Bioisosteric replacement of 1H-1,2,3-triazole with 1H-tetrazole ring enhances anti-leukemic activity of (5-benzylthiazol-2-yl)benzamides.

Previously, we discovered that N-(5-benzyl-1,3-thiazol-2-yl)-4-(5-methyl-1H-1,2,3-triazol-1-yl)benzamide possessed a remarkable cytotoxic effect on 28 cancer cell lines with IC50 < 50 µM, including 9 cancer cell lines, where IC50 was in the range of 2.02-4.70 µM. In the present study, we designed a novel N-(5-benzylthiazol-2-yl)amide compound 3d that was synthesized using the original bioisosteric replacement of 1H-1,2,3-triazole ring by the 1H-tetrazole ring. A significantly enhanced anticancer activity in vitro with an excellent anti-leukemic potency towards chronic myeloid leukemia cells of the K-562 line was demonstrated. Two compounds - 3d and 3l - were highly cytotoxic at nanomolar concentrations towards various tumor cells of the following lines: K-562, NCI-H460, HCT-15, KM12, SW-620, LOX IMVI, M14, UACC-62, CAKI-1, and T47D. As a highlight, the compound N-(5-(4-fluorobenzyl)thiazol-2-yl)-4-(1H-tetrazol-1-yl)benzamide 3d inhibited the growth of leukemia K-562 cells and melanoma UACC-62 cells with IС50 of 56.4 and 56.9 nM (SRB test), respectively. The viability of leukemia K-562 and pseudo-normal HaCaT, NIH-3T3, and J774.2 cells was measured by the MTT assay. Together with SAR analysis, it allowed the selection of a lead compound 3d, which demonstrated the highest selectivity (SI = 101.0) towards treated leukemic cells. The compound 3d caused DNA damage (single-strand breaks detected by the alkaline comet assay) in the leukemic K-562 cells. The morphological study of the K-562 cells treated with compound 3d revealed changes consistent with apoptosis. Thus, the bioisosteric replacement in (5-benzylthiazol-2-yl)amide scaffold proved to be a perspective approach in the design of novel heterocyclic compounds with enhanced anticancer potential.

Novel N-(4-thiocyanatophenyl)-1H-1,2,3-triazole-4-carboxamides exhibit selective cytotoxic activity at nanomolar doses towards human leukemic T-cells.

The N-(4-thiocyanatophenyl)-1H-1,2,3-triazole-4-carboxamides were synthesized via the condensation of variety of 1H-1,2,3-triazole-4-carboxylic acids and 4-thiocyanatoaniline using CDI as amide coupling reagents. According to computer-aided calculations, all synthesized compounds are expected to have acceptable ADME profile for drug design. The antiproliferative potency of derivatives was evaluated towards different cell lines. The specific activity of four N-(4-thiocyanatophenyl)-1H-1,2,3-triazole-4-carboxamides (4a, 4b, 4c, 4f) was comparable to doxorubicin (GI50 = 0.65 µM) at nanomolar level against Jurkat cells in the range of GI50 0.63-0.69 µM. According to the results of toxicity studies of the compounds for HEK293, HaCaT, Balb/c 3T3 cells, compound 4a was selected for further studies as a biocompatible agent with promising anticancer activity in the NCI60 cell lines. A remarkable antiproliferative activity of compound 4a towards leukemia cell lines (SR, MOLT-4; CCRF-CEM; HL-60(TB); K-562; RPMI-8226) was observed and high cytotoxicity towards the CAKI-1 (kidney cancer), LOX IMVI (melanoma) and UO-31 (renal cancer) cells lines was detected. Compound 4a inhibits LOX IMVI cells growth at a GI50 value of 0.15 µM. COMPARE analysis to indicate potential mechanisms of action of novel compound, as well as in silico SwissTargetPrediction and SwissSimilarity were performed. Compound 4a induced morphological changes (apoptotic bodies, membrane blebbing, chromatin condensation), and DNA fragmentation in Jurkat T-cells. It reduced mitochondrial membrane potential and induced DNA damage in Jurkat cells without binding and/or intercalation to DNA molecule.

Synthesis, Biological Evaluation and Molecular Docking Studies of 5-Indolylmethylen-4-oxo-2-thioxothiazolidine Derivatives.

