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

Telescoping Synthesis of 4-Organyl-5-(organylselanyl)thiazol-2-amines Promoted by Ultrasound

In this work, we describe the synthesis of new 4-organyl-5-(organylselanyl)thiazol-2-amine hybrids through a one-pot two-step protocol. The transition metal-free method involves the use of ultrasound as an alternative energy source and Oxone® as oxidant. To obtain the products, a telescoping approach was used, in which 4-organylthiazol-2-amines were firstly prepared under ultrasonic irradiation, followed by the addition of diorganyl diselenides and Oxone®. Thus, 16 compounds were prepared, with yields ranging from 61 % to 98 %, using 2-bromoacetophenone derivatives and diorganyl diselenides as easily available starting materials.

Quinoline-based thiazolyl-hydrazones target cancer cells through autophagy inhibition

Heterocyclic pharmacophores such as thiazole and quinoline rings have a significant role in medicinal chemistry. They are considered privileged structures since they constitute several Food and Drug Administration (FDA)-approved drugs for cancer treatment. Herein, we report the synthesis, in silico evaluation of the ADMET profiles, and in vitro investigation of the anticancer activity of a series of novel thiazolyl-hydrazones based on the 8-quinoline (1a-c), 2-quinoline (2a-c), and 8-hydroxy-2-quinolyl moiety (3a-c). The panel of several human cancer cell lines and the nontumorigenic human embryonic kidney cell line HEK-293 were used to evaluate the compound-mediated in vitro anticancer activities, leading to [2-(2-(quinolyl-8-ol-2-ylmethylene)hydrazinyl)]-4-(4-methoxyphenyl)-1,3-thiazole (3c) as the most promising compound. The study revealed that 3c blocks the cell-cycle progression of a human colon cancer cell line (HCT-116) in the S phase and induces DNA double-strand breaks. Also, our findings demonstrate that 3c accumulates in lysosomes, ultimately leading to the cell death of the hepatocellular carcinoma cell line (Hep-G2) and HCT-116 cells, by the mechanism of autophagy inhibition.

Design, synthesis, and antimicrobial evaluation of 2-aminothiazole derivatives bearing the 4-aminoquinazoline moiety against plant pathogenic bacteria and fungi

BACKGROUND

To find more effective agricultural antibiotics, a class of new 2-aminothiazole derivatives containing the 4-aminoquinazoline moiety were synthesized and evaluated for their antimicrobial properties against phytopathogenic bacteria and fungi of agricultural importance.

RESULTS

All the target compounds were fully characterized by 1 H NMR, 13 C NMR, and high-resolution mass spectrometry. The bioassay results showed that compound F29 with a 2-pyridinyl substituent exhibited an outstanding antibacterial effect against Xanthomonas oryzae pv. oryzicola (Xoc) in vitro, having an half-maximal effective concentration (EC50 ) value as low as 2.0 μg/mL (over 30-fold more effective than the commercialized agrobactericide bismerthiazol, with an EC50 value of 64.3 μg/mL). In addition, compound F8 with a 2-fluorophenyl group demonstrated a good inhibitory activity toward the bacterium Xanthomonas axonopodis pv. citri (Xac), around twofold more active than bismerthiazol in terms of their EC50 values (22.8 versus 71.5 μg/mL). Interestingly, this compound also demonstrated a notable fungicidal effect against Phytophthora parasitica var. nicotianae, with an EC50 value largely comparable with that of the commercialized fungicide carbendazim. Finally, mechanistic studies revealed that compound F29 exerted its antibacterial effects by increasing the permeability of bacterial membranes, reducing the release of extracellular polysaccharides, and triggering morphological changes of bacterial cells.

CONCLUSION

Compound F29 has promising potential as a lead compound for developing more efficient bactericides to fight against Xoc. © 2023 Society of Chemical Industry.

Green synthesis of highly functionalized heterocyclic bearing pyrazole moiety for cancer-targeted chemo/radioisotope therapy

New derivatives of heterocyclic bearing pyrazole moiety were synthesized (eight new compounds from 2 to 9) via green synthesis methods (microwave-assisted and grinding techniques). 4,6-Diamino-1,3-diphenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (2) shows high anti-cancer activity against both HepG2 and HCT-116 with IC50 of 9.2 ± 2.8 and 7.7 ± 1.8 µM, respectively, which referenced to 5-Fu which is showing activity of 7.86 ± 0.5 and 5.35 ± 0.3 against both HepG2 and HCT-116, respectively. The cytotoxic activity against HCT-116 and HepG2 was slightly decreased and slightly increased, respectively, by a different pyrazole moiety (compound 5). Pharmacokinetics of compound 2 was carried out using the radioiodination technique in tumour-bearing Albino mice which shows good uptake at the tumour site. The biodistribution showed high accumulation in tumour tissues with a ratio of 13.7% ID/g organ after one hour in comparison with 2.97% ID/g organ at normal muscle at the same time point. As I-131 has maximum beta and gamma energies of 606.3 and 364.5 keV, respectively, therefore the newly synthesized compound 2 may be used for chemotherapy and TRT.

