Design and synthesis of novel nitrothiazolacetamide conjugated to different thioquinazolinone derivatives as anti-urease agents

Design, synthesis, and biological studies of the new cysteine-N-arylacetamide derivatives as a potent urease inhibitor

Inhibition of Helicobacter pylori urease is an effective method in the treatment of several gastrointestinal diseases in humans. This bacterium plays an important role in the pathogenesis of gastritis and peptic ulceration. Considering the presence of cysteine and N-arylacetamide derivatives in potent urease inhibitors, here, we designed hybrid derivatives of these pharmacophores. Therefore, cysteine-N-arylacetamide derivatives 5a-l were synthesized through simple nucleophilic reactions with good yield. In vitro urease inhibitory activity assay of these compounds demonstrated that all newly synthesized compounds exhibited high inhibitory activity (IC50 values = 0.35-5.83 μM) when compared with standard drugs (thiourea: IC50 = 21.1 ± 0.11 μM and hydroxyurea: IC50 = 100.0 ± 0.01 μM). Representatively, compound 5e with IC50 = 0.35 μM was 60 times more potent than strong urease inhibitor thiourea. Enzyme kinetic study of this compound revealed that compound 5e is a competitive urease inhibitor. Moreover, a docking study of compound 5e was performed to explore crucial interactions at the urease active site. This study revealed that compound 5e is capable to inhibit urease by interactions with two crucial residues at the active site: Ni and CME592. Furthermore, a molecular dynamics study confirmed the stability of the 5e-urease complex and Ni chelating properties of this compound. It should be considered that, in the following study, the focus was placed on jack bean urease instead of H. pylori urease, and this was acknowledged as a limitation.

Norfloxacin derivatives as DNA gyrase and urease inhibitors: synthesis, biological evaluation and molecular docking

Background: DNA gyrase and urease enzymes are important targets for the treatment of gastroenteritis, appendicitis, tuberculosis, urinary tract infections and Crohn's disease. Materials & methods: Esterification of norfloxacin was performed to enhance DNA gyrase and urease enzyme inhibition potential. Structure elucidation and chemical characterization were done through spectral (1H NMR, Fourier transform IR, 13C NMR) and carbon, hydrogen, nitrogen and sulfur analysis along with molecular docking. Results & conclusion: The majority of derivatives exhibited significant results but the 3e derivative showed maximum bactericidal, DPPH scavenging (96%), DNA gyrase and urease enzyme inhibitory activity with IC50 of 0.15 ± 0.24 and 1.14 ± 0.11 μM respectively which was further supported by molecular docking studies. So, the active derivatives can serve as a lead compound for the treatment of various pathological conditions.

Structure-based drug discovery and antimicrobial activity of ciprofloxacin-grafted Ugi adducts

A new series of ciprofloxacin-derived Ugi adducts were rationally designed and synthesized. The synthesized molecules were explored for their potential antimicrobial activities against four pathogenic microorganisms. Among these derivatives, compound 7h with a 4-nitrophenyl substituent at R2 exhibited significant activity against two tested Gram-positive bacteria with a minimum inhibitory concentration value of 0.097 µg/mL while 7i bearing 4-chlorophenyl pendant demonstrated the best antimicrobial activities against Gram-negative bacteria. Furthermore, the analysis of the structure-activity relationships disclosed that types of substitutions differently affect the bacteria so the most potent derivative against Gram-negative infections was the least active one in Gram-positive microorganisms. Also, the molecular docking and molecular dynamic simulations were executed on 7i as the most potent Gram-negative anti-bacterial agent against ATP-binding sites of DNA gyrase B. Accordingly, our findings suggest that ciprofloxacin-based Ugi adducts are an interesting precursor for the design of potent antimicrobial agents.Communicated by Ramaswamy H. Sarma.

