Bifunctional ethyl 2-amino-4-methylthiazole-5-carboxylate derivatives: Synthesis and in vitro biological evaluation as antimicrobial and anticancer agents

Combined In Silico and In Vitro Analyses to Assess the Anticancer Potential of Thiazolidinedione-Thiosemicarbazone Hybrid Molecules

The number of people affected by cancer and antibiotic-resistant bacterial infections has increased, such that both diseases are already seen as current and future leading causes of death globally. To address this issue, based on a combined in silico and in vitro approach, we explored the anticancer potential of known antibacterials with a thiazolidinedione-thiosemicarbazone (TZD-TSC) core structure. A cytotoxicity assessment showed encouraging results for compounds 2-4, with IC50 values against T98G and HepG2 cells in the low micromolar range. TZD-TSC 3 proved to be most toxic to cancer cell lines, with IC50 values of 2.97 ± 0.39 µM against human hepatoma HepG2 cells and IC50 values of 28.34 ± 2.21 µM against human glioblastoma T98G cells. Additionally, compound 3 induced apoptosis and showed no specific hemolytic activity. Furthermore, treatment using 3 on cancer cell lines alters these cells' morphology and further suppresses migratory activity. Molecular docking, in turn, suggests that 3 would have the capacity to simultaneously target HDACs and PPARγ, by the activation of PPARγ and the inhibition of both HDAC4 and HDAC8. Thus, the promising preliminary results obtained with TZD-TSC 3 represent an encouraging starting point for the rational design of novel chemotherapeutics with dual antibacterial and anticancer activities.

Expedition of sulfur-containing heterocyclic derivatives as cytotoxic agents in medicinal chemistry: A decade update

This review article proposes a comprehensive report of the design strategies engaged in the development of various sulfur-bearing cytotoxic agents. The outcomes of various studies depict that the sulfur heterocyclic framework is a fundamental structure in diverse synthetic analogs representing a myriad scope of therapeutic activities. A number of five-, six- and seven-membered sulfur-containing heterocyclic scaffolds, such as thiazoles, thiadiazoles, thiazolidinediones, thiophenes, thiopyrans, benzothiazoles, benzothiophenes, thienopyrimidines, simple and modified phenothiazines, and thiazepines have been discussed. The subsequent studies of the derivatives unveiled their cytotoxic effects through multiple mechanisms (viz. inhibition of tyrosine kinases, topoisomerase I and II, tubulin, COX, DNA synthesis, and PI3K/Akt and Raf/MEK/ERK signaling pathways), and several others. Thus, our concise illustration explains the design strategy and anticancer potential of these five- and six-membered sulfur-containing heterocyclic molecules along with a brief outline on seven-membered sulfur heterocycles. The thorough assessment of antiproliferative activities with the reference drug allows a proficient assessment of the structure-activity relationships (SARs) of the diversely synthesized molecules of the series.

Isatin-derived azoles as new potential antimicrobial agents: Design, synthesis and biological evaluation

Novel antibiotics are forced to be developed on account of multidrug-resistant bacteria with serious threats to human health. This work developed isatin-derived azoles as new potential antimicrobial agents. Bioactive assay revealed that isatin hybridized 1,2,4-triazole 7a exhibited excellent inhibitory activity against E. coli ATCC 25,922 with an MIC value of 1 µg/mL, which was 8-fold more potent than reference drug norfloxacin. The active molecule 7a possessed the ability to kill some bacteria and fungi as well as displayed low propensity to induce resistance towards E. coli ATCC25922. Preliminary mechanism investigation indicated that hybrid 7a might block deoxyribonucleic acid (DNA) replication by intercalating with DNA and possibly interacting with DNA polymerase III, thus exerting its antimicrobial potency.

Synthesis, molecular docking and ADME studies of thiazole-thiazolidinedione hybrids as antimicrobial agents

New thiazole-thiazolidinedione hybrids (5a-k) were efficiently synthesized and evaluated for their in-vitro antimicrobial activity against four fungal and bacterial strains. The chemical structures of the compounds were elucidated by FTIR, ¹H NMR, and ¹³C NMR spectral data. Most of the synthesized compounds were sensitive against gram positive, gram negative bacterial and fungal strains. Among the synthesized molecules, compounds 5h, and 5i exhibited promising inhibitory activity against all selected fungal strains and gram positive bacteria namely, Staphylococcus aureus, and Enterococcus faecalis. The molecular docking results predicted that the thiazole-thiazolidinedione derivatives bind to the active site protein ATP-binding pocket from E. coli, S. aureus and C. albicans with good interaction energy scores. Ct-DNA was used to evaluate the binding interactions of the selected compounds by means of absorption spectroscopy. To further characterize the drug-likeness and ADME properties were calculated using the Qikprop, the result of present study suggests that thiazole-thiazolidinedione hybrid could be an interesting approach for the design of new antimicrobial agents.Communicated by Ramaswamy H. Sarma.

