Synthesis, In Vitro Screening and Docking Studies of New Thiosemicarbazide Derivatives as Antitubercular Agents

Structure-activity relationship and cytotoxicity of the new thiosemicarbazide derivatives and their Cu(II) complexes against prostate and melanoma cancer cells

In this study, eighteen new ligands (B1-B18) containing a thiosemicarbazide core were synthesized and characterized in terms of physicochemical properties, molecular docking and in vitro biological activity. The structures of eleven ligands were investigated using X-Ray diffraction and Hirschfeld Surface analysis. To study the structure-activity relationship, the organic ligands contained pyridin-2-ylmethyl, pyridin-3-ylmethyl or pyridin-4-ylmethyl moieties and various substituents. Their pharmakokinetic profiles and molecular docking results suggest high potential as new drug candidates. The complexing ability of the selected organic ligands was also evaluated, yielding five new Cu(II) complexes (Cu(B1)Cl2, Cu(B4)Cl2, Cu(B10)Cl2, Cu(B17)Cl2, Cu(B18)Cl2). The obtained results suggest the formation of the polymeric structures. All organic ligands and Cu(II) complexes were tested for anticancer activity against prostate and melanoma cancer cells (PC-3, DU-145, LNCaP, A375, G-361, SK-MEL-28) and normal fibroblasts (BJ), as well as antimicrobial activity against six selected bateria strains. Among B1-B18 compounds, B3, B5, B9, B10, B12 and B14 exhibited cytotoxic activity. The studied Cu(II) complexes were in general more active, with Cu(B1)Cl2 exhibiting antincancer activity agains all three prostate cancer cells and Cu(B10)Cl2 reaching the IC50 value equal to 88 μM against G-361 melanoma cells. Several compounds also exhibited antimicrobial activity against gram-positive and gram-negative bacteria. It was found that the type of specific substituents, especially the presence of -chloro and -dichloro substituents had a greated impact on the cytotoxicity than the position of the nitrogen atom in the pyridylacetyl moiety.

New Thiosemicarbazide Derivatives with Multidirectional Biological Action

Over the years, several new medicinal substances have been introduced for the treatment of diseases caused by bacteria and parasites. Unfortunately, due to the production of numerous defense mechanisms by microorganisms and parasites, they still pose a serious threat to humanity around the world. Therefore, laboratories all over the world are still working on finding new, effective methods of pharmacotherapy. This research work aimed to synthesize new compounds derived from 3-trifluoromethylbenzoic acid hydrazide and to determine their biological activity. The first stage of the research was to obtain seven new compounds, including six linear compounds and one derivative of 1,2,4-triazole. The PASS software was used to estimate the potential probabilities of biological activity of the newly obtained derivatives. Next, studies were carried out to determine the nematocidal potential of the compounds with the use of nematodes of the genus Rhabditis sp. and antibacterial activity using the ACCT standard strains. To determine the lack of cytotoxicity, tests were performed on two cell lines. Additionally, an antioxidant activity test was performed due to the importance of scavenging free radicals in infections with pathogenic microorganisms. The conducted research proved the anthelmintic and antibacterial potential of the newly obtained compounds. The most effective were two compounds with a 3-chlorophenyl substituent, both linear and cyclic derivatives. They demonstrated higher efficacy than the drugs used in treatment.

Experimental and computational studies of tautomerism pyridine carbonyl thiosemicarbazide derivatives

Tautomerism is one of the most important phenomena to consider when designing biologically active molecules. In this work, we use NMR spectroscopy, IR, and X-ray analysis as well as quantum-chemical calculations in the gas phase and in a solvent to study tautomerism of 1- (2-, 3- and 4-pyridinecarbonyl)-4-substituted thiosemicarbazide derivatives. The tautomer containing both carbonyl and thione groups turned out to be the most stable. The results of the calculations are consistent with the experimental data obtained from NMR and IR spectroscopy and with the crystalline forms from the X-ray studies. The obtained results broaden the knowledge in the field of structural studies of the thiosemicarbazide scaffold, which will translate into an understanding of the interactions of compounds with a potential molecular target.

