Rational design, synthesis and biological evaluation of ubiquinone derivatives as IDO1 inhibitors.

Indoleamine 2,3-dioxygenase 1 (IDO1) is an attractive therapeutic target for the treatment of cancer, chronic viral infections and neurological disorders characterized by pathological immune stimulation. Herein, a series of known metal-chelating ubiquinone derivatives were designed, synthesized and evaluated for the IDO1 inhibiting activities. The docking studies showed that the compounds 11, 16, 18 and coenzyme-Q1 exhibited different binding modes to IDO1 protein. Among these compounds, the most active compound is 16d with an IC50 of 0.13 μM in enzymatic assay. The results reveal that a possible halogen bonding interaction between the bromine atom (3-Br) and Cys129 significantly enhances the inhibition activity against IDO1. This study provides structural insights of the interactions between ubiquinone analogues and IDO1 protein for the further modification and optimization.