Azaindole derivatives as potential kinase inhibitors and their SARs elucidation

Currently, heterocycles have occupied an important position in the fields of drug design. Among them, azaindole moiety is regarded as one privileged scaffold to develop therapeutic agents. Since two nitrogen atoms of azaindole increase the possibility to form hydrogen bonds in the adenosine triphosphate (ATP)-binding site, azaindole derivatives are important sources of kinase inhibitors. Moreover, some of them have been on the market or in clinical trials for the treatment of some kinase-related diseases (e.g., vemurafenib, pexidartinib, decernotinib). In this review, we focused on the recent development of azaindole derivatives as potential kinase inhibitors based on kinase targets, such as adaptor-associated kinase 1 (AAK1), anaplastic lymphoma kinase (ALK), AXL, cell division cycle 7 (Cdc7), cyclin-dependent kinases (CDKs), dual-specificity tyrosine (Y)-phosphorylation regulated kinase 1A (DYRK1A), fibroblast growth factor receptor 4 (FGFR4), phosphatidylinositol 3-kinase (PI3K) and proviral insertion site in moloney murine leukemia virus (PIM) kinases. Meanwhile, the structure-activity relationships (SARs) of most azaindole derivatives were also elucidated. In addition, the binding modes of some azaindoles complexed with kinases were also investigated during the SARs elucidation. This review may offer an insight for medicinal chemists to rationally design more potent kinase inhibitors bearing the azaindole scaffold.

From Bench to Bedside: What Do We Know about Imidazothiazole Derivatives So Far?

Imidazothiazole derivatives are becoming increasingly important in therapeutic use due to their outstanding physiological activities. Recently, applying imidazothiazole as the core, researchers have synthesized a series of derivatives with biological effects such as antitumor, anti-infection, anti-inflammatory and antioxidant effects. In this review, we summarize the main pharmacological effects and pharmacological mechanisms of imidazothiazole derivates; the contents summarized herein are intended to advance the research and rational development of imidazothiazole-based drugs in the future.

Catalysis-free synthesis of thiazolidine-thiourea ligands for metal coordination (Au and Ag) and preliminary cytotoxic studies

The reaction of propargylamines with isothiocyanates results in the selective formation of iminothiazolidines, aminothiazolines or mixed thiazolidine-thiourea compounds under mild conditions. It has been observed that secondary propargylamines lead to the selective formation of cyclic 2-amino-2-thiazoline derivatives, while primary propargylamines form iminothiazoline species. In addition, these cyclic thiazoline derivatives can further react with an excess of isothiocyanate to give rise to thiazolidine-thiourea compounds. These species can also be achieved by reaction of propargylamines with isothiocynates in a molar ratio of 1 : 2. Coordination studies of these heterocyclic species towards silver and gold with different stoichiometries have been carried out and complexes of the type [ML(PPh₃)]OTf, [ML₂]OTf (M = Ag, Au) or [Au(C₆F₅)L] have been synthesised. Preliminary studies of the cytotoxic activity in lung cancer cells have also been performed in both ligands and complexes, showing that although the ligands do not exhibit anticancer activity, their coordination to metals, especially silver, greatly enhances the cytotoxic activity.

Methyl 9-(2-Iminothiazol-3(2H)-yl)-9-oxononanoate

Methyl 9-(2-iminothiazol-3(2H)-yl)-9-oxononanoate was synthesized through Schotten–Baumann type reaction between 2–aminothiazole and methyl 9-chloro-9-oxononanoate. The structure of the newly synthesized compound was elucidated based on 1H-NMR, 13C-NMR, DEPT, NOE, ESI-MS, FT-IR and UV-Vis spectroscopy.