Development and therapeutic potential of 2-aminothiazole derivatives in anticancer drug discovery

Currently, the development of anticancer drug resistance is significantly restricted the clinical efficacy of the most commonly prescribed anticancer drug. Malignant disease is widely prevalent and considered to be the major challenges of this century, which concerns the medical community all over the world. Consequently, investigating small molecule antitumor agents, which could decrease drug resistance and reduce unpleasant side effect is more desirable. 2-aminothiazole scaffold has emerged as a promising scaffold in medicinal chemistry and drug discovery research. This nucleus is a fundamental part of some clinically applied anticancer drugs such as dasatinib and alpelisib. Literature survey documented that different 2-aminothiazole analogs exhibited their potent and selective nanomolar inhibitory activity against a wide range of human cancerous cell lines such as breast, leukemia, lung, colon, CNS, melanoma, ovarian, renal, and prostate. In this paper, we have reviewed the progresses and structural modification of 2-aminothiazole to pursuit potent anticancers and also highlighted in vitro activities and in silico studies. The information will useful for future innovation. Representatives of 2-aminothiazole-containing compounds classification.

2-Aminothiazole: A privileged scaffold for the discovery of anti-cancer agents

Cancer has been the second heath killer being next only to cardiovascular diseases in human society. Although many efforts have been taken for cancer therapy and many achievements have been yielded in the diagnosis and treatment of cancer, the current first-line anti-cancer agents are insufficient owing to the emergence of multi-drug resistance and side effects. Therefore, it is urgent to develop new anti-cancer agents with high activity and low toxicity. 2-Aminothiazole is a class of important scaffold which widely distributes in many natural and synthetic compounds with many pharmacological effects including the potential anti-cancer activity. In this review, we summarized the recent progress of 2-aminothiazole as a privileged scaffold for the discovery of anti-cancer agents based on biological targets, such as tubulin protein, histone acetylase/histone deacetylase (HAT/HDAC), phosphatidylinositol 3-kinases (PI3Ks), Src/Abl kinase, BRAF kinase, epidermal growth factor receptor (EGFR) kinase and sphingosine kinase (SphK), and also investigated the structure-activity relationships (SARs) of most compounds. It is believed that this review could be helpful for medicinal chemists in the discovery of more anti-cancer agents bearing 2-aminothiazole scaffold with excellent activity and high therapeutic index.

Design and synthesis of amphiphilic 2-hydroxybenzylphosphonium salts with antimicrobial and antitumor dual action

Here we report the synthesis and biological evaluation of a series of new 2-hydroxybenzylphosphonium salts (QPS) with antimicrobial and antitumor dual action. The most active compounds exhibit antimicrobial activity at a micromolar level against Gram-positive bacteria Sa (ATCC 209p and clinical isolates), Bc (1-2 μM) and fungi Tm and Ca, and induced no notable hemolysis at MIC. The change in nature of substituents of the same length led to a drastic change of biological activity. Self-assembly behavior of the octadecyl and oleyl derivatives was studied. QPS demonstrated self-assembly within the micromolar range with the formation of nanosized aggregates capable of the solubilizing hydrophobic probe. The synthesized phosphonium salts were tested for cytotoxicity. The most potent salt was active against on M-Hela cell line with IC₅₀ on the level of doxorubicin and good selectivity. According to the cytofluorimetry analysis, the salts induced mitochondria-dependent apoptosis.

Thiazole-containing compounds as therapeutic targets for cancer therapy

In the last few decades, considerable progress has been made in anticancer agents development, and several new anticancer agents of natural and synthetic origin have been produced. Among heterocyclic compounds, thiazole, a 5-membered unique heterocyclic motif containing sulphur and nitrogen atoms, serves as an essential core scaffold in several medicinally important compounds. Thiazole nucleus is a fundamental part of some clinically applied anticancer drugs, such as dasatinib, dabrafenib, ixabepilone, patellamide A, and epothilone. Recently, thiazole-containing compounds have been successfully developed as possible inhibitors of several biological targets, including enzyme-linked receptor(s) located on the cell membrane, (i.e., polymerase inhibitors) and the cell cycle (i.e., microtubular inhibitors). Moreover, these compounds have been proven to exhibit high effectiveness, potent anticancer activity, and less toxicity. This review presents current research on thiazoles and elucidates their biological importance in anticancer drug discovery. The findings may aid researchers in the rational design of more potent and bio-target specific anticancer drug molecules.

