Substituted 2-thioxoimidazolidin-4-ones and imidazolidine-2,4-diones as fatty acid amide hydrolase inhibitors templates

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.

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.

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.

Appraisal of novel azomethine-thioxoimidazolidinone conjugates as ecto-5'-nucleotidase inhibitors: synthesis and molecular docking studies

Purinergic signaling is regulated by a group of extracellular enzymes called ectonucleotidases. One of its members i.e., ecto-5′-nucleotidase (h-e5′NT) is involved in the final step of the enzymatic hydrolysis cascade that is the conversion of adenosine monophosphate (AMP) to adenosine and therefore, involves the regulation of adenosine level in extracellular space. The overexpression of h-e5′NT has been observed in various pathological conditions such as hypoxia, inflammation and cancers, and led to various complications. Hence, the identification of a potent as well as selective inhibitor of h-e5′NT is of greater importance in therapeutic treatment of various diseases. Azomethine-thioxoimidazolidinone derivatives were studied for their inhibition potential against e5′NT enzyme along with cytotoxic potential against cancer cell lines possessing overexpression of e5′NT enzyme. The derivative (E)-3-((4-((3-methoxybenzyl)oxy)benzylidene)amino)-2-thioxoimidazolidin-4-one (4g) displayed selective and significant inhibition towards h-e5′NT with an IC₅₀ value of 0.23 ± 0.08 μM. While two other derivatives i.e., (E)-3-(((5-bromothiophen-2-yl)methylene)amino)-2-thioxoimidazolidin-4-one (4b) and 2-thioxo-3-((3,4,5-trimethoxybenzylidene)amino)imidazolidin-4-one (4e), exhibited non-selective potent inhibitory behavior against both human and rat enzymes. Moreover, these derivatives (4b, 4e and 4g) were further investigated for their effect on the expression of h-e5′NT using quantitative real time polymerase chain reaction. Additionally, molecular docking and DFT studies were also performed to determine the putative binding mode of potent inhibitors within the enzyme active site. HOMO, LUMO, ΔE, and molecular electrostatic potential maps were computed by DFT and the charge transfer regions within the molecules were identified to find out the regions for electrophilic and nucleophilic attack.

Azomethine–thioxoimidazolidinone conjugates as ecto-5′-nucleotidase inhibitors.

Copper-Mediated N-Arylations of Hydantoins

A set of two broadly applicable procedures for the N-arylation of hydantoins is reported. The first one relies on the use of stoichiometric copper(I) oxide under ligand- and base-free conditions and enables a clean regioselective arylation at the N³ nitrogen atom, while the second one is based on the use of catalytic copper(I) iodide and trans- N, N'-dimethylcyclohexane-1,2-diamine and promotes arylation at the N¹ nitrogen atom. Importantly, the combination of these two procedures affords a straightforward entry to diarylated hydantoins.

Design, synthesis and evaluation of anticancer activity of novel 2-thioxoimidazolidin-4-one derivatives bearing pyrazole, triazole and benzoxazole moieties

A novel series of substituted 2-thiohydantoin incorporated with benzoimidazole, pyrazole, triazole and/or benzoxazole moieties has been synthesized using (E)-3-[1-(4-bromophenyl)ethylideneamino]-2-thioxoimidazolidin-4-one 1 as the key starting material. The key material 1 also, reacted with an acetic anhydride, aromatic aldehydes, secondary amines, formaldehyde and triethyl orthoformate to give the corresponding acetyl, chalcone, Mannich bases and ethoxymethylene derivatives, respectively. The structures of the novel compounds were confirmed by spectral data and elemental analysis. The cytotoxic activity of all synthesized compounds was assessed in vitro against human hepatocellular cancer cell line (HePG-2) and breast carcinoma cell line (MCF-7). The bioassay results revealed that compound 14 has the best activity against HePG-2 cell line (IC₅₀ = 2.33 μg/mL), while compound 5 has the best activity against MCF-7 cell line (IC₅₀ = 3.98 μg/mL).

Recent Advances in the Synthesis of Hydantoins: The State of the Art of a Valuable Scaffold

The review highlights the hydantoin syntheses presented from the point of view of the preparation methods. Novel synthetic routes to various hydantoin structures, the advances brought to the classical methods in the aim of producing more sustainable and environmentally friendly procedures for the preparation of these biomolecules, and a critical comparison of the different synthetic approaches developed in the last twelve years are also described. The review is composed of 95 schemes, 8 figures and 528 references for the last 12 years and includes the description of the hydantoin-based marketed drugs and clinical candidates.

Design and synthesis of uracil urea derivatives as potent and selective fatty acid amide hydrolase inhibitors

Fatty acid amide hydrolase (FAAH) is one of the key enzymes involved in the biological degradation of endocannabinoids, especially anandamide.

Umbelliferone–oxindole hybrids as novel apoptosis inducing agents

Synthesis and biological evaluation of umbelliferone–oxindole hybrids as novel apoptosis inducing agents.

