Hybrid molecules of thiadiazole-based benzothioate and benzenesulfonothioate: synthesis, structural analysis, and evaluation as potential inhibitors of thymidine phosphorylase and β-glucuronidase through in vitro and in silico approaches

Abstract

The thiadiazole-based benzothioate (3a-f) and benzenesulfonothioate (5a-f) hybrid derivatives were designed and synthesized in a single step reaction. All the synthesized compounds structures were confirmed through spectroscopic techniques including 1H NMR, 13C NMR and HRMS (ESI). Then, the synthesized compounds were subjected to in vitro thymidine phosphorylase and beta-glucuronidase inhibition profile. All the newly synthesized moieties (3a-f) & (5a-f) were found potent and showed moderately to good inhibition profile. Among benzothioate analogues (3a-f), the analogues 3d and 3c were identified to be active inhibitors of thymidine phosphorylase and beta-glucuronidase enzymes having IC50 values of 2.11 ± 0.31 μM & 3.28 ± 0.20 μM (against thymidine phosphorylase) and 2.50 ± 0.20 μM & 3.71 ± 0.10 μM (against beta-glucuronidase) respectively. However, among benzenesulfonothioate (5a-f) analogues, analogues 5a and 5d were found to be significantly active, even more than standard drugs with IC50 values of 2.23 ± 0.13 μM & 3.10 ± 0.17 μM (against thymidine phosphorylase) and 3.12 ± 0.20 μM & 5.60 ± 0.34 μM respectively. The results were compared to standard drugs such as D-saccharic acid with IC50 values of 10.10 ± 0.10 µM (for benzothioate series) & 8.50 ± 0.10 µM (for benzenesulfonothioate series) and 7-Deazaxanthine having IC50 values of 12.20 ± 0.10 µM (for benzothioate series) & 9.20 ± 0.30 µM (benzenesulfonothioate series) respectively. From structure-activity (SAR) analysis, it was confirmed that any variation found in inhibitory activities of both thymidine phosphorylase beta-glucuronidase enzymes was due to different substitution pattern of substituent(s) at variable position of aryl ring. Moreover, a good protein-ligand interaction (PLI) subjected to molecular docking study against shown by the most active analogues against corresponding target with key binding interactions with least binding energies. These findings reveal that thiadiazole-containing benzothioate (3a-f) and benzenesulfonothioate (5a-f) act as thymidine phosphorylase beta-glucuronidase inhibitors to develop novel therapeutics agents for the purpose of drug discovery.