Synthesis of 2-Amino-5-Carboxamide Thiazole Derivatives via Dehydrative Cyclization of Thiourea Intermediate Resin on Solid Phase

In this study, we synthesized 2-amino-5-carboxamide thiazole derivatives on solid phase. The synthesis of the library starts with the reductive amination of the 4-formyl-3-methoxy phenoxy resin to prevent isomer formation. The dehydrative cyclization of thiourea intermediate resin, which is the key step in the synthetic process, was successfully synthesized using α-bromoketone in the presence of the DMF so as to afford 2-amino-5-carboxylate thiazole resin. The resulting resin is coupled with various amines. Finally, the 2-amino-5-carboxamide thiazole resin was cleaved from the polymer support using a TFA and DCM cocktail. The physicochemical properties of the proposed 2-amino-5-carboxamide thiazole derivatives were calculated and showed potential to be an reasonable oral bioavailability drug properties as determined by Lipinski's Rule.

Revealing quinquennial anticancer journey of morpholine: A SAR based review

Morpholine, a six-membered heterocycle containing one nitrogen and one oxygen atom, is a moiety of great significance. It forms an important intermediate in many industrial and organic syntheses. Morpholine containing drugs are of high therapeutic value. Its wide array of pharmacological activity includes anti-diabetic, anti-emetic, growth stimulant, anti-depressant, bronchodilator and anticancer. Multi-drug resistance in cancer cases have emerged in the last few years and have led to the failure of many chemotherapeutic drugs. Newer treatment methods and drugs are being developed to overcome this problem. Target based drug discovery is an effective method to develop novel anticancer drugs. To develop newer drugs, previously reported work needs to be studied. Keeping this in mind, last five year's literature on morpholine used as anticancer agents has been reviewed and summarized in the paper herein.

Chitosan-MgO Nanocomposite: One Pot Preparation and Its Utility as an Ecofriendly Biocatalyst in the Synthesis of Thiazoles and [1,3,4]thiadiazoles

A chitosan-MgO hybrid nanocomposite was prepared using a simple chemical precipitation method and characterized using Fourier transform spectroscopy (FTIR), elemental analysis (EDX), and scanning electron microscopy (SEM). The nanocomposite was served as a powerful ecofriendly basic catalyst under microwave irradiation in the synthesis of two novel series of 5-arylazo-2-hydrazonothiazoles 4a–j and 2-hydrazono[1,3,4]thiadiazoles 8a–d, incorporating a sulfonamide group. The structures of the synthesized products were elucidated by spectral data and elemental analyses. Also, their yield percentages were calculated using triethylamine (as a traditional catalyst) and chitosan-MgO nanocomposite (as a green recyclable catalyst) in a comparative study.

Synthesis and evaluation of steroidal thiazoline conjugates as potential antiviral agents

Aim: Many heterocyclic compounds derived from natural steroids exhibited broad activities, so this work focused on the investigations on a series of steroidal thiazoline conjugates as antiviral agents. Materials & methods: A series of steroid derivatives containing thiazoline heterocycles were designed and synthesized via a convenient condensation procedure. The compounds were screened for their potential antivirus activities against Enterovirus 71 (EV71) and Coxsackie Virus Type B (CVB3). Results and Conclusion: The in vitro bioassay indicated that compounds 5b, 5g and 5i exhibited excellent antiviral effects on EV71, and compounds 5b, 5e, 6c and 6g presented better antiviral activities against CVB3 compared with the controls ribavirin or pirodavir. These results indicate that these steroidal thiazoline conjugates might be feasible therapeutic candidates against EV71 infection, which might also be considered as promising compounds for optimization of potential antivirus agents.

Synthesis and anti-proliferative activity of some new quinoline based 4,5-dihydropyrazoles and their thiazole hybrids as EGFR inhibitors

Quinoline derivatives 2, 3, quinolinyl based pyrazolines 4a,b, 5 and quinolinyl pyrazolinyl thiazole hybrids 6a-d, 7a-c and 8a-d were synthesized and screened for their anti-proliferative activity against MCF-7, HeLa and DLD1 cancer cell lines as well as normal fibroblast WI-38. Most of the tested compounds showed promising anticancer activity in addition to their safety towards the normal cell line. Eight compounds eliciting superior cytotoxicity against DLD1 and safe to the normal cell line 2, 3, 5, 6a, 6b, 7b, 7c and 8a were evaluated for their efficacy as EGFR inhibitors. They revealed inhibitory activity at nanomolar level especially compounds 6b, 2 and 7c with IC₅₀ (31.80, 37.07 and 42.52 nM) in comparison to Gefitinib (IC₅₀ = 29.16 nM).

