Synthesis and antiviral properties of novel indole-based thiosemicarbazides and 4-thiazolidinones

Microwave-induced one-pot synthesis of 3-imidazolyl indole clubbed 1,2,3-triazole hybrids as antiproliferative agents and density functional theory study

Herein, we outline a highly efficient PEG-4000-mediated one-pot three-component reaction for the synthesis of 3-imidazolyl indole clubbed 1,2,3-triazole derivatives (5a-r) at up to 96% yield as antiproliferative agents. This three-component protocol offers the advantages of an environmentally benign reaction, excellent yield, quick response time, and operational simplicity triggered by the copper catalyst under microwave irradiation. All the synthesized compounds were tested for antiproliferative activity against six human solid tumor cell lines, that is, A549 and SW1573 (nonsmall cell lung), HBL100 and T-47D (breast), HeLa (cervix), and WiDr (colon). Among them, six compounds, 5g-j, 5m, and 5p, demonstrated effective antiproliferative action with GI50 values under 10 μM. Furthermore, density functional theory (DFT) calculations were performed for all the synthesized molecules through geometry optimizations, frontier molecular orbital approach, and molecular electrostatic potential (MESP). The theoretical DFT calculation was performed using the DFT/B3LYP/6-31+G (d,p) basis set. Moreover, the biological reactivity of all the representative synthesized molecules was compared with the theoretically calculated quantum chemical descriptors and MESP 3D plots. We also investigated the drug-likeness characteristic and absorption, distribution, metabolism, excretion, and toxicity (ADMET) prediction. In general, our approach enables environmentally friendly access to 3-imidazolyl indole clubbed 1,2,3-triazole derivatives as prospective antiproliferative agents.

N-Substituted 2-(Benzenosulfonyl)-1-Carbotioamide Derivatives Exert Antimicrobial and Cytotoxic Effects via Aldehyde Dehydrogenase Pathway: Synthesis, In Silico and In Vitro Studies

A series of N-Substituted 2-(benzenosulfonyl)-1-carbotioamide derivatives (WZ1-WZ4) were synthesized and characterized using spectral methods. A comprehensive activity study was performed for each compound. All compounds were tested for antibacterial activity. Moreover, in silico studies were carried out to determine the anticancer potential of the designed WZ1-WZ4 ligands. Based on molecular docking, aldehyde dehydrogenase was selected as a molecular target. The obtained data were compared with experimental data in vitro tests. Novel hybrids of the thiosemicarbazide scaffold and sulfonyl groups may have promising anticancer activity via the aldehyde dehydrogenase pathway. The best candidate for further studies appears to be WZ2, due to its superior selectivity in comparison to the other tested compounds.

In silico approach identified benzoylguanidines as SARS-CoV-2 main protease (Mpro) potential inhibitors

The coronavirus disease-2019 (COVID-19) pandemic, caused by the novel coronavirus severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), became the highest public health crisis nowadays. Although the use of approved vaccines for emergency immunization and the reuse of FDA-approved drugs remains at the forefront, the search for new, more selective, and potent drug candidates from synthetic compounds is also a viable alternative to combat this viral disease. In this context, the present study employed a computational virtual screening approach based on molecular docking and molecular dynamics (MD) simulation to identify possible inhibitors for SARS-CoV-2 Mpro (main protease), an important molecular target required for the maturation of the various polyproteins involved in viral replication. The virtual screening approach selected four potential inhibitors against SARS-CoV-2 Mpro. In addition, MD simulation studies revealed changes in the positions of the ligands during the simulations compared to the complex obtained in the molecular docking studies, showing the benzoylguanidines LMed-110 and LMed-136 have a higher affinity for the active site compared to the other structures that tended to leave the active site. Besides, there was a better understanding of the formation and stability of the existing H-bonds in the formed complexes and the energetic contributions to the stability of the target-ligand molecular complexes. Finally, the in silico prediction of the ADME profile suggested that LMed-136 has drug-like characteristics and good pharmacokinetic properties. Therefore, from the present study, it can be suggested that these structures can inhibit SARS-CoV-2 Mpro. Nevertheless, further studies are needed in vitro assays to investigate the antiviral properties of these structures against SARS-CoV-2.

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.

Exploring Synthesis and Chemotherapeutic Potential of Thiosemicarbazide Analogs

BACKGROUND

Cancer is a leading cause of death worldwide, accounting for nearly 10 million deaths in 2020. Researchers are continually finding new and more effective medications to battle the diseases.

