Current developments in chemistry, coordination, structure and biological aspects of 1-(acyl/aroyl)-3- (substituted)thioureas: advances Continue …

Novel pyrimidine linked acyl thiourea derivatives as potent α-amylase and proteinase K inhibitors: design, synthesis, molecular docking and ADME studies

To discover promising therapeutic agents, novel diaryl pyrimidine linked acyl thiourea derivatives (6a-j) were designed and synthesized via straightforward and multistep synthesis. The structure of these derivatives (6a-j) was confirmed by FTIR, 1H, and 13C NMR spectroscopic techniques. The in vitro biological screening of these compounds was carried out to assess their bacterial, α-amylase, and proteinase K inhibition potential. The results manifested that the developed molecules (6a-j) possessed a remarkable inhibition potential against targeted α-amylase and proteinase K enzymes. The compounds 6j and 6g were found to be the most potent α-amylase inhibitors with IC50 values of 1.478 ± 0.051 and 1.509 ± 0.039 μM, respectively. Meanwhile, the compounds 6a, 6f, and 6e having IC50 values of 1.790 ± 0.079, 1.794 ± 0.080, and 1.795 ± 0.080 μM, respectively, showed high proteinase K inhibitory activity. A moderate antibacterial activity is also displayed by these compounds (6a-j). The different substitution on the framework of pyrimidine linked acyl thiourea pharmacophore, provided the valuable basis for structure-activity relationship studies. Additionally, to identify the binding affinities of our desired compounds, molecular docking study was used. ADME analysis was also conducted to explore the physicochemical properties. Hence, these studies shed light on the significance of pyrimidine-based acyl thiourea to attain potent efficacy in drug discovery.

Effect of Terminal Hydroxy Groups on the Structural Properties of Acyl Thioureas

The 1-acyl thiourea family [R1C(O)NHC(S)NR2R3] exhibits the flexibility to incorporate a wide variety of substituents into their structure. The structural attributes of these compounds are intricately tied to the type and extent of substitution. In the case of 3-mono-substituted thioureas (R2=H), the conformational behavior is predominantly shaped by the presence of an intramolecular N-H ⋅ ⋅ ⋅ O=C hydrogen bond. This study delves into the structural consequences stemming from the inclusion of substituents possessing hydrogen-donor capabilities within four novel 1-acyl-3-mono-substituted thiourea derivatives. A comprehensive suite of analytical techniques, encompassing FTIR, Raman spectroscopy, multinuclear (1H and 13C) NMR spectroscopy, single-crystal X-ray diffraction, and supported by computational methods, notably NBO (Natural Bond Orbital) population analysis, Hirshfeld analysis, and QTAIM (Quantum Theory of Atoms in Molecules), was harnessed to scrutinize and characterize these compounds. In the crystalline state, these compounds exhibit an intricate interplay of intermolecular interactions, prominently featuring an expansive network of hydrogen bonds between the hydroxy (-OH) groups and the carbonyl and thiocarbonyl bonds within the 1-acyl thiourea fragment. Notably, the topological analysis underscores significant distinctions in the properties of the acyl thiourea fragment and the intramolecular >C=O ⋅ ⋅ ⋅ H-N bond when transitioning from the isolated molecule to the crystalline environment.

Exploring the latest trends in chemistry, structure, coordination, and diverse applications of 1-acyl-3-substituted thioureas: a comprehensive review

Acyl thioureas represent a privileged moiety with vast potential applicability across diverse fields, making them the subject of extensive research efforts. The inherent flexibility of thiourea facilitates the synthesis of a wide range of core structures with diverse functionalities and properties. The distinctive presence of hard and soft donor sites renders acyl thioureas inclined to act as versatile ligands, thereby engendering a diverse array of metal complexes incorporating acyl thiourea as a pivotal ligand. Extensive investigations into the synthesized acyl thioureas and their derivatives have culminated in the elucidation of their substantial potential across a spectrum of applications, spanning biological activities, materials chemistry, catalysis, and beyond. This literature review represents a continuation of our ongoing endeavor to compile comprehensive data on research endeavors concerning acyl thioureas over the past two years.

