Synthesis and molecular docking study of piperazine derivatives as potent urease inhibitors

Synthesis, Characterization, Optical Properties, Molecular Modeling and Urease Inhibition Analysis of Organic Ligands and Their Metal Complexes

Recently, screening of efficient urease inhibitors by employing organic small molecules metalloderivatives interests the scientific community due to their efficacy for treatment of urease triggered health complications. This study comprises the synthesis, urease inhibition activity, optical analysis and molecular modeling of hydrazinecarbothioamide and hydrazinecarboxamide metalloderivatives. Characterization of synthesized materials was done by UV-visible, fluorescence, NMR and FTIR spectroscopic analysis. Metalloderivatization of ligands induce increment in urease inhibition potential and effect was prominent for copper complexes with 10-fold enhancement, cobalt complex with 3.5 fold's enhancement and palladium with 2-fold increment in the inhibition efficacy toward urease when it was compared with reference urease inhibitor. Zinc and iron complexes cause declined urease inhibition activity of the bare ligand. The overall activity of hydrazinecarbothioamide slightly exceeds than that of hydrazinecarboxamide, possibly due to larger complexation ability of sulfur-based ligand in comparison to oxygenated derivatives i.e., hydrazinecarboxamide. The enzyme inhibition kinetics for the most active complexes represent the mixed type urease inhibition for 3a and competitive urease inhibition for 5a, as determined by Lineweaver-Burk plots. The docked scoring values for both the ligands were calculated to be 61.34, 64.72, 56.68, 62.94, 64.98 and 58.98. Three active hydrogen bonds were observed in docking complex upon computational analysis of most potent metallodrug 3a inside active region of targeted protein.

Gold(i)-catalyzed cycloisomerization of alcohol or amine tethered-vinylidenecyclopropanes providing access to morpholine, piperazine or oxazepane derivatives: a carbene versus non-carbene process

A gold(i)-catalyzed adjustable intramolecular cyclization of alcohol or amine tethered-vinylidenecyclopropanes (VDCPs).

New Triazinoindole Bearing Benzimidazole/Benzoxazole Hybrids Analogs as Potent Inhibitors of Urease: Synthesis, In Vitro Analysis and Molecular Docking Studies

Twenty-four analogs based on triazinoindole bearing benzimidazole/benzoxazole moieties (1-25) were synthesized. Utilizing a variety of spectroscopic methods, including ¹H-, ¹³C-NMR, and HREI-MS, the newly afforded compounds (1-25) were analyzed. The synthesized analogs were tested against urease enzyme (in vitro) as compared to the standard thiourea drug. All triazinoindole-based benzimidazole/benzoxazole analogs (1-25) exhibited moderate to excellent inhibition profiles, having IC₅₀ values of 0.20 ± 0.01 to 36.20 ± 0.70 μM when evaluated under the positive control of thiourea as a standard drug. To better understand the structure-activity relationship, the synthesized compounds were split into two groups, "A" and "B." Among category "A" analogs, analogs 8 (bearing tri-hydroxy substitutions at the 2,4,6-position of aryl ring C) and 5 (bearing di-hydroxy substitutions at the 3,4-position of aryl ring C) emerged as the most potent inhibitors of urease enzyme and displayed many times more potency than a standard thiourea drug. Besides that, analog 22 (which holds di-hydroxy substitutions at the 2,3-position of the aryl ring) and analog 23 (bearing ortho-fluoro substitution) showed ten-fold-enhanced inhibitory potential compared to standard thiourea among category "B" analogs. Molecular docking studies on the active analogs of each category were performed; the results obtained revealed that the presence of hydroxy and fluoro-substitutions on different positions of aryl ring C play a pivotal role in binding interactions with the active site of the targeted urease enzyme.

