Design, synthesis, biological and computational analysis of isatin-based bis-thiourea analogues as anti-diabetic and anti-nematode agents

Abstract

A new series of isatin derivatives were synthesized, characterized by ¹HNMR, ¹³CNMR and HREI-MS, and screened for α-glucosidase and alpha amylase inhibition. All the analogues were found to be dual inhibitors and showed good inhibitory potentials with IC₅₀ values ranging from 5.28 ± 0.10 to 38.66 ± 0.30 µM (against alpha-amylase), and 5.45 ± 0.10 to 39.25 ± 0.50 µM (against alpha-glucosidase), as compared to the standard drug acarbose (IC₅₀ = 11.12 ± 0.15 and 11.29 ± 0.07 µM, respectively). The most potent inhibitor among the series was analogue 24 (IC₅₀ = 5.28 ± 0.10 for alpha-amylase and IC₅₀ = 5.46 ± 0.10 µM for alpha-glucosidase), which has a nitro group attached at the meta-position of the phenyl ring A and the para position of phenyl ring B. Structure-activity relationship has been established mainly based on the position, nature and number of the substituent(s) attached to the phenyl ring. To investigate the binding interaction of the potent analog with the active site of an enzyme, molecular docking studies were carried out. To study the drug-likeness properties, the ADME study was also carried out. The most active compounds engage most of the amino acids composing the active site and display maximum interactions. These interactions majorly include formation of strong hydrogen bonds, which might be due to the presence of highly electronegative heteroatoms on aromatic rings. All the analogues were also tested for in vivo anti-nematodal activity against C. elegans to assess their cytotoxicity in comparison to the reference Levamisole. The cytotoxicity profile demonstrated that analogues 2, 7, 20 and 22 displayed minimum cytotoxicity at every concentration.