Exploration of thioxothiazolidinone-sulfonate conjugates as a new class of aldehyde/aldose reductase inhibitors: A synthetic and computational investigation.

In the present study, the pharmacophore integration methodology provided an efficient access to a new library of thioxothiazolidinone-sulfonate conjugates (8a-r) from easily available synthetic precursors. The approach was excellently high yielding with flexible structural sites for chemical modifications. The designed hybrid scaffolds were assessed for aldehyde/aldose reductase inhibition activities. The results for the in vitro bioassays were promising with the identification of compound 8e as the lead and selective candidate for ALR2 inhibition with an IC50 value of 0.468±0.003µMas compared to 3.1±0.2µM for the standard (sorbinil), whereas compound 8o demonstrated high inhibitory potency for both ALR2 and ALR1 enzymes. Molecular modeling analysis of the potent compounds provided further insight into the biological properties where detailed binding mode analysis revealed that the conjugates (8a-r) were found stabilized in the active site of the enzymes through the development of a number of interactions with catalytic residues.

Identification of new potent inhibitor of aldose reductase from Ocimum basilicum.

Recent efforts to develop cure for chronic diabetic complications have led to the discovery of potent inhibitors against aldose reductase (AKR1B1, EC 1.1.1.21) whose role in diabetes is well-evident. In the present work, two new natural products were isolated from the ariel part of Ocimum basilicum; 7-(3-hydroxypropyl)-3-methyl-8-ß-O-d-glucoside-2H-chromen-2-one (1) and E-4-(6'-hydroxyhex-3'-en-1-yl)phenyl propionate (2) and confirmed their structures with different spectroscopic techniques including NMR spectroscopy etc. The isolated compounds (1, 2) were evaluated for in vitro inhibitory activity against aldose reductase (AKR1B1) and aldehyde reductase (AKR1A1). The natural product (1) showed better inhibitory activity for AKR1B1 with IC50 value of 2.095±0.77µM compare to standard sorbinil (IC50=3.14±0.02µM). Moreover, the compound (1) also showed multifolds higher activity (IC50=0.783±0.07µM) against AKR1A1 as compared to standard valproic acid (IC50=57.4±0.89µM). However, the natural product (2) showed slightly lower activity for AKR1B1 (IC50=4.324±1.25µM). Moreover, the molecular docking studies of the potent inhibitors were also performed to identify the putative binding modes within the active site of aldose/aldehyde reductases.

Coumarin-thiazole and -oxadiazole derivatives: Synthesis, bioactivity and docking studies for aldose/aldehyde reductase inhibitors.

In continuation of our previous efforts directed towards the development of potent and selective inhibitors of aldose reductase (ALR2), and to control the diabetes mellitus (DM), a chronic metabolic disease, we synthesized novel coumarin-thiazole 6(a-o) and coumarin-oxadiazole 11(a-h) hybrids and screened for their inhibitory activity against aldose reductase (ALR2), for the selectivity against aldehyde reductase (ALR1). Compounds were also screened against ALR1. Among the newly designed compounds, 6c, 11d, and 11g were selective inhibitors of ALR2. Whereas, (E)-3-(2-(2-(2-bromobenzylidene)hydrazinyl)thiazol-4-yl)-2H-chromen-2-one 6c yielded the lowest IC50 value of 0.16±0.06µM for ALR2. Moreover, compounds (E)-3-(2-(2-benzylidenehydrazinyl)thiazol-4-yl)-2H-chromen-2-one (6a; IC50=2.94±1.23µM for ARL1 and 0.12±0.05µM for ARL2) and (E)-3-(2-(2-(1-(4-bromophenyl)ethylidene)hydrazinyl)thiazol-4-yl)-2H-chromen-2-one (6e; IC50=1.71±0.01µM for ARL1 and 0.11±0.001µM for ARL2) were confirmed as dual inhibitors. Furthermore, compounds 6i, 6k, 6m, and 11b were found to be selective inhibitors for ALR1, among which (E)-3-(2-(2-((2-amino-4-chlorophenyl)(phenyl)methylene)hydrazinyl)thiazol-4-yl)-2H-chromen-2-one (6m) was most potent (IC50=0.459±0.001µM). Docking studies performed using X-ray structures of ALR1 and ALR2 with the given synthesized inhibitors showed that coumarinyl thiazole series lacks the carboxylate function that could interact with the anionic binding site being a common ALR1/ALR2 inhibitors trait. Molecular docking study with dual inhibitor 6e also suggested plausible binding modes for the ALR1 and ALR2 enzymes. Hence, the results of this study revealed that coumarinyl thiazole and oxadiazole derivatives could act as potential ALR1/ALR2 inhibitors.

Synthesis, characterization, hypoglycemic and aldose reductase inhibition activity of arylsulfonylspiro[fluorene-9,5'-imidazolidine]-2',4'-diones.

A series of 3-arylsulfonylspiroimidazolidine-2,4-diones (2a-g) and their corresponding rearranged products, 1-arylsulfonylspiroimidazolidine-2,4-diones (3a-g) were synthesized and evaluated for antidiabetic and aldose reductase inhibition activity. Three of the compounds (2b, 2c and 3c) were found more potent in-vivo hypoglycemic agents than the commercial drug glibenclamide. The free energy of binding (ΔG) values showed that the compounds are active against aldose reductase and aldehyde reductase enzymes, which was also estimated using molecular mechanics Poisson-Boltzmann surface area method. Of the tested compounds, 2b was found to be the most potent in-vitro selective inhibitor of ALR2 possessing an IC50 value of 0.89 µm. Structure activity relationship and molecular docking revealed the importance of substitution features of aryl group of aryllsulfonylimidazolidine-2,4-dione scaffold. It was observed that the substitution with a halogen at para position of the aryl group had a remarkable effect on ALR2 inhibition potency.