Promoting the Anticancer Activity with Multidentate Furan-2-Carboxamide Functionalized Aroyl Thiourea Chelation in Binuclear Half-Sandwich Ruthenium(II) Complexes

A new set of binuclear arene ruthenium complexes [Ru2(p-cymene)2(k4-N2OS)(L1-L3)Cl2] (Ru2L1-Ru2L3) encompassing furan-2-carboxamide-based aroylthiourea derivatives (H2L1-H2L3) was synthesized and characterized by various spectral and analytical techniques. Single-crystal XRD analysis unveils the N^O and N^S mixed monobasic bidentate coordination of the ligands constructing N, S, Cl/N, O, and Cl legged piano stool octahedral geometry. DFT analysis demonstrates the predilection for the formation of stable arene ruthenium complexes. In vitro antiproliferative activity of the complexes was examined against human cervical (HeLa), breast (MCF-7), and lung (A549) cancerous and noncancerous monkey kidney epithelial (Vero) cells. All the complexes are more efficacious against HeLa and MCF-7 cells with low inhibitory doses (3.86-11.02 μM). Specifically, Ru2L3 incorporating p-cymene and -OCH3 fragments exhibits high lipophilicity, significant cytotoxicity against cancer cells, and lower toxicity on noncancerous cells. Staining analysis indicates the apoptosis-associated cell morphological changes expressively in MCF-7 cells. Mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) analyses reveal that Ru2L3 can raise ROS levels, reduce MMP, and trigger mitochondrial dysfunction-mediated apoptosis. The catalytic oxidation of glutathione (GSH) to its disulfide form (GSSG) by the complexes may simultaneously increase the ROS levels, alluding to their observed cytotoxicity and apoptosis induction. Flow cytometry determined the quantitative classification of late apoptosis and S-phase arrest in MCF-7 and HeLa cells. Western blotting analysis confirmed that the complexes promote apoptosis by upregulating Caspase-3 and Caspase-9 and downregulating BCL-2. Molecular docking studies unfolded the strong binding affinities of the complexes with VEGFR2, an angiogenic signaling receptor, and BCL2, Cyclin D1, and HER2 proteins typically overexpressed on tumor cells.

Evaluation of synthetic aminoquinoline derivatives as urease inhibitors: in vitro, in silico and kinetic studies

Background: Quinoline and acyl thiourea scaffolds have major chemical significance in medicinal chemistry. Quinoline-based acyl thiourea derivatives may potentially target the urease enzyme. Materials & methods: Quinoline-based acyl thiourea derivatives 1-26 were synthesized and tested for urease inhibitory activity. Results: 19 derivatives (1-19) showed enhanced urease enzyme inhibitory potential (IC50 = 1.19-18.92 μM) compared with standard thiourea (IC50 = 19.53 ± 0.032 μM), whereas compounds 20-26 were inactive. Compounds with OCH3, OC2H5, Br and CH3 on the aryl ring showed significantly greater inhibitory potential than compounds with hydrocarbon chains of varying length. Molecular docking studies were conducted to investigate ligand interactions with the enzyme's active site. Conclusion: The identified hits can serve as potential leads against the drug target urease in advanced studies.

The influence of N-alkyl chains in benzoyl-thiourea derivatives on urease inhibition: Soil studies and biophysical and theoretical investigations on the mechanism of interaction

