Diphenyleneiodonium chloride is primarily used in biochemical and pharmacological research as a potent inhibitor of NADPH oxidase. This enzyme plays a crucial role in the production of reactive oxygen species (ROS) in various cellular processes. By inhibiting NADPH oxidase, the compound helps in studying the effects of reduced ROS levels on cellular signaling, inflammation, and oxidative stress-related diseases. Additionally, it is utilized in experimental settings to explore its potential therapeutic applications in conditions like cardiovascular diseases, neurodegenerative disorders, and cancer, where oxidative stress is a contributing factor. Its ability to selectively target NADPH oxidase makes it a valuable tool for understanding the underlying mechanisms of these diseases and for developing targeted treatments.