OBJECTIVE

The objective of this study is to identify the emerging role of Thiosemicarbazide analogs for different types of cancer targets with a glance at different novel synthetic routes reported for their synthesis.

METHODS

A systematic literature review was conducted from various sources over the last 15 years with the inclusion of published research and review articles that involves the synthesis and use of thiosemicarbazide analogs for different targets of cancer. Data from the literature review for synthesis and anticancer potential for specific targets for cancer studies of thiosemicarbazide analogs are summarized in the paper.

RESULTS

There are several emerging studies for new synthetic routes of thiosemicarbazide derivatives with their role in various types of cancers. The main limitation is the lack of clinical trial of the key findings for the emergence of new anticancer medication with thiosemicarbazide moiety.

CONCLUSION

Emerging therapies exist for use of a limited number of medications for the treatment of cancer; results of the ongoing studies will provide more robust evidence in the future.

Synthesis, antimicrobial activity and molecular docking studies of spiroquinoline-indoline-dione and spiropyrazolo-indoline-dione derivatives

Spiro[benzo[h]quinoline-7,3'-indoline]diones and spiro[indoline-3,4'-pyrazolo[3,4-b]quinoline]diones were efficiently synthesized via one-pot multi-component reactions under ultrasound-promoted conditions. Spiro[benzo[h]quinoline-7,3'-indoline]dione derivatives were successfully developed by the reaction of isatins, naphthalene-1-amine and 1,3-dicarbonyl compounds. The spiro[indoline-3,4'-pyrazolo[3,4-b]quinoline]dione derivatives were prepared by the reaction of isatins, 5-amino-1-methyl-3-pheylpyrazole, and 1,3-dicarbonyl compounds by using ( ±)-camphor-10-sulfonic acid as a catalyst in H₂O/EtOH (3:1 v/v) solvent mixture. The antibacterial activity of the synthesized compounds was evaluated against, Enterococcus faecalis, Staphylococcus aureus and Candida albicans. Compounds 4b, 4h, and 6h showed the strongest antimicrobial activity toward both bacteria. The MIC values of these compounds ranged from 375-3000 µg/mL. The effect of these compounds (4b, 4h, 6h) as a function of applied dose and time was investigated by a kinetic study, and the interaction with these antimicrobial results was simulated by a molecular docking study. We also used the docking approach with Covid-19 since secondary bacterial infections. Docking showed that indoline-quinoline hybrid compounds 4b and 4h exerted the strongest docking binding value against the active sites of 6LU7. In addition, the synthesized compounds had a moderate to good free radical scavenging activity.

Recent Advances of Tubulin Inhibitors Targeting the Colchicine Binding Site for Cancer Therapy

Cancer accounts for numerous deaths each year, and it is one of the most common causes of death worldwide, despite many breakthroughs in the discovery of novel anticancer candidates. Each new year the FDA approves the use of new drugs for cancer treatments. In the last years, the biological targets of anticancer agents have started to be clearer and one of these main targets is tubulin protein; this protein plays an essential role in cell division, as well as in intracellular transportation. The inhibition of microtubule formation by targeting tubulin protein induces cell death by apoptosis. In the last years, numerous novel structures were designed and synthesized to target tubulin, and this can be achieved by inhibiting the polymerization or depolymerization of the microtubules. In this review article, recent novel compounds that have antiproliferation activities against a panel of cancer cell lines that target tubulin are explored in detail. This review article emphasizes the recent developments of tubulin inhibitors, with insights into their antiproliferative and anti-tubulin activities. A full literature review shows that tubulin inhibitors are associated with properties in the inhibition of cancer cell line viability, inducing apoptosis, and good binding interaction with the colchicine binding site of tubulin. Furthermore, some drugs, such as cabazitaxel and fosbretabulin, have been approved by FDA in the last three years as tubulin inhibitors. The design and development of efficient tubulin inhibitors is progressively becoming a credible solution in treating many species of cancers.