BACKGROUND: Infectious diseases represent a significant global strain on public health security and impact on socio-economic stability all over the world. The increasing resistance to the current antimicrobial treatment has resulted in the crucial need for the discovery and development of novel entities for the infectious treatment with different modes of action that could target both sensitive and resistant strains. METHODS: Compounds were synthesized using the classical organic chemistry methods. Prediction of biological activity spectra was carried out using PASS and PASS-based web applications. Pharmacophore modeling in LigandScout software was used for quantitative modeling of the antibacterial activity. Antimicrobial activity was evaluated using the microdilution method. AutoDock 4.2® software was used to elucidate probable bacterial and fungal molecular targets of the studied compounds. RESULTS: All compounds exhibited better antibacterial potency than ampicillin against all bacteria tested. Three compounds were tested against resistant strains MRSA, P. aeruginosa and E. coli and were found to be more potent than MRSA than reference drugs. All compounds demonstrated a higher degree of antifungal activity than the reference drugs bifonazole (6-17-fold) and ketoconazole (13-52-fold). Three of the most active compounds could be considered for further development of the new, more potent antimicrobial agents. CONCLUSION: Compounds 5b (Z)-3-(3-hydroxyphenyl)-5-((1-methyl-1H-indol-3-yl)methylene)-2-thioxothiazolidin-4-one and 5g (Z)-3-[5-(1H-Indol-3-ylmethylene)-4-oxo-2-thioxo-thiazolidin-3-yl]-benzoic acid as well as 5h (Z)-3-(5-((5-methoxy-1H-indol-3-yl)methylene)-4-oxo-2-thioxothiazolidin-3-yl)benzoic acid can be considered as lead compounds for further development of more potent and safe antibacterial and antifungal agents.

Synthesis and biological evaluation of new 4-oxo-thiazolidin-2-ylidene derivatives as antimicrobial agents.

In this study, an efficient synthesis and the antimicrobial activity evaluation of some 4-oxo-thiazolidin-2-ylidene derivatives are presented. The structures of the target substances were confirmed by using 1 H and 13 C nuclear magnetic resonance spectroscopy, mass spectrometry, infrared spectroscopy, and elemental analysis. The synthesized compounds were evaluated for antimicrobial activity against five bacterial strains (Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus) and two fungal strains (Candida albicans and Cryptococcus neoformans). It was shown that the compounds in this series possess antibacterial and antifungal activities.

3-Amino-5-(indol-3-yl)methylene-4-oxo-2-thioxothiazolidine Derivatives as Antimicrobial Agents: Synthesis, Computational and Biological Evaluation.

Herein we report the design, synthesis, computational, and experimental evaluation of the antimicrobial activity of fourteen new 3-amino-5-(indol-3-yl) methylene-4-oxo-2-thioxothiazolidine derivatives. The structures were designed, and their antimicrobial activity and toxicity were predicted in silico. All synthesized compounds exhibited antibacterial activity against eight Gram-positive and Gram-negative bacteria. Their activity exceeded those of ampicillin and (for the majority of compounds) streptomycin. The most sensitive bacterium was S. aureus (American Type Culture Collection ATCC 6538), while L. monocytogenes (NCTC 7973) was the most resistant. The best antibacterial activity was observed for compound 5d (Z)-N-(5-((1H-indol-3-yl)methylene)-4-oxo-2-thioxothiazolidin-3-yl)-4-hydroxybenzamide (Minimal inhibitory concentration, MIC at 37.9-113.8 µM, and Minimal bactericidal concentration MBC at 57.8-118.3 µM). Three most active compounds 5d, 5g, and 5k being evaluated against three resistant strains, Methicillin resistant Staphilococcus aureus (MRSA), P. aeruginosa, and E. coli, were more potent against MRSA than ampicillin (MIC at 248-372 µM, MBC at 372-1240 µM). At the same time, streptomycin (MIC at 43-172 µM, MBC at 86-344 µM) did not show bactericidal activity at all. The compound 5d was also more active than ampicillin towards resistant P. aeruginosa strain. Antifungal activity of all compounds exceeded those of the reference antifungal agents bifonazole (MIC at 480-640 µM, and MFC at 640-800 µM) and ketoconazole (MIC 285-475 µM and MFC 380-950 µM). The best activity was exhibited by compound 5g. The most sensitive fungal was T. viride (IAM 5061), while A. fumigatus (human isolate) was the most resistant. Low cytotoxicity against HEK-293 human embryonic kidney cell line and reasonable selectivity indices were shown for the most active compounds 5d, 5g, 5k, 7c using thiazolyl blue tetrazolium bromide MTT assay. The docking studies indicated a probable involvement of E. coli Mur B inhibition in the antibacterial action, while CYP51 inhibition is likely responsible for the antifungal activity of the tested compounds.

