Design, synthesis and antibacterial activities of thiouracil derivatives containing acyl thiourea as SecA inhibitors

Towards new bioactive fluorine-containing 1,3,4-oxadiazole-amide derivatives: synthesis, antibacterial activity, molecular docking and molecular dynamics simulation study

Through the approach of molecular hybridization, this study rationally designed and synthesized new trifluoromethyl-1,3,4-oxadiazole amide derivatives, denoted as 1a-1n. The findings reveal that these novel molecules exhibit potent inhibitory effects against various bacterial strains. Thereinto, compounds 1c, 1d, 1i, 1j and 1n, demonstrate relatively superior antimicrobial performance against B. cereus FM314, with a minimum inhibitory concentration (MIC) of 0.03907 μg/mL. Molecular docking analysis suggests the potential importance of the Ser57 and Thr125 amino acid residues (PDB ID: 4EI9) in contributing to the inhibitory activity against B. cereus. The consistency of these results was further corroborated through subsequent molecular dynamics simulations and MMPBSA validations. The insights gained from this study serve to facilitate the rational design and efficient development of novel eco-friendly antimicrobial inhibitors based on the trifluoromethyl-1,3,4-oxadiazole amide scaffold.

New N-acyl Thiourea Derivatives: Synthesis, Standardized Quantification Method and In Vitro Evaluation of Potential Biological Activities

New N-acyl thiourea derivatives with heterocyclic rings have been synthesized by first obtaining isothiocyanate, which further reacted with a heterocyclic amine, characterized by (FT-IR, NMR spectroscopy and FT-ICR) and tested for their in vitro antimicrobial, anti-biofilm and antioxidant activities to obtain a drug candidate in a lead-optimization process. From the tested compounds, those bearing benzothiazole (1b) and 6-methylpyridine (1d) moieties revealed anti-biofilm activity against E. coli ATCC 25922 at MBIC values of 625 µg/mL. Compound 1d exhibited the highest antioxidant capacity (~43%) in the in vitro assay using 1,1-diphenyl-2-picrylhydrazyl (DPPH). Considering the in vitro results, the highest anti-biofilm and antioxidant activities were obtained for compound 1d. Therefore, a reversed-phase high-performance liquid chromatography (RP-HPLC) method has been optimized and validated for the quantitative determination of compound 1d. The detection and quantitation limits were 0.0174 μg/mL and 0.0521 μg/mL, respectively. The R² correlation coefficient of the LOQ and linearity curves were greater than 0.99, over the concentration range of 0.05 μg/mL-40 μg/mL. The precision and accuracy of the analytical method were within 98-102%, confirming that the method is suitable for the quantitative determination of compound 1d in routine quality control analyses. Evaluating the results, the promising potential of the new N-acyl thiourea derivatives bearing 6-methylpyridine moiety will be further investigated for developing agents with anti-biofilm and antioxidant activities.

Evaluation of Antibacterial Activity of Thiourea Derivative TD4 against Methicillin-Resistant Staphylococcus aureus via Destroying the NAD+/NADH Homeostasis

To develop effective agents to combat bacterial infections, a series of thiourea derivatives (TDs) were prepared and their antibacterial activities were evaluated. Our results showed that TD4 exerted the most potent antibacterial activity against a number of Staphylococcus aureus (S. aureus), including the methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis and Enterococcus faecalis strains, with the minimum inhibitory concentration (MIC) at 2-16 µg/mL. It inhibited the MRSA growth curve in a dose-dependent manner and reduced the colony formation unit in 4× MIC within 4 h. Under the transmission electron microscope, TD4 disrupted the integrity of MRSA cell wall. Additionally, it reduced the infective lesion size and the bacterial number in the MRSA-induced infection tissue of mice and possessed a good drug likeness according to the Lipinski rules. Our results indicate that TD4 is a potential lead compound for the development of novel antibacterial agent against the MRSA infection.

