Fluorogenic glycosidase substrate and associated detection method

Compounds of formula (I):

• in which:
• R1 is such that HOR1, obtained after cleavage of the —C(O)—OR1 bond present in formula (I), belongs to the class of fluorophores leading to an intramolecular proton transfer in an excited state, called ESIPT,
• R3 is an (C1-C4) alkyl or a hydrogen atom and R2 and R4 are bonded together and form, with the carbon and nitrogen atoms to which they are bonded, an aliphatic heterocycle which can be substituted by a water-solubilizing group,
• R5 and R6 are identical or different and represent, independently of each other, a hydrogen atom, an (C1-C4) alkyl, or an (C5-C10)aryl,
• R7 is selected from the group consisting of hydrogen atom, a (C1-C4) alkyl and (C1-C4) alkoxy,
• R8 represents a hydrogen atom or a (C1-C10) alkyl group, non-substituted or substituted by one or more substituents selected from the group consisting of chlorine, bromine, iodine, fluorine, cyano, alkyl, trifluoralkyl, trifluoromethyl, alkenyl, alkynyl, cycloalkyl, aryl, hetero-aryl, heterocyclo-alkyl, amino, alkylamino, diaklyamino, hydroxy, alkoxy, aryloxy, alkoxycarbonyl and aryloxycarbonyl,
• or R8 represents a -D1-D2-D3 group with:
• D1 representing a triazolyl or —CH2-triazolyl group,
• D2 representing an (C1-C10) alkylene, (C1-C10) alkenylene or (C1-C10) alkynylene group, said groups possibly being interrupted by one or more selected from the group consisting of O, N, a divalent glycosyl group, an —O—(CHR—CHR′)n-, —N—(CHR—CHR′—O)n- group, n being an integer varying from 1 to 20, R and R′, identical or different, representing H or CH3 upon condition that R and R′ are not simultaneously CH3, an amino acid or a peptide, and a combination of these groups,
• D3 representing a maleimidocaproyl motif, amino acid, peptide, folic acid, antibody or antibody fragment bonded to D2, by a carboxylic acid function comprised in it, forming an ester or amide bond,
• R9 and R′9, identical or different, represent a hydrogen atom, an electron-withdrawing group, or a —NH—C(O)—CH2-Ab group, with Ab representing an antibody,
• V represents an oxygen atom or a sulfur atom,
• X, Y and Z are such that:
• either X represents CR10, Y represents CR′ 10 and Z represents OR0,
• or X represents CR10, Y represents COR0 and Z represents R′ 10,
• or X represents CR10, Y represents a nitrogen atom and Z represents OR0,
• or X represents a nitrogen atom, Y represents COR0 and Z represents R10 with:
• R0 representing a glycosyl group bound by its anomeric carbon atom to the rest of the molecule of formula (I), and
• R10 and R′ 10, identical or different, representing a hydrogen atom or an electron-donating group,
• in the form of a mixture of optical isomers according to all proportions, or in an optical isomer enriched form.