Highly efficient microwave synthesis of rhodanine and 2-thiohydantoin derivatives and determination of relationships between their chemical structures and antibacterial activity

Synthesis of bis-thiohydantoin derivatives as an antiproliferative agents targeting EGFR inhibitory pathway

(R)/(S)-the two enantiomers of 3-substituted-1-[2-(5)-3-substituted-4-benzyl-5-oxo-4-phenyl-2-thioxoimid-azolidin-1-yl]ethyl/propyl-5-benzyl-5-phenyl-2-thioxoimidazolidin-4-ones were formed during the diastereoselective reaction between N,N″-1,ω-alkanediylbis[N'-organylthiourea] derivatives and 2,3-diphenylcyclopropenone in refluxing ethanol. The structures of the isolated compounds were confirmed by NMR, IR, mass spectra and elemental analyses. Moreover, single-crystal X-ray structure analysis was also used to elucidate the structure of the isolated compounds. The mechanism describes the reaction was also discussed. The tested compounds showed EGFR inhibitory activity with IC50 values ranging from 90 to 178 nM in comparison to the erlotinib as a reference with IC50 value of 70 nM. Compound 4c (R = allyl, n = 3) was found as the most potent antiproliferative, had the highest inhibitory effect on EGFR with an IC50 value of 90 nM, compared to erlotinib's IC50 value of 70 nM. The second and third-most active compounds were 4e (R = phenyl, n = 3) and 4d (R = ethyl, n = 3) and with IC50 values of 107 nM and 128 nM. These findings imply that the compounds tested had a significant antiproliferative effect as well as the ability to act as an EGFR inhibitor. Docking studies showed that compound 4c showed high affinity to EGFR based on its docking score (S; kcal/mol) within five test compounds.

Synthesis and Identification of Heterobivalent Anticancer Compounds Containing Urea and 5-Arylidene-2-Thiohydantoin Motifs

Urea and thiohydantoin are among the important privileged structures for drug discovery. We have developed a synthetic approach to the high-throughput synthesis of the heterobivalent compounds containing both urea and 5-arylidene-2-thiohydantoin functional groups. This synthetic methodology was applied to the synthesis of a mixture-based library containing a total of 5280 compounds in a positional scanning format. The library was screened for its antiproliferative activity against cancer cells using a tetrazolium dye (MTT) based assay. Deconvolution of the library identified six hit compounds exhibiting moderate inhibitory potency against cancer cell proliferation.

How Can Deep Eutectic Systems Promote Greener Processes in Medicinal Chemistry and Drug Discovery?

Chemists in the medicinal chemistry field are constantly searching for alternatives towards more sustainable and eco-friendly processes for the design and synthesis of drug candidates. The pharmaceutical industry is one of the most polluting industries, having a high E-factor, which is driving the adoption of more sustainable processes not only for new drug candidates, but also in the production of well-established active pharmaceutical ingredients. Deep eutectic systems (DESs) have emerged as a greener alternative to ionic liquids, and their potential to substitute traditional organic solvents in drug discovery has raised interest among scientists. With the use of DESs as alternative solvents, the processes become more attractive in terms of eco-friendliness and recyclability. Furthermore, they might be more effective through making the process simpler, faster, and with maximum efficiency. This review will be focused on the role and application of deep eutectic systems in drug discovery, using biocatalytic processes and traditional organic chemical reactions, as new environmentally benign alternative solvents. Furthermore, herein we also show that DESs, if used in the pharmaceutical industry, may have a significant effect on lowering production costs and decreasing the impact of this industry on the quality of the environment.

