Patent ID: 8163479

Claim:
A compound of formula (1) R 1 -A-X—CH 2 —R 3 —R 4 -L 1 (1) wherein the group R 1 -A is a purine radical of formula (2) X is oxygen; R 1 is a group —R 2 -L 2 ; R 2 and R 4 are, independently of each other, a straight or branched chain alkylene group or polyvalent branched chain alkyl group with 1 to 300 carbon atoms, optionally substituted by a lower alkyl, lower alkoxy, lower acyloxy or halogen wherein optionally (a) one or more carbon atoms are replaced by oxygen; (b) one or more carbon atoms are replaced by nitrogen carrying a hydrogen atom, and the adjacent carbon atom is substituted by oxo; (c) one or more carbon atoms are replaced by oxygen, and the adjacent carbon atom is substituted by oxo; (d) the bond between two adjacent carbon atoms is a double or a triple bond; (e) one or more carbon atoms are replaced by a phenylene, a saturated or unsaturated cycloalkylene, a saturated or unsaturated bicycloalkylene, a divalent heteroaromatic or a divalent saturated or unsaturated heterocyclyl group; (f) two adjacent carbon atoms are replaced by a disulfide linkage; or a combination of two or more alkylene and/or modified alkylene groups as defined under (a) to (f) hereinbefore; R 3 is an aromatic or a heteroaromatic group, or an optionally substituted 1-alkylene, 1-alkenylene, 1-cycloalkenylene, or an unsaturated heterocyclyl group with the double bond connected to CH 2 ; R 6 is hydrogen, hydroxy or unsubstituted amino; one of R 7 or R 8 is R 1 and the other one is hydrogen; and L 1 and L 2 are the same or different labels and each is selected from the group consisting of a fluorophore or a chromophore, a magnetic probe, a contrast reagent, a radioactive moiety, avidin, streptavidin, biotin, a moiety which is capable of crosslinking to other molecules selected from a maleimide, an activated carboxy group, an azide and a benzophenone; a tethered metal-chelate which is capable of generating hydroxyl radicals upon exposure to H 2 O 2 , ascorbate, malachite green, a solid support, a lipid, methotrexate, a linear poly(arginine) of D- and/or L-arginine with 6-15 arginine residues, oligomers of 6-50 subunits wherein at least one subunit has an attached guanidine group or a peptide having an RKKRRQRRR amino acid sequence (SEQ ID NO: 1); or L 1 is a bond connecting R 4 to A forming a cyclic substrate; a further group —R 3 —CH 2 —X-A-R 1 ; or a nucleic acid or a derivative thereof capable of undergoing base-pairing with its complementary strand; or if R 7 is a hydrogen then L 2 is capable of undergoing base-pairing with its complementary strand where L 2 is a nucleic acid.