Recent Efforts in the Discovery of Urease Inhibitor Identifications

Urease is an attractive drug target for designing anti-infective agents against pathogens such as Helicobacter pylori, Proteus mirabilis, and Ureaplasma urealyticum. In the past century, hundreds of medicinal chemists focused their efforts on explorations of urease inhibitors. Despite the FDA's approval of acetohydroxamic acid as a urease inhibitor for the treatment of struvite nephrolithiasis and the widespread use of N-(n-butyl)thiophosphoric triamide as a soil urease inhibitor as nitrogen fertilizer synergists in agriculture, urease inhibitors with high potency and safety are urgently needed. Exploration of novel urease inhibitors has therefore become a hot research topic recently. Herein, inhibitors identified worldwide from 2016 to 2021 have been reviewed. They structurally belong to more than 20 classes of compounds such as urea/thioure analogues, hydroxamic acids, sulfonamides, metal complexes, and triazoles. Some inhibitors showed excellent potency with IC50 values lower than 10 nM, having 10000-fold higher potency than the positive control thiourea.

Synthesis of new urease enzyme inhibitors as antiulcer drug and computational study

In search of potent urease inhibitor indole analogues (1-22) were synthesized and evaluated for their urease inhibitory potential. All analogues (1-22) showed a variable degree of inhibitory interaction potential having IC₅₀ value ranging between 0.60 ± 0.05 to 30.90 ± 0.90 µM when compared with standard thiourea having IC₅₀ value 21.86 ± 0.90 µM. Among the synthesized analogues, the compounds 1, 2, 3, 5, 6, 8, 12, 14, 18, 20 and 22 having IC₅₀ value 3.10 ± 0.10, 1.20 ± 0.10, 4.60 ± 0.10, 0.60 ± 0.05, 5.30 ± 0.20, 2.50 ± 0.10, 7.50 ± 0.20, 3.90 ± 0.10, 3.90 ± 0.10, 2.30 ± 0.05 and 0.90 ± 0.05 µM respectively were found many fold better than the standard thiourea. All other analogues showed better urease interaction inhibition. Structure activity relationship (SAR) has been established for all analogues containing different substituents on the phenyl ring. To understand the binding interaction of most active analogues with enzyme active site docking study were performed.Communicated by Ramaswamy H. Sarma.

Exploring biologically active hybrid pharmacophore N-substituted hydrazine-carbothioamides for urease inhibition: In vitro and in silico approach

Urease is potential target for various human's health complications, such as peptic ulcer, gastric cancer and kidney stone formation. The present study was based on synthesis of new hybrid pharmacophore N-substituted hydrazine-carbothioamides as potential urease inhibitors. Presented method gave excellent yield in range of 85-95% for hydrazine-carbothioamides derivatives (3a-s) after reaction of mono- and disubstituted hydrazides (1a-k) and substituted isothiocyanates (2a-d). All newly derivatives were characterized by advanced spectroscopic techniques (FTIR, ¹HNMR, ¹³CNMR, EMS) and were assessed for their urease inhibition potential. All analogs except for 3k, 3l and 3m demonstrated strong inhibitory potential for urease with IC₅₀ values of 8.45 ± 0.14 to 25.72 ± 0.23 μM as compared to standard thiourea (IC₅₀ 21.26 ± 0.35 μM). The structure-activity relationship and mode of interaction was established by molecular docking studies. It was revealed that the N-substituted hydrazine-carbothioamides interacted with nickel atoms present in the active site of urease and supported the correlations with the experimental findings. Therefore, the afforded hydrazine-carbothioamides derivatives are interesting hits for urease inhibition studies with future prospects of modification and optimization.

N-monoarylacetothioureas as potent urease inhibitors: synthesis, SAR, and biological evaluation

A urease inhibitor with good in vivo profile is considered as an alternative agent for treating infections caused by urease-producing bacteria such as Helicobacter pylori. Here, we report a series of N-monosubstituted thioureas, which act as effective urease inhibitors with very low cytotoxicity. One compound (b19) was evaluated in detail and shows promising features for further development as an agent to treat H. pylori caused diseases. Excellent values for the inhibition of b19 against both extracted urease and urease in intact cell were observed, which shows IC₅₀ values of 0.16 ± 0.05 and 3.86 ± 0.10 µM, being 170- and 44-fold more potent than the clinically used drug AHA, respectively. Docking simulations suggested that the monosubstituted thiourea moiety penetrates urea binding site. In addition, b19 is a rapid and reversible urease inhibitor, and displays nM affinity to urease with very slow dissociation (k_off=1.60 × 10⁻³ s⁻¹) from the catalytic domain.

