Research progress of NADPH oxidases and their inhibitors

NADPH oxidases (NOXs) are the key enzymes of redox signaling in vivo and also the main source of reactive oxygen species (ROS) in the body. ROS plays a role of double-edged sword. On the one hand, ROS, at the level of physiological amount, has the effect of immune defense and also acts as a second messenger involved in the regulation of cellular signaling pathways. On the other hand, excessive ROS can cause oxidative stress, leading to the disorder of cellular functions. Recently, studies showed that ROS plays an important role in acceleration of some pathological reactions such as inflammation, fibrosis and tumor formation. As a major source of ROS, NOX has become a popular target in treating oxidative stress, inflammation, fibrosis and tumor. Herein, the role of NOX in these pathological processes and the research progress of NOX inhibitors are reviewed.