Discovery of 5-(N-hydroxycarbamimidoyl) benzofuran derivatives as novel indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors

Bioorg Med Chem Lett. 2021 May 15:40:127963. doi: 10.1016/j.bmcl.2021.127963. Epub 2021 Mar 17.

Abstract

Human indoleamine 2,3-dioxygenase 1 (hIDO1) and tryptophan dioxygenase (hTDO) are rate-limiting enzymes in the kynurenine pathway (KP) of l-tryptophan (l-Trp) metabolism and are becoming key drug targets in the combination therapy of checkpoint inhibitors in immunoncology. To discover a selective and potent IDO1 inhibitor, a structure-activity relationship (SAR) study of N-hydroxybenzofuran-5-carboximidamide as a novel scaffold was investigated in a systematic manner. Among the synthesized compounds, the N-3-bromophenyl derivative 19 showed the most potent inhibition, with an IC50 value of 0.44 μM for the enzyme and 1.1 μM in HeLa cells. The molecular modeling of 19 with the X-ray crystal structure of IDO1 indicated that dipole-ionic interactions with heme iron, halogen bonding with Cys129 and the two hydrophobic interactions were important for the high potency of 19.

Keywords: 3-Dioxygenase 1; Immunotherapy; Indoleamine 2; Kynurenine Pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amidines / chemical synthesis
  • Amidines / metabolism
  • Amidines / pharmacology*
  • Benzofurans / chemical synthesis
  • Benzofurans / metabolism
  • Benzofurans / pharmacology*
  • Catalytic Domain
  • Enzyme Inhibitors / chemical synthesis
  • Enzyme Inhibitors / metabolism
  • Enzyme Inhibitors / pharmacology*
  • HeLa Cells
  • Humans
  • Hydrophobic and Hydrophilic Interactions
  • Indoleamine-Pyrrole 2,3,-Dioxygenase / antagonists & inhibitors*
  • Indoleamine-Pyrrole 2,3,-Dioxygenase / chemistry
  • Indoleamine-Pyrrole 2,3,-Dioxygenase / metabolism
  • Molecular Docking Simulation
  • Molecular Structure
  • Oximes / chemical synthesis
  • Oximes / metabolism
  • Oximes / pharmacology*
  • Protein Binding
  • Static Electricity
  • Structure-Activity Relationship

Substances

  • Amidines
  • Benzofurans
  • Enzyme Inhibitors
  • IDO1 protein, human
  • Indoleamine-Pyrrole 2,3,-Dioxygenase
  • Oximes