Investigation of Newly Synthesized Bis-Acyl-Thiourea Derivatives of 4-Nitrobenzene-1,2-Diamine for Their DNA Binding, Urease Inhibition, and Anti-Brain-Tumor Activities

Bis-acyl-thiourea derivatives, namely N,N’-(((4-nitro-1,2-phenylene)bis(azanediyl)) bis(carbonothioyl))bis(2,4-dichlorobenzamide) (UP-1), N,N’-(((4-nitro-1,2-phenylene) bis(azanediyl))bis(carbonothioyl))diheptanamide (UP-2), and N,N’-(((4-nitro-1,2-phenylene)bis(azanediyl))bis(carbonothioyl))dibutannamide (UP-3), were synthesized in two steps. The structural characterization of the derivatives was carried out by FTIR, 1H-NMR, and 13C-NMR, and then their DNA binding, anti-urease, and anticancer activities were explored. Both theoretical and experimental results, as obtained by density functional theory, molecular docking, UV-visible spectroscopy, fluorescence (Flu-)spectroscopy, cyclic voltammetry (CV), and viscometry, pointed towards compounds’ interactions with DNA. However, the values of binding constant (Kb), binding site size (n), and negative Gibbs free energy change (ΔG) (as evaluated by docking, UV-vis, Flu-, and CV) indicated that all the derivatives exhibited binding interactions with the DNA in the order UP-3 > UP-2 > UP-1. The experimental findings from spectral and electrochemical analysis complemented each other and supported the theoretical analysis. The lower diffusion coefficient (Do) values, as obtained from CV responses of each compound after DNA addition at various scan rates, further confirmed the formation of a bulky compound–DNA complex that caused slow diffusion. The mixed binding mode of interaction as seen in docking was further verified by changes in DNA viscosity with varying compound concentrations. All compounds showed strong anti-urease activity, whereas UP-1 was found to have comparatively better inhibitory efficiency, with an IC50 value of 1.55 ± 0.0288 µM. The dose-dependent cytotoxicity of the synthesized derivatives against glioblastoma MG-U87 cells (a human brain cancer cell line) followed by HEK-293 cells (a normal human embryonic kidney cell line) indicated that UP-1 and UP-3 have greater cytotoxicity against both cancerous and healthy cell lines at 400 µM. However, dose-dependent responses of UP-2 showed cytotoxicity against cancerous cells, while it showed no cytotoxicity on the healthy cell line at a low concentration range of 40–120 µM.

Novel 2-Thiouracil-5-Sulfonamide Derivatives: Design, Synthesis, Molecular Docking, and Biological Evaluation as Antioxidants with 15-LOX Inhibition

New antioxidant agents are urgently required to combat oxidative stress, which is linked to the emergence of serious diseases. In an effort to discover potent antioxidant agents, a novel series of 2-thiouracil-5-sulfonamides (4-9) were designed and synthesized. In line with this approach, our target new compounds were prepared from methyl ketone derivative 3, which was used as a blocking unit for further synthesis of a novel series of chalcone derivatives 4a-d, thiosemicarbazone derivatives 5a-d, pyridine derivatives 6a-d and 7a-d, bromo acetyl derivative 8, and thiazole derivatives 9a-d. All compounds were evaluated as antioxidants against 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide (H₂O₂), lipid peroxidation, and 15-lipoxygenase (15-LOX) inhibition activity. Compounds 5c, 6d, 7d, 9b, 9c, and 9d demonstrated significant RSA in all three techniques in comparison with ascorbic acid and 15-LOX inhibitory effectiveness using quercetin as a standard. Molecular docking of compound 9b endorsed its proper binding at the active site pocket of the human 15-LOX which explains its potent antioxidant activity in comparison with standard ascorbic acid.

Analysis of 1-Aroyl-3-[3-chloro-2-methylphenyl] Thiourea Hybrids as Potent Urease Inhibitors: Synthesis, Biochemical Evaluation and Computational Approach

