Microwave-promoted synthesis and biological activity of some 2-hetarylmethyl-4-(4-hetarylphenyl)-5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one derivatives

Efficient, rapid, and high-yield synthesis of aryl Schiff base derivatives and their in vitro and in silico inhibition studies of hCA I, hCA II, AChE, and BuChE

This study reports a rapid and efficient synthesis of four novel aryl Schiff base derivatives. Biological activity and molecular modeling studies were conducted to evaluate the inhibitory effects of these compounds on human carbonic anhydrases (hCA) and cholinesterases. The results indicate that the triazole-ring-containing compounds have strong inhibitory effects on hCA I, hCA II, acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) targets. Besides comparing the Schiff bases synthesized in our study to reference molecules, we conducted in silico investigations to examine how these compounds interact with their targets. Our studies revealed that these compounds can occupy binding sites and establish interactions with crucial residues, thus inhibiting the functions of the targets. These findings have significant implications as they can be utilized to develop more potent compounds for treating the diseases that these target proteins play crucial roles in or to obtain drug precursors with enhanced efficacy.

Vision on Synthetic and Medicinal Facets of 1,2,4-Triazolo[3,4-b][1,3,4]thiadiazine Scaffold

The present review article strives to compile the latest synthetic approaches for the synthesis of triazolothiadiazine and its derivatives, along with their diverse pharmacological activities, viz. anticancer, antimicrobial, analgesic and anti-inflammatory, antioxidant, antiviral, enzyme inhibitors (carbonic anhydrase inhibitors, cholinesterase inhibitors, alkaline phosphatase inhibitors, anti-lipase activity, and aromatase inhibitors) and antitubercular agents. The review focuses particularly on the structure–activity relationship of biologically important 1,2,4-triazolo[3,4-b][1,3,4]thiadiazines, which have profound importance in drug design, discovery and development. In silico pharmacokinetic and molecular modeling studies have also been summarized. It is hoped that this review article will be of help to researchers engaged in the development of new biologically active entities for the rational design and development of new target-oriented 1,2,4-triazolo[3,4-b][1,3,4]thiadiazine-based drugs for the treatment of multifunctional diseases.

Developing a scaffold for urease inhibition based on benzothiazoles: Synthesis, docking analysis, and therapeutic potential

The synthesis, in silico molecular docking, and in vitro urease inhibition studies of a novel series of benzothiazole derivatives are reported. The title compounds in the two series, namely, 2-({5-[(benzothiazol-2-ylthio)methyl]-1,3,4-oxadiazol-2-yl}thio)-1-(4-substituted-phenyl)ethan-1-one and 2-(benzothiazol-2-ylthio)-1-(4-substituted-phenyl)ethan-1-one oxime, were synthesized by the reaction of benzo[d]thiazole-2-thiol with different kinds of intermediates in several steps using both conventional and microwave techniques. All compounds were found to have an excellent degree of urease-inhibitory potential ranging between 16.16 ± 0.54 and 105.32 ± 2.10 µM when compared with the standard inhibitor acetohydroxamic acid with IC₅₀  = 320.70 ± 4.24 µM. The structure-activity relationship was established in detail. The binding interactions of the compounds with the enzyme were confirmed through molecular docking. Further, 100 -ns molecular dynamics simulations were performed to investigate the stability and structural perturbations experienced by the most potent compound over the urease active site.

The different modes of chiral [1,2,3]triazolo[5,1-b][1,3,4]thiadiazines: crystal packing, conformation investigation and cellular activity

The crystal structures of four new chiral [1,2,3]triazolo[5,1-b][1,3,4]thiadiazines are described, namely, ethyl 5'-benzoyl-5'H,7'H-spiro[cyclohexane-1,6'-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3'-carboxylate, C₁₉H₂₂N₄O₃S, ethyl 5'-(4-methoxybenzoyl)-5'H,7'H-spiro[cyclohexane-1,6'-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3'-carboxylate, C₂₀H₂₄N₄O₄S, ethyl 6,6-dimethyl-5-(4-methylbenzoyl)-6,7-dihydro-5H-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine-3-carboxylate, C₁₇H₂₀N₄O₃S, and ethyl 5-benzoyl-6-(4-methoxyphenyl)-6,7-dihydro-5H-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine-3-carboxylate, C₂₁H₂₀N₄O₄S. The crystallographic data and cell activities of these four compounds and of the structures of three previously reported similar compounds, namely, ethyl 5'-(4-methylbenzoyl)-5'H,7'H-spiro[cyclopentane-1,6'-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3'-carboxylate, C₁₉H₂₂N₄O₃S, ethyl 5'-(4-methoxybenzoyl)-5'H,7'H-spiro[cyclopentane-1,6'-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3'-carboxylate, C₁₉H₂₂N₄O₄S, and ethyl 6-methyl-5-(4-methylbenzoyl)-6-phenyl-6,7-dihydro-5H-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine-3-carboxylate, C₂₂H₂₂N₄O₃S, are contrasted and compared. For both crystallization and an MTT assay, racemic mixtures of the corresponding [1,2,3]triazolo[5,1-b][1,3,4]thiadiazines were used. The main manner of molecular packing in these compounds is the organization of either enantiomeric pairs or dimers. In both cases, the formation of two three-centre hydrogen bonds can be detected resulting from intramolecular N-H...O and intermolecular N-H...O or N-H...N interactions. Molecules of different enantiomeric forms can also form chains through N-H...O hydrogen bonds or form layers between which only weak hydrophobic contacts exist. Unlike other [1,2,3]triazolo[5,1-b][1,3,4]thiadiazines, ethyl 5'-benzoyl-5'H,7'H-spiro[cyclohexane-1,6'-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3'-carboxylate contains molecules of only the (R)-enantiomer; moreover, the N-H group does not participate in any significant intermolecular interactions. Molecular mechanics methods (force field OPLS3e) and the DFT B3LYP/6-31G+(d,p) method show that the compound forming enantiomeric pairs via weak N-H...N hydrogen bonds is subject to greater distortion of the geometry under the influence of the intermolecular interactions in the crystal. For intramolecular N-H...O and S...O interactions, an analysis of the noncovalent interactions (NCIs) was carried out. The cellular activities of the compounds were tested by evaluating their antiproliferative effect against two normal human cell lines and two cancer cell lines in terms of half-maximum inhibitory concentration (IC₅₀). Some derivatives have been found to be very effective in inhibiting the growth of Hela cells at nanomolar and submicromolar concentrations with minimal cytotoxicity in relation to normal cells.

