Synthesis of acridinyl-thiazolino derivatives and their evaluation for anti-inflammatory, analgesic and kinase inhibition activities

Green advancements towards the electrochemical synthesis of heterocycles

Heterocyclic chemistry is a large field with diverse applications in the areas of biological research and pharmaceutical advancement. Numerous initiatives have been proposed to further enhance the reaction conditions to reach these compounds without using harmful compounds. This paper focuses on the recent advances in the eco-friendly and green synthetic procedures to synthesize N-, S-, and O-heterocycles. This approach demonstrates considerable potential in accessing such compounds while circumventing the need for stoichiometric quantities of oxidizing/reducing agents or catalysts containing precious metals. Merely employing catalytic quantities of these substances proves sufficient, thereby offering an optimal means of contributing to resource efficiency. Renewable electricity plays a crucial role in generating environmentally friendly electrons (oxidant/reductant) that serve as catalysts for a series of reactions. These reactions involve the production of reactive intermediates, which in turn allow the synthesis of new chemical bonds, enabling beneficial transformations to occur. Furthermore, the utilization of metals as active catalysts in electrochemical activation has been recognized as an effective approach for achieving selective functionalization. The aim of this review was to summarize the electrochemical synthetic procedures so that the undesirable side reactions can be considerably reduced and the practical potential range of the chemical reactions can be expanded significantly.

Study on Regio- and Diastereoselectivity of the 1,3-Dipolar Cycloaddition Reaction of Azomethine Ylide with 2-(Benzo[d]thiazol-2-yl)-3-(aryl)acrylonitrile: Synthesis, Spectroscopic, and Computational Approach

An unprecedented and efficient three-component 1,3-dipolar cycloaddition reaction using (E)-2-(benzo[d]thiazol-2-yl)-3-(aryl)acrylonitriles 4a-g and an in situ generated azomethine ylide 3 from isatin and N-methylglycine is described. The reaction exhibits exclusive regioselectivity, resulting in the formation of 3'-(benzo[d]thiazol-2-yl)-1'-methyl-2-oxo-4'-(aryl)spiro[indoline-3,2'-pyrrolidine]-3'-carbonitriles regioisomers through exo/endo approaches. The diastereoselectivity of the reaction is highly dependent on the substitution pattern of the phenyl ring in dipolarophiles 4a-g, leading to the formation of exo-/endo-cycloadducts in varying ratios. To understand the stereoselectivity, the transition state structures were optimized using the TS guess geometry with the QST3-based method. The reaction mechanism and regioselectivity were elucidated by evaluating global and local electrophilicity and nucleophilicity descriptors at the B3LYP/cc-pVTZ level of theory, along with considerations based on the HSAB principle. The analysis of global electron density transfer (GEDT) showed that the reactions are polar and electron density fluxes from azomethine ylide 3 toward dipolarophile 4a-g. It was found from the molecular electrostatic potential map (MESP) that at the more favorable transition state, approach of reactants locates the oppositely charged regions over each other resulting in attractive forces between the two fragments. The computational results are consistent with the experimental observations, confirming that the reactions proceed through an asynchronous one-step mechanism.

Synthesis, kinetic studies and in-silico investigations of novel quinolinyl-iminothiazolines as alkaline phosphatase inhibitors

Deposition of hydroxyapatite (HA) or alkaline phosphate crystals on soft tissues causes the pathological calcification diseases comprising of end-stage osteoarthritis (OA), ankylosing spondylitis (AS), medial artery calcification and tumour calcification. The pathological calcification is symbolised by increased concentration of tissue non-specific alkaline phosphatase (TNAP). An efficient therapeutic strategy to eradicate these diseases is required, and for this the alkaline phosphatase inhibitors can play a potential role. In this context a series of novel quinolinyl iminothiazolines was synthesised and evaluated for alkaline phosphatase inhibition potential. All the compounds were subjected to DFT studies where N-benzamide quinolinyl iminothiazoline (6g), N-dichlorobenzamide quinolinyl iminothiazoline (6i) and N-nitrobenzamide quinolinyl iminothiazoline (6j) were found as the most reactive compounds. Then during the in-vitro testing, the compound N-benzamide quinolinyl iminothiazoline (6g) exhibited the maximum alkaline phosphatase inhibitory effect (IC₅₀ = 0.337 ± 0.015 µM) as compared to other analogues and standard KH₂PO₄ (IC₅₀ = 5.245 ± 0.477 µM). The results were supported by the molecular docking studies, molecular dynamics simulations and kinetic analysis which also revealed the inhibitory potential of compound N-benzamide quinolinyl iminothiazoline (6g) against alkaline phosphatase. This compound can be act as lead molecule for the synthesis of more effective inhibitors and can be suggested to test at the molecular level.

