Design and synthesis of potent and selective aldose reductase inhibitors based on pyridylthiadiazine scaffold

Chemoselective Reactions of Functionalized Sulfonyl Halides

Chemoselective transformations of functionalized sulfonyl fluorides and chlorides are surveyed comprehensively. It is shown that sulfonyl fluorides provide an excellent selectivity control in their reactions. Thus, numerous conditions are tolerated by the SO2 F group - from amide and ester formation to directed ortho-lithiation and transition-metal-catalyzed cross-couplings. Meanwhile, sulfur (VI) fluoride exchange (SuFEx) is also compatible with numerous functional groups, thus confirming its title of "another click reaction". On the contrary, with a few exceptions, most transformations of functionalized sulfonyl chlorides typically occur at the SO2 Cl moiety.

Aldose Reductase: a cause and a potential target for the treatment of diabetic complications

Diabetes mellitus, a disorder of metabolism, results in the elevation of glucose level in the blood. In this hyperglycaemic condition, aldose reductase overexpresses and leads to further complications of diabetes through the polyol pathway. Glucose metabolism-related disorders are the accumulation of sorbitol, overproduction of NADH and fructose, reduction in NAD⁺, and excessive NADPH usage, leading to diabetic pathogenesis and its complications such as retinopathy, neuropathy, and nephropathy. Accumulation of sorbitol results in the alteration of osmotic pressure and leads to osmotic stress. The overproduction of NADH causes an increase in reactive oxygen species production which leads to oxidative stress. The overproduction of fructose causes cell death and non-alcoholic fatty liver disease. Apart from these disorders, many other complications have also been discussed in the literature. Therefore, the article overviews the aldose reductase as the causative agent and a potential target for the treatment of diabetic complications. So, aldose reductase inhibitors have gained much importance worldwide right now. Several inhibitors, like derivatives of carboxylic acid, spirohydantoin, phenolic derivatives, etc. could prevent diabetic complications are discussed in this article.

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.

Addressing selectivity issues of aldose reductase 2 inhibitors for the management of diabetic complications

Aldose Reductase 2 (ALR2), the rate-limiting enzyme of the polyol pathway, plays an important role in detoxification of some toxic aldehydes. Under hyperglycemia, this enzyme overactivates and causes diabetic complications (DC). Therefore, ALR2 inhibition has been established as a potential approach to manage these complications. Several ALR2 inhibitors have been reported, but none of them could reach US FDA approval. One of the main reasons is their poor selectivity over ALR1, which leads to the toxicity. The current review underlines the molecular connectivity of ALR2 with DC and comparative analysis of the catalytic domains of ALR2 and ALR1, to better understand the selectivity issues. This report also discusses the key features required for ALR2 inhibition and to limit toxicity due to off-target activity.

Oxidative reaction of 2-aminopyridine-3-sulfonyl chlorides with tertiary amines

2-Aminopyridine-3-sulfonyl chlorides undergo a reaction with tertiary amines in the presence of air to produce sulfonylethenamines. The 2-aminopyridine-3-sulfonyl chloride apparently plays a dual role in the process promoting the aerobic oxidation of the amine and electrophilically trapping the resulting enamine.

Pyridothiadiazine derivatives as aldose reductase inhibitors having antioxidant activity

A series of aldose reductase (ALR2) inhibitors based on pyridothiadiazine were prepared and evaluated for their activities in ALR2 inhibition, DPPH scavenging, and MDA inhibition. Comparison studies were carried out between analogs having either hydroxyl or methoxy groups substituted on the N2-benzyl side chains of the compounds. Most of the hydroxy-substituted compounds were found to be more potent compared to their methoxy-substituted analogs with respect to DPPH inhibition (>93%) and MDA inhibition (>73%). However, ALR2 inhibitory activity was found to be affected by the electron-withdrawing substituent at the C7 position in addition to the effect of the N2-substituted benzyl group. These results provide an array of multifunctional ALR2 inhibitors possessing capacities both for ALR2 inhibition and as antioxidants.

Multifunctional aldose reductase inhibitors based on 2H-benzothiazine 1,1-dioxide

A series of benzothiazine derivatives were designed and synthesized for the development of drug candidates for diabetic complications.

Copper-catalyzed asymmetric synthesis and comparative aldose reductase inhibition activity of (+)/(-)-1,2-benzothiazine-1,1-dioxide acetic acid derivatives

A copper catalyst system for the asymmetric 1,4-hydrosilylation of the α,β-unsaturated carboxylate class was developed by which synthesis of (+)- and (-)-enantiomers of 1,2-benzothiazine-1,1-dioxide acetates has been achieved with a good yield and an excellent level of enantioselectivity. A comparative structure-activity relationship study yielded the following order of aldose reductase inhibition activity: (-)-enantiomers > racemic > (+)-enantiomers. Further, a molecular docking study suggested that the (-)-enantiomer had significant binding affinity and thus increased inhibition activity.

Predictive QSAR modeling of aldose reductase inhibitors using Monte Carlo feature selection

This study explores the chemical space and quantitative structure-activity relationship (QSAR) of a set of 60 sulfonylpyridazinones with aldose reductase inhibitory activity. The physicochemical properties of the investigated compounds were described by a total of 3230 descriptors comprising of 6 quantum chemical descriptors and 3224 molecular descriptors. A subset of 5 descriptors was selected from the aforementioned pool by means of Monte Carlo (MC) feature selection coupled to multiple linear regression (MLR). Predictive QSAR models were then constructed by MLR, support vector machine and artificial neural network, which afforded good predictive performance as deduced from internal and external validation. The investigated models are capable of accounting for the origins of aldose reductase inhibitory activity and could be utilized in predicting this property in screening for novel and robust compounds.

1,2-Benzothiazine 1,1-dioxide carboxylate derivatives as novel potent inhibitors of aldose reductase

Due to the importance of aldose reductase (ALR2) as a potential drug target in the treatment of diabetic complications, there are increasing interests in design and synthesis of ALR2 inhibitors. Here, we prepared 1,2-benzothiazine 1,1-dioxide acetic acid derivatives and investigated their inhibition activity. Most of these derivatives were found to be active with IC(50) values ranging from 0.11 μM to 10.42 μM, and compound 8d, 2-[2-(4-bromo-2-fluorobenzyl)-1,1-dioxido-2H-1,2-benzothiazin-4(3H)-ylidene]acetic acid, showed the most potent inhibition activity. Further, SAR and docking studies suggest that in comparison with the α,β-unsaturated derivatives, the saturated carboxylic acid derivatives had a greater binding affinity with the enzyme and thus an enhanced inhibition activity. Therefore, development of more powerful ARIs based on benzothiazine 1,1-dioxide by stereo-controlled synthesis could be expected.