Ureases are enzymes produced by fungi, plants, and bacteria associated with agricultural and clinical problems. The urea hydrolysis in NH₃ and CO₂ leads to the loss of N-urea fertilizers in soils and changes the human stomach microenvironment, favoring the colonization of H. pylori. In this sense, it is necessary to evaluate potential enzyme inhibitors to mitigate the effects of their activities and respond to scientific and market demands to produce fertilizers with enhanced efficiency. Thus, biophysical and theoretical studies were carried out to evaluate the influence of the N-alkyl chain in benzoyl-thiourea derivatives on urease enzyme inhibition. A screening based on IC₅₀, binding constants, and theoretical studies demonstrated that BTU1 without the N-alkyl chain (R = H) was more active than other compounds, so the magnitude of the interaction was determined as BTU1 > BTU2 > BTU3 > BTU4 > BTU5, corresponding to progressively increased chain length. Thus, BTU1 was selected for interaction and soil application essays. The binding constants (K_b) for the supramolecular urease-BTU1 complex ranged from 7.95 to 5.71 × 10³ M^-1 at different temperatures (22, 30, and 38 °C), indicating that the preferential forces responsible for the stabilization of the complex are hydrogen bonds and van der Waals forces (ΔH = -15.84 kJ mol^-1 and ΔS = -36.61 J mol^-1 K^-1). Theoretical and experimental results (thermodynamics, synchronous fluorescence, and competition assay) agree and indicate that BTU1 is a mixed inhibitor. Finally, urease inhibition was evaluated in the four soil samples, where BTU1 was as efficient as NBPT (based on ANOVA two-way and Tukey test with 95% confidence), with an average inhibition of 20% of urease activity. Thus, the biophysics and theoretical studies are strategies for evaluating potential inhibitors and showed that increasing the N-alkyl chain in benzoyl-thiourea derivatives did not favor urease inhibition.

Recent trends in chemistry, structure, and various applications of 1-acyl-3-substituted thioureas: a detailed review

The interest in acyl thioureas has continually been escalating owing to their extensive applications in diverse fields, such as synthetic precursors of new heterocycles, pharmacological and materials science, and technology. These scaffolds exhibit a wide variety of biological activities such as antitumor, enzyme inhibitory, anti-bacterial, anti-fungal, and anti-malarial activities and find utilization as chemosensors, adhesives, flame retardants, thermal stabilizers, antioxidants, polymers and organocatalysts. In addition, the synthesis, and applications of coordination complexes of these ligands have also been overviewed. The current review is a continuation of our previous efforts in this area, focusing on the recent advancements during the period 2017 to present.

This review encapsulates the recently designed acyl thioureas, and their crystal structures, metal complexes and various applications from 2017 to present, including pharmacological aspects, chemosensing and heterogenous catalysis.

Evaluation of Antimicrobial and Anti-Biofilm Formation Activities of Novel Poly(vinyl alcohol) Hydrogels Reinforced with Crosslinked Chitosan and Silver Nano-Particles

Novel hydrogels were prepared by blending chitosan and poly(vinyl alcohol), PVA, then crosslinking the resulting blends using trimellitic anhydride isothiocyanate at a concentration based on chitosan content in the blends. The weight ratios of chitosan: PVA in the blends were 1:3, 1:1, and 3:1 to produce three hydrogels symbolized as H13, H11, and H31, respectively. For a comparison, H10 was also prepared by crosslinking pure chitosan with trimellitic anhydride isothiocyanate. For further modification, three H31/silver nanocomposites (AgNPs) were synthesized using three different concentrations of silver nitrate to obtain H31/AgNPs1%, H31/AgNPs3% and H31/AgNPs5%. The structures of the prepared samples were emphasized using various analytical techniques. PVA has no inhibition activity against the tested microbes and biofilms. The antimicrobial and anti-biofilm formation activities of the investigated samples was arranged as: H31/AgNPs5% ≥ H31/AgNPs3% > H31/AgNPs1% > H10 > H31 > H11 > H13 > chitosan. H31/AgNPs5% and H31/AgNPs3% were more potent than Vancomycin and Amphotericin B against most of the tested microbes. Interestingly, H31 and H31/AgNPs3% were safe on the normal human cells. Consequently, hydrogels resulting from crosslinked blends of chitosan and PVA loaded with AgNPs in the same structure have significantly reinforced the antimicrobial and inhibition activity against the biofilms of PVA.

