Thiosemicarbazone derivatives as potent antidiabetic agents: Synthesis, in vitro, molecular docking and DFT investigations

Abstract

A library of thiosemicarbazones derivatives have been synthesized by multi step reactions, characterized and screened for their in vitro α-amylase and α-glucosidase inhibitory actions. Among them, three compounds including 4b (IC50 = 3.18 ± 1.72 and 2.11 ± 1.29 µM), 4a (IC50 = 5.16 ± 1.12 and 7.23 ± 0.11 µM), and 4 g (IC50 = 7.13 ± 1.21 and 9.53 ± 0.29 µM) are found as potential dual inhibitors of α-amylase and α-glucosidase enzymes, powerfull than the standard acarbose drug (IC50 = 21.55 ± 1.31 and 16.65 ± 0.07 µM). In addition, compounds 4c, 4f, 4 h, 4d, and 4e indicated significant to less inhibitory potential. Molecular docking was performed to know the binding affinities and various interactions between the synthesized compounds and targeted proteins. For the docking analysis, the protein structure of α-amylase was taken from the Protein Data Bank (PDB) with the code 3BAJ, derived from Homo sapiens. Meanwhile, the protein structure of α-glucosidase was obtained from Beta vulgaris with the PDB code 3W37. The chemical nature of the product compounds was identified using the density functional theory (DFT) method, and the calculations were performed using the B3LYP/6–311++G(d,p) method. Intramolecular interactions were explored using DFT-d3 and Reduced Density Gradient (RDG) analysis. Furthermore, the chemical nature of all the compounds was identified using TD-DFT at the CAM-B3LYP/6–311++G(d,p) method. Among the synthesized compounds, 4a, 4b, and 4g show similar inhibition activities with targeted proteins. Similar activities have been confirmed using the TD-DFT method. The energy gap between the highest occupied molecular orbitals and lowest unoccopied was found as, 6.07, 6.08, and 6.07 eV, respectively. The similarty in energy gap indicated these compounds have similiar reactivity nature.