Robust therapeutic potential of carbazole-triazine hybrids as a new class of urease inhibitors: A distinctive combination of nitrogen-containing heterocycles

The inhibition of urease enzyme is very important as it plays a key role in the treatment of several urinary and gastrointestinal tract infections. This enzyme provides a suitable environment for Helicobacter pylori at the low pH of the stomach, a causative agent of gastric and peptic ulcer that may lead to cancer. In agriculture, the high urease content causes environmental and economic problems. In this pursuit, given the well-established importance of integrated pharmacophores in medicinal chemistry and to explore new inhibitors of urease featuring two distinct heterocyclic functionalities, we herein report a facile synthesis of carbazole-triazine hybrids (3a-j). These new propeller-shaped chemical scaffolds were evaluated for their urease inhibitory potential in order to identify suitable leads. The initial structure-activity survey work guided through in vitro bioactivity results recognized 3e and 3f as new starting point hits incorporating bulky iodo (3e) and strong electron-withdrawing nitro (3f) groups at the para-position of aryl amine component. The potent compounds (3e &3f) exhibited the highest activity with IC₅₀ values of 5.6 and 6.7 µM, respectively. In the molecular docking analysis, these compounds depicted excellent binding interactions with the active site residues. The key interactions observed include hydrogen bonding, π-π interactions, π-cation and nickel atom coordination to the triazine nitrogen of both inhibitors.

Utility of anthranilic acid and diethylacetylenedicarboxylate for the synthesis of nitrogenous organo/organometallic compounds as urease inhibitors

Fumarate diester 3 was synthesized upon reacting anthranilic acid with diethylacetylenedicarboxylate. Compound 3 was reacted with different nucleophiles in mild reaction conditions. Selected reaction routes that afforded products 6, 9, 10, 11, and 12 were explained. The estimated mechanism for the reaction of 3 with ethylenediamine to afford 9 was proved by X-ray single-crystal and retro-synthetic reaction. Acetyl anthranilic acid was utilized with zinc and copper to afford the organometallic compounds 14a and 14b, respectively. Three single crystals were afforded for 3, 9 and the organocopper complex 14b. Target compounds were screened for their inhibitory potential against urease enzyme. Most compounds were more potent than thiourea as standard inhibitor, considering that oxopiperazine 9 exhibited double the activity: IC₅₀ = 8.16 ± 0.65 µM (thiourea IC₅₀ = 20.04 ± 0.33 µM). Docking studies were in agreement with the in vitro enzyme assay.

2-Furoic piperazide derivatives as promising drug candidates of type 2 diabetes and Alzheimer's diseases: In vitro and in silico studies

The heterocyclic compounds have been extensively reported for their bioactivity potential. The current research work reports the synthesis of some new multi-functional derivatives of 2-furoic piperazide (1; 1-(2-furoyl)piperazine). The synthesis was initiated by reacting the starting compound 1 with 3,5-dichloro-2-hydroxybenzenesulfonyl chloride (2) in a basic, polar and protic medium to obtain the parent sulfonamide 3 which was then treated with different electrophiles, 4a-g, in a polar and aprotic medium to acquire the designed molecules, 5a-g. These convergent derivatives were evaluated for their inhibitory potential against α-glucosidase, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. Acarbose was used as a reference standard for α-glucosidase inhibition while eserine for AChE and BChE inhibition. Some of the synthesized compounds were identified as promising inhibitors of these three enzymes and their bioactivity potentials were also supported by molecular docking study. The most active compounds among the synthetic analogues might be helpful in drug discovery and development for the treatment of type 2 diabetes and Alzhiemer's diseases.

Developing potential Helicobacter pylori urease inhibitors from novel oxoindoline derivatives: Synthesis, biological evaluation and in silico study

By recruiting the important moiety from Shikonin, a series of novel oxoindoline derivatives S1-S20 have been synthesized for inhibiting H. pylori urease. The most potent compound S18 displayed better activity (IC₅₀ = 0.71 μM; MIC = 0.48 μM) than the positive controls AHA (IC₅₀ = 17.2 μM) and Metronidazole (MIC = 31.3 μM). With low cytotoxicity, it showed considerable potential for further development. Docking simulation revealed the possible binding pattern of this series. 3D QSAR model was built to discuss SAR and give useful hints for future modification.