2,4-Disubstituted pyridine derivatives are effective against intracellular and biofilm-forming tubercle bacilli

It was recently reported that 4-substituted picolinohydrazonamides carrying hydrophilic cyclic amines, such as morpholine and pyrrolidine, at the end of their thiosemicarbazide chain have potent antimycobacterial activity in vitro at concentrations below 1 μg/ml. Here, two selected compounds, 2,4-disubstituted pyridine derivatives 11 and 15, revealed significant bactericidal activity against Mycobacterium tuberculosis localized intracellularly within human macrophages, as well as against biofilm-forming tubercle bacilli. Mutants were selected that were resistant to the investigated compounds at an efficiency similar to that identified in the presence of the first line antituberculosis drug rifampicin. The resistant mutants were viable in the presence of the tested compounds exclusively on solid media. Genome-wide sequencing of the mutants selected in the presence of compound 11 revealed the accumulation of nonsynonymous mutations in the mmpR5 gene encoding a transcriptional repressor of the MmpS5-MmpL5 efflux pump, whose upregulation has been associated with bedaquiline resistance. The depletion of MmpR5 in wild-type M. tuberculosis using CRISPR–Cas9 technology increased the resistance of this strain to compound 11. Mass spectrometry-based proteomics (LC–MS/MS) of wild-type tubercle bacilli growing in subinhibitory concentrations of compounds 11 or 15 revealed 15 overproduced proteins not detectable in the control cells, including virulence-related proteins.

Antitumor Activity and Physicochemical Properties of New Thiosemicarbazide Derivative and Its Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) Complexes

A novel biologically active thiosemicarbazide derivative ligand L (N-[(phenylcarbamothioyl)amino]pyridine-3-carboxamide) and a series of its five metal(II) complexes, namely: [Co(L)Cl₂], [Ni(L)Cl₂(H₂O)], [Cu(L)Cl₂(H₂O)], [Zn(L)Cl₂] and [Cd(L)Cl₂(H₂O)] have been synthesized and thoroughly investigated. The physicochemical characterization of the newly obtained compounds has been performed using appropriate analytical techniques, such as ¹H and ^l3C nuclear magnetic resonance (NMR), inductively coupled plasma (ICP), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR) and magnetic measurements. In order to study the pharmacokinetic profile of the compounds, ADMET analysis was performed. The in vitro studies revealed that the synthesized compounds exhibit potent biological activity against A549 human cancer cell line.

Design, synthesis, and in vitro and in vivo anticancer activity studies of new (S)-Naproxen thiosemicarbazide/1,2,4-triazole derivatives

This study includes the synthesis of new Naproxen derivatives and in vitro–in vivo molecular mechanistic studies.

Synthesis, Cytotoxicity, Antioxidant and Antimicrobial Activity of Indole Based Novel Small Molecules

Aim:

In this study experiments were carried out to explore antioxidant, antimicrobial, cytotoxic properties of novel indole derivative 1-ethyl-2-phenyl-3-phenylethyl-3-thiophen-2-yl-1Hindole (EPI) together with its effect on glutathione S-transferases (GST) activities in human liver carcinoma (HepG2) cells.

Background::

Indoles probably represent one of the most important heterocyclic structures that have been attracting the interest of many scientists in drug discovery.

Objective:

The present study was carried out to explore antioxidant, antimicrobial, cytotoxic properties of novel indole derivative 1-ethyl-2-phenyl-3-phenylethyl-3-thiophen-2-yl-1H-indole (EPI) and its effect on glutathione S-transferases (GST) activities in human liver carcinoma (HepG2) cells.

Materials and Methods:

Pd-catalyst Sonogashira coupling reactions, MTT Assay, Antioxidant capacity test, Antimicrobial test, GST enzyme activity test.

Results:

1-ethyl-2-phenyl-3-(phenylethynyl)-1H-indole had antioxidant and antimicrobial properties. It displayed significant induction in glutathione S-transferases (GST) enzyme activity in human liver cancer cell lines (HepG2), but cytotoxic effect on all tested cancer cell lines could not be observed.

Conclusion::

All of these results showed that 1-ethyl-2-phenyl-3-(phenylethynyl)-1H-indole had antioxidant and antimicrobial properties without cytotoxic effect, which could make it a promising active component with further studies.

Design, synthesis, and bioassay of 4-thiazolinone derivatives as influenza neuraminidase inhibitors