Urease is an amidohydrolase enzyme that is responsible for fatal morbidities in the human body, such as catheter encrustation, encephalopathy, peptic ulcers, hepatic coma, kidney stone formation, and many others. In recent years, scientists have devoted considerable efforts to the quest for efficient urease inhibitors. In the pharmaceutical chemistry, the thiourea skeleton plays a vital role. Thus, the present work focused on the development and discovery of novel urease inhibitors and reported the synthesis of a set of 1-aroyl-3-[3-chloro-2-methylphenyl] thiourea hybrids with aliphatic and aromatic side chains 4a-j. The compounds were characterized by different analytical techniques including FT-IR, ¹H-NMR, and ¹³C-NMR, and were evaluated for in-vitro enzyme inhibitory activity against jack bean urease (JBU), where they were found to be potent anti-urease inhibitors and the inhibitory activity IC₅₀ was found in the range of 0.0019 ± 0.0011 to 0.0532 ± 0.9951 μM as compared to the standard thiourea (IC₅₀ = 4.7455 ± 0.0545 μM). Other studies included density functional theory (DFT), antioxidant radical scavenging assay, physicochemical properties (ADMET properties), molecular docking and molecular dynamics simulations. All compounds were found to be more active than the standard, with compound 4i exhibiting the greatest JBU enzyme inhibition (IC₅₀ value of 0.0019 ± 0.0011 µM). The kinetics of enzyme inhibition revealed that compound 4i exhibited non-competitive inhibition with a Ki value of 0.0003 µM. The correlation between DFT experiments with a modest HOMO-LUMO energy gap and biological data was optimal. These recently identified urease enzyme inhibitors may serve as a starting point for future research and development.

Single-Crystal Investigation, Hirshfeld Surface Analysis, and DFT Study of Third-Order NLO Properties of Unsymmetrical Acyl Thiourea Derivatives

In the current research work, unsymmetrical acyl thiourea derivatives, 4-((3-benzoylthioureido)methyl)cyclohexane-1-carboxylic acid (BTCC) and methyl 2-(3-benzoylthioureido)benzoate (MBTB), have been synthesized efficiently. The structures of these crystalline thioureas were unambiguously confirmed by single-crystal diffractional analysis. The crystallographic investigation showed that the molecular configuration of both compounds is stabilized by intramolecular N-H···O bonding. The crystal packing of BTCC is stabilized by strong N-H···O bonding and comparatively weak O-H···S, C-H···O, C-H···π, and C-O···π interactions, whereas strong N-H···O bonding and comparatively weak C-H···O, C-H···S, and C-H···π interactions are responsible for the crystal packing of MBTB. The noncovalent interactions that are responsible for the crystal packing are explored by the Hirshfeld surface analysis for both compounds. The void analysis is performed to find the quantitative strength of crystal packing in both compounds. Additionally, state-of-the-art applied quantum chemical techniques are used to further explore the structure-property relationship in the above-entitled molecules. The optimization of molecular geometries showed a reasonably good correlation with their respective experimental structures. Third-order nonlinear optical (NLO) polarizability calculations were performed to see the advanced functional application of entitled compounds as efficient NLO materials. The average static γ amplitudes are found to be 27.30 × 10^-36 and 102.91 × 10^-36 esu for the compounds BTCC and MBTB, respectively. The γ amplitude of MBTB is calculated to be 3.77 times larger, which is probably due to better charge-transfer characteristics in MBTB. The quantum chemical analysis in the form of 3-D plots was also performed for their frontier molecular orbitals and molecular electrostatic potentials for understanding charge-transfer characteristics. We believe that the current investigation will not only report the new BTCC and MBTB compounds but also evoke the interest of the materials science community in their potential use in NLO applications.

Synthesis, antifungal activity and 3D-QSAR study of novel acyl thiourea compounds containing gem-dimethylcyclopropane ring

A series of novel acyl thiourea compounds containing gem-dimethylcyclopropane ring were designed and synthesized by multi-step reactions in search of novel antifungal molecules. Structures of all the target compounds were characterized by spectral techniques of UV-vis, FT-IR, ¹H-NMR, ¹³C-NMR, and ESI-MS. The antifungal activity of the target compounds was preliminarily evaluated by agar dilution method. The antifungal bioassay revealed that, at 50 μg/mL, compounds 5h (R = o-F), 5m (R = p-Br), and 5n (R = o-NO₂) showed the same antifungal activity of 73.6% against Physalospora piricola, which was comparable than that of the positive control. Furthermore, against Gibberella zeae, compounds 5k (R = m-Cl), 5l (R = m-Br), 5m (R = p-Br), and 5n (R = o-NO₂) displayed the same antifungal activity of 75.6%, and compound 5o (R = p-NO₂) displayed antifungal activity of 78.8%, which were all better than that of the positive control. The preliminary analysis of 3D-QSAR model was performed to study the effect of molecular structure on biological activity using the comparative molecular field analysis (CoMFA) method. The results showed 3D-QSAR model (r² = 0.995, q² = 0.503) was reasonable and effective.

