NADPH oxidase 1 (NOX1) generates reactive oxygen species (ROS) in colon epithelial cells that interacts with both pathogenic and normal bacteria. Excess ROS production, however, is associated with damage to the intestinal mucosa, inflammatory bowel disease, and prostate cancer. ML-090 is the first identified NOX1-specific inhibitor (IC50 = 360 nM in HEK293 cells) based on a quinoxaline scaffold that demonstrates potent selectivity over NOX2, NOX3, and NOX4 (IC50s ≥ 10 μM) and xanthine oxidase (IC50 = 3.5 μM).