A series of 4-thiazolinone derivatives (D1-D58) were designed and synthesized. All of the derivatives were evaluated in vitro for neuraminidase (NA) inhibitory activities against influenza virus A (H1N1), and the inhibitory activities of the five most potent compounds were further evaluated on NA from two different influenza viral subtypes (H3N2 and B), and then their in vitro anti-viral activities were evaluated using the cytopathic effect (CPE) reduction assay. The results showed that the majority of the target compounds exhibited moderate to good NA inhibitory activity. Compound D18 presented the most potent inhibitory activity with IC₅₀ values of 13.06 μM against influenza H1N1 subtype. Among the selected compounds, D18 and D41 turned out to be the most potent inhibitors against influenza virus H3N2 subtype (IC₅₀ = 15.00 μM and IC₅₀ = 14.97 μM, respectively). D25 was the most potent compound against influenza B subtype (IC₅₀ = 16.09 μM). In addition, D41 showed low toxicity and greater potency than reference compounds Oseltamivir and Amantadine against N1-H275Y variant in cellular assays. The structure-activity relationship (SAR) analysis showed that introducing 4-CO₂H, 4-OH, 3-OCH₃-4-OH substituted benzyl methylene can greatly improve the activity of 4-thiazolinones. Further SAR analysis indicated that 4-thiazolinone and ferulic acid fragments are necessary fragments of target compounds for inhibiting NA. Molecular docking was performed to study the interaction between compound D41 and the active site of NA. This study may providing important information for new drug development for anti-influenza virus including mutant influenza virus.

The design, synthesis, and in vitro trypanocidal and leishmanicidal activities of 1,3-thiazole and 4-thiazolidinone ester derivatives

Chagas and leishmaniasis are both neglected tropical diseases, whose inefficient therapies have made them remain the cause for millions of deaths worldwide. Given this, we synthesized 27 novel 1,3-thiazoles and 4-thiazolidinones using bioisosteric and esterification strategies to develop improved and safer drug candidates. After an easy, rapid and low-cost synthesis with satisfactory yields, compounds were structurally characterized. Then, in vitro assays were performed, against Leishmania infantum and Leishmania amazonensis promastigotes, Trypanosoma cruzi trypomastigotes and amastigotes, for selected compounds to determine IC₅₀ and SI, with cytotoxicity on LLC-MK2 cell lines. Overall, 1,3-thiazoles exhibited better trypanocidal activity than 4-thiazolidinones. The compound 1f, an ortho-bromobenzylidene-substituted 1,3-thiazole (IC₅₀ = 0.83 μM), is the most potent of them all. In addition, compounds had negligible cytotoxicity in mammalian cells (CC₅₀ values > 50 μM). Also noteworthy is the examination of the cell death mechanism of T. cruzi, which showed that compound 1f induced necrosis and apoptosis in the parasite. Scanning electron microscopy analysis demonstrated that the treatment of Trypanosoma cruzi trypomastigote cells with the compound 1f at different IC₅₀ concentrations promoted alterations in the shape, flagella and body surface, inducing parasite death. Together, our data revealed a novel series of 1,3-thiazole structure-based compounds with promising activity against Trypanosoma cruzi and Leishmania spp., broadening ways for scaffold optimization.

Chagas and leishmaniasis are both neglected tropical diseases, whose inefficient therapies have made them remain the cause for millions of deaths worldwide.

A brief review of the biological potential of indole derivatives

Background

Various bioactive aromatic compounds containing the indole nucleus showed clinical and biological applications. Indole scaffold has been found in many of the important synthetic drug molecules which gave a valuable idea for treatment and binds with high affinity to the multiple receptors helpful in developing new useful derivatives.

Main text

Indole derivatives possess various biological activities, i.e., antiviral, anti-inflammatory, anticancer, anti-HIV, antioxidant, antimicrobial, antitubercular, antidiabetic, antimalarial, anticholinesterase activities, etc. which created interest among researchers to synthesize a variety of indole derivatives.

Conclusion

From the literature, it is revealed that indole derivatives have diverse biological activities and also have an immeasurable potential to be explored for newer therapeutic possibilities.

Synthesis of Cobalt Hydroxide Nano-flakes Functionalized with Glutamic Acid and Conjugated with Thiosemicarbazide for Anticancer Activities Against Human Breast Cancer Cells

In recent years, researchers were attracted to nanomaterials components for their potential role in cancer treatment. This study aimed to develop a novel and biocompatible cobalt hydroxide (Co(OH)₂) nano-flakes that is functionalized by glutamic acid (Glu) and conjugated to thiosemicarbazide (TSC) for anticancer activities against human breast cancer MCF-7 cells. Physico-chemical properties of the Co(OH)₂@Glu-TSC nanomaterial are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, and Fourier-transform infrared (FT-IR) spectroscopy. MTT assay, flow cytometry, and caspase-3 activity analysis used for evaluating anticancer properties of the Co(OH)₂@Glu-TSC nanomaterial. The MTT assay result showed cellular uptake of Co(OH)₂@Glu-TSC and cell viability loss in a concentration-dependent. Results of flow cytometry and caspase-3 activity analysis indicated the stimulation of apoptosis through an increase in Caspase-3 and nucleus fragmentation. In general, our findings indicate the anticancer activities of Co(OH)₂@Glu-TSC nanomaterial and so it can be considered as a new treatment for breast cancer. However, further in vivo studies are required to evaluate the accumulation of Co(OH)₂@Glu-TSC nanomaterial in healthy organs, such as the liver, kidneys, brain, and testes, and potential toxic effects.

