugated nanoclusters could anchor the bacteria to trigger the bacterial aggregation quickly and efficiently kill them. These conjugated nanoclusters could significantly inhibit levofloxacin-resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Bacillus amyloliquefaciens at 5.5 μg/mL under NIR laser irradiation (980 nm, 1.5 W cm^-2, 5 min), which suggested that the heat and reactive oxygen species (ROS) generated from the irradiated CuSNPs attached to bacteria were effective in eliminating and preventing the regrowth of the bacteria. Importantly, the conjugated nanoclusters could promote healing in bacteria-infected rat wounds without nonspecific damage to normal tissue. These findings highlight the promise of the highly versatile multifunctional nanoantibiotics in bacterial infection.

Efficient construction of C–N and C–S bonds in 2-iminothiazoles via cascade reaction of enaminones with potassium thiocyanate

Regioselective cascade reactions have been developed by using enaminones and potassium thiocyanate, offering a novel protocol for the synthesis of thiazoles from enaminones.

Structural features of the carbon-sulfur chemical bond: a semi-experimental perspective

In this work semi-experimental and theoretical equilibrium geometries of 10 sulfur-containing organic molecules, as well as 4 oxygenated ones, are determined by means of a computational protocol based on density functional theory. The results collected in the present paper further enhance our online database of accurate semi-experimental equilibrium molecular geometries, adding 13 new molecules containing up to 8 atoms, for 12 of which the first semi-experimental equilibrium structure is reported, to the best of our knowledge. We focus in particular on sulfur-containing compounds, aiming both to provide new accurate data on some rather important chemical moieties, only marginally represented in the literature of the field, and to examine the structural features of carbon-sulfur bonds in the light of the previously presented linear regression approach. The structural changes issuing from substitution of oxygen by sulfur are discussed to get deeper insights on how modifications in electronic structure and nuclear potential can affect equilibrium geometries. With respect to our previous works, we perform non-linear constrained optimizations of equilibrium SE structures with a new general and user-friendly software under development in our group with updated definition of useful statistical indicators.

Crystal structure of 4-(benzofuran-2-yl)-2-(3-(4-fluorophenyl)-3,3a,4,5-tetrahydro-2H-benzo[g]indazol-2-yl)thiazole, C28H20FN3OS

C28H20FN3OS, triclinic, P1̅ (no. 2), a = 9.5719(5) Å, b = 10.7499(6) Å, c = 10.9238(5) Å, α = 95.470(4)°, β = 102.133(4)°, γ = 97.962(4)°, V = 1079.30(10) Å3, Rgt(F) = 0.0482, wRref(F2) = 0.1143, T = 150(2) K.

Synthesis and study on the binding of thiazol-2(3H)-ylidine derivative with human serum albumin using spectroscopic and molecular docking methods

In this article, a facile and convenient synthesis of thiazol-2(3H)-ylidine derivatives of fatty acid (3a-c) is described. The binding of N'-(4,5-dimethyl-3-penylthiazol-2(3H)-ylidine)octadec-9-enehydrazide (3a) with human serum albumin (HSA) is explored using various spectral methods and molecular docking. Fluorescence quenching results show that 3a induces conformational changes in HSA and the polarity around the tryptophan residues is increased. Stern-Volmer quenching plots at different temperatures (298, 305 and 312 K) show that the fluorescence quenching mechanism is static quenching. Synchronous fluorescence, 3D fluorescence spectra, circular dichroism and Fourier transform infrared spectroscopy are used to determine the structural change in HSA on interaction with 3a. Förster resonance energy transfer analysis shows that the binding distance (r₀  = 2.78 nm) between HSA (Trp214) and 3a is within the of range 2-8 nm for quenching to occur. The molecular docking study also confirms that 3a is located in subdomain IIA (site I) of HSA and is stabilized by hydrogen bonding and hydrophobic forces.

Intramolecular oxyacetoxylation of N-allylamides: an expeditious synthesis of oxazolines and oxazines by using a PhI(OAc)2/hydrogen fluoride-pyridine system

The synthesis of oxazolines and oxazines from N-allylamides was accomplished via an unprecedented reaction set. This reaction involved an intramolecular cyclization of N-allylamides resulting from nucleophilic attack of the allylamine on the benzoxazin-4-one. Unlike the previous literature, the isolable N-allylamide could readily be subjected to exo and endo fashion ring-closure under conditions to afford the title compounds.