Synthesis of New Thioureas Derivatives and Evaluation of Their Efficacy as Proliferation Inhibitors in MCF-7 Breast Cancer Cells by Using 99mTc-MIBI Radiotracer

BACKGROUND AND OBJECTIVES

Anti-tumor activity of some thioureas derivatives is well documented in literature and received considerable attention. The present study aims to synthesize and characterize some novel thioureas and carbonylthioureas as anti-tumor agents for MCF-7 breast cancer cells in vitro and in vivo.

MATERIALS AND METHODS

Several 1-allyl-3-(substituted phenyl), N,N'-(phenylene) bis(3- allyldithithiourea) and 1-cyclopropanecarbonyl-3-(substituted phenyl)-thioureas derivatives were synthesized and confirmed by FT-IR spectroscopy, NMR and 13C-NMR. Anti-tumor activity of these compounds was determined by various in vitro and in vivo assays including; MTT, tumor volume measurement as well as,99mTc-MIBI tumor uptake in MCF-7 tumor bearing nude mice.

RESULTS

Among all of the synthesized compounds, some thioureas derivatives [3i] and [4b] at 100 nM concentration exhibited significant inhibitory effects on the proliferation of MCF-7 cell in vitro. However, this inhibition was not observed in HUVEC human endothelial normal cells. In vivo anti-tumor effects of the synthesized compounds on MCF-7 xenograft mouse models demonstrated a reduction in the tumor volume for various concentrations between 2 to 10 mg/kg after 21 days. These effects were comparable with Tamoxifen as standard anti-estrogen drug. According to the 99mTc-MIBI biodistribution result, treatment of MCF-7 bearing nude mice with both [3i] and [4b] compounds at the maximum concentration (10 mg/kg) can lead to a significant decrease of 99mTc- MIBI tumor uptake.

CONCLUSION

Compounds [3i] and [4b] suppressed the growth of MCF-7 cells in the xenograft nude mice at the doses that were well-tolerated. Our study suggests that these new compounds with their significant anti-tumor effects, may serve as useful candidates for breast cancer therapy.

Synthesis, crystal structure and Hirshfeld Surface analysis of benzamide derivatives of thiourea as potent inhibitors of α-glucosidase in-vitro

Benzamide based structural analogues 1-15 were synthesized, and evaluated for α-glucosidase inhibition activity in vitro for the first time. Compounds 1-9 were found to be known, while compounds 10-15 were found to be new. However, to the best of our knowledge we are reporting α-glucosidase inhibitory activity of these bezamide derivatives of thiourea for the first time. Compounds 1, 3, 6-8, 10-14 were found to be potent inhibitors of α-glucosidase within IC₅₀ range of 20.44-333.41 µM, in comparison to the standard inhibitor, acarbose (IC₅₀ = 875.75 ± 2.08 µM). Mode of the enzyme inhibition was determined on the basis of kinetic studies which demonstrated that compounds 8, and 10 were non-competitive and competitive inhibitors of α-glucosidase enzyme, respectively. These compounds were also evaluated for their DPPH radical scavenging activity, and cytotoxicity against 3T3 mouse fibroblast cell lines. All synthesized compounds showed a significant to moderate DPPH radical scavenging activity and appeared to be non-cytotoxic except compound 9 which showed cytotoxicity against 3T3 normal mouse fibroblast cell lines. A single crystal X-ray and Hirshfeld Surface analysis of a representative compound is also presented.

New Potential Biologically Active Compounds: Synthesis and Characterization of Urea and Thiourea Derivativpes Bearing 1,2,4-oxadiazole Ring

Background:

Urea, thiourea, and 1,2,4-oxadiazole compounds are of great interest due to their different activities such as anti-inflammatory, antiviral, analgesic, fungicidal, herbicidal, diuretic, antihelminthic and antitumor along with antimicrobial activities.

Objective:

In this work, we provide a new series of potential biologically active compounds containing both 1,2,4-oxadiazole and urea/thiouprea moiety.