Gastroprotective effect of rhodanine and 2,4-thiazolidinediones scaffolds in rat stomachs by contribution of anti-apoptotic (BCL-2) and tumor suppressor (P53) proteins

In recent times, the methods used to evaluate gastric ulcer healing worldwide have been based on visual examinations and estimating ulcer dimensions in experimental animals. In this study, the protective effect of rhodanine and 2,4-thiazolidinediones scaffolds compared to esomeprazole was investigated in an ethanol model of stomach ulcers in rats. Pretreatment with experimental treatments or esomeprazole prevented the development of ethanol-induced gastric ulcers. The severity of the lesions and injuries was significantly lower than that of vehicle (10% Tween 80) treated rats. Significant and excellent results were obtained with the compound 6 group, with inhibition percentage and ulcer area values of 97.8% and 12.8 ± 1.1 mm2, respectively. Synthesized compounds 2, 7 and 8 exhibited inhibition percentages and ulcer areas of 94.3% and 31.2 ± 1.1 mm2, 91. 3% and 48.1 ± 0. 8 mm2, 89. 5% and 57. 6 ± 1. 2 mm2, and 89. 1% and 60.3 ± 0. 8 mm2, respectively. These biological outcomes are consistent with the docking studies in which Compounds 7 and 8 showed remarkable binding site affinities toward human H+/K+-ATPase α protein (ID: P20648), rat H+/K+-ATPase α protein (ID: P09626), and Na+/K+-ATPase crystal structure (PDB ID:2ZXE) with binding site energies of - 10.7, - 9.0, and - 10.4 (kcal/mol) and - 8.7, - 8.5, and - 8.0 (kcal/mol), respectively. These results indicate that these test samples were as effective as esomeprazole. Likewise, immunohistochemical staining of antiapoptotic (BCL2) and tumor suppressor (P53) proteins showed strong positive marks in the10% Tween 80- treated group, opposing the mild staining results for the esomeprazole-treated group. Similarly, the staining intensity of the group treated with Compounds 2-8 was variable for both proteins.

Chalcogen-Varied Imidazolone Derivatives as Antibiotic Resistance Breakers in Staphylococcus aureus Strains

In this study, a search for new therapeutic agents that may improve the antibacterial activity of conventional antibiotics and help to successfully overcome methicillin-resistant Staphylococcus aureus (MRSA) infections has been conducted. The purpose of this work was to extend the scope of our preliminary studies and to evaluate the adjuvant potency of new derivatives in a set of S. aureus clinical isolates. The study confirmed the high efficacy of piperazine derivatives of 5-arylideneimidazol-4-one (7-9) tested previously, and it enabled the authors to identify even more efficient modulators of bacterial resistance among new analogs. The greatest capacity to enhance oxacillin activity was determined for 1-benzhydrylpiperazine 5-spirofluorenehydantoin derivative (13) which, at concentrations as low as 0.0625 mM, restores the effectiveness of β-lactam antibiotics against MRSA strains. In silico studies showed that the probable mechanism of action of 13 is related to the binding of the molecule with the allosteric site of PBP2a. Interestingly, thiazole derivatives tested were shown to act as both oxacillin and erythromycin conjugators in S. aureus isolates, suggesting a complex mode of action (i.e., influence on the Msr(A) efflux pump). This high enhancer activity indicates the high potential of imidazolones to become commercially available antibiotic adjuvants.

Development of Novel 1,3-Disubstituted-2-Thiohydantoin Analogues with Potent Anti-Inflammatory Activity; In Vitro and In Silico Assessments

Inflammation is the main cause of several autoimmune diseases, including type I diabetes, rheumatoid arthritis, bullous pemphigoid, paraneoplastic pemphigoid, and multiple sclerosis. Currently, there is an urgent demand for the discovery of novel anti-inflammatory drugs with potent activity but also safe for long-term application. Toward this aim, the present study reported the design, synthesis, and characterization of a set of novel 1,3-disubstituted-2-thiohydantoins derivatives. The anti-inflammatory activity of synthesized compounds was assessed against murine leukemia cell line (RAW264.7) by evaluating the cytotoxicity activity and their potency to prevent nitric oxide (NO) production. The results revealed that the synthesized compounds possess a considerable cytotoxic activity together with the ability to reduce the NO production in murine leukemia cell line (RAW264.7). Among synthesized compounds, compound 7 exhibited the most potent cytotoxic activity with IC₅₀ of 197.68 μg/mL, compared to celecoxib drug (IC₅₀ value 251.2 μg/mL), and demonstrated a significant ability to diminish the NO production (six-fold reduction). Exploring the mode of action responsible for the anti-inflammatory activity revealed that compound 7 displays a significant and dose-dependent inhibitory effect on the expression of pro-inflammatory cytokines IL-1β. Furthermore, compound 7 demonstrated the ability to significantly reduce the expression of the inflammatory cytokines IL-6 and TNF-α at 50 μg/mL, as compared to Celecoxib. Finally, detailed molecular modelling studies indicated that compound 7 exhibits a substantial binding affinity toward the binding pocket of the cyclooxygenase 2 enzyme. Taken together, our study reveals that 1,3-disubstituted-2-thiohydantoin could be considered as a promising scaffold for the development of potent anti-inflammatory agents.

