Synthesis of indole-substituted thiosemicarbazones as an aldose reductase inhibitor: an in vitro, selectivity and in silico study

The challenging inhibition of Aldose Reductase for the treatment of diabetic complications: a 2019-2023 update of the patent literature

INTRODUCTION

Aldose reductase (AKR1B1, EC: 1.1.1.21) is a recognized target for the treatment of long-term diabetic complications since its activation in hyperglycemia and role in the polyol pathway. In particular, the tissue-specificity of AKR1B1 expression makes the design of the traditional Aldose Reductase Inhibitors (ARIs) and the more recent Aldose Reductase Differential Inhibitors (ARDIs) exploitable strategies to treat pathologies resulting from diabetic conditions.

AREAS COVERED

A brief overview of the roles and functions of AKR1B1 along with known ARIs and ARDIs was provided. Then, the design of the latest inhibitors in the scientific scenario was discussed, aiming at introducing the research achievement in the field of intellectual properties. Patents dealing with AKR1B1 and diabetes filed in the 2019-2023 period were collected and analyzed. Reaxys, Espacenet, SciFindern, and Google Patents were surveyed, using 'aldose reductase' and 'inhibitor' as the reference keywords. The search results were then filtered by PRISMA protocol, thus obtaining 16 records to review.

EXPERT OPINION

Although fewer in number than in the early 2000s, patent applications are still being filed in the field of ARIs, with a large number of Chinese inventors reporting new synthetic ARIs in favor of the repositioning approach.

Development, Molecular Docking, and In Silico ADME Evaluation of Selective ALR2 Inhibitors for the Treatment of Diabetic Complications via Suppression of the Polyol Pathway

Diabetic complications are associated with overexpression of aldose reductase, an enzyme that catalyzes the first step of the polyol pathway. Osmotic stress in the hyperglycemic state is linked with the intracellular accumulation of sorbitol along with the depletion of NADPH and eventually leads to oxidative stress via formation of reactive oxygen species and advanced glycation end products (AGEs). These kinds of mechanisms cause the development of various diabetic complications including neuropathy, nephropathy, retinopathy, and atherosclerotic plaque formation. Various aldose reductase inhibitors have been developed to date for the treatment of diabetic complications, but all have failed in different stages of clinical trials due to toxicity and poor pharmacokinetic profiles. This toxicity is rooted in a nonselective inhibition of both ALR2 and ALR1, homologous enzymes involved in the metabolism of toxic aldehydes such as methylglyoxal and 3-oxyglucosazone. In the present study, we developed a series of thiosemicarbazone derivatives as selective inhibitors of ALR2 with both antioxidant and antiglycation potential. Among the synthesized compounds, 3c exhibited strong and selective inhibition of ALR2 (IC₅₀ 1.42 μM) along with good antioxidant and antiglycative properties. The binding mode of 3c was assessed through molecular docking and cluster analysis via MD simulations, while in silico ADME evaluation studies predicted the compounds' druglike properties. Therefore, we report 3c as a drug candidate with promising antioxidant and antiglycative properties that may be useful for the treatment of diabetic complications through selective inhibition of ALR2.

The Molecular Diversity of 1H-Indole-3-Carbaldehyde Derivatives and Their Role in Multicomponent Reactions

1H-Indole-3-carbaldehyde and related members of the indole family are ideal precursors for the synthesis of active molecules. 1H-Indole-3-carbaldehyde and its derivatives are essential and efficient chemical precursors for generating biologically active structures. Multicomponent reactions (MCRs) offer access to complex molecules. This review highlights the recent applications of 1H-indole-3-carbaldehyde in such inherently sustainable multicomponent reactions from the period, 2014 to 2021 and provides an overview of the field that awaits further exploitation in the assembly of pharmaceutically interesting scaffolds.

Thio- and selenosemicarbazones as antiprotozoal agents against Trypanosoma cruzi and Trichomonas vaginalis

Herein, we report the preparation of a panel of Schiff bases analogues as antiprotozoal agents by modification of the stereoelectronic effects of the substituents on N-1 and N-4 and the nature of the chalcogen atom (S, Se). These compounds were evaluated towards Trypanosoma cruzi and Trichomonas vaginalis. Thiosemicarbazide 31 showed the best trypanocidal profile (epimastigotes), similar to benznidazole (BZ): IC₅₀ (31)=28.72 μM (CL-B5 strain) and 33.65 μM (Y strain), IC₅₀ (BZ)=25.31 μM (CL-B5) and 22.73 μM (Y); it lacked toxicity over mammalian cells (CC₅₀ > 256 µM). Thiosemicarbazones 49, 51 and 63 showed remarkable trichomonacidal effects (IC₅₀ =16.39, 14.84 and 14.89 µM) and no unspecific cytotoxicity towards Vero cells (CC₅₀ ≥ 275 µM). Selenoisosters 74 and 75 presented a slightly enhanced activity (IC₅₀=11.10 and 11.02 µM, respectively). Hydrogenosome membrane potential and structural changes were analysed to get more insight into the trichomonacidal mechanism.