Synthesis, enzyme inhibitory kinetics, & computational studies of N-(substituted phenyl)-(5-(3,4-dichlorobenzyl)-4-(4-chlorophenyl)-4H-1,2,4-triazol-3-ylthio)methylbenzamides: As potent alkaline phosphatase inhibitors

The present research work encompass an innovative approach towards the synthesis of potent series of target compounds (8a-j) having 1,2,4-triazole and benzamide moieties as alkaline phosphatase inhibitors. The synthetic methodology was initiated by Fischer's esterification of 3,4-dichlorophenylacetic acid (1) to achieve ethyl 2-(3,4-dichlorophenyl)acetate (2) which underwent hydrazinolysis using hydrazine hydrate under reflux to 2-(3,4-dichlorophenyl)acetohydrazide (3). The compound (3) with 4-chlorophenyl isothiocyanate (4) was base-catalyzed cyclization (10% aqueous NaOH) to 4-(4-chlorophenyl)-5-(3,4-dichlorobenzyl)-4H-1,2,4-triazole-3-thiol (5) under reflux via N-(4-chlorophenyl)-2-(2-(3,4-dichlorophenyl)acetyl)hydrazinecarbocarbothioamide, as an intermediate. Finally, a series of derivatives (8a-j) was synthesized by reacting (5) with different electrophiles; N-(aryl)-4-(chloromethyl)benzamides (7a-j) which were obtained by the reaction of substituted aryl amines (6a-j) with 4-(chloromethyl)benzoyl chloride in aqueous alkaline medium. The structural confirmation of all these novel derivatives was corroborated by contemporary spectral analysis i.e., IR, EI-MS, H-1 and (CNMR)-C-13 . The in vitro inhibitory potential of these benzamides against alkaline phosphatase enzyme disclosed that nine out of ten exhibited potent inhibition relative to standard used. Among these, 8i was identified as most potent molecule with IC50 value of (0.046 +/- 0.013 mu M), comparative to standard (5.241 +/- 0.471 mu M). The Kinetics mechanism examined by Lineweaver-Burk Plots (LBP), which revealed that 8i inhibited alkaline phosphatase enzyme competitively by forming an enzyme-inhibitor complex. The inhibition constant Ki determined from Dixon plots of this compound was 0.02 mu M. The results of computational study were in full agreement with experimental proceedings and these ligands showed good interactions with the active site of enzyme. Based on the current investigations, these potent inhibitotrs might lead to further research gateways for the discovery of non-toxic medicinal scaffolds for dealing with the alkaline phosphatase ailments such as bone diseases and liver dysfunction. DFT analysis was also performed.