The invention provides a compound, useful as an optical probe or sensor of the activity of at least one
cytochrome P450
enzyme, and methods of using the compound to screen candidate drugs, and candidate drugs identified by these methods. The optical probe of the invention is a compound having the generic structure Y-L-Q, wherein Y is selected from the group consisting of Q as herein defined, saturated C1-C20
alkyl, unsaturated C1-C20 alkenyl, unsaturated C1-C20 alkynyl, substituted saturated C1-C20
alkyl, substituted unsaturated C1-C20 alkenyl, substituted unsaturated C1-C20 alkynyl, C1-C20 cycloalkyl, C1-C20 cycloalkenyl, substituted saturated C1-C20 cycloalkyl, substituted unsaturated C1-C20 cycloalkenyl,
aryl, substituted
aryl, heteroaryl and substituted heteroaryl; L is selected from the group of (-OCR<2>H)p-, wherein for each p, all R<2 >are separately selected from the group consisting of a
hydrogen atom, saturated C1-C20
alkyl, unsaturated C1-C20 alkenyl, unsaturated C1-C20 alkynyl, substituted saturated C1-C20 alkyl, substituted unsaturated C1-C20 alkenyl, substituted unsaturated C1-C20 alkynyl, C1-C20 cycloalkyl, C1-C20 cycloalkenyl, substituted saturated C1-C20 cycloalkyl, substituted unsaturated C1-C20 cycloalkenyl,
aryl, substituted aryl, heteroaryl, substituted heteroaryl, and p is a positive integer no greater than twelve; and Q is a
chemical moiety that gives rise to optical properties in its hydroxy or hyrdoxylate,
phenol or phenoxide form that are different from the optical properties that arise from its
ether form. Most preferably, p is one, R<2 >is
hydrogen, and Q is the
ether form of a phenoxide
fluorophore.