Design, synthesis, and biological evaluation of ocotillol derivatives fused with 2-aminothiazole via A-ring as modulators of P-glycoprotein-mediated multidrug resistance

Overexpression of P-glycoprotein (P-gp) plays a key role in the development of multidrug resistance (MDR), the major reason for the failure of chemotherapy in clinics. Ocotillol and its derivatives had been reported with good P-gp-mediated tumor MDR reversal activity in vitro. Herein, a series of ocotillol derivatives fused with 2-aminothiazole (2-AT) via A-ring were designed and synthesized to further improve the tumor MDR reversal potency. These compounds were evaluated for their MDR reversal activity against the KBV cells by MTT assay. Among them, the most promising derivative against P-gp-mediated MDR was compound 12 with 2-AT and glycine in the A-ring. Rhodamine123 (Rh123) accumulation assay, Western blot assay, and P-gp-Glo™ assay showed that compound 12 efficiently inhibited the efflux function of P-gp by stimulating P-gp ATPase rather than downregulating its expression. Moreover, compound 12 sensitized KBV cells to paclitaxel arrested cells in the G₂/M phase and induced cell apoptosis. Importantly, compound 12 significantly inhibited the growth of KBV cell-derived xenograft tumors in nude mice by increasing the sensitivity of paclitaxel in vivo. Finally, the structure-activity relationships (SARs) of ocotillol derivatives were further investigated. In summary, compound 12 has the potential to overcome MDR in cancer caused by P-gp.

Synthesis, Anticancer Activities and Molecular Docking Studies of a Novel Class of 2-Phenyl-5,6,7,8-tetrahydroimidazo [1,2-b]pyridazine Derivatives Bearing Sulfonamides

In the present study, new 2-phenyl-5,6,7,8-tetrahydroimidazo [1,2-b]pyridazines bearing sulfonamides were synthesized, characterized and evaluated for their anticancer activities. The structures of these derivatives were elucidated by 1H NMR, 13C NMR, infrared and high-resolution mass spectrometry for further validation of the target compound structures. The anticancer activities of the new molecules were evaluated against five human cancer cell lines, including A-549, Hs-683, MCF-7, SK-MEL-28 and B16-F10 cell lines using 5-fluorouracil and etoposide as the reference drugs. Among the tested compounds, 4e and 4f exhibited excellent activities in the same range of the positive controls, 5-fluorouracil and etoposide, against MCF-7 and SK-MEL-28 cancer cell lines, with IC50 values ranging from 1 to 10 μM. The molecular docking studies of 4e and 4f showed a strong binding with some kinases, which are linked to MCF-7 and SK-MEL-28 cancer cell lines.

A green synthesis and antibacterial activity of ferrocene-based thiazole derivatives in choline chloride/glycerol eutectic solvent

In this work, a green Hantzsch synthesis of 4-ferrocenylthiazole derivatives has been accomplished successfully. The Hantzsch reaction between bromoacetylferrocene and various aryl thioureas, 1-alkylindole-3- or 9-alkylcarbazole-3-carbothioamides proceeded efficiently in a deep eutectic solvent (DES) that is, choline chloride/glycerol (ChCl/Gly) (1 : 2 molar ratio) at 80 °C, avoiding the use of common volatile organic solvents. Moreover, the DES media could be reused up to three times without any appreciable decrease in the yield. The synthetic strategy has the attractive features such as mild and environmentally benign reaction conditions, experimental simplicity, easy work-up procedure and good yields. Subsequently, a preliminary screening for in vitro antibacterial activities of all these newly-synthesized compounds revealed that the halo-substituted (F, Cl, Br) compounds 3f–h showed significant antibacterial activities against Gram (+) bacterial B. subtilis and Gram (−) E. coli, among which the fluoro-substituted 3f possessed the best activity with the MIC value of 7.8125 μg mL⁻¹, being higher than the reference drug ciprofoxacin (15.625 μg mL⁻¹).

A green and effective Hantzsch thiazole synthesis of structurally intriguing ferrocene-based derivatives employing the eutectic mixture choline chloride/glycerol (1 : 2 molar ratio) as a sustainable solvent is described.

Cascade Reaction of Tertiary Enaminones, KSCN, and Anilines: Temperature-Controlled Synthesis of 2-Aminothiazoles and 2-Iminothiazoline

A one-pot cascade strategy for the synthesis of 2-aminothiazole derivatives by tertiary enaminones, KSCN, and anilines was developed. By changing the reaction temperature, the three-component reaction could be transformed in different ways to obtain moderate to good yields of polysubstituted 2-aminothiazoles and 2-iminothiazolines. This protocol provides an efficient and concise approach to accessing 2-aminothiazole derivatives with potential bioactivity from readily accessible building blocks and reagents.