Synthesis, DFT and molecular docking of novel (Z)-4-bromo-N-(4-butyl-3 (quinolin-3-yl)thiazol-2(3H)-ylidene)benzamide as elastase inhibitor

A new compound, C23H20BrN3OS, containing a quinoline-based iminothiazoline with a thiazoline ring, was synthesized and its crystal and molecular structures were analyzed through single crystal X-ray analysis. The compound belongs to the triclinic system P - 1 space group, with dimensions of a = 9.2304 (6) Å, b = 11.1780 (8) Å, c = 11.3006 (6) Å, α = 107.146 (5)°, β = 93.701 (5)°, γ = 110.435 (6)°, Z = 2 and V = 1025.61 (12) Å3. The crystal structure showed that C-H···N and C-H···O hydrogen bond linkages, forming infinite double chains along the b-axis direction, and enclosing R22(14) and R22(16) ring motifs. The Hirshfeld surface analysis revealed that H…H (44.1%) and H…C/C…H (15.3%) interactions made the most significant contribution. The newly synthesized (Z)-4-bromo-N-(4-butyl-3 (quinolin-3-yl)thiazol-2(3H)-ylidene)benzamide, in comparison to oleanolic acid, exhibited more strong potential against elastase with an inhibition value of 1.21 µM. Additionally, the derivative was evaluated using molecular docking and molecular dynamics simulation studies, which showed that the quinoline based iminothiazoline derivative has the potential to be a novel inhibitor of elastase enzyme. Both theoretical and experimental findings suggested that this compound could have a number of biological activities.

Quantum Mechanical Prediction of Dissociation Constants for Thiazol-2-imine Derivatives

As weak acids or bases, in solution, drug molecules are in either their ionized or nonionized states. A high degree of ionization is essential for good water solubility of a drug molecule and is required for drug-receptor interactions, whereas the nonionized form improves a drug's lipophilicity, allowing the ligand to cross the cell membrane. The penetration of a drug ligand through cell membranes is mainly governed by the pKa of the drug molecule and the membrane environment. In this study, with the aim of predicting the acetonitrile pKa's (pKa(MeCN)) of eight drug-like thiazol-2-imine derivatives, we propose a very accurate and computationally affordable protocol by using several quantum mechanical approaches. Benchmark studies were conducted on a set of training molecules, which were selected from the literature with known pKa(water) and pKa(MeCN). Highly well-correlated pKa values were obtained when the calculations were performed with the isodesmic method at the M062X/6-31G** level of theory in conjunction with SMD solvation model for nitrogen-containing heterocycles. Finally, experimentally unknown pKa(MeCN) values of eight thiazol-2-imine structures, which were previously synthesized by some of us, are proposed.

Heterocyclic Electrochemistry: Renewable Electricity in the Construction of Heterocycles

Numerous applications in the realm of biological exploration and drug synthesis can be found in heterocyclic chemistry, which is a vast subject. Many efforts have been developed to further improve the reaction conditions to access this interesting family to prevent employing hazardous ingredients. In this instance, it has been stated that green and environmentally friendly manufacturing methodologies have been introduced to create N-, S-, and O-heterocycles. It appears to be one of the most promising methods to access these types of compounds avoiding use of stoichiometric amounts of oxidizing/reducing species or precious metal catalysts, in which only catalytic amounts are sufficient, and it represent an ideal way of contributing toward the resource economy. Thus, renewable electricity provides clean electrons (oxidant/reductant) that initiate a reaction cascade via producing reactive intermediates that facilitate in building new bonds for valuable chemical transformations. Moreover, electrochemical activation using metals as catalytic mediators has been identified as a more efficient strategy toward selective functionalization. Thus, indirect electrolysis makes the potential range more practical, and less side reactions can occur. The latest developments in using an electrolytic strategy to create N-, S-, and O-heterocycles are the main topic of this mini review, which was documented over the last five years.

