6-Bromo-2-naphthyl-alpha-D-galactopyranoside is a chromogenic substrate used in enzyme assays to detect and measure the activity of enzymes that act on alpha-galactosides. It is a type of glycoside inhibitor of ?-galactosidase and other glycosidases that hydrolyze galactose and other sugar derivatives. The product is used to study the changes in enzyme activity over time or in response to different conditions.