In Vitro and in Vivo Effects of Nitrofurantoin on Experimental Toxoplasmosis

Toxoplasma gondii is an important opportunistic pathogen that causes toxoplasmosis, which has very few therapeutic treatment options. The most effective therapy is a combination of pyrimethamine and sulfadiazine; however, their utility is limited because of drug toxicity and serious side effects. For these reasons, new drugs with lower toxicity are urgently needed. In this study, the compound, (Z)-1-[(5-nitrofuran-2-yl)methyleneamino]-imidazolidine-2,4-dione (nitrofurantoin), showed anti-T. gondii effects in vitro and in vivo. In HeLa cells, the selectivity of nitrofurantoin was 2.3, which was greater than that of pyrimethamine (0.9). In T. gondii-infected female ICR mice, the inhibition rate of T. gondii growth in the peritoneal cavity was 44.7% compared to the negative control group after 4-day treatment with 100 mg/kg of nitrofurantoin. In addition, hematology indicators showed that T. gondii infection-induced serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, biochemical parameters involved in liver injury, were reduced by nitrofurantoin significantly. Moreover, nitrofurantoin exerted significant effects on the index of antioxidant status, i.e., malondialdehyde (MDA) and glutathione (GSH). The nitrofurantoin-treated group inhibited the T. gondii-induced MDA levels while alleviating the decrease in GSH levels. Thus, nitrofurantoin is a potential anti-T. gondii candidate for clinical application.

Design, synthesis, and characterization of α-ketoheterocycles that additionally target the cytosolic port Cys269 of fatty acid amide hydrolase

A series of α-ketooxazoles incorporating electrophiles at the C5 position of the pyridyl ring of 2 (OL-135) and related compounds were prepared and examined as inhibitors of fatty acid amide hydrolase (FAAH) that additionally target the cytosolic port Cys269. From this series, a subset of the candidate inhibitors exhibited time-dependent FAAH inhibition and noncompetitive irreversible inactivation of the enzyme, consistent with the targeted Cys269 covalent alkylation or addition, and maintained or enhanced the intrinsic selectivity for FAAH versus other serine hydrolases. A preliminary in vivo assessment demonstrates that these inhibitors raise endogenous brain levels of anandamide and other FAAH substrates upon intraperitoneal (i.p.) administration to mice, with peak levels achieved within 1.5–3 h, and that the elevations of the signaling lipids were maintained >6 h, indicating that the inhibitors effectively reach and remain active in the brain, inhibiting FAAH for a sustained period.

Discovery of hybrid dual N-acylhydrazone and diaryl urea derivatives as potent antitumor agents: design, synthesis and cytotoxicity evaluation

Based on the hybrid pharmacophore design concept, a novel series of dual diaryl urea and N-acylhydrazone derivatives were synthesized and evaluated for their in vitro cytotoxicity by the standard MTT assay. The pharmacological results indicated that most compounds exhibited moderate to excellent activity. Moreover, compound 2g showed the most potent cytotoxicity against HL-60, A549 and MDA-MB-231 cell lines, with IC₅₀ values of 0.22, 0.34 and 0.41 μM, respectively, which was 3.8 to 22.5 times more active than the reference compounds sorafenib and PAC-1. The promising compound 2g thus emerges as a lead for further structural modifications.

Sulfonyl fluoride inhibitors of fatty acid amide hydrolase

Sulfonyl fluorides are known to inhibit esterases. Early work from our laboratory has identified hexadecyl sulfonylfluoride (AM374) as a potent in vitro and in vivo inhibitor of fatty acid amide hydrolase (FAAH). We now report on later generation sulfonyl fluoride analogs that exhibit potent and selective inhibition of FAAH. Using recombinant rat and human FAAH, we show that 5-(4-hydroxyphenyl)pentanesulfonyl fluoride (AM3506) has similar inhibitory activity for both the rat and the human enzyme, while rapid dilution assays and mass spectrometry analysis suggest that the compound is a covalent modifier for FAAH and inhibits its action in an irreversible manner. Our SAR results are highlighted by molecular docking of key analogs.

Identification and recombinant expression of anandamide hydrolyzing enzyme from Dictyostelium discoideum

Background

Anandamide (Arachidonoyl ethanolamide) is a potent bioactive lipid studied extensively in humans, which regulates several neurobehavioral processes including pain, feeding and memory. Bioactivity is terminated when hydrolyzed into free arachidonic acid and ethanolamine by the enzyme fatty acid amide hydrolase (FAAH). In this study we report the identification of a FAAH homolog from Dictyostelium discoideum and its function to hydrolyze anandamide.

Results

A putative FAAH DNA sequence coding for a conserved amidase signature motif was identified in the Dictyostelium genome database and the corresponding cDNA was isolated and expressed as an epitope tagged fusion protein in either E.coli or Dictyostelium. Wild type Dictyostelium cells express FAAH throughout their development life cycle and the protein was found to be predominantly membrane associated. Production of recombinant HIS tagged FAAH protein was not supported in E.coli host, but homologous Dictyostelium host was able to produce the same successfully. Recombinant FAAH protein isolated from Dictyostelium was shown to hydrolyze anandamide and related synthetic fatty acid amide substrates.

