Synthesis and Antimicrobial Activity of Some New Thiadiazoles, Thioamides, 5-Arylazothiazoles and Pyrimido[4,5-d][1,2,4]triazolo[4,3-a]pyrimidines

Synthesis, Antifungal Ergosterol Inhibition, Antibiofilm Activities, and Molecular Docking on β-Tubulin and Sterol 14-Alpha Demethylase along with DFT-Based Quantum Mechanical Calculation of Pyrazole Containing Fused Pyridine-Pyrimidine Derivatives

Multidrug-resistant fungal infections have become much more common in recent years, especially in immune-compromised patients. Therefore, researchers and pharmaceutical professionals have focused on the development of novel antifungal agents that can tackle the problem of resistance. In continuation to this, a novel series of pyrazole-bearing pyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione derivatives (4a-4o) have been developed. These compounds have been screened against Candida albicans, Aspergillus niger, and Aspergillus clavatus. The synthesized compounds were characterized by well-known spectroscopic techniques, i.e., IR, 1H NMR, 13C NMR, and mass spectrometry. In vitro antifungal results revealed that compound 4n showed activity against C. albicans having MIC value of 200 μg/mL. To know the plausible mode of action, the active derivatives were screened for anti-biofilm and ergosterol biosynthesis inhibition activities. The compounds 4h, 4j, 4k, and 4n showed greater ergosterol biosynthesis inhibition than the control DMSO. To comprehend how molecules interact with the receptor, studies of molecular docking of 4k and 4n have been performed on the homology-modeled protein of β-tubulin. The molecular docking revealed that the active compounds 4h, 4j, 4k, 4l, and 4n interacting with the active site amino acid of sterol 14-alpha demethylase (PDB ID: 5v5z) indicate one of the possible modes of action of ergosterol inhibition activity. The synthesized compounds 4c, 4e, 4h, 4i, 4j, 4k, 4l, and 4n inhibited biofilm formation and possessed the potential for anti-biofilm activity. DFT-based quantum mechanical calculations were carried out to optimize, predict, and compare the vibration modes of the molecule 4a.

Exploration of Thiourea-Based Scaffolds for the Construction of Bacterial Ureases Inhibitors

A series of 32 thiourea-based urease inhibitors were synthesized and evaluated against native bacterial enzyme and whole cells of Sporosarcina pasteurii and Proteus mirabilis strains. The proposed inhibitors represented structurally diverse thiosemicarbazones and thiocarbohydrazones, benzyl-substituted thiazolyl thioureas, 1H-pyrazole-1-carbothioamides, and dihydropirimidine-2(1H)-thiones. Kinetic characteristics with purified S. pasteurii enzyme determined low micromolar inhibitors within each structural group. (E)-2-(1-Phenylethylidene)hydrazine-1-carbothioamide 19 (Ki = 0.39 ± 0.01 μM), (E)-2-(4-methylbenzylidene)hydrazine-1-carbothioamide 16 (Ki = 0.99 ± 0.04 μM), and N'-((1E,2E)-1,3-diphenylallylidene)hydrazinecarbothiohydrazide 29 (Ki = 2.23 ± 0.19 μM) were used in modeling studies that revealed sulfur ion coordination of the active site nickel ion and hydrogen bonds between the amide group and the side chain of Asp363 and Ala366 carbonyl moiety. Whole-cell studies proved the activity of compounds in Gram-positive and Gram-negative microorganisms. Ureolysis control observed in P. mirabilis PCM 543 (e.g., IC50 = 304 ± 14 μM for 1-benzyl-3-(4-(4-hydroxyphenyl)thiazol-2-yl)thiourea 52) is a valuable achievement, as urease is recognized as a major virulence factor of this urinary tract pathogen.

Synthesis, Anticancer and Antitubercular Properties of New Chalcones and Their Nitrogen-Containing Five-Membered Heterocyclic Hybrids Bearing Sulfonamide Moiety

A new series of sulfonamides, 8a-b, 10, 12, and 14a-b, were synthesized by N-sulfonation reaction with sulfonyl chlorides 6a-b. Five new series of chalcone-sulfonamide hybrids (16-20)a-f were prepared via Claisen–Schmidt condensation of the newly obtained sulfonamides with aromatic aldehydes 15a-f in basic medium. Chalcones substituted with chlorine at position 4 of each series were used as precursors for the generation of their five-membered heterocyclic pyrazoline (22-23)a-d, (24-25)a-b and carbothioamide 27a-f derivatives. The synthesized compounds were evaluated for their anticancer and antituberculosis activities. To determine their anticancer activity, compounds were screened against sixty human cancer cell lines at a single dose (10 μM). Compounds 17a-c were highly active against LOX IMVI (melanoma), with IC₅₀ values of 0.34, 0.73 and 0.54 μM, respectively. Chalcone 18e showed remarkable results against the entire panel of leukemia cell lines with IC₅₀ values between 0.99–2.52 μM. Moreover, compounds 20e and 20f displayed growth inhibition of Mycobacterium tuberculosis H37Rv at concentrations below 10 μM. Although they showed low selectivity in cytotoxicity tests against the Vero cell line, further optimization could advance the potential biological activity of the selected compounds.