Synthesis and Biological Evaluation of Benzodioxol Derivatives as Cyclooxygenase Inhibitors

Background:

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used therapeutics; they are competitive inhibitors of cyclooxygenase (COX), the enzyme which mediates the conversion of arachidonic acid to inflammatory prostaglandins.

Objective:

In this study, new benzodioxol derivatives with different core cycles and functional groups (i.e., aryl acetate, aryl acetic acid and diazepine) were designed, synthesized, identified and evaluated for their analgesic and anti-inflammatory activity, as a preliminary screening study to identify the most potent and more selective groups.

Methods:

The synthesized compounds were identified using FTIR, HRMS, 1H-NMR and 13C-NMR, and evaluated for their inhibitory activity against ovine COX-1 and COX-2 using an in vitro cyclooxygenase (COX) inhibition assay kit.

Results:

Six compounds were synthesized as a preliminary screening study to identify which was the most potent and more selective group towards COX-2 versus COX-1, compared to ketoprofen as non-selective NSAIDs. The compounds have three different groups: aryl acetate, aryl acetic acid and diazepine. The results showed that the most potent compound against the COX- 1 enzyme was 4b (which has diazepine and 2-chlorophenyl) with IC50 = 0.363 μM, and the selectivity ratio of 4b was found to be better than ketoprofen. In contrast, compound 4a (which has diazepine and 3-chlorophenyl) was the most selective with a COX-1/COX-2 ratio value of 0.85 in comparison with a ketoprofen ratio value of 0.20.

Conclusion:

In general, the synthesized library has moderate activity against both enzymes (i.e., COX-1 and COX-2). Moreover, all six compounds have better COX-2 inhibition selectivity compared to the commercial drug ketoprofen.

Thiosemicarbazides: Updates on Antivirals Strategy

The challenges of viral infection have increased in recent decades due to the emergence of resistance, cross-resistance and drying up of antiviral drug discovery. Many neglected tropical viruses including the chikungunya virus, dengue virus & Japanese encephalitis virus have gradually become global pathogens. This has further increased the burden of viral infection which necessitates the continuous development of antiviral therapy. The antiviral chemistry began with the development of thiosemicarbazide derived thiosemicarbazones as antiviral. Although very few thiosemicarbazides have progressed into clinical application, it still inspires antiviral development. During last 3 decades (1990- 2020), several efforts have been made to develop suitable antiviral by using thiosemicarbazide scaffold. Its hybridization with other pharmacophores has been used as a strategy to enhance safety and efficacy. Cyclization and substitution of thiosemicarbazides have also been used to develop potent antiviral. With the ability to form coordinate bonds, thiosemicarbazides have been used either as metal complex or chelator against viruses. This work is an attempt to systematically review the research on the use of thiosemicarbazides as an antiviral scaffold. It also reviews the structure-activity relationship and translational suitability of thiosemicarbazide derived compounds.

Saturated Five-Membered Thiazolidines and Their Derivatives: From Synthesis to Biological Applications

In past decades, interdisciplinary research has been of great interest for scholars. Thiazolidine motifs behave as a bridge between organic synthesis and medicinal chemistry and compel researchers to explore new drug candidates. Thiazolidine motifs are very intriguing heterocyclic five-membered moieties present in diverse natural and bioactive compounds having sulfur at the first position and nitrogen at the third position. The presence of sulfur enhances their pharmacological properties, and, therefore, they are used as vehicles in the synthesis of valuable organic combinations. They show varied biological properties viz. anticancer, anticonvulsant, antimicrobial, anti-inflammatory, neuroprotective, antioxidant activity and so on. This diversity in the biological response makes it a highly prized moiety. Based on literature studies, various synthetic approaches like multicomponent reaction, click reaction, nano-catalysis and green chemistry have been employed to improve their selectivity, purity, product yield and pharmacokinetic activity. In this review article, we have summarized systematic approaches for the synthesis of thiazolidine and its derivatives, along with their pharmacological activity, including advantages of green synthesis, atom economy, cleaner reaction profile and catalyst recovery which will help scientists to probe and stimulate the study of these scaffolds.

