ChEBI: An aryl phosphate that is indoxyl phopshate in which the indole moiety is substituted at positions 4 and 5 by chlorine and bromine, respectively. It is used to test for the presence of an enzyme, alkaline phosphatase, which cleaves the phosphate group to g
ve 5-bromo-4-chloroindoxyl, which immediately dimerises to give an intensely blue product.
