Cholesterol-esterase colour substrate

It becomes a cholesterol esterase substrate of the general formula I. X - - A - - Y - Chol I described in which A is an alkylene or alkenylene group having 1 to 20 C atoms, Chol is the 3-cholesterol residue, X is the radical of an aromatic hydroxy or thiol compound and Y is -S- or -O-. For the optical determination of cholesterol esterase such a substrate is subjected to the action of the cholesterol esterase-containing sample and determines the amount of the released aromatic hydroxy or thiol compound directly or, after coupling with a suitable chromogen, the color formed therefrom optically.