The anti-Alzheimer potential of novel spiroindolin-1,2-diazepine derivatives as targeted cholinesterase inhibitors with modified substituents

In this study, a new series of spiro indolin-1,2-diazepine were designed, synthesized, and screened for their cholinesterase inhibitory activities. A novel, green, high-yielding approach was constructed to synthesize spiro indolin-1,2-diazepine derivatives through a cascade reaction of different isatins, malononitrile and 1,1-enediamines (EDAMs) via sequential four-component reactions to produce the target compounds with good to excellent yields. Next the inhibitory potencies of all derivatives were determined spectroscopically at 415 nm using the modified Ellman method. The results of the in vitro screening indicated that 5l with spiroindolin-1,2-diazepine core bearing 5-NO₂ at R¹ and 4-OH at R² was the most potent and selective AChE inhibitor with an IC₅₀ value of 3.98 ± 1.07 µM with no significant inhibition against BChE while 5j was the most active analog against both AChE and BChE enzymes. The structure-activity relationships suggested the variation in the inhibitory activities of derivatives was affected by different substitutions on the indolinone ring as well as the phenyl moiety. The enzyme kinetic studies of the most potent compound 5l at five different concentrations and acetylthiocholine substrate (0.1-1 mM) by Ellman's method revealed that it inhibited AChE in a mixed mode with a K_i of 0.044 μM. A molecular docking study was performed via induced fit docking protocol to predict the putative binding interaction. It was shown that the moieties used in the initial structure design play a fundamental role in interacting with the enzyme's binding site. Further, molecular dynamics simulations with the Schrödinger package were performed for 5l in a complex with AChE and revealed that compound 5l formed the stable complex with the enzyme. The MTT toxicity assessments against the neuroblastoma cell line were executed, and no toxicity was seen for 5l under the tested concentrations.

N-Arylacetamide derivatives of methyl 1,2-benzothiazine-3-carboxylate as potential drug candidates for urease inhibition

Urease enzyme is an infectious factor that provokes the growth and colonization of virulence pathogenic bacteria in humans. To overcome the deleterious effects of bacterial infections, inhibition of urease enzyme is one of the promising approaches. The current study is designed to synthesize new 1,2-benzothiazine-N-arylacetamide derivatives 5(a-n) that can effectively provide a new drug candidate to avoid bacterial infections by urease inhibition. After structural elucidation by FT-IR, proton and carbon-13 NMR and mass spectroscopy, the synthesized compounds 5(a-n) were investigated to evaluate their inhibitory potential against urease enzyme. In vitro analysis against positive control of thiourea indicated that all the synthesized compounds have strong inhibitory strengths as compared to the reference drug. Compound 5k, being the most potent inhibitor, strongly inhibited the urease enzymes and revealed an IC50 value of 9.8 ± 0.023 µM when compared with the IC50 of thiourea (22.3 ± 0.031 µM)-a far more robust inhibitory potential. Docking studies of 5k within the urease active site revealed various significant interactions such as H-bond, π-alkyl with amino acid residues like Val744, Lys716, Ala16, Glu7452, Ala37 and Asp730.

New thioxothiazolidinyl-acetamides derivatives as potent urease inhibitors: design, synthesis, in vitro inhibition, and molecular dynamic simulation

