Isoniazid (INH) is one of the key molecules employed in the treatment of tuberculosis (TB), the most deadly infectious disease worldwide. However, the efficacy of this cornerstone drug has seriously decreased due to emerging INH-resistant strains of Mycobacterium tuberculosis (Mtb). In the present study, we aimed to chemically tailor INH to overcome this resistance. We obtained thirteen novel compounds by linking INH to in-house synthesized sulfonate esters via a hydrazone bridge (SIH1–SIH13). Following structural characterization by FTIR, ¹H NMR, ¹³C NMR, and HRMS, all compounds were screened for their antitubercular activity against Mtb H37Rv strain and INH-resistant clinical isolates carrying katG and inhA mutations. Additionally, the cytotoxic effects of SIH1–SIH13 were assessed on three different healthy host cell lines; HEK293, IMR-90, and BEAS-2B. Based on the obtained data, the synthesized compounds appeared as attractive antimycobacterial drug candidates with low cytotoxicity. Moreover, the stability of the hydrazone moiety in the chemical structure of the final compounds was confirmed by using UV/Vis spectroscopy in both aqueous medium and DMSO. Subsequently, the compounds were tested for their inhibitory activities against enoyl acyl carrier protein reductase (InhA), the primary target enzyme of INH. Although most of the synthesized compounds are hosted by the InhA binding pocket, SIH1–SIH13 do not primarily show their antitubercular activities by direct InhA inhibition. Finally, in silico determination of important physicochemical parameters of the molecules showed that SIH1–SIH13 adhered to Lipinski’s rule of five. Overall, our study revealed a new strategy for modifying INH to cope with the emerging drug-resistant strains of Mtb.

Butyrylcholinesterase (BChE) is considered a promising therapeutic target for treating Alzheimer's disease due to the increase in the levels and activity of BChE in the late stage of the disease. In this study, a series of novel 1,2,4‐triazole derivatives bearing the naphthalene moiety linked to the benzothiazole, thiazole, and phenyl scaffolds via amid chain were designed and synthesized as potential and selective BChE inhibitors. The results of the inhibitory activity studies revealed that most of these compounds exhibited significant inhibitor potency on BChE. Compounds 35a (0.025 ± 0.01 μM) and 37a (0.035 ± 0.01 μM) displayed the most potent inhibitory activity, with excellent selectivity against BChE over acetylcholinesterase (SI_BChE, 23,686 and 16,936, respectively) among the target compounds. The kinetics studies revealed that these compounds behaved with noncompetitive BChE inhibitors. Molecular docking studies indicated that 35a and 37a fit well into the active side of BChE. In addition, 35a and 37a also had the lowest cytotoxicity for human neuroblastoma cells (SH‐SY5Y), potential antioxidant capacity, moderate inhibition potency on amyloid‐β_1‐42 aggregation, and significant neuroprotective effect against SH‐SY5Y cell injury induced by H₂O₂ and amyloid‐β_1‐42. All results suggest that these compounds might be considered as promising new lead compounds in the drug discovery process for the treatment of late‐stage Alzheimer's disease.

Objectives: Drug repurposing is a highly popular approach to find new indications for drugs, which greatly reduces time and costs for drug design and discovery. Non-selective inhibitors of histone deacetylase (HDAC) isoforms including sirtuins (SIRTs) are effective against conditions like cancer. In this study, we used molecular docking to screen Food and Drug Administration (FDA)-approved drugs to identify a number of drugs with a potential to be repurposed for pan-HDAC and pan-SIRT inhibitor activity. Materials and Methods: The library of FDA-approved drugs was optimized using MacroModel. The crystal structures of HDAC1-4, 6-8, SIRT1-3, 5, 6 were prepared before the library was docked to each structure using Glide, FRED, and AutoDock Vina/PyRx. Consensus scores were derived from the docking scores obtained from each software. Pharmacophore modeling was performed using Phase. Results: Based on the consensus scores, belinostat, bexarotene, and cianidanol emerged as top virtual pan-HDAC inhibitors whereas alosetron, cinacalcet, and indacaterol emerged as virtual pan-SIRT inhibitors. Pharmacophore hypotheses for these virtual inhibitors were also suggested through pharmacophore modeling in agreement with the molecular docking models. Conclusion: The consensus approach enabled selection of the best performing drug molecules according to different software, and good scores against isoforms (virtual pan-HDAC and pan-SIRT inhibitors). The study not only proposes potential drugs to be repurposed for HDAC and SIRTrelated diseases but also provides insights for designing potent de novo derivatives.