Synthesis and Antiviral Bioassay of New Diphenyl Ether-based Compounds

Discovery, Optimization, and Biological Evaluation of Novel Pyrazol-5-yl-phenoxybenzamide Derivatives as Potent Succinate Dehydrogenase Inhibitors

The diphenyl ether molecular pharmacophore has played a significant role in the development of fungicidal compounds. In this study, a variety of pyrazol-5-yl-phenoxybenzamide derivatives were synthesized and evaluated for their potential to act as succinate dehydrogenase inhibitors (SDHIs). The bioassay results indicate certain compounds to display a remarkable and broad-spectrum in their antifungal activities. Notably, compound 12x exhibited significant in vitro activities against Valsa mali, Gaeumannomyces graminis, and Botrytis cinerea, with EC50 values of 0.52, 1.46, and 3.42 mg/L, respectively. These values were lower or comparable to those of Fluxapyroxad (EC50 = 12.5, 1.93, and 8.33 mg/L, respectively). Additionally, compound 12x showed promising antifungal activities against Sclerotinia sclerotiorum (EC50 = 0.82 mg/L) and Rhizoctonia solani (EC50 = 1.86 mg/L), albeit lower than Fluxapyroxad (EC50 = 0.23 and 0.62 mg/L). Further in vivo experiments demonstrated compound 12x to possess effective protective antifungal activities against V. mali and S. sclerotiorum at a concentration of 100 mg/L, with inhibition rates of 66.7 and 89.3%, respectively. In comparison, Fluxapyroxad showed inhibition rates of 29.2 and 96.4% against V. mali and S. sclerotiorum, respectively. Molecular docking analysis revealed that compound 12x interacts with SDH through hydrogen bonding, π-cation, and π-π interactions, providing insights into the probable mechanism of action. Furthermore, compound 12x exhibited greater binding energy and SDH enzyme inhibitory activity than Fluxapyroxad (ΔGcal = -46.8 kcal/mol, IC50 = 1.22 mg/L, compared to ΔGcal = -41.1 kcal/mol, IC50 = 8.32 mg/L). Collectively, our results suggest that compound 12x could serve as a promising fungicidal lead compound for the development of more potent SDHIs for crop protection.

Identifying potential monkeypox virus inhibitors: an in silico study targeting the A42R protein

Monkeypox (now Mpox), a zoonotic disease caused by the monkeypox virus (MPXV) is an emerging threat to global health. In the time span of only six months, from May to October 2022, the number of MPXV cases breached 80,000 and many of the outbreaks occurred in locations that had never previously reported MPXV. Currently there are no FDA-approved MPXV-specific vaccines or treatments, therefore, finding drugs to combat MPXV is of utmost importance. The A42R profilin-like protein of the MPXV is involved in cell development and motility making it a critical drug target. A42R protein is highly conserved across orthopoxviruses, thus A42R inhibitors may work for other family members. This study sought to identify potential A42R inhibitors for MPXV treatment using computational approaches. The energy minimized 3D structure of the A42R profilin-like protein (PDB ID: 4QWO) underwent virtual screening using a library of 36,366 compounds from Traditional Chinese Medicine (TCM), AfroDb, and PubChem databases as well as known inhibitor tecovirimat via AutoDock Vina. A total of seven compounds comprising PubChem CID: 11371962, ZINC000000899909, ZINC000001632866, ZINC000015151344, ZINC000013378519, ZINC000000086470, and ZINC000095486204, predicted to have favorable binding were shortlisted. Molecular docking suggested that all seven proposed compounds have higher binding affinities to A42R (-7.2 to -8.3 kcal/mol) than tecovirimat (-6.7 kcal/mol). This was corroborated by MM/PBSA calculations, with tecovirimat demonstrating the highest binding free energy of -68.694 kJ/mol (lowest binding affinity) compared to the seven shortlisted compounds that ranged from -73.252 to -97.140 kJ/mol. Furthermore, the 7 compounds in complex with A42R demonstrated higher stability than the A42R-tecovirimat complex when subjected to 100 ns molecular dynamics simulations. The protein-ligand interaction maps generated using LigPlot+ suggested that residues Met1, Glu3, Trp4, Ile7, Arg127, Val128, Thr131, and Asn133 are important for binding. These seven compounds were adequately profiled to be potential antivirals via PASS predictions and structural similarity searches. All seven potential lead compounds were scored Pa > Pi for antiviral activity while ZINC000001632866 and ZINC000015151344 were predicted as poxvirus inhibitors with Pa values of 0.315 and 0.215, and Pi values of 0.052 and 0.136, respectively. Further experimental validations of the identified lead compounds are required to corroborate their predicted activity. These seven identified compounds represent solid footing for development of antivirals against MPXV and other orthopoxviruses.

Synthesis and antiviral activity of diverse heterocyclic scaffolds

Heterocyclic moieties form a major part of organic chemistry as they are widely distributed in nature and have wide scale practical applications ranging from extensive clinical use to diverse fields such as medicine, agriculture, photochemistry, biocidal formulations, and polymer science. By virtue of their therapeutic properties, they could be employed in combating many infectious diseases. Among the common infectious diseases, viral infections are of great public health importance worldwide. Thus, there is an urgent need for the discovery and development of antiviral drugs and clinical methods to prevent various viral infections so as to increase the life expectancy. This review presents the comprehensive overview of the synthesis and antiviral activity of different heterocyclic compounds 2015 onwards, which aids in present knowledge and helps the researchers and other stakeholders to explore their field.

Malebari A, Khayyat AN, Mohamed MFA, Bokhtia RM, AlAwadh MA, Seliem IA, Asfour HZ, Alhakamy NA, Panda SS, AL-Mahmoudy AMM. In Vitro Antimycobacterial Activity and Physicochemical Characterization of Diaryl Ether Triclosan Analogues as Potential InhA Reductase Inhibitors

Two sets of diphenyl ether derivatives incorporating five-membered 1,3,4-oxadiazoles, and their open-chain aryl hydrazone analogs were synthesized in good yields. Most of the synthesized compounds showed promising in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv. Three diphenyl ether derivatives, namely hydrazide 3, oxadiazole 4 and naphthylarylidene 8g exhibited pronounced activity with minimum inhibitory concentrations (MICs) of 0.61, 0.86 and 0.99 μg/mL, respectively compared to triclosan (10 μg/mL) and isoniazid (INH) (0.2 μg/mL). Compounds 3, 4, and 8g showed the InhA reductase enzyme inhibition with higher IC₅₀ values (3.28–4.23 µM) in comparison to triclosan (1.10 µM). Correlation between calculated physicochemical parameters and biological activity has been discussed which justifies a strong correlation with respect to the inhibition of InhA reductase enzyme. Molecular modeling and drug-likeness studies showed good agreement with the obtained biological evaluation. The structural and experimental information concerning these three InhA inhibitors will likely contribute to the lead optimization of new antibiotics for M. tuberculosis.