To identify potent urease inhibitors, in the current study, a series of thioxothiazolidinyl-acetamides were designed and synthesized. The prepared compounds were characterized by spectroscopic techniques, including FTIR, ¹HNMR, ¹³CNMR, and elemental analysis. In the enzymatic assessments, it was demonstrated that all derivatives had significant urease inhibition with IC₅₀ values in the range of 1.473-9.274 µM in comparison with the positive control hydroxyurea (IC₅₀ = 100.21 ± 2.5 µM) and thiourea (IC₅₀ = 23.62 ± 0.84 µM). Compound 6i (N-benzyl-3-butyl-4-oxo-2-thioxothiazolidine-5-carboxamide) was the most active agent with an IC₅₀ value of 1.473 µM. Additionally, kinetic investigation and in silico assessments of 6i was carried out to understand the type of inhibition and behavior of the most potent derivative within the binding site of the enzyme. Noteworthy, the anti-urease assay against P. vulgaris revealed 6e and 6i as the most active agents with IC₅₀ values of 15.27 ± 2.40 and 17.78 ± 3.75 µg/mL, respectively. Antimicrobial evaluations of all compounds reveal that compounds 6n and 6o were the most potent antimicrobial agents against the standard and resistant S. aureus. 6n and 6o also showed 37 and 27% inhibition in the development of biofilm by S. aureus at 512 µg/ml. Furthermore, the MTT test showed no toxicity up to 100 µM. Taken together, the study suggests that the synthesized thioxothiazolidinyl-acetamides bases derivatives may serve as potential hits as urease inhibitors.

Ugi Bis-Amide Derivatives as Tyrosinase Inhibitor; Synthesis, Biology Assessment, and in Silico Analysis

Herein, a straightforward synthetic strategy mediated by Ugi reaction was developed to synthesize novel series of compounds as tyrosinase inhibitors. The structures of all compounds were confirmed by FT-IR, ¹ H-NMR, ¹³ C-NMR, and CHNOS techniques. The tyrosinase inhibitory activities of all synthesized derivatives 5a-m were determined against mushroom tyrosinase and it was found that derivative 5c possesses the best inhibition with an IC₅₀  value of 69.53±0.042 μM compared to the rest of the synthesized derivatives. Structure-activity relationships (SARs) showed that the presence of 4-MeO or 4-NO₂ at the R² position plays a key role in tyrosinase inhibitory activities. The enzyme kinetics studies showed that compound 5c is an noncompetitive inhibitor. For in silico study, the allosteric site detection was first applied to find the appropriate binding site and then molecular docking and molecular dynamic studies were performed to reveal the position and interactions of 5c as the most potent inhibitor within the tyrosinase active site. The results showed that 5c bind well with the proposed binding site and formed a stable complex with the target protein.

Design, synthesis, in silico and biological evaluations of novel polysubstituted pyrroles as selective acetylcholinesterase inhibitors against Alzheimer's disease

The objective of this study was to design new polysubstituted pyrrole derivatives as selective acetylcholinesterase (AChE) inhibitors to target Alzheimer's disease. In this context, a highly efficient, one-pot, sequential, multi-component synthesis of a diverse range of polysubstituted pyrroles was developed through a sequential domino strategy by the condensation of amines with 1,1-bis(methylthio)-2-nitroethene (BMTNE), Knovenagle reaction of arylglyoxals with malono derivatives and subsequent Michael addition and intramolecular cyclization reaction in EtOH at reflux. Thirty-nine synthesized compounds were evaluated as AChE and butyrylcholinesterase (BChE) inhibitors. Among the synthesized compounds, compound 4ad (IC₅₀ = 2.95 ± 1.31 µM) was the most potent and selective AChE inhibitor with no significant inhibition against butyrylcholinesterase BChE. A kinetic study of 4ad revealed that this compound inhibited AChE in an uncompetitive mode. Based on a molecular modeling study, compound 4ad due to its small size properly fitted into the active site of AChE compared to BChE and stabilized by H-bond and hydrophobic interactions with the critical residues of the AChE binding pocket. Consequently, it was proposed that the 4ad derivative can be an ideal lead candidate against AD with a simple and practical operation of synthetic procedures.

