Synthesis and aldose reductase inhibitory activities of novel dibenzocycloheptenone derivatives

Novel spiroindoline derivatives targeting aldose reductase against diabetic complications: Bioactivity, cytotoxicity, and molecular modeling studies

Despite significant developments in therapeutic strategies, Diabetes Mellitus remains an increasing concern, leading to various complications, e.g., cataracts, neuropathy, retinopathy, nephropathy, and several cardiovascular diseases. The polyol pathway, which involves Aldose reductase (AR) as a critical enzyme, has been focused on by many researchers as a target for intervention. On the other hand, spiroindoline-based compounds possess remarkable biological properties. This guided us to synthesize novel spiroindoline oxadiazolyl-based acetate derivatives and investigate their biological activities. The synthesized molecules' structures were confirmed herein, using IR, NMR (1H and 13C), and Mass spectroscopy. All compounds were potent inhibitors with KI constants spanning from 0.186 ± 0.020 μM to 0.662 ± 0.042 μM versus AR and appeared as better inhibitors than the clinically used drug, Epalrestat (EPR, KI: 0.841 ± 0.051 μM). Besides its remarkable inhibitory profile compared to EPR, compound 6k (KI: 0.186 ± 0.020 μM) was also determined to have an unusual pharmacokinetic profile. The results showed that 6k had less cytotoxic effect on normal mouse fibroblast (L929) cells (IC50 of 569.58 ± 0.80 μM) and reduced the viability of human breast adenocarcinoma (MCF-7) cells (IC50 of 110.87 ± 0.42 μM) more than the reference drug Doxorubicin (IC50s of 98.26 ± 0.45 μM and 158.49 ± 2.73 μM, respectively), thus exhibiting more potent anticancer activity. Moreover, molecular dynamic simulations for 200 ns were conducted to predict the docked complex's stability and reveal significant amino acid residues that 6k interacts with throughout the simulation.

Aldose reductase and protein tyrosine phosphatase 1B inhibitors as a promising therapeutic approach for diabetes mellitus

Diabetes mellitus is a metabolic disease characterized by high blood glucose levels and usually associated with several chronic pathologies. Aldose reductase and protein tyrosine phosphatase 1B enzymes have identified as two novel molecular targets associated with the onset and progression of type II diabetes and related comorbidities. Although many inhibitors against these enzymes have already found in the field of diabetic mellitus, the research for discovering more effective and selective agents with optimal pharmacokinetic properties continues. In addition, dual inhibition of these target proteins has proved as a promising therapeutic approach. A variety of diverse scaffolds are presented in this review for the future design of potent and selective inhibitors of aldose reductase and protein tyrosine phosphatase 1B based on the most important structural features of both enzymes. The discovery of novel dual aldose reductase and protein tyrosine phosphatase 1B inhibitors could be effective therapeutic molecules for the treatment of insulin-resistant type II diabetes mellitus. The methods used comprise a literature survey and X-ray crystal structures derived from Protein Databank (PDB). Despite the available therapeutic options for type II diabetes mellitus, the inhibitors of aldose reductase and protein tyrosine phosphatase 1B could be two promising approaches for the effective treatment of hyperglycemia and diabetes-associated pathologies. Due to the poor pharmacokinetic profile and low in vivo efficacy of existing inhibitors of both targets, the research turned to more selective and cell-permeable agents as well as multi-target molecules.

Virtual screening for inhibitors of human aldose reductase

The inhibition of aldose reductase (AR) provides an interesting strategy to prevent the complications of chronic diabetes. Although a large number of different AR inhibitors are known, very few of these compounds exhibit sufficient efficacy in clinical trials. We performed a virtual screening based on the ultrahigh resolution crystal structure of the inhibitor IDD594 in complex with human AR. AR operates on a large scale of structurally different substrates. To achieve this pronounced promiscuity, the enzyme can adapt rather flexibly to its substrates. Likewise, it has a similar adaptability for the binding of inhibitors. We applied a protocol of consecutive hierarchical filters to search the Available Chemicals Directory. In the first selection step, putative ligands were chosen that exhibit functional groups to anchor the anion-binding pocket of AR. Subsequently, a pharmacophore model based on the binding geometry of IDD594 and the mapping of the binding pocket in terms of putative "hot spots" of binding was applied as a second consecutive filter. In a third and final filtering step, the remaining candidate molecules were flexibly docked into the binding pocket of IDD594 with FlexX and ranked according to their estimated DrugScore values. Out of 206 compounds selected by this search and complemented by a cluster analysis and visual inspection, 9 compounds were selected and subjected to biological testing. Of these, 6 compounds showed IC50 values in the micromolar range. According to the proposed binding mode, the two inhibitors BTB02809 (IC50 = 2.4 +/- 0.5 microM) and JFD00882 (IC50 = 4.1 +/- 1.0 microM) both place a nitro group into the hydrophobic specificity pocket of human AR in an orientation coinciding with the position of the bromine atom of IDD594. The interaction of this Br with Thr113 has been identified as a key feature that is responsible for selectivity enhancement.