Two decades of the synthesis of mono- and bis-aminomercapto[1,2,4]triazoles

4-Amino-5-mercapto[1,2,4]triazole and its 3-substituted derivatives have proven to be of biological interest and provide access to a new class of biologically active heterocyclic compounds for biomedical applications. This study will be helpful for scientific researchers interested in the chemistry of bifunctional versatile compounds as it provides a collection of all the methods for the preparation of 3-substituted-4-amino-5-mercapto[1,2,4]triazoles with aliphatic, aromatic, and heterocyclic moieties during the period from 2000 to mid-2020.

F. A review on the development of urease inhibitors as antimicrobial agents against pathogenic bacteria

Ureases are enzymes that hydrolyze urea into ammonium and carbon dioxide. They have received considerable attention due to their impacts on living organism health, since the urease activity in microorganisms, particularly in bacteria, are potential causes and/or factors contributing to the persistence of some pathogen infections. This review compiles examples of the most potent antiurease organic substances. Emphasis was given to systematic screening studies on the inhibitory activity of rationally designed series of compounds with the corresponding SAR considerations. Ureases of Canavalia ensiformis, the usual model in antiureolytic studies, are emphasized. Although the active site of this class of hydrolases is conserved among bacteria and vegetal ureases, the same is not observerd for allosteric site. Therefore, inhibitors acting by participating in interactions with the allosteric site are more susceptible to a potential lack of association among their inhibitory profile for different ureases. The information about the inhibitory activity of different classes of compounds can be usefull to guide the development of new urease inhibitors that may be used in future in small molecular therapy against pathogenic bacteria.

Synthesis and glutathione reductase inhibitory properties of 5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one's aryl Schiff base derivatives

Glutathione reductase (GR) is responsible for the existence of the reduced glutathione (GSH) molecule, a crucial antioxidant against oxidative stress reagents. The antimalarial activities of some redox active compounds are attributed to their inhibition of antioxidant flavoenzyme GR, and inhibitors are therefore expected to be useful for the treatment of malaria. In this work, a fast and effective synthesis and the GR inhibitory properties of 5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one's aryl Schiff base derivatives are reported. For this aim, the triazol nucleus was obtained, which was substituted with identical groups: ester, hydrazide, and Schiff base system at the N-2 and N-4 nitrogen atoms. The majority of the reactions were carried out by utilizing both microwave and conventional methods in order to compare their yields and reaction times. Beside this, the occuring E/Z geometrical isomers from the CN double bond and the cis/trans amide conformers at the CONH single bond were studied. In the biological activity section of this work, it was found that all synthesized compounds have better inhibitory activity than N,N-bis(2-chloroethyl)-N-nitrosourea against GR; especially, two molecules, 6e and 6f, are the best among them. The evidence indicates that these Schiff base derivatives, with triazole ring, are strong GR inhibitors and novel antimalaria candidates.

Synthesis and Biological Evaluation of Novel Glycosyl-Containing 1,2,4-Triazolo[3,4-b][1,3,4]Thiadiazole Derivatives as Acetylcholinesterase Inhibitors

An efficient protocol for the synthesis of novel glycosyl-containing 1,2,4-triazolo[3,4- b][1,3,4]thiadiazole derivatives starting from the commercially available D-glucosamine hydrochloride is described by reaction of glycosyl isothiocyanate with various aminotriazoles in DMF. Glycosyl isothiocyanate is an important intermediate and synthetic methods are discussed. The acetylcholinesterase inhibitory activity of these compounds was tested by Ellman's method. It was found that most compounds exhibited over 90% inhibition and they were subsequently evaluated for their IC50 values.