Design, synthesis, structure-activity relationships and X-ray structural studies of novel 1-oxopyrimido[4,5-c]quinoline-2-acetic acid derivatives as selective and potent inhibitors of human aldose reductase

Eur J Med Chem. 2018 May 25;152:160-174. doi: 10.1016/j.ejmech.2018.04.015. Epub 2018 Apr 12.


Human aldose reductase (AKR1B1, AR) is a key enzyme of the polyol pathway, catalyzing the reduction of glucose to sorbitol at high glucose concentrations, as those found in diabetic condition. Indeed, AKR1B1 overexpression is related to diabetes secondary complications and, in some cases, with cancer. For many years, research has been focused on finding new AKR1B1 inhibitors (ARIs) to overcome these diseases. Despite the efforts, most of the new drug candidates failed because of their poor pharmacokinetic properties and/or unacceptable side effects. Here we report the synthesis of a series of 1-oxopyrimido[4,5-c]quinoline-2-acetic acid derivatives as novel ARIs. IC50 assays and X-ray crystallographic studies proved that these compounds are promising hits for further drug development, with high potency and selectivity against AKR1B1. Based on the determined X-ray structures with hit-to-lead compounds, we designed and synthesized a second series that yielded lead compound 68 (Kiappvs. AKR1B1 = 73 nM). These compounds are related to the previously reported 2-aminopyrimido[4,5-c]quinolin-1(2H)-ones, which exhibit antimitotic activity. Regardless of their similarity, the 2-amino compounds are unable to inhibit AKR1B1 while the 2-acetic acid derivatives are not cytotoxic against fibrosarcoma HT-1080 cells. Thus, the replacement of the amino group by an acetic acid moiety changes their biological activity, improving their potency as ARIs.

Keywords: 1-Oxopyrimido[4,5-c]quinoline-2-acetic acids; AKR1B1; AKR1B10; Molecular modeling; X-ray crystallography.

MeSH terms

  • Aldehyde Reductase / antagonists & inhibitors*
  • Aldehyde Reductase / metabolism
  • Aldo-Keto Reductases
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Crystallography, X-Ray
  • Dose-Response Relationship, Drug
  • Drug Design*
  • Enzyme Inhibitors / chemical synthesis
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology*
  • Humans
  • Models, Molecular
  • Molecular Structure
  • Quinolines / chemical synthesis
  • Quinolines / chemistry
  • Quinolines / pharmacology*
  • Structure-Activity Relationship


  • Enzyme Inhibitors
  • Quinolines
  • AKR1B10 protein, human
  • Aldo-Keto Reductases
  • AKR1B1 protein, human
  • Aldehyde Reductase