Used as a chromogenic substrate in enzymatic assays to detect and quantify β-D-xylosidase activity. Upon hydrolysis by the enzyme, it releases 4-nitrophenol, which produces a yellow color detectable at around 400–410 nm. This allows for easy monitoring of enzyme activity in biochemical research, particularly in studies related to hemicellulose degradation, microbial enzyme profiling, and characterization of glycosidases. Commonly used in both solution-based assays and solid media for screening microorganisms producing xylan-degrading enzymes.