Used primarily in biochemical research as a substrate for enzyme assays, particularly for detecting β-galactosidase activity. Upon reaction with the enzyme, it releases 2-naphthol, which can be measured by spectrophotometry for accurate enzyme activity assessment. It helps in studying gene expression and regulation in molecular biology, often in conjunction with reporter gene systems. Additionally, it aids in the identification and characterization of bacterial species that produce β-galactosidase, contributing to microbiological diagnostics. Its application extends to histochemistry, where it assists in visualizing enzyme activity in tissue samples.