Evaluation of developmental toxicity in zebrafish embryos and antiproliferative potential against human tumor cell lines of new derivatives containing 4-nitrophenyl group

The aim of the studies was to evaluate the antiproliferative potential against human tumor cell lines of newly synthetized derivatives containing 4-nitrophenyl group, as well as its impact on developmental toxicity in zebrafish model. We selected 1-(4-nitrobenzoyl)-4-ethylsemicarbazide (APS-1) and 1-[(4-nitrophenyl)acetyl]-4-hexyl-thiosemicarbazide (APS-18) for research. The antiproliferative properties of semicarbazide derivatives were assessed against human cancer cell lines derived from hepatocellular adenocarcinoma (HepG2), renal cell carcinoma (769-P), non-small cell lung cancer (NCI-H1563) and glioblastoma multiforme (LN229) in comparison to the physiological human embryonic kidney (HEK-293) cell line. The influence of the tested substances on the cell cycle and apoptosis was also evaluated. Fish embryo acute toxicity test (FET) was performed based on OECD Guidelines (Test No. 236), and was carried out for the first 5 days post fertilization. The following concentrations of APS-1 and APS-18 were tested: 125-2000 μM and 0.125-1000 μM, respectively. The presented studies on the antiproliferative properties of the new semicarbazide derivatives showed that the compounds APS-1 and APS-18 reduce the viability of human tumor lines. Particularly noteworthy is the strong and selective antiproliferative activity of APS-18 against all neoplastic cell lines, in particular against glioblastoma. Against this tumor line, the compound APS-1 showed an effective inhibitory effect. In the FET we noted that the direct exposure of zebrafish embryos to APS-1 and APS-18 in used range of concentration did not cause morphological abnormalities, including cardiotoxicity. On basis of obtained outcomes it could be concluded that APS-1 and APS-18 may constitute models for further research, design and synthesis of new, safer drugs with more favorable anticancer properties.

X-ray Structures and Computational Studies of Two Bioactive 2-(Adamantane-1-carbonyl)-N-substituted Hydrazine-1-carbothioamides

Two biologically active adamantane-linked hydrazine-1-carbothioamide derivatives, namely 2-(adamantane-1-carbonyl)-N-(tert-butyl)hydrazine-1-carbothioamide) 1 and 2-(adamantane-1-carbonyl)-N-cyclohexylhydrazine-1-carbothioamide 2, have been synthesized. X-ray analysis was conducted to study the effect of the t-butyl and cyclohexyl moieties on the intermolecular interactions and conformation of the molecules in the solid state. X-ray analysis reveals that compound 1 exhibits folded conformation, whereas compound 2 adopts extended conformation. The Hirshfeld surface analysis indicates that the contributions of the major intercontacts involved in the stabilization of the crystal structures do not change much as a result of the t-butyl and cyclohexyl moieties. However, the presence and absence of these contacts is revealed by the 2D-fingerprint plots. The CLP-Pixel method was used to identify the energetically significant molecular dimers. These dimers are stabilized by different types of intermolecular interactions such as N-H···S, N-H···O, C-H···S, C-H···O, H-H bonding and C-H···π interactions. The strength of these interactions was quantified by using the QTAIM approach. The results suggest that N-H···O interaction is found to be stronger among other interactions. The in vitro assay suggests that both compounds 1 and 2 exhibit urease inhibition potential, and these compounds also display moderate antiproliferative activities. Molecular docking analysis shows the key interaction between urease enzyme and title compounds.

