4-Nitrophenyl b-D-thioglucopyranoside is a highly sensitive chromogenic substrate designed for the colorimetric detection and quantification of thioglucosidase enzymes. Upon enzymatic cleavage, it releases a highly absorbing 4-nitrophenyl moiety, generating a yellow color that can be readily measured spectrophotometrically. This substrate is widely utilized in the study of enzyme kinetics, substrate specificity, and inhibitor screening for thioglucosidases involved in various metabolic pathways and biological processes.