Exploring 2-Tetradecanoylimino-3-aryl-4-methyl-1,3-thiazolines Derivatives as Alkaline Phosphatase Inhibitors: Biochemical Evaluation and Computational Analysis

The current study focused on the laboratory approach in conjunction with computational methods for the synthesis and bioactivity assessment of unique 2-tetradecanoylimino-3-aryl-4-methyl-1,3-thiazolines (2a-2k). Processes included cyclizing 1-aroyl-3-arylthioureas with propan-2-one in the presence of trimethylamine and bromine. By using spectroscopic techniques and elemental analyses, structures were elucidated. To assess the electronic properties, density functional theory (DFT) calculations were made, while binding interactions of synthesized derivatives were studied by the molecular docking tool. Promising results were found during the evaluation of bioactivity of synthesized compounds against alkaline phosphatase. The drug likeliness score, an indicator used for any chemical entity posing as a drug, was within acceptable limits. The data suggested that most of the derivatives were potent inhibitors of alkaline phosphatase, which in turn may act as lead molecules to synthesize derivatives having desired pharmacological profiles for the treatment of specific diseases associated with abnormal levels of ALPs.

Ameliorative effects of 9-diaminoacridine derivative against Ehrlich ascites carcinoma-induced hepatorenal injury in mice

Ehrlich ascites carcinoma induces hepatorenal injuries while acridine derivatives have antioxidant, anticancer, and anti-inflammatory. Thus, this study evaluated the protective potential of a newly synthesized the 9-diaminoacridine derivative (9-DAAD), N1-(acridin-9-yl) propane-1, 3-diamine hydrochloride, against Ehrlich ascites carcinoma (EAC) induced hepatorenal injury in female mice. Forty female mice were allocated into 4 groups. Group I was injected with 0.1% DMSO subcutaneously and kept a control. Group II received 9-DAAD (30 mg/kg bw/2 days) subcutaneously for 2 weeks. Group III was injected interaperitonealy with 2.5 × 106 cells of EAC/20 g bw. Group IV was injected with EAC as the third group and administered with 9-DAAD as the second group for 2 weeks after induction of EAC. EAC significantly elevated total leukocytes and platelets counts; activities of serum AST, ALT, and ALP; serum levels of alpha-fetoprotein; carcinoembryonic antigen; urea and creatinine; and expression of vascular endothelial growth factor protein in hepatic and renal tissues. Meanwhile it decreased red blood cells count, hemoglobin concentration and hematocrit value. At the same time, it significantly reduced serum levels of total protein and albumin and altered hepatic and renal tissues structures. Also, EAC decreased apoptosis and DNA synthesis in hepatic and renal cells. However, treatment of EAC-bearing mice with 9-DAAD improved liver and kidney structures, functions and modulated EAC altered parameters, as well as it reduced hepatic and renal cells proliferation and DNA synthesis. This study indicated that 9-DAAD had a potential ameliorative effect against EAC-induced hepatorenal injury.

Derivatives of pyridine and thiazole hybrid: Synthesis, DFT, biological evaluation via antimicrobial and DNA cleavage activity

A novel series of the 2-pyridine substituted 3a-e and 4-pyridine substituted 4a-e thiazole derivatives were synthesized, characterized, and evaluated for the biological activity. Crystallographic parameters and inter- and intramolecular interactions of 3a and 3c single crystals were examined through XRD analysis. The chemical reactivity potentials of the compounds were evaluated, by comparing with a theoretical approach based on DFT. The biological activity properties of synthesized compounds were determined by antimicrobial activity with Gram positive, Gram negative, Yeast via minimal inhibitory concentration (MIC) method and DNA cleavage activity studies. The most obvious findings to emerge from this study are that on the basis of both biological activity and chemical reactivity 4-pyridine thiazole hybrid compounds 4a-e showed more potent activity than 3a-e. In general, the antimicrobial activity of synthesized compounds follows the Bacillus cereus > Staphylococcus aureus > Candida albicans > Escherichia coli > Pseudomonas aeruginosa. The most potent compound 4c (MIC values 0.02 mM) exhibited antimicrobial activity against Staphylococcus aureus and Bacillus cereus. Furthermore, this compound has a good electrophilicity index value (4.56 eV).