Solvent dependent hindered rotation versus epimerization in axially chiral thiohydantoin derivatives: an experimental and a computational study

5-Benzyl-3-(o-aryl)-2-thiohydantoin and 5-isobutyl-3-(o-aryl)-2-thiohydantoin derivatives (o-aryl = o-tolyl and o-bromophenyl) have been synthesized by reacting o-aryl isothiocyanates with S-phenylalanine methyl ester hydrochloride or with S-leucine methyl ester hydrochloride in the presence of triethylamine (TEA). The synthesized compounds have a chirality center at C5 of the heterocyclic ring and a chirality axis, the N3-C_(aryl) bond. The axially chiral compounds were shown to exist in unequal amounts of SM, SP, RM and RP stereoisomeric forms with a high prevalence of the P isomers over the M isomers. The isomeric assignments were done by comparing the ¹H NMR spectra with the HPLC chromatograms. The stereoisomers were resolved micropreparatively by HPLC on chiral stationary phases and the interconversion of the single isomers has been investigated. The conversion type has been determined as epimerization or rotation by the HPLC analyses. It has been found that although the stereoisomers converted to each other only by rotation in toluene, in ethanol epimerization (racemization at C5 of the heteroring) was accompanied with rotation depending on the duration, temperature of the thermal interconversion experiment and the nature of the ortho substituent. The occurrence of epimerization was also proved through H/D exchange reactions via¹H NMR experiments done in CD₃OD. The rotation and epimerization mechanisms of synthesized compounds were further elucidated by Density Functional Theory (DFT) calculations at M062X/6-311 + G** level of theory and the results were shown to be in harmony with experimental findings.

One-Pot High-throughput Synthesis of N3-Substituted 5-Arylidene-2-Thiohydantoin Amides and Acids

A one-pot high-throughput solid-phase method for the synthesis of N3-substituted 5-arylidene-2-thiohydantoin amide and acid has been developed. A tandem ring-closure and ring-open pathway is proposed as the mechanism of forming the two products.

Discovery of Cinnamylidene Derivative of Rhodanine with High Anthelmintic Activity against Rhabditis sp

The treatment of parasitic infections requires the application of chemotherapy. In view of increasing resistance to currently in-use drugs, there is a constant need to search for new compounds with anthelmintic activity. A series of 16 cinnamylidene derivatives of rhodanine, including newly synthesized methoxy derivatives (1-11) and previously obtained chloro, nitro, and diethylamine derivatives (12-16), was investigated towards anthelmintic activity. Compounds (1-16) were evaluated against free-living nematodes of the genus Rhabditis sp. In the tested group of rhodanine derivatives, only compound 2 shows very high biological activity (LC50 = 0.93 µg/µL), which is higher than the reference drug albendazole (LC50 = 19.24 µg/µL). Crystal structures of two compounds, active 2 and inactive 4, were determined by the X-ray diffraction method to compare molecular geometry and search for differences responsible for observed biological activity/inactivity. Molecular modelling and selected physicochemical properties prediction were performed to assess the potential mechanism of action and applied in the search for an explanation as to why amongst all similar compounds only one is active. We can conclude that the tested compound 2 can be further investigated as a potential anthelmintic drug.