Design and synthesis of new N-thioacylated ciprofloxacin derivatives as urease inhibitors with potential antibacterial activity

A new series of N-thioacylated ciprofloxacin 3a-n were designed and synthesized based on Willgerodt-Kindler reaction. The results of in vitro urease inhibitory assay indicated that almost all the synthesized compounds 3a-n (IC₅₀ = 2.05 ± 0.03-32.49 ± 0.32 μM) were more potent than standard inhibitors, hydroxyurea (IC₅₀ = 100 ± 2.5 μM) and thiourea (IC₅₀ = 23 ± 0.84 μM). The study of antibacterial activity against Gram-positive species (S. aureus and S. epidermidis) revealed that the majority of compounds were more active than ciprofloxacin as the standard drug, and 3h derivative bearing 3-fluoro group had the same effect as ciprofloxacin against Gram-negative bacteria (P. aeruginosa and E. coli). Based on molecular dynamic simulations, compound 3n exhibited pronounced interactions with the critical residues of the urease active site and mobile flap pocket so that the quinolone ring coordinated toward the metal bi-nickel center and the essential residues at the flap site like His593, His594, and Arg609. These interactions caused blocking the active site and stabilized the movement of the mobile flap at the entrance of the active site channel, which significantly reduced the catalytic activity of urease. Noteworthy, 3n also exhibited IC₅₀ values of 5.59 ± 2.38 and 5.72 ± 1.312 µg/ml to inhibit urease enzyme against C. neoformans and P. vulgaris in the ureolytic assay.

New solid phase methodology for the synthesis of biscoumarin derivatives: experimental and in silico approaches

The simple and greener one-pot approach for the synthesis of biscoumarin derivatives using catalytic amounts of nano-MoO₃ catalyst under mortar-pestle grinding was described. The use of non-toxic and mild catalyst, cost-effectiveness, ordinary grinding, and good to the excellent yield of the final product makes this procedure a more attractive pathway for the synthesis of biologically remarkable pharmacophores. Accordingly, biscoumarin derivatives were successfully extended in the developed protocols. Next, a computational investigation was performed to identify the potential biological targets of this set of compounds. In this case, first, a similarity search on different virtual libraries was performed to find an ideal biological target for these derivatives. Results showed that the synthesized derivatives can be α-glucosidase inhibitors. In another step, molecular docking studies were carried out against human lysosomal acid-alpha-glucosidase (PDB ID: 5NN8) to determine the detailed binding modes and critical interactions with the proposed target. In silico assessments showed the gold score value in the range of 17.56 to 29.49. Additionally, molecular dynamic simulations and the MM-GBSA method of the most active derivative against α-glucosidase were conducted to study the behavior of selected compounds in the biological system. Ligand 1 stabilized after around 30 ns and participated in various interactions with Trp481, Asp518, Asp616, His674, Phe649, and Leu677 residues.

Synthesis, molecular docking, and cytotoxicity of quinazolinone and dihydroquinazolinone derivatives as cytotoxic agents

Background

Cancer is the most cause of morbidity and mortality, and a major public health problem worldwide. In this context, two series of quinazolinone 5a–e and dihydroquinazolinone 10a–f compounds were designed, synthesized as cytotoxic agents.

Methodology

All derivatives (5a–e and 10a–f) were synthesized via straightforward pathways and elucidated by FTIR, ¹H-NMR, CHNS elemental analysis, as well as the melting point. All the compounds were evaluated for their in vitro cytotoxicity effects using the MTT assay against two human cancer cell lines (MCF-7 and HCT-116) using doxorubicin as the standard drug. The test derivatives were additionally docked into the PARP10 active site using Gold software.

Results and discussion

Most of the synthesized compounds, especially 5a and 10f were found to be highly potent against both cell lines. Synthesized compounds demonstrated IC₅₀ in the range of 4.87–205.9 μM against HCT-116 cell line and 14.70–98.45 μM against MCF-7 cell line compared with doxorubicin with IC₅₀ values of 1.20 and 1.08 μM after 72 h, respectively, indicated the plausible activities of the synthesized compounds.

Conclusion

The compounds quinazolinone 5a–e and dihydroquinazolinone 10a–f showed potential activity against cancer cell lines which can lead to rational drug designing of the cytotoxic agents.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13065-022-00825-x.