Conclusions

This study describes the first identification and characterisation of an anandamide hydrolyzing enzyme from Dictyostelium discoideum, suggesting the potential of Dictyostelium as a simple eukaryotic model system for studying mechanisms of action of any FAAH inhibitors as drug targets.

Design and development of novel insect growth regulators: synthesis, characterization and effect of benzoyl thymyl thioureas and ureas on total haemocyte count of Dysdercus koenigii

Insect-growth regulators (IGRs) have been receiving foremost attention as potential means of selective insect control. Benzoyl phenyl urea (BPU) is a well-known IGR having chitin synthesis inhibitor activity. Mimics of BPU have been synthesized by suitable derivatization of a naturally occurring monoterpenoid, thymol (2-isopropyl-5-methyl phenol) to form a = series of substituted benzoyl thymyl thioureas (BTTUs) [IVa-f] and benzoyl thymyl ureas (BTUs) [Va-f]. The synthesized compounds have been characterized by (1)H and (13)C NMR, LC-MS and elemental analysis. These derivatives have been screened for their effect on total haemocyte count of Dysdercus koenigii. It has been observed that the introduction of substituted benzoyl thiourea and urea linkage into a thymol ring via an amino group results in higher activity than the parent compound thymol and a comparable pattern of results with the standard insect-growth regulators, Penfluron. Urea [Va-f] compounds exhibited greater effect on Total Haemocyte Count (THC) than thiourea [IVa-f]. Fluoro substitution enhanced the effect on THC more than chloro substituted compounds, while ortho-substitution resulted in a better effect than para-substitution. The results described in this paper are promising and provide new array of synthetic chemicals that may be utilized as insect growth regulators.

The discovery and development of inhibitors of fatty acid amide hydrolase (FAAH)

A summary of the discovery and advancement of inhibitors of fatty acid amide hydrolase (FAAH) is presented.

Fluoride-mediated capture of a noncovalent bound state of a reversible covalent enzyme inhibitor: X-ray crystallographic analysis of an exceptionally potent α-ketoheterocycle inhibitor of fatty acid amide hydrolase

Two cocrystal X-ray structures of the exceptionally potent α-ketoheterocycle inhibitor 1 (K(i) = 290 pM) bound to a humanized variant of rat fatty acid amide hydrolase (FAAH) are disclosed, representing noncovalently and covalently bound states of the same inhibitor with the enzyme. Key to securing the structure of the noncovalently bound state of the inhibitor was the inclusion of fluoride ion in the crystallization conditions that is proposed to bind the oxyanion hole precluding inhibitor covalent adduct formation with stabilization of the tetrahedral hemiketal. This permitted the opportunity to detect important noncovalent interactions stabilizing the binding of the inhibitor within the FAAH active site independent of the covalent reaction. Remarkably, noncovalently bound 1 in the presence of fluoride appears to capture the active site in the same "in action" state with the three catalytic residues Ser241-Ser217-Lys142 occupying essentially identical positions observed in the covalently bound structure of 1, suggesting that this technique of introducing fluoride may have important applications in structural studies beyond inhibiting substrate or inhibitor oxyanion hole binding. Key insights to emerge from the studies include the observations that noncovalently bound 1 binds in its ketone (not gem diol) form, that the terminal phenyl group in the acyl side chain of the inhibitor serves as the key anchoring interaction overriding the intricate polar interactions in the cytosolic port, and that the role of the central activating heterocycle is dominated by its intrinsic electron-withdrawing properties. These two structures are also briefly compared with five X-ray structures of α-ketoheterocycle-based inhibitors bound to FAAH recently disclosed.

Reversible competitive α-ketoheterocycle inhibitors of fatty acid amide hydrolase containing additional conformational constraints in the acyl side chain: orally active, long-acting analgesics

A series of α-ketooxazoles containing conformational constraints in the C2 acyl side chain of 2 (OL-135) were examined as inhibitors of fatty acid amide hydrolase (FAAH). Only one of the two possible enantiomers displayed potent FAAH inhibition (S vs R enantiomer), and their potency is comparable or improved relative to 2, indicating that the conformational restriction in the C2 acyl side chain is achievable. A cocrystal X-ray structure of the α-ketoheterocycle 12 bound to a humanized variant of rat FAAH revealed its binding details, confirmed that the (S)-enantiomer is the bound active inhibitor, shed light on the origin of the enantiomeric selectivity, and confirmed that the catalytic Ser241 is covalently bound to the electrophilic carbonyl as a deprotonated hemiketal. Preliminary in vivo characterization of the inhibitors 12 and 14 is reported demonstrating that they raise brain anandamide levels following either intraperitoneal (ip) or oral (po) administration indicative of effective in vivo FAAH inhibition. Significantly, the oral administration of 12 caused dramatic accumulation of anandamide in the brain, with peak levels achieved between 1.5 and 3 h, and these elevations were maintained over 9 h. Additional studies of these two representative members of the series (12 and 14) in models of thermal hyperalgesia and neuropathic pain are reported, including the demonstration that 12 administered orally significantly attenuated mechanical (>6 h) and cold (>9 h) allodynia for sustained periods consistent with its long-acting effects in raising the endogenous concentration of anandamide.