Thioureas and their cyclized derivatives: Synthesis, conformational analysis and antimicrobial evaluation

Synthesis, antimicrobial evaluation, HPLC-based compound accumulation and docking studies of 2-methoxybenzoyl thioureas

INTRODUCTION

In this study, we presented the synthesis, antimicrobial activity, High Performance Liquid Chromatography (HPLC)-based compound accumulation and molecular docking of 2-methoxybenzoyl substituted thiourea derivatives.

MATERIALS AND METHODS

The antimicrobial activity of a total of eight synthesized compounds was evaluated against seven species of bacteria and fungi. HPLC-based compound accumulation assay, molecular docking, in silico toxicity and ADME analyses were performed for selected compounds for further evaluation of compound activity relationship.

RESULTS AND DISCUSSION

The compounds exhibited greater activity against fungi than bacteria, with compounds 1b, 1c, 1d, and 1g showing particularly strong activity against Candida species. Compounds 1a, 1b, 1d, and 1h that had varying biological activities were selected for further analyses. Compounds 1a, 1b, 1d, and 1h accumulated intracellularly reaching up to 36.77% within 1 hours. Molecular docking studies revealed compatible interactions among the compounds in comparison to their varying biological activities. Additionally, all compounds had low toxicity and showed no physicochemical violations when compared to Lipinski's rule of five.

CONCLUSION

The results suggest that optimizing the position of substituents on the phenyl rings of acyl thioureas could enhance the antimicrobial activity of our compounds.

Thiourea compounds as multifaceted bioactive agents in medicinal chemistry

Microbial resistance (MR) and cancer are global healthcare pitfalls that have caused millions of deaths and pose a significant pharmaceutical challenge, with clinical cases increasing. Thioureas are preferred structures in medicinal chemistry, chemosensors, and organic synthesis platforms. In fact, thiourea (TU) moieties serve as a common framework for several medications and bioactive substances, demonstrating a wide range of therapeutic and pharmacological accomplishments. The integration of the thiourea moiety into a diverse range of organic molecules has resulted in very flexible compounds with widespread uses in medicinal chemistry. Moreover, for over a century, TU and its metal complexes have been characterized for their biological activity. Finally, we provide an assessment and future outlook of different organo-thiourea derivatives, from the very beginning to the most recent discoveries in medicinal activity.

Enantiodifferentiation of Thiohydantoin Derivatives by NMR in the Presence of Chiral Solvating Agent: (1R,2S)-Ephedrine and Chiral Symmetrical and Unsymmetrical Thioureas

2-Thiohydantoin derivatives, including different substitutions at N-1 and C-5 (5-methyl-, 5-isopropyl-, 1-acetyl-5-methyl-, and 1-acetyl-5-isopropyl-) (1-4, respectively), were synthesized by the known literature methods. In these synthetic pathways, it was reported that enantiomerically pure 2-thiohydantions were obtained in the absence of any solvent via the reaction of L-amino acids with thiourea (1&2) and via the reaction of L-amino acids with NH4SCN and acetic anhydride (3&4). However, in this study, in contrary to the previous literature studies, racemic mixtures of 2-thiohydantoins were obtained although the same synthetic methods were used. The racemic nature of 2-thiohydantoin derivatives (1-4) was proved by using 1H NMR analysis in the presence of (1R,2S)-(-)-ephedrine as a chiral auxiliary. In addition, the enantiomers of 3&4 were also resolved on chiral stationary phases by HPLC analyses. Furthermore, newly synthesized unsymmetrical chiral thioureas (S-1&S-2) and previously synthesized symmetrical ones (SS-3&SS-4) were used as chiral solvating agent (CSA) for the enantiodiscrimination of the thiohydantoins (5&6), previously reported. Optimal CSA/substrate ratios were determined for the best enantiodiscrimination.

Synthesis, Computational Study, and In Vitro α-Glucosidase Inhibitory Action of Thiourea Derivatives Based on 3-Aminopyridin-2(1H)-Ones