Materials and Methods:

Firstly, 5-chloromethyl-3-aryl-1,2,4-oxadiazoles (3a-j) were synthesized from the reaction of different substituted amidoximes (2a-j) and chloroacetyl chloride in the presence of pyridine by conventional and microwave-assisted methods. In the conventional method, 1,2,4-oxadiazoles were obtained in two steps. O-acylamidoximes obtained in the first step at room temperature were heated in toluene for an average of one hour to obtain 1,2,4-oxadiazoles. The yields varied from 70 to 96 %. 1,2,4-oxadiazoles were obtained under microwave irradiation in a single step in a 90-98 % yield at 160 °C in five minutes. 5-aminomethyl-3-aryl-1,2,4- oxadiazoles (5a-j) were obtained by Gabriel amine synthesis in two steps from corresponding 5-chloromethyl-3- aryl-1,2,4-oxadiazoles. Finally, twenty new urea (6a-j) and thiourea (7a-j) compounds bearing oxadiazole ring were synthesized by reacting 5-aminomethyl-3-aryl-1,2,4-oxadiazoles with phenyl isocyanate and isothiocyanate in tetrahydrofuran (THF) at room temperature with average yields (40-70%).

Results and Discussions:

An efficient and rapid method for the synthesis of 1,2,4-oxadiazoles from the reaction of amidoximes and acyl halides without using any coupling reagent under microwave irradiation has been developed, and twenty new urea/thiourea compounds bearing 1,2,4-oxadiazole ring have been synthesized and characterized.

Conclusion:

We have synthesized a new series of urea/thiourea derivatives bearing 1,2,4-oxadiazole ring. Also facile synthesis of 3,5-disubstituted 1,2,4-oxadiazoles from amidoximes and acyl chlorides under microwave irradiation was reported. The compounds were characterized using FTIR, 1H NMR, 13C NMR, and elemental analysis techniques.

Synthesis of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines

A series of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines was synthesized for the first time by the reactions of chloroethynylphosphonates with unsubstituted and 5(6)-substituted 2-thiouracils. The reaction of chloroethynylphosphonates with 6-substituted 2-thiouracils bearing electron-donor groups (CH₃, Ph) proceeded with high regioselectivity involving the cyclization through the N³-nitrogen atom to form new 3-phosphonylated thiazolo[3,2-a]-5-oxopyrimidines with good yield. In the case of unsubstituted and 5-methyl-2-thiouracils, cyclization occurred predominantly through the N¹ atom and partially via the N³-nitrogen atom to form a mixture of the corresponding thiazolo[3,2-a]-7- and 5-oxopyrimidines. A dramatic change in the reaction regioselectivity was observed in the case of 6-trifluoromethyl-2-thiouracil that afforded 2- and 3-phosphonylated 5-oxothiazolopyrimidines in a 1:1 ratio.

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.

SecA inhibitors as potential antimicrobial agents: differential actions on SecA-only and SecA-SecYEG protein-conducting channels

Sec-dependent protein translocation is an essential process in bacteria. SecA is a key component of the translocation machinery and has multiple domains that interact with various ligands. SecA acts as an ATPase motor to drive the precursor protein/peptide through the SecYEG protein translocation channels. As SecA is unique to bacteria and there is no mammalian counterpart, it is an ideal target for the development of new antimicrobials. Several reviews detail the assays for ATPase and protein translocation, as well as the search for SecA inhibitors. Recent studies have shown that, in addition to the SecA-SecYEG translocation channels, there are SecA-only channels in the lipid bilayers, which function independently from the SecYEG machinery. This mini-review focuses on recent advances on the newly developed SecA inhibitors that allow the evaluation of their potential as antimicrobial agents, as well as a fundamental understanding of mechanisms of SecA function(s). These SecA inhibitors abrogate the effects of efflux pumps in both Gram-positive and Gram-negative bacteria. We also discuss recent findings that SecA binds to ribosomes and nascent peptides, which suggest other roles of SecA. A model for the multiple roles of SecA is presented.

Inhibitors of protein translocation across membranes of the secretory pathway: novel antimicrobial and anticancer agents

Proteins routed to the secretory pathway start their journey by being transported across biological membranes, such as the endoplasmic reticulum. The essential nature of this protein translocation process has led to the evolution of several factors that specifically target the translocon and block translocation. In this review, various translocation pathways are discussed together with known inhibitors of translocation. Properties of signal peptide-specific systems are highlighted for the development of new therapeutic and antimicrobial applications, as compounds can target signal peptides from either host cells or pathogens and thereby selectively prevent translocation of those specific proteins. Broad inhibition of translocation is also an interesting target for the development of new anticancer drugs because cancer cells heavily depend on efficient protein translocation into the endoplasmic reticulum to support their fast growth.