Widely used in histochemistry and microbiology as a chromogenic substrate for detecting β-galactosaminidase enzyme activity. When the enzyme cleaves the glycosidic bond, it releases an indoxyl derivative that oxidizes to form a blue-colored insoluble precipitate, enabling visualization of enzyme expression in tissues or cells. This reaction is particularly useful in immunohistochemical staining and in situ hybridization techniques where precise localization of cellular activity is required. Also employed in bacterial identification assays, especially for distinguishing specific microbial strains in clinical and environmental samples based on their enzymatic profiles. The compound’s sensitivity and specificity make it valuable in diagnostic applications and biochemical research involving glycosidase activity.