Antitubercular activity assessment of fluorinated chalcones, 2-aminopyridine-3-carbonitrile and 2-amino-4H-pyran-3-carbonitrile derivatives: In vitro, molecular docking and in-silico drug likeliness studies

A series of newer previously synthesized fluorinated chalcones and their 2-amino-pyridine-3-carbonitrile and 2-amino-4H-pyran-3-carbonitrile derivatives were screened for their in vitro antitubercular activity and in silico methods. Compound 40 (MIC~ 8 μM) was the most potent among all 60 compounds, whose potency is comparable with broad spectrum antibiotics like ciprofloxacin and streptomycin and three times more potent than pyrazinamide. Additionally, compound 40 was also less selective and hence non-toxic towards the human live cell lines-LO2 in its MTT assay. Compounds 30, 27, 50, 41, 51, and 60 have exhibited streptomycin like activity (MIC~16–18 μM). Fluorinated chalcones, pyridine and pyran derivatives were found to occupy prime position in thymidylate kinase enzymatic pockets in molecular docking studies. The molecule 40 being most potent had shown a binding energy of -9.67 Kcal/mol, while docking against thymidylate kinase, which was compared with its in vitro MIC value (~8 μM). These findings suggest that 2-aminopyridine-3-carbonitrile and 2-amino-4H-pyran-3-carbonitrile derivatives are prospective lead molecules for the development of novel antitubercular drugs.

Potential Anticancer Agents against Melanoma Cells Based on an As-Synthesized Thiosemicarbazide Derivative

In this paper, thiosemicarbazide derivatives were synthesized as potential anticancer agents. X-ray investigations for 1-(2,4-dichlorophenoxy)acetyl-4-(2-fluorophenyl) thiosemicarbazide, 1-(2,4-dichlorophenoxy)acetyl-4-(4-metylothiophenyl)thiosemicarbazide and 1-(2,4-di chlorophenoxy)acetyl-4-(4-iodophenyl)thiosemicarbazide were carried out in order to confirm the synthesis pathways, identify their tautomeric forms, analyze the conformational preferences of molecules, and identify intra- and intermolecular interactions in the crystalline state. TLC and RP-HPLC analyses were used to determine lipophilicity. The lipophilicity analysis revealed that the 4-substituted halogen derivatives of thiosemicarbazides showed greater lipophilicity compared with 2-substituted derivatives. The optimal range of lipophilicity for biologically active compounds logkw is between 4.14 and 4.78. However, as the analysis showed, it is not a decisive parameter. The cytotoxicity of the new compounds was evaluated against both the G-361 and BJ cell lines. Cytotoxicity analyses and cell-cycle and cell apoptosis assays were performed. The MTT test demonstrated that three compounds were cytotoxic to melanoma cells and not toxic to normal fibroblasts in the concentration range used. The cell cycle analysis showed that the compounds had no significant effect on the cell cycle inhibition. An extensive gene expression analysis additionally revealed that all compounds tested downregulated the expression of dihydroorotate dehydrogenase (DHODH). DHODH is a mitochondrial enzyme involved in the de novo synthesis of pyrimidines. Due to the rapid rate of cancer cell proliferation and the increased demand for nucleotide synthesis, it has become a potential therapeutic target.

New Application of 1,2,4-Triazole Derivatives as Antitubercular Agents. Structure, In Vitro Screening and Docking Studies

A series of 1,2,4-triazole derivatives were synthesized and assigned as potential anti-tuberculosis substances. The molecular and crystal structures for the model compounds C1, C12, and C13 were determined using X-ray analysis. The X-ray investigation confirmed the synthesis pathway and the assumed molecular structures for analyzed 1,2,4-triazol-5-thione derivatives. The conformational preferences resulting from rotational degrees of freedom of the 1,2,4-triazole ring substituents were characterized. The lipophilicity (logP) and electronic parameters as the energy of frontier orbitals, dipole moments, NBO net charge distribution on the atoms, and electrostatic potential distribution for all structures were calculated at AM1 and DFT/B3LYP/6-311++G(d,p) level. The in vitro test was done against M. tuberculosis H37Ra, M. phlei, M. smegmatis, and M. timereck. The obtained results clearly confirmed the antituberculosis potential of compound C4, which turned out to be the most active against Mycobacterium H37Ra (MIC = 0.976 μg/mL), Mycobaterium pheli (MIC = 7.81 μg/mL) and Mycobacerium timereck (62.6 μg/mL). Satisfactory results were obtained with compounds C8, C11, C14 versus Myc. H37Ra, Myc. pheli, Myc. timereck (MIC = 31.25-62.5 μg/mL). The molecular docking studies were carried out for all investigated compounds using the Mycobacterium tuberculosis cytochrome P450 CYP121 enzyme as molecular a target connected with antimycobacterial activity.