Identification of 5,6-dihydroimidazo[2,1-b]thiazoles as a new class of antimicrobial agents

In an effort to develop novel antimicrobial agents against drug-resistant bacterial infections, 5,6-dihydroimidazo[2,1-b]thiazole compounds were synthesized and tested for their antimicrobial activity. Eight compounds comprised by two sub-scaffolds were identified as hits against methicillin-resistant Staphylococcus aureus (MRSA). These hits were modified at 6-position by replacing (S)-6 to (R)-6 configuration and the (R)-isomers increased their antimicrobial activities by two-fold. The most active compound showed a MIC₉₀ value of 3.7μg/mL against MRSA in a standard microdilution bacterial growth inhibitory assay. This compound protected wax moth worms against MRSA at a dose of 5× MIC using a worm infectious model. This compound also exhibited inhibition of DNA gyrase activity in a DNA gyrase supercoil assay, suggesting the 5,6-dihydroimidazo[2,1-b]thiazoles may target DNA gyrase for the antimicrobial action.

Crystal structure of N-(5-bromo-4-(p-tolyl)thiazol-2-yl)-4-chlorobutanamide, C14H14BrClN2OS

C14H14BrClN2OS, monoclinic, P21/c (no. 14), a = 9.8377(5) Å, b = 9.6008(5) Å, c = 17.5784(11) Å, β = 113.107(4)°, V = 1527.08(15) Å3, Z = 4, R gt (F) = 0.0665, wR ref (F 2 ) = 0.1597, T = 293 K.

Crystal structure of 2-(4-(4-bromophenyl)thiazol-2-yl)isoindoline-1,3-dione, C17H9BrN2O2S

C17H9BrN2O2S, monoclinic, P21/c (no. 14), a = 11.2908(2) Å, b = 8.3281(2) Å, c = 16.1037(3) Å, β = 94.453(1)°, V = 1509.67(5) Å3, Z = 4, R gt (F) = 0.0348, wR ref (F 2 ) = 0.1204, T = 296 K.

Design, Synthesis, Characterization and Antimicrobial Evaluation of Some Heterocyclic Condensed Systems with Bridgehead Nitrogen from Thiazolotriazole Class

In the present study, a series of new heterocyclic condensed systems with bridgehead nitrogen from the thiazolo[3,2-b][1,2,4]triazoles class was synthesized starting from some 4-(4-X-phenylsulfonyl)phenyl)-4H-1,2,4-triazole-3-thioles 1a-c (X=H, Cl, Br). The intermediates of S-alkylated 1,2,4-triazoles, 2-(5-(4-(4-X-phenylsulfonyl)phenyl)-2H-1,2,4-triazol-3-ylthio)-1-(4-fluorophenyl)ethanones 2a-c, were obtained by treatment of triazoles 1a-c with 2-bromo-4'-fluoroacetophenone. The 2-(4-(4-X-phenylsulfonyl)phenyl)-6-(4-fluorophenyl)thiazolo[3,2-b][1,2,4]triazoles 3a-c were obtained by cyclization of S-alkylated 1,2,4-triazoles 2a-c in sulfuric acid media, at 0 °C. For the synthesis of 2-(4-(4-X-phenylsulfonyl)phenyl)-5-(4-fluorobenzylidene)-thiazolo[3,2-b][1,2,4]triazol-6(5H)-ones 4a-c, the triazoles 1a-c were treated with 4-fluorobenzaldehyde, chloroacetic acid and anhydrous sodium acetate, in the presence of acetic acid and acetic anhydride. The structures of the newly synthesized compounds have been confirmed by elemental analysis and spectral methods (IR, 1H-NMR, 13C-NMR, MS). The antimicrobial activity of all new compounds has been screened against some bacteria and yeasts.

Antitumor and immunomodulatory activities of thiosemicarbazones and 1,3-Thiazoles in Jurkat and HT-29 cells

Cancer remains a high incidence and mortality disease, causing around 8.2 million of deaths in the last year. Current chemotherapy needs to be expanded, making research for new drugs a necessary task. Immune system modulation is an emerging concept in cancer cell proliferation control. In fact, there are a number of mechanisms underlying the role immune system plays in tumor cells. In this work, we describe the structural design, synthesis, antitumor and immunomodulatory potential of 31 new 1,3-thiazole and thiosemicarbazone compounds. Cisplatin was used as anticancer drug control. Cytotoxicity against J774A.1 macrophages and antitumor activity against HT-29 and Jurkat cells was determined. These 1,3-thiazole and thiosemicarbazone compounds not only exhibited cytotoxicity in cancer cells, but were able to cause irreversible cancer cell damage by inducing necrosis and apoptosis. In addition, these compounds, especially pyridyl-thiazoles compounds, regulated immune factors such as interleukin 10 and tumor necrosis factor, possible by directing immune system in favor of modulating cancer cell proliferation. By examining their pharmacological activity, we were able to identify new potent and selective anticancer compounds.