Synthesis and Biological Evaluation of Some Novel Thiazole-Based Heterocycles as Potential Anticancer and Antimicrobial Agents

A novel series of thiazole-based heterocycles was synthesized using 1,3-dipolar cycloaddition reactions in the presence of chitosan-grafted-poly(vinylpyridine) as an eco-friendly biopolymeric basic catalyst. The molecular structure of the synthesized compounds was illustrated by spectroscopic and elemental analysis. Various in vitro biological assays were performed to explore the potential antitumor, antimicrobial and hepatoprotective activities of the newly synthesized compounds. The cytotoxic activities were assessed against human hepatocellular carcinoma (HepG-2), colorectal carcinoma (HCT-116) and breast cancer (MCF-7) cell lines and results revealed that all compounds displayed antitumor activities with the chlorine-containing derivatives, 11c and 6g, being the most potent. The majority of the tested thiazole derivatives exhibited satisfactory antibacterial activity towards the used gram positive and gram-negative bacterial species. Moreover, many derivatives showed weak hepatoprotective activity against CCl₄-induced hepatotoxicity.

Eco-Friendly Synthesis, Characterization and Biological Evaluation of Some Novel Pyrazolines Containing Thiazole Moiety as Potential Anticancer and Antimicrobial Agents

The one-pot synthesis of a series of pyrazoline derivatives containing the bioactive thiazole ring has been performed through a 1,3-dipolar cycloaddition reaction of N-thiocarbamoylpyrazoline and different hydrazonoyl halides or α-haloketones in the presence of DABCO (1,4-diazabicyclo[2.2.2] octane) as an eco-friendly catalyst using the solvent-drop grinding method. The structure of the synthesized compounds was elucidated using elemental and spectroscopic analyses (IR, NMR, and Mass). The activity of these compounds against human hepatocellular carcinoma cell line (HepG2) was tested and the results showed that the pyrazoline 11f, which has a fluorine substituent, is the most active. The antimicrobial activities of the newly synthesized compounds were determined against two fungi and four bacterial strains, and the results indicated that some of the newly synthesized pyrazolines are more potent than the standard drugs against test organisms.

Stereoselective synthesis, X-ray analysis, computational studies and biological evaluation of new thiazole derivatives as potential anticancer agents

Background

The synthesis of new thiazole derivatives is very important because of their diverse biological activities. Also , many drugs containing thiazole ring in their skeletons are available in the market such as Abafungin, Acotiamide, Alagebrium, Amiphenazole, Brecanavir, Carumonam, Cefepime, and Cefmatilen.

Results

Ethyl cyanoacetate reacted with phenylisothiocyanate, chloroacetone, in two different basic mediums to afford the thiazole derivative 6, which reacted with dimethylformamide- dimethyl acetal in the presence of DMF to afford the unexpected thiazole derivative 11. The structures of the thiazoles 6 and 11 were optimized using B3LYP/6-31G(d,p) method. The experimentally and theoretically geometric parameters agreed very well. Also, the natural charges at the different atomic sites were predicted. HOMO and LUMO demands were discussed. The anticancer activity of the prepared compounds was evaluated and showed moderate activity.

Conclusions

Synthesis of novel thiazole derivatives was done. The structure was established using X-ray and spectral analysis. Optimized molecular structures at the B3LYP/6-31G(d,p) level were investigated. Thiazole derivative 11 has more electropositive S-atom than thiazole 6. The HOMO–LUMO energy gap is lower in the former compared to the latter. The synthesized compounds showed moderate anticancer activity.

Electronic supplementary material

The online version of this article (10.1186/s13065-018-0420-7) contains supplementary material, which is available to authorized users.

Synthesis of aminothiazoles: polymer-supported approaches

Aminothiazoles and their derivatives are of immense biological importance and have been consistently synthesizedviavarious methods.

Trypsin-catalyzed multicomponent reaction: A novel and efficient one-pot synthesis of thiazole-2-imine derivatives

The first Trypsin from porcine pancreas catalyzed a novel one-pot three-component reaction of α-bromoketone, primary alkylamines, and phenylisothiocyanate for the synthesis of thiazole-imine derivatives with high yields (up to 98%) in a short time under mild conditions. The results revealed that Trypsin exhibited excellent catalytic activity and great tolerance for broad substrates. This Trypsin-catalyzed three component convergent method provides a novel strategy for the synthesis of thiazole-2-imine derivatives and expands the promiscuous functions of enzymes in organic synthesis.

