Fluorescent probe for detecting activation of sialidase

A compound represented by a general formula (I) described below or a salt thereof:

• wherein
• R1, if present, represents the same or different monovalent substituent present on a benzene ring;
• R2 and R3 each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom;
• R4 and R5 each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom;
• R6 represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5 carbon atoms;
• R6′ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and
• R6′ may form, together with R3 or R5, a five to seven-membered heterocyclyl or heteroaryl containing a nitrogen atom to which R6′ is bonded;
• R7 and R8, if present, each independently represent an alkyl group having 1 to 6 carbon atoms or an aryl group, and
• in a case where X is an oxygen atom, R7 and R8 are not present;
• R9 in each occurrence is independently selected from a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group, a hydroxyl group, a carboxyl group, a halogen atom, a sulfo group, an amino group, an alkoxycarbonyl group, or an oxo group;
• in a case where R10 is present, R10 represents the same or different monovalent substituent present on a benzene ring;
• X represents an oxygen atom, a silicon atom, or a carbon atom;
• m is an integer of 0 to 4;
• n is an integer of 1 to 3;
• s is an integer of 1;
• and
• t is an integer of 0 to 4.