7-Ethoxy-5-(trifluoromethyl)coumarin is a fluorogenic substrate for cytochrome P450s (CYPs).Upon O-deethylation by CYPs, 7-hydroxy-4-(trifluoromethyl)coumarin (HFC) is released and its fluorescence can be used to quantify CYP activity. HFC displays excitation/emission maxima of 410/510 nm, respectively.