4-Substituted picolinohydrazonamides as a new class of potential antitubercular agents

The series of new 4-substituted picolinohydrazonamides were synthesized (6-25) and evaluated for tuberculostatic activity. Compounds having a hydrophilic cyclic amine such as morpholine and pyrrolidine at the end of the thiosemicarbazide chain, exhibited the highest antimycobacterial activity. The antimycobacterial activity of compounds 6, 11, and 15 (MIC 0.4-0.8 μg/mL) was higher than that of reference drugs. Moreover, derivative 15 exhibited lower activity against other tested microorganism such as bacteria gram-positive, gram-negative or fungi. Thus, this compound is characterized by the selectivity of antimicrobial activity. Antiproliferative study conducted against human dermal fibroblasts (HDF) and mouse melanoma cell line (B16-F10) revealed low cytotoxicity of compound 15. Conducted research allowed to identify compound 15 as leading for further research.

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.

Synthesis, crystal structures, antiproliferative activities and reverse docking studies of eight novel Schiff bases derived from benzil

Eight novel Schiff bases derived from benzil dihydrazone (BDH) or benzil monohydrazone (BMH) and four fused-ring carbonyl compounds (3-formylindole, FI; 3-acetylindole, AI; 3-formyl-1-methylindole, MFI; 1-formylnaphthalene, FN) were synthesized and characterized by elemental analysis, ESI-QTOF-MS, ¹H and ¹³C NMR spectroscopy, as well as single-crystal X-ray diffraction. They are (1Z,2Z)-1,2-bis{(E)-[(1H-indol-3-yl)methylidene]hydrazinylidene}-1,2-diphenylethane (BDHFI), C₃₂H₂₄N₆, (1Z,2Z)-1,2-bis{(E)-[1-(1H-indol-3-yl)ethylidene]hydrazinylidene}-1,2-diphenylethane (BDHAI), C₃₄H₂₈N₆, (1Z,2Z)-1,2-bis{(E)-[(1-methyl-1H-indol-3-yl)methylidene]hydrazinylidene}-1,2-diphenylethane (BMHMFI) acetonitrile hemisolvate, C₃₄H₂₈N₆·0.5CH₃CN, (1Z,2Z)-1,2-bis{(E)-[(naphthalen-1-yl)methylidene]hydrazinylidene}-1,2-diphenylethane (BDHFN), C₃₆H₂₆N₄, (Z)-2-{(E)-[(1H-indol-3-yl)methylidene]hydrazinylidene}-1,2-diphenylethanone (BMHFI), C₂₃H₁₇N₃O, (Z)-2-{(E)-[1-(1H-indol-3-yl)ethylidene]hydrazinylidene}-1,2-diphenylethanone (BMHAI), C₂₄H₁₉N₃O, (Z)-2-{(E)-[(1-methyl-1H-indol-3-yl)methylidene]hydrazinylidene}-1,2-diphenylethanone (BMHMFI), C₂₄H₁₉N₃O, and (Z)-2-{(E)-[(naphthalen-1-yl)methylidene]hydrazinylidene}-1,2-diphenylethanone (BMHFN) C₂₅H₁₈N₂O. Moreover, the in vitro cytotoxicity of the eight title compounds was evaluated against two tumour cell lines (A549 human lung cancer and 4T₁ mouse breast cancer) and two normal cell lines (MRC-5 normal lung cells and NIH 3T3 fibroblasts) by MTT assay. The results indicate that four (BDHMFI, BDHFN, BMHMFI and BMHFN) are inactive and the other four (BDHFI, BDHAI, BMHFI and BMHAI) show severe toxicities against human A549 and mouse 4T₁ cells, similar to the standard cisplatin. All the compounds exhibited weaker cytotoxicity against normal cells than cancer cells. The Swiss Target Prediction web server was applied for the prediction of protein targets. After analyzing the differences in frequency hits between these active and inactive Schiff bases, 18 probable targets were selected for reverse docking with the Surflex-dock function in SYBYL-X 2.0 software. Three target proteins, i.e. human ether-á-go-go-related (hERG) potassium channel, the inhibitor of apoptosis protein 3 and serine/threonine-protein kinase PIM1, were chosen as the targets. Finally, the ligand-based structure-activity relationships were analyzed based on the putative protein target (hERG) docking results, which will be used to design and synthesize novel hERG ion channel inhibitors.