Synthesis and reactions of C-phosphanylated thiazol-2-thiones

Regioselective synthesis of the P(iii) substituted thiazole-2-thione I is presented. Oxidation of I resulted in P(V) chalcogenide thiazole-2-thiones (E = O, S, Se). Desulfurization of I (E = O) using hydrogenperoxide led to the first C-phosphanoyl thiazolium salt II. Deprotonation of II and reaction with cyclooctadiene rhodium(i) chloride dimer yielded thiazole-2-ylidene rhodium(i) complex III.

Utility of 3-Acetyl-6-bromo-2H-chromen-2-one for the Synthesis of New Heterocycles as Potential Antiproliferative Agents

Coumarin derivatives containing pyrazolo[1,5-a]pyrimidine, tetrazolo[1,5-a]pyrimidine, imidazo[1,2-a]pyrimidine, pyrazolo[3,4-d]pyrimidine, 1,3,4-thiadiazoles and thiazoles were synthesized from 6-bromo-3-(3-(dimethylamino)acryloyl)-2H-chromen-2-one, methyl 2-(1-(6-bromo-2-oxo-2H-chromen-3-yl)ethylidene)hydrazine carbodithioate, 2-(1-(6-bromo-2-oxo-2H-chromen-3-yl)ethylidene) hydrazine carbothioamide and each of heterocyclic amine, hydrazonoyl chlorides and hydroximoyl chlorides. The structures of the newly synthesized compounds were elucidated on the basis of elemental analysis, spectral data, and alternative synthetic routes whenever possible. Moreover, selected newly synthesized products were evaluated for their antitumor activity against a liver carcinoma cancer cell line (HEPG2-1). The results revealed that pyrazolo[1,5-a]pyrimidine 7c, thiazole 23g and 1,3,4-thiadiazole 18a (IC50 = 2.70 ± 0.28, 3.50 ± 0.23 and 4.90 ± 0.69 µM, respectively) have promising antitumor activity against liver carcinoma (HEPG2-1) while most of the tested compounds showed moderate activity.

Copolymers of acrylonitrile with quaternizable thiazole and triazole side-chain methacrylates as potent antimicrobial and hemocompatible systems

A series of six copolymeric families, P(AN-co-MTAs) with various molar fractions of acrylonitrile (fAN) and methacrylates (fMTA) based on 1,3-thiazole and 1,2,3-triazole pendant groups with several spacers of different length and nature (alkyl or succinic), have been synthesized by conventional radical polymerization. The molar fraction of acrylonitrile in the copolymers (FAN) was determined by CHNS elemental analysis. The copolymers were also characterized by ATR-FTIR and molecular weights were determined by size exclusion chromatography (SEC). Due to the nucleophilic nature of the azole heterocycles the copolymers have been easily modified by N-alkylation reaction with butyl iodide leading to polyelectrolytes of diverse amphiphilic balance, P(AN-co-MTAs-BuI). The degree of quaternization (DQ) was quantitative in all instances and was determined by (1)H NMR spectroscopy. Dynamic light scattering (DLS) measurements were performed in order to determine the particle size and the charge density of the systems. The antimicrobial activity of the copolymers was studied in terms of minimal inhibitory concentration (MIC) against the Gram-positive bacteria Staphylococcus aureus, the Gram-negative Pseudomonas aeruginosa and the yeast Candida parapsilosis, as well as the cytotoxic activity toward human red blood cells (RBCs). These types of amphiphilic copolycations presented high selectivity (>300) maintaining moderate to good antimicrobial activity (MIC=4-64 μg/mL) and being non-hemolytic even at high molar fractions of AN in the copolymers compared to PMTAs-BuI homopolymers. Moreover, two examples of acrylonitrile-enriched copolymers (FAN=0.6) presented an excellent time-killing efficiency against microorganisms with 99.9% of killing ranging from 5 to 30 min. Besides, important changes in the morphology of the cell envelop of the microorganisms after treatment with P(AN-co-MTAs) were observed by Field Emission Scanning Electron Microscopy (FE-SEM) compared to untreated samples. These results indicate that these quaternized copolymers (QUATs) behave like the corresponding PMTAs-BuI homopolymers, being microbiostatic and also highly effective microbiocidal agents.