Experimental and Theoretical DFT Study of Cu(I)/N,N-Disubstituted-N'-acylthioureato Anticancer Complexes: Actin Cytoskeleton and Induction of Death by Apoptosis in Triple-Negative Breast Tumor Cells

Six complexes with the general formula [Cu(acylthioureato)(PPh3)2] were synthesized and characterized using spectroscopic techniques (IR, UV/visible, and 1D and 2D NMR), mass spectrometry, elemental analysis, and X-ray diffraction. Interpretation of the in vitro cytotoxicity data of Cu(I) complexes took into account their stability in cell culture medium. DFT calculations showed that NMR properties, such as the shielding of carbon atoms, are affected by relativistic effects, supported by the ZORA Hamiltonian in the theoretical calculations. Additionally, the calculation of the energies of the frontier molecular orbitals predicted that the structural changes of the acylthiourea ligands did not cause marked changes in the reactivity descriptors. All complexes were cytotoxic to the evaluated tumor cell lines [MDA-MB-231 (triple-negative breast cancer, TNBC), MCF-7 (breast cancer), and A549 (lung cancer)]. In the MDA-MB-231 cell line, complex 1 significantly altered the cytoskeleton of the cells, reducing the density and promoting the condensation of F-actin filaments. In addition, the compound caused an increase in the percentage of cells in the fragmented DNA region (sub-G0) and induced cell death via the apoptotic pathway starting at the IC50 concentration. Taken together, the results show that complex 1 has cytotoxic and apoptotic effects on TNBC cells, which is a cell line originating from an aggressive, difficult-to-treat breast cancer.

Selenourea and thiourea derivatives of chiral and achiral enetetramines: Synthesis, characterization and enzyme inhibitory properties

A series of chiral and achiral cyclic seleno- and thiourea compounds bearing benzyl groups on N-atoms were prepared from enetetramines and appropriate Group VI elements in good yields. All the synthesized compounds were characterized by elemental analysis, FT-IR, ¹H NMR and ¹³C NMR spectroscopy, and the molecular and crystal structures of (R,R)-4b and (R,R)-5b were confirmed by the single-crystal X-ray diffraction method. These assayed for their activities against metabolic enzymes acetylcholinesterase, butyrylcholinesterase, and α-glycosidase. These selenourea and thiourea derivatives of chiral and achiral enetetramines effectively inhibit AChE and BChE with IC₅₀ values in the range of 3.32-11.36 and 1.47-9.73 µM, respectively. Also, these compounds inhibited α-glycosidase enzyme with IC₅₀ values varying between 1.37 and 8.53 µM. The results indicated that all the synthesized compounds exhibited excellent inhibitory activities against mentioned enzymes as compared with standard inhibitors. Representatively, the most potent compound against α-glycosidase enzyme, (S,S)-5b, was 12-times more potent than standard inhibitor acarbose; 7b and 8a as most potent compounds against cholinesterase enzymes, were around 5 and 13-times more potent than standard inhibitor tacrine against achethylcholinesterase (AChE) and butyrylcholinesterase (BChE), respectively.

Biological properties and conformational studies of amphiphilic Pd(II) and Ni(II) complexes bearing functionalized aroylaminocarbo-N-thioylpyrrolinate units

A series of novel palladium(II) and nickel(II) complexes of multifunctionalized aroylaminocarbo-N-thioylpyrrolinates were synthesized and characterized by analytical and spectroscopic techniques. The biological properties of the freshly prepared compounds were screened against S. aureus, B. subtilis, A. hydrophila, E. coli, and A. baumannii bacteria and antituberculosis activity against M. tuberculosis H37Rv strains. Also, the antifungal activity was studied against C. albicans, C. tropicalis, and C. glabrata standard strains. A deep conformational survey was monitored using DFT calculations with the aim to explain the importance of the final conformation in the biological experimental results.

Synthesis and characterization of novel acylthiourea compounds used in ions recognition and sensing in organic media

A series of novel N-acyl-N'-aryl thiourea derivatives were designed and prepared with the aim to develop dual responsive receptors for anions and cations. The structure of the new products was confirmed by NMR spectroscopy (¹³C and ¹H), elemental analysis, and IR spectroscopy. Their thermal stability was studied by thermogravimetric analysis (TG) and it was found that these acyl thiourea derivatives are stable up to 160 °C. The ion recognition and sensing properties of the acyl thiourea compounds were investigated by UV-VIS absorption spectroscopy in organic media upon the addition of various salts. The UV-VIS studies revealed that these acyl thiourea derivatives are able to sense biological important ions such as fluoride and copper (II) ions.