Reactions with allyl-, acetyl-, and phenylisothiocyanate have been studied on the basis of 3-amino-4,6-dimethylpyridine-2(1H)-one, 3-amino-4-phenylpyridine-2-one, and 3-amino-4-(thiophene-2-yl)pyridine-2(1H)-one (benzoyl-)isothiocyanates, and the corresponding thioureide derivatives 8-11a-c were obtained. Twelve thiourea derivatives were obtained and studied for their anti-diabetic activity against the enzyme α-glucosidase in comparison with the standard drug acarbose. The comparison drug acarbose inhibits the activity of α-glucosidase at a concentration of 15 mM by 46.1% (IC50 for acarbose is 11.96 mM). According to the results of the conducted studies, it was shown that alkyl and phenyl thiourea derivatives 8,9a-c, in contrast to their acetyl-(benzoyl) derivatives and 10,11a-c, show high antidiabetic activity. Thus, 1-(4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)-3-phenylthiourea 9a has the highest inhibitory activity against the enzyme α-glucosidase, exceeding the activity of the comparison drug acarbose, which inhibits the activity of α-glucosidase by 56.6% at a concentration of 15 mm (IC50 = 9,77 mM). 1-(6-methyl-2-oxo 4-(thiophen-2-yl)-1,2-dihydropyridin-3-yl)-3-phenylthiourea 9c has inhibitory activity against the enzyme α-glucosidase, comparable to the comparison drug acarbose, inhibiting the activity of α-glucosidase at a concentration of 15 mm per 41.2% (IC50 = 12,94 mM). Compounds 8a, 8b, and 9b showed inhibitory activity against the enzyme α-glucosidase, with a lower activity compared to acarbose, inhibiting the activity of α-glucosidase at a concentration of 15 mM by 23.3%, 26.9%, and 35.2%, respectively. The IC50 against α-glucosidase for compounds 8a, 8b, and 9b was found to be 16.64 mM, 19.79 mM, and 21.79 mM, respectively. The other compounds 8c, 10a, 10b, 10c, 11a, 11b, and 11c did not show inhibitory activity against α-glucosidase. Thus, the newly synthesized derivatives of thiourea based on 3-aminopyridine-2(1H)-ones are promising candidates for the further modification and study of their potential anti-diabetic activity. These positive bioanalytical results will stimulate further in-depth studies, including in vivo models.

A consensus reverse docking approach for identification of a competitive inhibitor of acetyltransferase enhanced intracellular survival protein from Mycobacterium tuberculosis

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb), which remains a significant global health challenge. The emergence of multidrug-resistant (MDR) Mtb strains imposes the development of new therapeutic strategies. This study focuses on the identification and evaluation of potential inhibitors against Mtb H37Ra through a comprehensive screening of an in-house chemolibrary. Subsequently, a promising pyrimidine derivative (LQM495) was identified as promising and then further investigated by experimental and in silico approaches. In this context, computational techniques were used to elucidate the potential molecular target underlying the inhibitory action of LQM495. Then, a consensus reverse docking (CRD) protocol was used to investigate the interactions between this compound and several Mtb targets. Out of 98 Mtb targets investigated, the enhanced intracellular survival (Eis) protein emerged as a target for LQM495. To gain insights into the stability of the LQM495-Eis complex, molecular dynamics (MD) simulations were conducted over a 400 ns trajectory. Further insights into its binding modes within the Eis binding site were obtained through a Quantum mechanics (QM) approach, using density functional theory (DFT), with B3LYP/D3 basis set. These calculations shed light on the electronic properties and reactivity of LQM495. Subsequently, inhibition assays and kinetic studies of the Eis activity were used to investigate the activity of LQM495. Then, an IC50 value of 11.0 ± 1.4 µM was found for LQM495 upon Eis protein. Additionally, its Vmax, Km, and Ki parameters indicated that it is a competitive inhibitor. Lastly, this study presents LQM495 as a promising inhibitor of Mtb Eis protein, which could be further explored for developing novel anti-TB drugs in the future.

Interplay between anti-anti and syn-anti conformations of thiourea modulating ON-OFF catalysis

The design, synthesis and operation of a readily accessible two-state switch are demonstrated. The switch initially exists in an intramolecularly hydrogen-bonded self-locked state, as evidenced by the solution-state NMR and solid-state structure. The switch can be reversibly altered between anti-anti and syn-anti conformations by adding and removing Cu+ ions, as evidenced by the NMR and crystallographic study. The anti-anti form was found to be catalytically active in the Michael addition reaction, whereas the syn-anti form was catalytically inactive.

Stable hemiaminals from axially chiral pyridine compounds

In this study, we have synthesized a series of 3-(pyridin-2-yl)-2-(pyridin-2-ylimino)thiazolidin-4-ol derivatives regioselectively from 2-iminothiazolidin-4-ones using LiAlH₄ at room temperature. Due to the presence of the restricted rotation around the N3-C_aryl single bond, the formation of M/P isomers was observed. The OH group of the hemiaminal was found to orient itself on the same side with pyridyl nitrogen during this restricted rotation to form an intramolecular hydrogen bond, which was demonstrated by the computational DFT study. This orientation presumably inhibited the occurrence of dehydration and stabilized the molecule.

