An efficient synthesis and antimicrobial activity of N-bridged triazolo[3,4-b]thiadiazine and triazolo[3,4-b]thiadiazole derivatives under microwave irradiation

Exploring theophylline-1,2,4-triazole tethered N-phenylacetamide derivatives as antimicrobial agents: unraveling mechanisms via structure-activity relationship, in vitro validation, and in silico insights

Theophylline, a nitrogen-containing heterocycle, serves as a promising focal point for medicinal researchers aiming to create derivatives with diverse pharmacological applications. In this work, we present an improved synthetic method for a range of theophylline-1,2,4-triazole-S-linked N-phenyl acetamides (4a‒g) utilizing ultrasound-assisted synthetic approach. The objective was to assess the effectiveness of synthesized theophylline-1,2,4-triazoles (4a‒g) as inhibitors of HCV serine protease and as antibacterial agents against B. subtilis QB-928 and E. coli AB-274. Theophylline-1,2,4-triazoles were obtained in good to excellent yields (69%-95%) in a shorter time than conventional approach. 4-Chlorophenyl moiety containing theophylline-1,2,4-triazole 4c displayed significantly higher inhibitory activity against HCV serine protease enzyme (IC50 = 0.015 ± 0.25 mg) in comparison to ribavirin (IC50 = 0.165 ± 0.053 mg), but showed excellent binding affinity (-7.55 kcal/mol) with the active site of serine protease, better than compound 4c (-6.90 kcal/mol) as well as indole-based control compound 5 (-7.42 kcal/mol). In terms of percentage inhibition of serine protease, 2-chlorophenyl compound 4b showed the maximum percentage inhibition (86%), more than that of the 3,4-dichlorophenyl compound 4c (76%) and ribavirin (81%). 3,4-Dimethylphenyl-based theophylline-1,2,4-triazole 4g showed the lowest minimum inhibitory concentration (MIC = 0.28 ± 0.50 μg/mL) against the B. subtilis bacterial strain as compared to the standard drug penicillin (MIC = 1 ± 1.50 μg/mL). The other 4-methylphenyl theophylline-1,2,4-triazole 4e (MIC = 0.20 ± 0.08 μg/mL) displayed the most potent antibacterial potential against E. coli in comparison to the standard drug penicillin (MIC = 2.4 ± 1.00 μg/mL). Molecular docking studies further helped in an extensive understanding of all of the interactions between compounds and the enzyme active site, and DFT studies were also employed to gain insights into the molecular structure of the synthesized compounds. The results indicated that theophylline-linked triazole derivatives 4b and 4c showed promise as leading contenders in the fight against the HCV virus. Moreover, compounds 4e and 4g demonstrated potential as effective chemotherapeutic agents against E. coli and B. subtilis, respectively. To substantiate these findings, additional in vivo studies and clinical trials are imperative, laying the groundwork for their integration into future drug design and development.

Novel [1,2,4]triazolo[3,4-b][1,3,4]thiadiazine and [1,2,4]triazolo[3,4-b][1,3,4]thiadiazepine Derivatives: Synthesis, Anti-Viral In Vitro Study and Target Validation Activity

This study of the interaction system of binucleophilic 3-substituted 4-amino-4H-1,2,4-triazole-5-thiols and 3-phenyl-2-propynal made it possible to develop a new approach to synthesis of such isomeric classes as 7-benzylidene-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine and 8-phenyl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazepine. Among the 20 compounds studied in vitro against influenza A/Puerto Rico/8/34 (H1N1) virus, half of them demonstrated selectivity index (SI) of 10 or higher and one of them (4-((3-phenylprop-2-yn-1-yl)amino)-4H-1,2,4-triazole-3-thiol) possessed the highest (SI > 300). Docking results and values showed that the preferred interactant for our ligands was M2 proton channel of the influenza A virus. Protein-ligand interactions modeling showed that the aliphatic moiety of ligands could negatively regulate target activity level.

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.

3-(Bromoacetyl)coumarins: unraveling their synthesis, chemistry, and applications

This review emphasizes recent developments in synthetic routes of 3-(bromoacetyl)coumarin derivatives. Also, chemical reactions of 3-(bromoacetyl)coumarins as versatile building blocks in the preparation of critical polyfunctionalized heterocyclic systems and other industrially significant scaffolds are described. Recent advances of 3-(bromoacetyl)coumarins as attractive starting points towards a wide scale of five and six-membered heterocyclic systems such as thiophenes, imidazoles, pyrazoles, thiazoles, triazoles, pyrans, pyridines, thiadiazins as well as fused heterocyclic systems have been reported. Additionally, this review covers a wide range of analytical chemistry, fluorescent sensors, and biological applications of these moieties, covering the literature till May 2021.