One-Pot Three-Component Synthesis of 2-Imino-1,3-Thiazolines on Soluble Ionic Liquid Support

An efficient one-pot, three-component synthesis of 2-imino-1,3-thiazolidines and 2-imino-1,3-thiazolines using ionic liquid-tethered 2-aminobenzimidazoles was reported. The protocol includes reaction of ionic liquid attached 2-aminobenzimidazoles with isothiocyanates to afford isothioureas, followed by its base induced inter and intramolecular nucleophilic displacement reactions with 1,2-dichloroethane (EDC) which results in thiazolidine ring formation. In the next to the last step, the ionic liquid support was removed by methanolysis to deliver 2-imino-1,3-thiazolidines, which were sequentially oxidized with manganese(III) triacetate to yield 2-imino-1,3-thiazolines. The salient feature of this method is the use of 1,2-dichloroethane as a synthetic equivalent for α-haloketone to avoid the use of toxic halogenating reagents.

QSAR studies and antimicrobial potential of 1,3-thiazolylphosphonium salts

The regression QSAR models were built to predict the antimicrobial activity of new thiazole derivatives. Compounds with high predicting activity were synthesized and evaluated against Gram-positive and Gram-negative bacteria and fungi. 1,3-Thiazole-4-ylphosphonium salts 4 and 5 displayed good antibacterial properties and high antifungal activity. The predictions are in a good agreement with the experiment results, which indicate the good predictive power of the created QSAR models.

C–H functionalization of azines. Anodic dehydroaromatization of 9-(hetero)aryl-9,10-dihydroacridines

A simple and efficient electrochemical method for the oxidative conversion of dihydroacridines into the corresponding 9-(hetero)aryl-N-methylacridinium salts has been developed. Current–voltage characteristics of dihydroacridines are given.

Iminothiazoline-Sulfonamide Hybrids as Jack Bean Urease Inhibitors; Synthesis, Kinetic Mechanism and Computational Molecular Modeling

The present work reports the synthesis of several 2-iminothiazoline derivatives of sulfanilamide (3a-j) as inhibitors of jack bean ureases. The title compounds were synthesized by the heterocyclization of sulfanilamide thioureas with propragyl bromide in dry ethanol in the presence of 1,8-Diazabicyclo[5.4.0]undec-7-ene as a base. All of the compounds showed higher urease inhibitory activity than the standard thiourea. The compounds (3h) and (3i) exhibited excellent enzyme inhibitory activity with IC50 0.064 and 0.058 μm, respectively, while IC50 of thiourea is 20.9 μm. The kinetic mechanism analyzed by Dixon plot showed that compound (3h) is a mixed-type inhibitor while (3i) is a competitive one. Docking studies suggested that Asp633, Ala636, His492, Ala440, Lue523, Asp494 and Arg439 are the major interacting residues in the binding site of the protein and may have an instrumental role in the inhibition of enzyme's function. 2-iminothiazoline analogues (3a-j) showed good docking score (-10.6466 to -8.7215 Kcal/mol) and binding energy (London dG ranging from -14.4825 to -10.4087 Kcal/mol) which is far better than the standard thiourea (binding score in S field -4.5790 Kcal/mol London dG -4.7726 Kcal/mol). Our results inferred compound (3i) may serve as a structural model for the design of most potent urease inhibitors.

Acridine and its derivatives: a patent review (2009 - 2013)

INTRODUCTION

Acridine derivatives have been extensively explored as potential therapeutic agents for the treatment of a number of diseases, such as cancer, Alzheimer's, and bacterial and protozoan infections. Their mode of action is mainly attributed to DNA intercalation and the subsequent effects on the biological processes linked to DNA and its related enzymes.

AREA COVERED

This review covers the relevant efforts in developing acridine derivatives with enhanced therapeutic potency and selectivity and as fluorescent materials, with particular focus on the newly patented acridine derivatives in 2009 - 2013, acridine drugs in clinical trials and preclinical studies, and other new derivatives that emerged in 2009 - 2013.

EXPERT OPINION

Thousands of acridines with therapeutic and biological activities or with photochemical properties have been developed. In addition, to modify the position and the nature of the substituent on the acridine core, more attention may be paid to the development of azaacridine or other heteroatom-substituted acridine derivatives and their synthesis methods to broaden the application of acridine derivatives. In cancer chemotherapy, the mode of action of acridine derivatives needs to be further studied. Efficient methods for identification and optimization of acridine derivatives to localize at the sites of disease need to be further developed. Moreover, acridine drugs may be combined with such bioactive agents as DNA repair proteins inhibitors to overcome tumor resistance and improve outcomes.