2-Methyl-4-nitrophenoxy based thiosemicarbazide, 1,2,4-triazole and 1,3,4-thiadiazole compounds as multitarget enzyme inhibitors: Synthesis, biological and computational studies

Novel thiosemicarbazide (3a-d), 1,2,4-triazole (4a-d), and 1,3,4-thiadiazole (5a-d) derivatives were obtained in high total yields of 57–66%, 40–51%, and 40–53%, respectively, and they were evaluated for inhibitor activity against acetylcholinesterase, and human carbonic anhydrase isoforms I and II (hCAs I and II). They were demonstrated to have effective inhibition profiles with Ki values of 20.08±4.80–152.41±66.19 nM against hCA I, 64.57±20.74–356.58±176.92 nM against hCA II and 4.55±1.24–61.30±28.60 nM against AChE. On the other hand, acetazolamide showed Ki value of 30.69±9.31 nM against hCA I, and 40.08±6.38 nM against hCA II isoform. Additionally, Tacrine inhibited AChE and demonstrated Ki values of 3.51±1.56 nM. The affinities of the compounds towards hCA I, hCA II and AChE were evaluated by in silico studies. In molecular docking studies, 3c (-7.453 kcal/mol), 3d (-7.380), 5b (-7.372 kcal/mol) showed high affinity towards AChE. In MD simulation studies with the most active compound 3c, it was observed that the compound remained stable in the active site of AChE for 150 ns (Average RMSD < 3.0 Å). The ADMET properties of the synthesized compounds were evaluated in silico. All compounds exhibited pharmacological properties and did not display adverse toxic effects. The inhibition of CA and AChE is a powerful pharmacological tool with diverse clinical applications. By targeting different CA and AChE, inhibitors can treat eye diseases, neurological disorders, metabolic conditions, Alzheimer's disease and even cancer, highlighting their broad therapeutic potential. MD simulations of the most active compound, 3c, confirmed its stability in the AChE active site for 150 ns (average RMSD < 3.0 Å). Furthermore, in silico ADMET analysis showed that all compounds had favorable pharmacokinetic profiles without significant toxic effects. These results demonstrate that novel 1,3,4-thiadiazole derivatives have considerable potential as selective and potent multitarget enzyme inhibitors and are promising candidates for further pharmaceutical development.