Thiocyanatoarylation of Methyl Vinyl Ketone under Meerwein Conditions for the Synthesis of 2-Aminothiazole-Based Heterocyclic Systems

4-Aryl-3-thiocyanatobutan-2-ones were prepared by Meerwein reactions from methyl vinyl ketone and aryldiazonium salts under copper(II) catalysis in 35-75% yields. α-Thiocyanato ketones regioselectively react with 1-methyl-3-aminopyrazole forming N-(3-pyrazolyl)-substituted 2-aminothiazoles in 80-91% yields. An ester group in position 3 of the pyrazole induced a regioselective ring-closure reaction followed by an intramolecular cyclization, which gave first representatives of a new heterocyclic system, pyrazolo[4,3-e]thiazolo[3,2-a]pyrimidine, in 74-93% yields. In addition, the preparations of 5-benzyl-4-methylthiazol-2-ones in 84-93% yields are described.

Structure, Spectra and Photochemistry of 2-Amino-4-Methylthiazole: FTIR Matrix Isolation and Theoretical Studies

The structure, tautomerization pathways, vibrational spectra, and photochemistry of 2-amino-4-methylthiazole (AMT) molecule were studied by matrix isolation FTIR spectroscopy and DFT calculations undertaken at the B3LYP/6-311++G(3df,3pd) level of theory. The most stable tautomer with the five-membered ring stabilized by two double C=C and C=N bonds, was detected in argon matrices after deposition. When the AMT/Ar matrices were exposed to 265 nm selective irradiation, three main photoproducts, N-(1-sulfanylprop-1-en-2-yl)carbodiimide (fp1), N-(1-thioxopropan-2-yl)carbodiimide (fp2) and N-(2-methylthiiran-2-yl)carbodiimide (fp3), were photoproduced by a cleavage of the CS–CN bond together with hydrogen atom migration. The minor photoreaction caused by the cleavage of the CS–CC bond and followed by hydrogen migration formed 2-methyl-1H-azirene-1-carbimidothioic acid (fp15). We have also found that cleavage of the CS–CN bond followed by disruption of the N–C bond produced cyanamide (fp11) and the C(CH3)=CH–S biradical that transformed into 2-methylthiirene (fp12) and further photoreactions produced 1-propyne-1-thiole (fp13) or methylthioketene (fp14). Cleavage of the CS–CC bond followed by disruption of the N–C bond produced propyne (fp22) and the S–C(NH₂)=N biradical that transformed into 3-aminethiazirene (fp23); further photoreactions produced N-sulfanylcarbodiimide (fp25). As a result of these transformations, several molecular complexes were identified as photoproducts besides new molecules in the AMT photolysis process.

Identification of a 3-(5-methyl-2-thiazolylamino)phthalide as a new minor groove agent

A new 3-(5-methyl-2-thiazolylamino)phthalide molecule, 3-((5-methylthiazol-2-yl)amino)isobenzofuran-1(3H)-one, was synthesized and characterized experimentally by FT-IR, NMR, UV-Vis, and single-crystal X-ray analysis and theoretically by quantum chemical calculations. The single-crystal X-ray studies revealed that the compound crystallizes in the monoclinic space group P-2_1/c with unit-cell parameters a = 8.0550(6) Å, b = 6.1386(3) Å, c = 23.3228(18) Å, β = 97.724(6)° and Z = 4. Optimized geometries and the vibrational frequencies were studied at the density functional theory (DFT) level by using the hybrid functional B3LYP with a 6-311 G (d,p) basis set. The title compound was evaluated for its anti-quorum sensing (anti-QS) activity on Chromobacterium violaceum 12472 and additionally for its antibacterial activity against Staphylococcus aureus 29213, Staphylococcus epidermidis 12228, Pseudomonas aeruginosa 27853, Escherichia coli 25922, and Proteus mirabilis 14153. The lowest MIC value was 0.24 μg/mL for S. aureus 29213 and the highest MIC value was 30.75 μg/mL for E. coli 25922. While anti-bacterial activity was observed in those other than the S. epidermidis and P. Mirabilis, anti-QS activity wasn't detected. Investigations on dsDNA binding affinity indicate that the title compound binds to dsDNA via the groove binding mode. Molecular docking calculations and molecular dynamics simulations results showed also that the title compound prefers binding to the minor groove of dsDNA and remains stable in the minor groove throughout the molecular dynamics simulation.Communicated by Ramaswamy H. Sarma.