Synergy Effects in Heavy Metal Ion Chelation with Aryl- and Aroyl-Substituted Thiourea Derivatives

Detection and removal of metal ion contaminants have attracted great interest due to the health risks that they represent for humans and wildlife. Among the proposed compounds developed for these purposes, thiourea derivatives have been shown as quite efficient chelating agents of metal cations and have been proposed for heavy metal ion removal and for components of high-selectivity sensors. Understanding the nature of metal-ionophore activity for these compounds is thus of high relevance. We present a theoretical study on the interaction between substituted thioureas and metal cations, namely, Cd²⁺, Hg²⁺, and Pb²⁺. Two substituent groups have been chosen: 2-furoyl and m-trifluoromethylphenyl. Combining density functional theory simulations with wave function analysis techniques, we study the nature of the metal-thiourea interaction and characterize the bonding properties. Here, it is shown how the N,N'-disubstituted derivative has a strong affinity for Hg²⁺, through cation-hydrogen interactions, due to its greater oxidizing capacity.

Investigation of the reactivity properties of a thiourea derivative with anticancer activity by DFT and MD simulations

Spectroscopic analysis of 1-(2-fluorophenyl)-3-[3-(trifluoromethyl)phenyl]thiourea (FPTT) is reported. Experimental and theoretical analyses of FPTT, with molecular dynamics (MD) simulations, are reported for finding different parameters like identification of suitable excipients, interactions with water, and sensitivity towards autoxidation. Molecular dynamics and docking show that FPTT can act as a potential inhibitor for new drug. Additionally, local reactivity, interactivity with water, and compatibility of FPTT molecule with frequently used excipients have been studied by combined application of density functional theory (DFT) and MD simulations. Analysis of local reactivity has been performed based on selected fundamental quantum-molecular descriptors, while interactivity with water was studied by calculations of radial distribution functions (RDFs). Compatibility with excipients has been assessed through calculations of solubility parameters, applying MD simulations. Graphical abstract Reactive sites identified.

Novel 1,2,3-Triazole Derivatives as Potential Inhibitors against Covid-19 Main Protease: Synthesis, Characterization, Molecular Docking and DFT Studies

The highly contagious nature of Covid-19 attracted us to this challenging area of research, mainly because the disease is spreading very fast and until now, no effective method of a safe treatment or a vaccine is developed. A library of novel 1,2,3-triazoles based 1,2,4-triazole, 1,3,4-oxadiazole and/or 1,3,4-thiadiazole scaffolds were designed and successfully synthesized. Different spectroscopic tools efficiently characterized all the newly synthesized hybrid molecules. An interesting finding is that some of the newly designed compounds revealed two isomeric forms. The ratio is affected by the size of the attached group as well as the type of the heteroatom forming the side ring attached to the central 1,2,3-triazole ring. The experimental spectroscopic data is in agreement with the DFT calculations at B3LYP 6-31G (d,p) with regard to the geometrical conformation of the prepared compounds. The DFT results revealed that the stability of one isomeric form over the other in the range of 0.057-0.161 Kcal mol-1. A docking study was performed using PyRx and AutoDockVina to investigate the activity of the prepared 1,2,3-triazoles as antiviral agents. Bond affinity scores of the 1,2,3-triazole derivatives were detected in the range of -6.0 to -8.8 kcal/mol showing binding to the active sites of the 6LU7 protease and hence could be anticipated to inhibit the activity of the enzyme. Verification of the docking results was performed using the Mpro alignment of coronaviruses substrate-binding pockets of COVID-19 against the ligands. As per these results, it can be proposed that the title hybrid molecules are acceptable candidates against COVID-19 for possible medicinal agents.

