Imidazopyridines as fluorogenic substrates for esterase detection

Six substituted imidazo[1,5-a]pyridine and imidazo[5,1-a]isoquinoline derivatives have been designed and characterized as possible fluorogenic substrates for detection and application of esterase enzymes or other ester hydrolysis conditions. The optical tunability of the fluorescent scaffold has been evaluated introducing a free carboxylic acid or the corresponding methyl ester substituent, obtaining turn-on fluorescence sensing systems with large signal-to-noise ratios and high enzymatic reactivity. The probes have been tested in fluorescence imaging experiments with endogenous and exogenous esterases.