A wearable AIEgen-based lateral flow test strip for rapid detection of SARS-CoV-2 RBD protein and N protein

Accurate and rapid detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is significant for early tracing, isolation, and treatment of infected individuals, which will efficiently prevent large-scale transmission of coronavirus disease 2019 (COVID-19). Here, two kinds of test strips for receptor binding domain (RBD) and N antigens of SARS-CoV-2 are established with high sensitivity and specificity, in which AIE luminogens (AIEgens) are utilized as reporters. Because of the high brightness and resistance to quenching in aqueous solution, the limit of detection can be as low as 6.9 ng/mL for RBD protein and 7.2 ng/mL for N protein. As an antigen collector, an N95 mask equipped with a test strip with an excellent enrichment effect would efficiently simplify the sampling procedures. Compared with a test strip based on Au nanoparticles or fluorescein isothiocyanate (FITC), the AIEgen-based test strip shows high anti-interference capacity in complex biosamples. Therefore, an AIEgen-based test strip assay could be built as a promising platform for emergency use during the pandemic.

Preliminary Studies of Antimicrobial Activity of New Synthesized Hybrids of 2-Thiohydantoin and 2-Quinolone Derivatives Activated with Blue Light

Thiohydantoin and quinolone derivatives have attracted researchers’ attention because of a broad spectrum of their medical applications. The aim of our research was to synthesize and analyze the antimicrobial properties of novel 2-thiohydantoin and 2-quinolone derivatives. For this purpose, two series of hybrid compounds were synthesized. Both series consisted of 2-thiohydantoin core and 2-quinolone derivative ring, however one of them was enriched with an acetic acid group at N3 atom in 2-thiohydantoin core. Antibacterial properties of these compounds were examined against bacteria: Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. The antimicrobial assay was carried out using a serial dilution method to obtain the MIC. The influence of blue light irradiation on the tested compounds was investigated. The relative yield of singlet oxygen (¹O₂*, ¹Δ_g) generation upon excitation with 420 nm was determined by a comparative method, employing perinaphthenone (PN) as a standard. Antimicrobial properties were also investigated after blue light irradiation of the suspensions of the hybrids and bacteria placed in microtitrate plates. Preliminary results confirmed that some of the hybrid compounds showed bacteriostatic activity to the reference Gram-positive bacterial strains and a few of them were bacteriostatic towards Gram-negative bacteria, as well. Blue light activation enhanced bacteriostatic effect of the tested compounds.

A New Synthesis Strategy for Rhodanine and Its Derivatives

Rhodanine and its derivatives have been known as privileged structures in pharmacological research because of their wide spectrum of biological activities, but the synthesis method of rhodanine skeleton is limited. In this paper, not only rhodanine skeleton, but also N-aryl rhodanines can be directly prepared via the reaction of thioureas and thioglycolic acid in one step catalyzed by protic acid, which provides a new approach of the synthesis of rhodanine and its derivatives. The developed strategy is straightforward, efficient, atom economical, and convenient in good yields.

2-Thiohydantoin Moiety as a Novel Acceptor/Anchoring Group of Photosensitizers for Dye-Sensitized Solar Cells

Very recently, we have reported the synthesis and evaluation of biological properties of new merocyanine dyes composed of triphenylamine moiety, π-aromatic spacer, and rhodanine/2-thiohydantoin-based moiety. Interestingly, 2-thiohydantoin has never been studied before as an electron-accepting/anchoring group for the dye-sensitized solar cells (DSSCs). In the presented study, we examined the applicability of 2-thiohydantoin, an analog of rhodanine, in DSSC technology. The research included theoretical calculations, electrochemical measurements, optical characterization, and tests of the solar cells. As a result, we proved that 2-thiohydantoin might be considered as an acceptor/anchoring group since all the compounds examined in this study were active. The most efficient device showed power conversion efficiency of 2.59%, which is a promising value for molecules of such a simple structure. It was found that the cells' performances were mainly attributed to the dye loading and the ICT molecular absorption coefficients, both affected by the differences in the chemical structure of the dyes. Moreover, the effect of the aromatic spacer size and the introduction of carboxymethyl co-anchoring group on photovoltaic properties was observed and discussed.