5-(1H-Indol-3-ylmethylene)-4-oxo-2-thioxothiazolidin-3-yl)alkancarboxylic Acids as Antimicrobial Agents: Synthesis, Biological Evaluation, and Molecular Docking Studies.

BACKGROUND: Infectious diseases symbolize a global consequential strain on public health security and impact on the socio-economic stability all over the world. The increasing resistance to the current antimicrobial treatment has resulted in crucial need for the discovery and development of novel entity for the infectious treatment with different modes of action that could target both sensitive and resistant strains. METHODS: Compounds were synthesized using classical methods of organic synthesis. RESULTS: All 20 synthesized compounds showed antibacterial activity against eight Gram-positive and Gram-negative bacterial species. It should be mentioned that all compounds exhibited better antibacterial potency than ampicillin against all bacteria tested. Furthermore, 18 compounds appeared to be more potent than streptomycin against Staphylococcus aureus, Enterobacter cloacae, Pseudomonas aeruginosa, Listeria monocytogenes, and Escherichia coli. Three the most active compounds 4h, 5b, and 5g appeared to be more potent against MRSA than ampicillin, while streptomycin did not show any bactericidal activity. All three compounds displayed better activity also against resistant strains P. aeruginosa and E. coli than ampicillin. Furthermore, all compounds were able to inhibit biofilm formation 2- to 4-times more than both reference drugs. Compounds were evaluated also for their antifungal activity against eight species. The evaluation revealed that all compounds exhibited antifungal activity better than the reference drugs bifonazole and ketoconazole. Molecular docking studies on antibacterial and antifungal targets were performed in order to elucidate the mechanism of antibacterial activity of synthesized compounds. CONCLUSION: All tested compounds showed good antibacterial and antifungal activity better than that of reference drugs and three the most active compounds could consider as lead compounds for the development of new more potent agents.

A New Reagent for Spectrophotometric Determination of Ir(IV): 5-[2-(4-Hydroxyphenyl) hydrazineylidene]- 4-iminothiazolidin-2-one (HPIT).

The paper presents a new azolidone derivative - 5-[2-(4-hydroxyphenyl)hydrazineylidene]-4-iminothiazolidin-2-one (HPIT) studies and its interaction results with iridium(IV) ions. The Ir(IV) with this reagent in the pH = 5.0 without heating forms a stable complex (?max = 328 nm). The stoichiometric ratio of Ir(IV) to the reagent in complex is 1:1. The molar absorptivity and Sandell's sensitivity are 5.57×103 L mol-1 cm-1 and 0.034 µg cm-2 respectively. The calibration curve is linear in the range of 1.0-11.5 µg mL-1 of Ir(IV) (R = 0.9996). The limit of detection is 0.4 µg mL-1. Based on the conducted investigation a rapid and simple, spectrophotometric method for the determination of Ir(IV) using 5-[2-(4-hydroxyphenyl)hydrazineylidene]-4-iminothiazolidin-2-one as a chromophoric reagent was developed. The iridium(IV) was determined in various synthetic mixtures and alloys.

Synthesis, Molecular Docking and Biological Properties of Novel Thiazolo[4,5-b]pyridine Derivatives.