Novel Type of Tetranitrosyl Iron Salt: Synthesis, Structure and Antibacterial Activity of Complex [FeL'2(NO)2][FeL'L"(NO)2] with L'-thiobenzamide and L"-thiosulfate

In this work a new donor of nitric oxide (NO) with antibacterial properties, namely nitrosyl iron complex of [Fe(C6H5C-SNH2)2(NO)2][Fe(C6H5C-SNH2)(S2O3)(NO)2] composition (complex I), has been synthesized and studied. Complex I was produced by the reduction of the aqueous solution of [Fe2(S2O3)2(NO)2]2- dianion by the thiosulfate, with the further treatment of the mixture by the acidified alcohol solution of thiobenzamide. Based on the structural study of I (X-ray analysis, quantum chemical calculations by NBO and QTAIM methods in the frame of DFT), the data were obtained on the presence of the NO…NO interactions, which stabilize the DNIC dimer in the solid phase. The conformation properties, electronic structure and free energies of complex I hydration were studied using B3LYP functional and the set of 6-31 + G(d,p) basis functions. The effect of an aquatic surrounding was taken into account in the frame of a polarized continuous model (PCM). The NO-donating activity of complex I was studied by the amperometry method using an "amiNO-700" sensor electrode of the "inNO Nitric Oxide Measuring System". The antibacterial activity of I was studied on gram-negative (Escherichia coli) and gram-positive (Micrococcus luteus) bacteria. Cytotoxicity was studied using Vero cells. Complex I was found to exhibit antibacterial activity comparable to that of antibiotics, and moderate toxicity to Vero cells.

Novel spiroheterocycles containing a 1,3,4-thiadiazole unit: Synthesis and spectroscopic characterization

We describe the preparation of a series of novel spiroheterocycles, namely 1,3,4-thiadiazole derivatives possessing an indane unit. These active heterocyclic compounds are prepared starting from thiocarbohydrazide and 2-indanone via an intermediate indan-2-thiocarbohydrazone which is used to afford the corresponding 2-(1-acetylhydrazino)-4 H-acetyl-5-spiro(indano-2-yl)-1,3,4-thiadiazoline in an acidic medium. The 1,3,4-thiadiazole derivatives are obtained in good yields by reaction with aromatic carboxylic acids at reflux temperature in the presence of POCl3 as a catalyst, their structure–activity relationships are discussed and the structures of the newly synthesized derivatives are confirmed by spectroscopic techniques.

Utility of 5-(furan-2-yl)-3-(p-tolyl)-4,5-dihydro-1H-pyrazole-1-carbothioamide in the synthesis of heterocyclic compounds with antimicrobial activity

Background

Pyrazolines show different biological activities. In recent years, interest in the chemistry of hydrazonoyl halides has been renewed. 1,3,4-Thiadiazoles are one of the most common heterocyclic pharmacophores with a wide range of biological activities.

Results

Ethyl 2-(5-(furan-2-yl)-3-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)-4-methyl-thiazole-5-carboxylate, 2-(5-(furan-2-yl)-3-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)thiazol-4(5H)-one, and 1-(2-(5-(furan-2-yl)-3-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)-4-methylthiazol-5-yl)ethan-1-one were synthesized from the reaction of 5-(furan-2-yl)-3-(p-tolyl)-4,5-dihydro-1H-pyrazole-1-carbothioamide with different halogenated compounds. Thiazole, 1,3,4-thiadiazole and pyrano[2,3-d]thiazole derivatives were also synthesized. The structures of the newly synthesized compounds were elucidated based on elemental analysis, spectral data, and alternative synthetic routes whenever possible. Additionally, the newly synthesized compounds were screened for antimicrobial activity against various microorganisms.

Conclusions

A new series of novel functionalized 1,3,4-thiadiazoles, 1,3-thiazoles, and pyrazoline-containing moieties were synthesized using hydrazonoyl halides as precursors and evaluated for their in vitro antibacterial, and antifungal activities. The antimicrobial results of the examined compounds revealed promising results and some derivatives have activities similar to the references used.

Electronic supplementary material

The online version of this article (10.1186/s13065-019-0566-y) contains supplementary material, which is available to authorized users.