Used as a substrate in enzymatic assays, particularly for detecting esterase and lipase activity. The compound undergoes hydrolysis in the presence of these enzymes, releasing 4-nitrophenol, which is yellow and can be easily measured spectrophotometrically at around 400–410 nm. This color change allows for real-time monitoring of enzyme activity and is widely applied in biochemical research, diagnostic testing, and high-throughput screening. Its stability and clear signal output make it suitable for both solution-based assays and immobilized enzyme studies.