Sulfonamide derivatives as potential anti-cancer agents and their SARs elucidation

Currently, the arise of drug resistance and undesirable off-target effects of anti-cancer agents are major challenges for cancer treatment, which energizes medicinal chemists to develop more anti-cancer agents with high efficiency and low toxicity continuously. Sulfonamide derivatives are a class of promising compounds with diverse biological activities including anti-cancer, and parts of them have been marketed for cancer therapy, such as Belinostat, ABT-199 and Amsacrine. In this review, we summed up the recent advances of sulfonamide derivatives as potential anti-cancer agents based on the anti-cancer targets, such as aromatase, carbonic anhydrase (CA), anti-apoptotic B-cell lymphoma-2 (Bcl-2) proteins, topoisomerase and phosphatidylinositol 3-kinase (PI3K), and elucidated the corresponding structure-activity relationships (SARs) of most sulfonamide derivatives. We hope this review could provide a clear insight for medicinal chemists in the rational design of more potent and bio-target specific anti-cancer agents.

Design, Synthesis, Biological Evaluation, and Computational Studies of Novel Fluorinated Candidates as PI3K Inhibitors: Targeting Fluorophilic Binding Sites

Highly fluorinated candidates containing anticancer pharmacophores like thiosemicarbazone (5a-e) and its cyclic analogues hydrazineylidenethiazolidine (6a-e), 2-aminothiadiazole (7a-e), and 2-hydrazineylidenethiazolidin-4-one (8a-e) were synthesized, and their cytotoxic activity was assayed against 60 tumor cell lines. Compounds 6c, 7b, and 8b displayed the most potent activity with lower toxic effects on MCF-10a. In vitro phosphatidylinositol 3-kinase (PI3K) enzyme inhibition was performed. Compound 6c displayed half-maximal inhibitory concentration (IC₅₀, μM) values of 5.8, 2.3, and 7.9; compound 7b displayed IC₅₀ values of 19.4, 30.7, and 73.7; and compound 8b displayed IC₅₀ values of 77.5, 53.5, and 121.3 for PI3Kα, β, and δ, respectively. Moreover, cell cycle progression caused cell cycle arrest at the S phase for compounds 6c and 8b and at G1/S for compound 7b, while apoptosis was induced. In silico studies; molecular docking; physicochemical parameters; and absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis were performed. The results showed that compound 6c is the most potent one with a selectivity index (SI) of 39 and is considered as a latent lead for further optimization of anticancer agents.

Preparation and antitumor application of N-phenylcarbazole/triphenylamine-modified fluorescent half-sandwich iridium(III) Schiff base complexes

Four N-phenylcarbazole/triphenylamine-appended half-sandwich iridium(III) salicylaldehyde Schiff base complexes ([(η⁵-Cp^x)Ir(O^N)Cl]) were prepared and characterized. The complexes exhibited similar antitumor activity to cisplatin and effectively inhibited the migration of tumor cells. Furthermore, the complexes showed favourable hydrolytic activity, while remaining relatively stable in the plasma environment, which facilitated the binding of serum proteins and transport through them. These complexes could decrease the mitochondrial membrane potential, catalyze the oxidation of nicotinamide adenine dinucleotide, induce an increase in intracellular reactive oxygen species (ROS), and eventually result in apoptosis. Aided by their suitable fluorescence property, laser confocal detection showed that the complexes followed an energy-dependent mechanism for their cellular uptake, effectively accumulating in the lysosome and leading to lysosomal damage. In summary, the half-sandwich iridium(III) salicylaldehyde Schiff base complexes could induce lysosomal damage, increase intracellular ROS, and lead to apoptosis, which contributed to their antitumor mechanism of oxidation.

Novel Hybrid Compounds Containing Benzofuroxan and Aminothiazole Scaffolds: Synthesis and Evaluation of Their Anticancer Activity

A series of novel hybrid compounds containing benzofuroxan and 2-aminothiazole moieties are synthesized via aromatic nucleophilic substitution reaction. Possible reaction pathways have been considered quantum-chemically, which allowed us to suggest the most probable products. The quantum chemical results have been proved by X-ray data on one compound belonging to the synthesized series. It was shown that the introduction of substituents to both the thiazole and amine moieties of the compounds under study strongly influences their UV/Vis spectra. Initial substances and obtained hybrid compounds have been tested in vitro as anticancer agents. Target compounds showed selectivity towards M-HeLa tumor cell lines and were found to be more active than starting benzofuroxan and aminothiazoles. Furthermore, they are considerably less toxic to normal liver cells compared to Tamoxifen. The mechanism of action of the studied compounds can be associated with the induction of apoptosis, which proceeds along the mitochondrial pathway. Thus, new hybrids of benzofuroxan are promising candidates for further development as anticancer agents.