Resorufin ethyl ether is suitable for the study of dealkylating activity of cytochrome P450 isozymes 1A1 and 1A2, where arylalkyl and alkyl isothiocyanates, and their glutathione, cysteine, and A'-acetylcysteine conjugates are used as inhibitors. It is suitable to study the ethoxyresorufin-O-deethylase (EROD) activity of cytochrome P450 activity (CYP1A1).