Synthesis, Biological Evaluation, and Molecular Docking of Novel Thiazoles and [1,3,4]Thiadiazoles Incorporating Sulfonamide Group as DHFR Inhibitors

2-(1-{4-[(4-Methylphenyl)sulfonamido]phenyl}ethylidene)thiosemicarbazide (3) was exploited as a starting material for the synthesis of two novel series of 5-arylazo-2-hydrazonothiazoles 6a - 6j and 2-hydrazono[1,3,4]thiadiazoles 10a - 10d, incorporating sulfonamide group, through its reactions with appropriate hydrazonoyl halides. The structures of the newly synthesized products were confirmed by spectral and elemental analyses. Also, the antimicrobial, anticancer, and DHFR inhibition potency for two series of thiazoles and [1,3,4]thiadiazoles were evaluated and explained by molecular docking studies and SAR analysis.

New thiourea and 1,3-thiazolidin-4-one derivatives effective on the HIV-1 virus

Thiourea derivatives have been reported to possess many biological activities, among them antiviral and antitumoral properties. As part of our continuing effort to develop new active compounds, we report the synthesis and the evaluation of new fifteen thiourea derivatives with 1,3-benzothiazole-2-yl moiety, among them a group of biologically active (1-7) also underwent cyclization to 1,3-thiazolidin-4-ones. Molecular structure of four compounds (4, 13, 15 and 3a) was determined by an X-ray crystallography. We here report the evaluation of their cytotoxicity against human leukaemia/lymphoma- and solid tumour-derived cell lines and of their antiviral activity against HIV-1 and representatives of ssRNA and dsDNA viruses. Derivative 5 showed an interesting activity against HIV-1 wild type and against variants carrying clinically relevant mutations. A colorimetric enzyme immunoassay clarified its mode of action as a non-nucleoside inhibitor of the reverse transcriptase.

Structure-activity relationship (SAR) study and design strategies of nitrogen-containing heterocyclic moieties for their anticancer activities

The present review article offers a detailed account of the design strategies employed for the synthesis of nitrogen-containing anticancer agents. The results of different studies describe the N-heterocyclic ring system is a core structure in many synthetic compounds exhibiting a broad range of biological activities. Benzimidazole, benzothiazole, indole, acridine, oxadiazole, imidazole, isoxazole, pyrazole, triazoles, quinolines and quinazolines including others drugs containing pyridazine, pyridine and pyrimidines are covered. The following studies of these compounds suggested that these compounds showed their antitumor activities through multiple mechanisms including inhibiting protein kinase (CDK, MK-2, PLK1, kinesin-like protein Eg5 and IKK), topoisomerase I and II, microtubule inhibition, and many others. Our concise representation exploits the design and anticancer potency of these compounds. The direct comparison of anticancer activities with the standard enables a systematic analysis of the structure-activity relationship among the series.

Synthesis, Biological Activity, and Apoptotic Properties of NO-Donor/Enmein-Type ent-Kauranoid Hybrids

Herein, we reported on a series of synthetic nitric oxide-releasing enmein-type diterpenoid hybrids (9a–i). All the target compounds showed potent antibacterial activity against selected Gram-positive bacteria S. aureus and B. subtilis. The antiproliferative activity against human tumor K562, MGC-803, CaEs-17 and Bel-7402 cells, and human normal liver cells L-02 was tested and the structure activity relationships (SARs) were also concluded. Compounds 9b and 9d showed the best activity against S. aureus and B. subtilis with the same minimal inhibitory concentrations (MICs) of 4 and 2 μg/mL, respectively. The derivative 9f displayed IC₅₀ values of 1.68, 1.11, 3.60 and 0.72 μM against the four cancer cell lines above and 18.80 μM against normal liver cells L-02; meanwhile, 9f also released a high level of NO at the time point of 60 min of 22.24 μmol/L. Furthermore, it was also found that 9f induced apoptosis via the mitochondria-related pathway and arrested cell cycle of Bel-7402 cells at S phase. These findings might be important to explore new chemical entities for the main causes of in-hospital mortality of S. aureus infection, combined with a solid tumor.

2-(3'-Indolyl)-N-arylthiazole-4-carboxamides: Synthesis and evaluation of antibacterial and anticancer activities

A new series of 2-(3'-indolyl)-N-arylthiazole-4-carboxamides 17a-p has been designed and synthesized. Initial reaction of readily available thioamides 15 with bromopyruvic acid under refluxing conditions produced different thiazole carboxylic acids 16 which upon coupling with arylamines by using EDCI·HCl and HOBt afforded diverse arylthiazole-4-carboxamides 17a-p in 78-87% yields. Antibacterial activity evaluation against Gram-positive and Gram-negative bacterial strains led to compounds 17i-k and 17o as potent and selectively (Gram-negative) antibacterial agents. The cytotoxicity of thiazole carboxamides 17a-p was also evaluated on a panel of human cancer cell lines. Among the tested derivatives, compounds 17i (IC50=8.64μM; HEK293T) and 17l (IC50=3.41μM; HeLa) were identified as the most potent analogues of the series. Preliminary mechanism of action studies of thiazole carboxamide 17i suggested that its cytotoxicity against HeLa cells involves the induction of cell death by apoptosis.