Used as a substrate in enzymatic assays, particularly for detecting esterase and protease activity. When hydrolyzed by enzymes, it releases β-naphthol, which can be coupled with diazonium salts to form colored or fluorescent azo dyes, enabling visual or spectrophotometric detection. Commonly applied in histochemistry and cytochemistry to localize enzyme activity in tissues and cells. Also utilized in diagnostic reagents and biochemical research for monitoring enzyme kinetics and inhibition studies.