Targeting NOX2 with Bivalent Small-Molecule p47phox–p22phox Inhibitors

Nicotinamide adenine dinucleotide
phosphate oxidase isoform 2 (NOX2)
is an enzymatic complex whose function is the regulated generation
of reactive oxygen species (ROS). NOX2 activity is central to redox
signaling events and antibacterial response, but excessive ROS production
by NOX2 leads to oxidative stress and inflammation in a range of diseases.
The protein–protein interaction between the NOX2 subunits p47phox
and p22phox is essential for NOX2 activation, thus p47phox is a potential
drug target. Previously, we identified 2-aminoquinoline as a fragment
hit toward p47phoxSH3A‑B and converted it to a bivalent
small-molecule p47phox–p22phox inhibitor (Ki = 20 μM). Here, we systematically optimized the
bivalent compounds by exploring linker types and positioning as well
as substituents on the 2-aminoquinoline part and characterized the
bivalent binding mode with biophysical methods. We identified several
compounds with submicromolar binding affinities and cellular activity
and thereby demonstrated that p47phox can be targeted by potent small
molecules.