Synthesis and antituberculosis activity of new acylthiosemicarbazides designed by structural modification

Acylthiosemicarbazides 8a-n were designed by structural modification of lead Compound 7. The syntheses of 8a-n involve a five-step procedure starting from carboxylic acids. Compounds 8a-n were tested against three Mycobacterium tuberculosis strains to measure their inhibitory antituberculosis activities. These activities could be explained according to the presence or absence of the chlorine substituent in the aromatic ring of the amide joined to the thiosemicarbazide core. Thiosemicarbazide derivative 8n is a candidate for the development of novel antitubercular agents. Ongoing studies are focused on exploring the mechanism by which these compounds inhibit M. tuberculosis cell growth.

Antimicrobial and Structural Properties of Metal Ions Complexes with Thiosemicarbazide Motif and Related Heterocyclic Compounds

Antibiotic resistance acquired by various bacterial fungal and viral pathogens poses therapeutic problems of increasing severity. Among the infections that are very difficult to treat, biofilm-associated cases are one of the most hazardous. Complex structure of a biofilm and unique physiology of the biofilm cells contribute to their extremely high resistance to environmental conditions, antimicrobial agents and the mechanisms of host immune response. Therefore, the biofilm formation, especially by multidrugresistant pathogens, is a serious medical problem, playing a pivotal role in the development of chronic and recurrent infections. These factors create a limitation for using traditional chemiotherapeutics and contribute to a request for development of new approaches for treatment of infectious diseases. Therefore, early reports on antimicrobial activity of several complexes of metal ions, bearing thiosemicarbazide or thiosemicarbazones as the ligands, gave a boost to worldwide search for new, more efficient compounds of this class, to be used as alternatives to commonly known drugs. In general, depending on the presence of other heteroatoms, these ligands may function in a di-, tri- or tetradentate forms (e.g., of N,S,-, N,N,S-, N,N,N,S-, N,N,S,S-, or N,S,O-type), which impose different coordination geometries to the resultant complexes. In the first part of this review, we describe the ways of synthesis and the structures of the ligands based on the thiosemicarbazone motif, while the second part deals with the antimicrobial activity of their complexes with selected metal ions.

Privileged Structures in the Design of Potential Drug Candidates for Neglected Diseases

Background:

Privileged motifs are recurring in a wide range of biologically active compounds that reach different pharmaceutical targets and pathways and could represent a suitable start point to access potential candidates in the neglected diseases field. The current therapies to treat these diseases are based in drugs that lack of the desired effectiveness, affordable methods of synthesis and allow a way to emergence of resistant strains. Due the lack of financial return, only few pharmaceutical companies have been investing in research for new therapeutics for neglected diseases (ND).

Methods:

Based on the literature search from 2002 to 2016, we discuss how six privileged motifs, focusing phthalimide, isatin, indole, thiosemicarbazone, thiazole, and thiazolidinone are particularly recurrent in compounds active against some of neglected diseases.

Results:

It was observed that attention was paid particularly for Chagas disease, malaria, tuberculosis, schistosomiasis, leishmaniasis, dengue, African sleeping sickness (Human African Trypanosomiasis - HAT) and toxoplasmosis. It was possible to verify that, among the ND, antitrypanosomal and antiplasmodial activities were between the most searched. Besides, thiosemicarbazone moiety seems to be the most versatile and frequently explored scaffold. As well, phthalimide, isatin, thiazole, and thiazolidone nucleus have been also explored in the ND field.

Conclusion:

Some described compounds, appear to be promising drug candidates, while others could represent a valuable inspiration in the research for new lead compounds.

Design of a Thiosemicarbazide-Functionalized Calix[4]arene Ligand and Related Transition Metal Complexes: Synthesis, Characterization, and Biological Studies