Synthesis, X-ray, Hirshfeld surface analysis, exploration of DNA binding, urease enzyme inhibition and anticancer activities of novel adamantane-naphthyl thiourea conjugate

1-(adamantane-1-carbonyl-3-(1-naphthyl)) thiourea (C₂₂H₂₄N₂OS (4), was synthesized by the reaction of freshly prepared adamantane-1-carbonyl chloride from corresponding acid (3) with ammonium thiocyanate in 1:1 M ratio in dry acetone to afford the adamantane-1-carbonyl isothiocyanate (2) in situ followed by treatment with 1-naphthyl amine (3). The structure was established by elemental analyses, FTIR, ¹H, ¹³C NMR and mass spectroscopy. The molecular and crystal structure were determined by single crystal X-ray analysis. It belongs to triclinic system P - 1 space group with a = 6.7832(5) Å, b = 11.1810(8) Å, c = 13.6660(10) Å, α = 105.941(6)°, β = 103.730(6)°, γ = 104.562(6)°, Z = 2, V = 910.82(11) ų. The naphthyl group is almost planar. In the crystal structure, intermolecular CH···O hydrogen bonds link the molecules into centrosymmetric dimers, enclosing R₂²(14) ring motifs, while the intramolecular NH···O hydrogen bonds enclose S(6) ring motifs, in which they may be effective in the stabilization of the structure. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H … H (59.3%), H … C/C … H (19.8%) and H … S/S … H (10.1%) interactions. Hydrogen bonding and van der Waals interactions are the dominant interactions in the crystal packing. DFT, molecular docking and urease inhibition studies revealed stability and electron withdrawing nature of 4 as compared to DNA base pairs and residues of urease. The DNA binding results from docking, UV- visible spectroscopy, and viscosity studies indicated significant binding of 4 with the DNA via intercalation and groove binding. Further investigation of the compound was done on hepatocellular carcinoma; Huh-7 cell line as well as normal human embryonic kidney; Hek-293 cell line. The compound showed significant cytotoxic activity against Huh-7 cells in comparison to normal Hek-293 cells indicating selective cytotoxicity towards cancer cells.

Synthesis, computational studies and enzyme inhibitory kinetics of benzothiazole-linked thioureas as mushroom tyrosinase inhibitors

Herein, we report synthesis of a set of benzothiazole-thiourea hybrids with aromatic and aliphatic side chains (BT1 to BT9) using an elegant synthetic strategy. The newly synthesized benzothiazole-thiourea conjugates were subjected to In-vitro tyrosinase inhibition and free radical scavenging activity. Majority of the compounds indicated inhibition considerably improved than the standard; compound (Kojic acid with IC₅₀ = 16.8320 ± 1.1600 µM) BT2 with IC₅₀ = 1.3431 ± 0.0254 µM was found to be the best inhibitor. A non-competitive mode of inhibition of BT2 was disclosed with Ki value of 2.8 µM. In order to study enzyme-inhibitor interactions SAR analysis molecular docking was carried out. The amino groups of thiourea were involved in hydrogen bonding with Glu322 showing the bond length of 1.74 and 2.70 Å, respectively. Moreover, the coupling of π-π was displayed between benzothiazole and benzene rings of His244 and His263, respectively. The outcome of this study might help to develop new inhibitors of melanogenesis, important for cosmetic and food products. Communicated by Ramaswamy H. Sarma.

Synthesis, characterization, antimicrobial, antioxidant and computational evaluation of N-acyl-morpholine-4-carbothioamides

The present research paper reports the convenient synthesis, successful characterization, in vitro antibacterial, antifungal, antioxidant potency and biocompatibility of N-acyl-morpholine-4-carbothioamides (5a-5j). The biocompatible derivatives were found to be highly active against the tested bacterial and fungal strains. Moreover, some of the screened N-acyl-morpholine-4-carbothioamides exhibited excellent antioxidant potential. Docking simulation provided additional information about possibilities of their inhibitory potential against RNA. It has been predicted by in silico investigation of the binding pattern that compounds 5a and 5j can serve as the potential surrogate for design of novel and potent antibacterial agents. The results for the in vitro bioassays were promising with the identification of compounds 5a and 5j as the lead and selective candidate for RNA inhibition. Results of the docking computations further ascertained the inhibitory potential of compound 5a. Based on the in silico studies, it can be suggested that compounds 5a and 5j can serve as a structural model for the design of antibacterial agents with better inhibitory potential. Binding mode of compound 5j inside the active site of RNA in 3D space. 5j displayed highest antibacterial potential than the reference drug ampicillin with ZOI 10.50 mm against Staphylococcus aureus. 5j also displayed highest antifungal potential than the reference drug amphotericin B with ZOI 18.20 mm against Fusarium solani.