Patent ID: 8334387

Claim:
A compound having the structure shown in Formula 1: R-L-S (I) wherein R is a quinacridone dye of Formula III; wherein: groups R 3 and R 4 are attached to the Z 1 ring structure and groups R 5 and R 6 are attached to the Z 2 ring structure; Z 1 and Z 2 independently represent the atoms necessary to complete one or two fused ring aromatic or heteroaromatic systems, each ring having five or six atoms selected from carbon atoms and optionally no more than two atoms selected from oxygen, nitrogen and sulphur; R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are independently selected from hydrogen, halogen, amide, hydroxyl, cyano, amino, mono- or di-C 1 -C 4 alkyl-substituted amino, sulphydryl, carbonyl, carboxyl, C 1 -C 6 alkoxy, aryl, heteroaryl, C 1 -C 20 alkyl, aralkyl; the group -E-F where E is a spacer group having a chain from 1-60 atoms selected from the group consisting of carbon, nitrogen, oxygen, sulphur and phosphorus atoms and F is a target bonding group; and the group —(CH 2 —) n Y where Y is selected from sulphonate, sulphate, phosphonate, phosphate, quaternary ammonium and carboxyl and n is zero or an integer from 1 to 6; L is an optional linkage group containing from 2 to 30 atoms comprising hydrocarbon chains which may also contain other atoms such as N, O and S; and S is a substrate group of the enzyme aromatase of formula IX wherein: R 1 and R 2 are selected from H and methyl; R 3 is selected from H, C 1 -C 8 alkyl, cyano, —(CH 2 ) k —OR a ; —(CH 2 ) k —COOR a ; —(CH 2 ) k —SO 3 R a ; —(CH 2 ) k —CHO, —(CH 2 ) k —NR b R c and —(CH 2 ) k —COR d ; R 4 is selected from H, —COR a and hydroxyl; R 5 is selected from H, —COR a , hydroxyl, cyano and halide; R 6 is selected from H and hydroxyl; R 7 , R 8 and R 9 are independently selected from H, —COR a and hydroxyl; R 10 is selected from H and halide; and where R a is selected from H and C1-C4 alkyl, optionally substituted with OH; R b and R c are selected from H and C 1 -C 4 alkyl; R d is selected from C 1 -C 8 alkyl or C 1 -C 8 alkyl optionally substituted with COOR a , OH, OR a or SO 3 R a ; and k is zero or an integer from 1 to 8; and further wherein the fluorescence signal of said compound changes in respect of fluorescence lifetime when the compound is acted upon in vitro or in vivo by an enzyme with aromatase activity.