The synthesis, anti-inflammatory and antioxidant properties of novel 5-hydroxy-7-methyl-3H-thiazolo[4,5-b]pyridin-2-one derivatives were discussed. Fused thiazolo[4,5-b]pyridin-2-ones were synthesized and modified at the N3, C5 and C6 positions of the main core in order to obtain the compounds with a satisfactory pharmacological profile. The synthesized compounds were preselected via molecular docking for further testing of their anti-inflammatory activity in vitro. Evaluation of novel compounds over the carageenin induced rat paw edema revealed strong anti-inflammatory action of some compounds including (thiazolo[4,5-b]pyridin-3(2H)-yl) propanenitrile (5) and thiazolo[4,5-b]pyridin-3(2H)-yl) propanoic acid (6) even exceeding the standard - Ibuprofen. The antioxidant activity of the synthesized compounds was measured in vitro by the method of scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals.

ynthesis, Anti-Inflammatory and Antioxidant Activities of Novel 3H-Thiazolo[4,5-b]Pyridines.

5-Hydroxy-7-methyl-3H-thiazolo[4,5-b]pyridin-2-one was obtained by the reaction of 4-iminothiazolidin-2-one with acetoacetic ester. Further structural modifications include the introduction of diversity at the C5 and C6 positions. The anti-inflammatory action of novel thiazolo[4,5-b]pyridine-2-one derivatives was evaluated in vivo employing the carrageenan- induced rat paw edema method. The antioxidant activity of the synthesized compounds was evaluated in vitro by the method of scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals.

Proapoptotic effects of novel thiazole derivative on human glioma cells.

The aim of the present study was to investigate the antiproliferative and proapoptotic actions of N-(5-benzyl-1,3-thiazol-2-yl)-3,5-dimethyl-1-benzofuran-2-carboxamide derivative (compound 5) in glioma cells in comparison with the actions of temozolomide (TMZ) and doxorubicin (Dox), used as positive controls. The antiproliferative activity of the compound 5, TMZ, and Dox on human glioblastoma U251 and human glioblastoma multiform T98G cells was measured using the MTT test. Western blot analysis, fluorescent microscopy, agarose gel retardation assay, flow cytometric analysis, and the DNA comet assay under alkaline conditions were carried out to study the effect of compound 5 on U251 cells. This compound showed ~20 times higher cytotoxicity toward U251 and T98G cells compared with the effects of TMZ and approximately two times higher activity than that of the Dox. Compound 5 induced apoptosis in U251 cells by PARP1 and caspase 3 cleavage mechanisms, also inducing an increase in the level of Bax and Bim proapoptotic proteins and a decrease in the level of phosho-ERK1/2 kinase. The cytotoxicity of compound 5 was associated with an increase in the production of the hydrogen peroxide and the formation of DNA single-strand breaks. This compound 5 did not intercalate into a DNA molecule. Thus, the novel thiazole derivative (compound 5) proved to be a potential antiglioma drug that showed much higher cytotoxic action on human glioma cells compared with the effects of TMZ and Dox. Its cytotoxicity is associated with apoptosis induction, production of the reactive oxygen species, and formation of DNA single-strand breaks without significant DNA intercalation.

Anticancer Activity Evaluation of New Thieno[2,3-d]pyrimidin-4(3H)-ones and Thieno[3,2-d]pyrimidin-4(3H)-one Derivatives.

Anticancer screening of several novel thienopyrimidines has been performed. The thienopyrimidine derivatives were synthesized from available starting materials according to the convenient synthetic procedures using a one-pot solvent-free reaction which gave a wide access to thienopyrimidine-derivative production. The synthesized compounds were preselected via molecular docking to be tested for their anticancer activity in NCI 60 cell lines. It was observed that some compounds showed remarkable anticancer activity. It was found that the most active compound among thieno[2,3-d]pyrimidine-4(3H)-ones is 2-(benzylamino)-5,6-dimethylthieno[2,3-d]pyrimidin-4(3H)-one, which possesses cytotoxic activity on almost all cancer cell lines with mean growth 51.01%, where the most sensitive was the melanoma cell line MDA-MB-435 with GP (Growth Percent) = -31.02%. The patterns of structure⁻activity that are important for further optimization of the structure and the creation of more selective and active anticancer agents were proposed.

New Convenient Strategy for Annulation of Pyrimidines to Thiophenes or Furans via the One-pot Multistep Cascade Reaction of 1H-Tetrazoles with Aliphatic Amines.