Synthesis and Anthelmintic Activity of New Thiosemicarbazide Derivatives-A Preliminary Study

Parasitic infections caused by different species of intestinal helminths still poses a threat to public health. There is a need to search for new, effective anthelmintic drugs. A series of novel thiosemicarbazides were synthesized and evaluated for their in vitro anthelmintic activity. The preliminary results showed that the most of synthesized compounds were very active. 4-Phenyl-1-[(1-methyl-4-nitroimidazol-2-yl)carbonyl]thiosemicarbazide and 4-(3-chlorophenyl)-1-[(1-methyl-4-nitroimidazol-2-yl)carbonyl]thiosemicarbazide showed a 100% mortality of nematodes and a high anthelmintic activity in both tested concentrations.

2,4-Dichlorophenoxyacetic Thiosemicarbazides as a New Class of Compounds Against Stomach Cancer Potentially Intercalating with DNA

Thiosemicarbazide is a useful structural moiety that has the biological potential. Optimization of this structure can result in groundbreaking discovery of a new class of therapeutic agents. In the light of this, 1-(2,4-dichlorophenoxy)acetyl-4-(1-naphthyl)thiosemicarbazide (1) and 1,4-bis[(2,4-dichlorophenoxy)acetylthiosemicarbazide]phenyl (2) were synthesized and characterized by spectroscopic method. Cytotoxicity of obtained compounds was evaluated on MKN74 gastric cancer cell line and human skin fibroblast BJ based on methylthiazolyldiphenyl-tetrazolium bromide (MTT) test. The apoptosis/necrosis and cell cycle analysis were conducted using image cytometry. Additionally, in DNA of treated cells, abasic sites (AP) and double strands breaks (DSB) presence were measured. Intercalating properties of active compounds were evaluated using the UV–spectroscopic method. Among newly synthesized derivatives, compound 2 showed toxic effects on gastric cancer cells with simultaneous lack of toxicity to normal fibroblasts. Cell cycle analysis revealed that both compounds influence cell division mainly at the stage of replication. Simultaneously with DNA synthesis disorders, DNA damages like AP-sites and DSBs were observed. Spectroscopic studies revealed possible DNA intercalating properties of tested compounds. Obtained results indicate that the newly synthesized thiosemicarbazide derivatives are a promising group of compounds with potential anticancer activity resulted from interactions with DNA and cell cycle interrupt.

Identification and molecular modeling of new quinolin-2-one thiosemicarbazide scaffold with antimicrobial urease inhibitory activity

A new series of 6-substituted quinolin-2-one thiosemicarbazides 6a-j has been synthesized. The structure of the target compounds was proved by different spectroscopic and elemental analyses. All the designed final compounds were evaluated for their in vitro activity against the urease-producing R. mucilaginosa and Proteus mirabilis bacteria as fungal and bacterial pathogens, respectively. Moreover, all compounds were in vitro tested as potential urease inhibitors using the cup-plate diffusion method. Compounds 6a and 6b were the most active with (IC₅₀ = 0.58 ± 0.15 and 0.43 ± 0.09 µM), respectively, in comparison with lead compound I (IC₅₀ = 1.13 ± 0.00 µM). Also, the designed compounds were docked into urease proteins (ID: 3LA4 and ID: 4UBP) using Open Eye^® software to understand correctly about ligand-receptor interactions. The docking results revealed that the designed compounds can interact with the active site of the enzyme through multiple strong hydrogen bonds. Moreover, rapid overlay of chemical structures' analysis was described to understand the 3D QSAR of synthesized compounds as urease inhibitors. The results emphasize the importance of polar thiosemicarbazide directly linked to 6-substituted quinolone moieties as promising antimicrobial urease inhibitors.