Synthesis of thiazole-based-thiourea analogs: as anticancer, antiglycation and antioxidant agents, structure activity relationship analysis and docking study

This work reports the convenient approach for the synthesis of thiazole based thiourea derivatives (1-21) from 2-bromo-1-(4-fluorophenyl)thiazole-1-one and phenyl isothiocyanates. The scope and diversity were achieved from readily available phenyl isothiocyanates. This protocol involves an oxidative C-S bond formation. Moreover, hybrid thiazole based thiourea scaffolds (1-21) according to literature known protocol were screened in vitro for anticancer Potential against breast cancer, antiglycation and antioxidant inhibitory profile. All newly developed scaffolds were showed moderate to good inhibitory potentials ranging from 0.10 ± 0.01 µM to 11.40 ± 0.20 µM, 64.20 ± 0.40 µM to 385.10 ± 1.70 µM and 8.90 ± 0.20 µM to 39.20 ± 0.50 µM against anticancer, antiglycation and antioxidant respectively. Among the series, compounds 12 (IC50 = 0.10 ± 0.01 µM), 10 (IC50 = 64.20 ± 0.40 µM) and 12 (IC50 = 8.90 ± 0.20 µM) with flouro substitution at phenyl ring of thiourea were identified to be the most potent among the series having excellent anticancer, antiglycation and antioxidant potential. The structure of all the newly synthetics scaffolds were confirmed by using different types of spectroscopic techniques such as HREI-MS, 1H- and 13C-NMR spectroscopy. To find structure-activity relationship, molecular docking studies were carried out to understand the binding mode of active inhibitors with active site of enzymes and results supported the experimental data.Communicated by Ramaswamy H. Sarma.

Synthesis, Characterization and Biological Evaluation of Novel Thiourea Derivatives

Objective: A new series of 4-[3-(substitutedphenyl)thioureido]-N-(6-chloropyrazin-2-yl)benzenesulfonamide were synthesized from sulfaclozine. Methods: All compounds were characterized by IR, 1H-NMR spectroscopic methods and elemental analysis. In addition to the antioxidant activity of the synthesis series, enzyme inhibition activities such as anticholinesterase, tyrosinase, α-amylase and α-glycosidase were determined for the first time in this study. Results: According to these biological activity test results, compound 2a in the DPPH, 2c in the ABTS˙+ assay exhibited more antioxidant activity than reference standard. All thiourea derivatives demonstrated good BChE inhibitory activity than galantamine. Among the compounds, 2e and 2f showed the best tyrosinase enzyme inhibition activity, while 2g had the best α-amylase and α-glucosidase enzyme inhibition activity. In addition, we evaluated the druglikeness properties of compounds and their oral bioavailability were also found to be high. Conclusion: Thiourea derivatives exhibited remarkable antioxidant activity and enzyme inhibition activity against tyrosinase, cholinesterase, α-amylase and α-glucosidase.

Neto JDB, de Abreu FC, Figueiredo IM, Carinhanha C. Santos J, Pessoa CDÓ, da Silva-Júnior EF, de Araújo-Júnior JX, M. de Aquino T. Synthesis of hybrids thiazole–quinoline, thiazole–indole and their analogs: in vitro anti-proliferative effects on cancer cell lines, DNA binding properties and molecular modeling

A quinoline–thiazole hybrid was synthesized, which showed cytotoxicity against the HL-60 cell line. Electrochemical and spectroscopic experiments suggested DNA as the biological target.

Assessing the biological potential of new symmetrical ferrocene based bisthiourea analogues

In the present work synthesis and characterization of five new bisferrocenyl bisthiourea analogues (G_2M, S_2M, G_3F, G_4F and T_2M) is reported. UV-Visible and electrochemical studies were performed in order to have optical (absorption maximum, Molar absorption coefficient and optical band gap) and electrochemical parameters (Oxidation/reduction potentials and nature of the electrochemical process) of the compounds. In vitro various biological studies such as antibacterial, antifungal, anti-oxidant and antidiabetic activities were carried out to have comparative overview of the phermacochemical strength of the newly synthesized compounds. Similarly, theoretical analysis was accomplished utilizing density functional theory calculations. DFT/B3LYP (6-31G d, p) technique was used. With a view to explore the structure activity relationship (SAR) of the compounds theoretical docking analysis (against α-amylase, α-glucosidase) was also performed to have pictorial view and understanding of the actual interactions responsible for the activity. S_2M displayed best antibacterial activity. Similarly, Antifungal and antidiabetic activities showed G_3F as a best candidate, whereas T_2M proved to be the best antioxidant agent.

Synthesis of thiazol-2-imines from the reduction of single enantiomer 2-imino-thiazolidin-4-ones followed by a spontaneous water elimination

Chiral hemiaminals (5-8RR and 5-8SS) have been synthesized from the corresponding 2-iminothiazolidine-4-ones (1-4RR and 1-4SS) by LiAlH₄ reductions stereoselectively and were then converted to single enantiomer thiazol-2-imines (9-12RR and 9-12SS) by a water elimination reaction. The kinetics of the dehydration reactions which occurred spontaneously both in the solid state and in the solution have been followed by time dependent ¹ H nuclear magnetic resonance spectroscopy. The corresponding first order rate constants and free energies of activation values for the conversions have been reported.

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.