A near-infrared ratiometric fluorescent probe for selectively tracking human cytochrome P450 3A5 in living cells and tumor-bearing mice

Cytochrome P450 (CYP) 3A5 as the most important CYPs in the CYP3A isoform, is polymorphic and plays a significant role in drug metabolism. Herein, two novel enzyme-activatable near-infrared (NIR) ratiometric fluorescent probes (Hcy-Br and Hcy-Cl) are designed and synthesized to measure the activity of CYP3A5 in complex biological systems. Hcy-Br possesses excellent sensitivity in response to CYP3A5 enzyme with the LOD = 0.04903 nM and could quickly reach equilibrium within 30 min. The ability of targeting mitochondria, along with preferable Pearson’s correlation coefficients (Rr) of 0.8746, is realized in Hcy-Br. The application of Hcy-Br in living cells and tumor-bearing mice is also achieved successfully for monitoring endogenous CYP3A5 activity. Detecting CYP3A5 activity in living system via fluorescent probe, to the best of our knowledge, is reported for the first time. These findings suggest that Hcy-Br could be served as a useful tool for selectively detecting the activity of endogenous CYP3A5 in vivo, providing assistance for investigating the function of CYP3A5 in drug metabolism and pathologic process.