Design, synthesis, and biological evaluation of aminothiazole derivatives against the fungal pathogens Histoplasma capsulatum and Cryptococcus neoformans

Invasive fungal disease constitutes a growing health burden and development of novel antifungal drugs with high potency and selectivity against new fungal molecular targets are urgently needed. Previously, an aminothiazole derivative, designated as 41F5, was identified in our laboratories as highly active against Histoplasma yeast (MIC50 0.4-0.8 μM) through phenotypic high-throughput screening of a commercial library of 3600 purine mimicking compounds (Antimicrob. Agents Chemother.2013, 57, 4349). Consequently, 68 analogues of 41F5 were designed and synthesized or obtained from commercial sources and their MIC50s of growth inhibition were evaluated in Histoplasma capsulatum to establish a basic structure-activity-relationship (SAR) for this potentially new class of antifungals. The growth inhibiting potentials of smaller subsets of this library were also evaluated in Cryptococcus neoformans and human hepatocyte HepG2 cells, the latter to obtain selectivity indices (SIs). The results indicate that a thiazole core structure with a naphth-1-ylmethyl group at the 5-position and cyclohexylamide-, cyclohexylmethylamide-, or cyclohexylethylamide substituents at the 2-position caused the highest growth inhibition of Histoplasma yeast with MIC50s of 0.4 μM. For these analogues, SIs of 92 to >100 indicated generally low host toxicity. Substitution at the 3- and 4-position decreased antifungal activity. Similarities and differences were observed between Histoplasma and Cryptococcus SARs. For Cryptococcus, the naphth-1-ylmethyl substituent at the 5-position and smaller cyclopentylamide- or cyclohexylamide groups at the 2-position were important for activity. In contrast, slightly larger cyclohexylmethyl- and cyclohexylethyl substituents markedly decreased activity.

Antimicrobial polymethacrylates based on quaternized 1,3-thiazole and 1,2,3-triazole side-chain groups

Increasing antimicrobial and non-hemotoxic characteristics of polymers bearing thiazole and triazole groups by the appropriate selection of spacer and quaternization groups.

Analysis of the structural diversity, substitution patterns, and frequency of nitrogen heterocycles among U.S. FDA approved pharmaceuticals

Nitrogen heterocycles are among the most significant structural components of pharmaceuticals. Analysis of our database of U.S. FDA approved drugs reveals that 59% of unique small-molecule drugs contain a nitrogen heterocycle. In this review we report on the top 25 most commonly utilized nitrogen heterocycles found in pharmaceuticals. The main part of our analysis is divided into seven sections: (1) three- and four-membered heterocycles, (2) five-, (3) six-, and (4) seven- and eight-membered heterocycles, as well as (5) fused, (6) bridged bicyclic, and (7) macrocyclic nitrogen heterocycles. Each section reveals the top nitrogen heterocyclic structures and their relative impact for that ring type. For the most commonly used nitrogen heterocycles, we report detailed substitution patterns, highlight common architectural cores, and discuss unusual or rare structures.

Synthesis and in vitro evaluation of new nitro-substituted thiazolyl hydrazone derivatives as anticandidal and anticancer agents

Fourteen new thiazolyl hydrazone derivatives were synthesized and evaluated for their anticandidal activity using a broth microdilution assay. Among the synthesized compounds, 2-[2-((5-(4-chloro-2-nitrophenyl)furan-2-yl)methylene)hydrazinyl]-4-(4-fluorophenyl)thiazole and 2-[2-((5-(4-chloro-2-nitrophenyl)furan-2-yl)methylene) hydrazinyl]-4-(4-methoxyphenyl)thiazole were found to be the most effective antifungal compounds against Candida utilis, with a MIC value of 250 µg/mL, when compared with fluconazole (MIC=2 µg/mL). Additionally, the synthesized compounds were evaluated for their in vitro cytotoxic effects on the MCF-7 and NIH/3T3 cell lines. As a result, 2-[2-((5-(4-chloro-2-nitrophenyl)furan-2-yl)methylene)hydrazinyl]-4-(4-chlorophenyl)thiazole was identified as the most promising anticancer compound against MCF-7 cancer cells due to its inhibitory effects (IC50=125 µg/mL) and relatively low toxicity towards the NIH/3T3 cell line (IC50>500 µg/mL).