A versatile, convenient, efficient and high-yield synthetic method for 2-R(3),R(4)-amino-5-R(1)-6-R(2)-thieno[2,3-d]pyrimidin-4(3H)-ones, 2-R(3),R(4)-amino-5-R(1)-6-R(2)-thieno[3,2-d]pyrimidin-4(3H)-ones, and benzofuro[3,2-d]pyrimidin-4(3H)-ones preparation has been developed. The reaction proceeded without using solvents and included several steps. A variety of thieno[2,3-d]pyrimidine and thieno[3,2-d]pyrimidine derivatives with substituents of different nature were obtained in high yields from substituted alkyl 2-(1H-tetrazol-1-yl)thiophene-3-carboxylates, 3-(1H-tetrazol-1-yl)thiophene-2-carboxylates, and 3-(1H-tetrazol-1-yl)benzofuran-2-carboxylate after their treatment with aliphatic amines.

Synthesis of 1,2,3-Triazole Derivatives and Evaluation of their Anticancer Activity.

Anticancer screening of several 1,2,3-triazoles with heterocyclic fragments has been performed. The 1,2,3-triazole derivatives were synthesized from available starting materials according to convenient synthetic procedures. The antitumor activity of the synthesized compounds was tested in vitro by the National Cancer Institute in NCI60 cell lines. It was observed that some compounds showed slight anticancer activity. One of them possessed a moderate activity against melanoma, colon, and breast cancer. Standard COMPARE analysis was performed at the GI50 level.

5-Iodo-3-phenyl-2,1-benzoxazole.

The title compound, C13H8INO, was prepared by a condensation reaction of 4-nitro-benzene with phenyl-acetonitrile in NaOH-ethanol solution. There are two independent mol-ecules in the asymmetric unit, in which the dihedral angles between the benzene ring and the benzoisoxazole unit are 4.2 (3) and 4.1 (3)°. The crystal packing is governed by C-H⋯N, C-I⋯π and C-I⋯O inter-actions.

1-{5-[2-Chloro-5-(trifluoro-meth-yl)phen-yl]thio-phen-2-yl}ethanone.

In the title molecule, C(13)H(8)ClF(3)OS, the dihedral angle between the mean planes of 2-chloro-5-(trifluoro-meth-yl)phenyl and tiophene rings is 54.37 (5)°. The acethyl group is twisted by 8.1 (2)° with respect to the thio-phene ring. The CF(3) group is disordered over two sets of sites with occupations of 0.49 (3) and 0.51 (3). The crystal packing features C-H⋯F and C-H⋯O hydrogen bonds, forming dimers which are connected into chains along the c axis by C-H⋯O hydrogen bonds and C-Cl⋯π [Cl⋯π = 3.415 (1) Šand C-Cl⋯π = 151.56 (5)°] inter-actions. The chains are further connected into layers perpendicular to the a axis by C-H⋯O inter-actions.

One-pot multicomponent synthesis of 1-aryl-5-methyl-N-R2-1H-1,2,3-triazole-4-carboxamides: an easy procedure for combinatorial chemistry.

A convenient synthetic protocol was elaborated for creation of combinatorial libraries of 1-(R(1)-phenyl)-5-methyl-N-R(2)-1H-1,2,3-triazole-4-carboxamides. As starting materials, commercially available or readily prepared azides, amines, and diketene were selected for the reaction which has proceeded in a one-pot system with high yields and in short time.

3-(4-Chloro-phen-yl)-2,1-benzisoxazole-5-carbonyl chloride.

The molecule of the title compound, C(14)H(7)Cl(2)NO(2), is not planar; the dihedral angle between the mean planes of the chloro-phenyl and benzisoxazole rings is 20.32 (7)°. The carbonyl chloride group is twisted with respect to the benzisoxazole ring by 2.5 (1)°. The mol-ecular conformation is stabilized by an intra-molecular C-H⋯Cl hydrogen bond. In the crystal packing, adjacent mol-ecules are linked into dimers by inter-molecular C-H⋯O hydrogen bonds. The dimers are further stacked into columns along the unique axis direction by π-π stacking inter-actions, with a centroid⋯centroid distance of 3.828 (5) Å. Other weak inter-molecular C-H⋯O and C-H⋯Cl inter-actions are also present.