In this study, we synthesized a new thiosemicarbazide-functionalized calix[4]arene L and its Co2+, Ni2+, Cu2+, and Zn2+ transition metal complexes. For characterization several techniques were employed: Fourier-transform infrared (FT-IR), 1H nuclear magnetic resonance (NMR), 13C-NMR, 15N-NMR, correlation spectroscopy (COZY), nuclear Overhauser enhancement spectroscopy (NOESY), electrospray ionization (ESI)-mass spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and elemental analysis. To explore the capability of the thiosemicarbazide function hosted on a calix[4]arene scaffold for growth inhibition of bacteria, fungi, and cancerous tumor cells, a series of biological evaluations were performed. For L, the antimicrobial tests revealed a higher antibacterial activity against gram-positive Bacillus subtilis and a lower activity against gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), whereas the gram-positive Staphylococcus aureus shows resistance. All examined metal derivatives show an enhancement of the antibacterial activity against gram-negative E. coli bacteria, with a more significant improvement for the Ni2+ and Zn2+ complexes. MTT assays showed a considerable in vitro anticancer activity of Co2+, Ni2+, and Cu2+ complexes against Saos-2 bone cancer cell lines. The activity is ascribable to the inorganic ions rather than calixarene ligand. Hemolysis assay results demonstrated that all compounds have high blood compatibility.

A Review Exploring Therapeutic Worth of 1,3,4-Oxadiazole Tailored Compounds

1,3,4-Oxadiazole, a five-membered aromatic ring can be seen in a number of synthetic molecules. The peculiar structural feature of 1,3,4-oxadiazole ring with pyridine type of nitrogen atom is beneficial for 1,3,4-oxadiazole derivatives to have effective binding with different enzymes and receptors in biological systems through numerous weak interactions, thereby eliciting an array of bioactivities. Research in the area of development of 1,3,4-oxadiazole-based derivatives has become an interesting topic for the scientists. A number of 1,3,4-oxadiazole based compounds with high therapeutic potency are being extensively used for the treatment of different ailments, contributing to enormous development value. This work provides a systematic and comprehensive review highlighting current developments of 1,3,4-oxadiazole based compounds in the entire range of medicinal chemistry such as anticancer, antifungal, antibacterial, antitubercular, anti-inflammatory, antineuropathic, antihypertensive, antihistaminic, antiparasitic, antiobesity, antiviral, and other medicinal agents. It is believed that this review will be of great help for new thoughts in the pursuit for rational designs for the development of more active and less toxic 1,3,4-oxadiazole based medicinal agents.

Isatin Derivatives and Their Antiviral Properties Against Arboviruses: A Review

Arboviruses have been spreading rapidly throughout the Western Hemisphere in recent decades. Among the arboviruses with high morbidity and mortality are the members of the Alphavirus and Flavivirus genera. Within the first genus, Chikungunya Virus (CHIKV) is considered one of the most challenging human arboviral infection worldwide, against which there is no specific antivirals. Flaviviruses are some of the main viruses responsible for encephalitis, haemorrhagic disease and developmental defects. Dengue virus (DENV), Japanese Encephalitis Virus (JEV), West Nile Virus (WNV) and Zika Virus (ZIKV) are examples of flaviviruses without clinically approved antiviral agents. Thus, the search for new antivirals becomes highly important. One of the strategies that can be employed to obtain new drugs is the identification and utilization of privileged structures. Isatin is an example of a privileged molecular framework, displaying a broad spectrum of biological activities, including antiviral action. Obtaining and studying the antiviral properties of isatin derivatives have helped to identify important agents with potential activity against different arboviruses. This article reviews some of these isatin derivatives, their structures and antiviral properties reported against this important group of viruses.

Synthesis and Aldose Reductase Inhibitory Effect of Some New Hydrazinecarbothioamides and 4-Thiazolidinones Bearing an Imidazo[2,1-b]Thiazole Moiety

Objectives

To synthesize and characterize 2-[[6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl]acetyl]-N-alkyl/arylhydrazinecarbothioamide and 3-alkyl/aryl-2-[((6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl)acetyl)hydrazono]-5-nonsubstituted/methyl-4-thiazolidinone derivatives and evaluate them for their aldose reductase (AR) inhibitory effect.

Materials and Methods

2-[[6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl]acetyl]-N-alkyl/arylhydrazinecarbothioamides (3a-f) and 3-alkyl/aryl-2-[((6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl)acetyl)hydrazono]-5-nonsubstituted/methyl-4-thiazolidinones (4a-j) were synthesized from 2-[6-(4-bromophenyl)imidazo[2,1-b]thiazole-3-yl]acetohydrazide (2). Their structures were elucidated by elemental analyses and spectroscopic data. The synthesized compounds were tested for their ability to inhibit rat kidney AR.

Results

Among the synthesized compounds, 2-[[6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl]acetyl]-N-benzoylhydrazinecarbothioamide (3d) showed the best AR inhibitory activity.

Conclusion

The findings of this study indicate that the different derivatives of the compounds in this study may be considered interesting candidates for future research.