Synthesis of a selective ratiometric fluorescent probe based on Naphthalimide and its application in human cytochrome P450 1A.

Cytochrome P450s have brought considerable attention to researchers for their significant correlations with metabolic behaviors of procarcinogenic chemicals. To better understand the roles of CYP1A in biological and physiological systems, we developed a novel ratiometric fluorescence probe N-((2-hydroxyl ethoxy) ethyl)- 4-methoxy-1, 8-naphthalimide (NEMN) allowing for selectively and sensitively monitoring the target enzymes under physiological conditions and living cells. The probe was designed based on substrate predilection of CYP1A and its outstanding O-dealkylation capacity, and 1, 8-naphthalimide was chosen as fluorophore on account of its desirable photophysical properties. Absorption and emission spectra of the probe solution and reacted metabolism showed obvious red-shift with remarkable colour changes, which indicated that NEMN could be a promising ratiometric detector of CYP1A. Additionally, the selectivity assays displayed that NEMN only sensitive to CYP1A1 and CYP1A2 enzymes with scarce interference of other CYPs. Furthermore, the excellent linear relationships between the ratio of fluorescent intensities and incubation time and enzymes concentration signified time- and concentration- dependence of the probe, which were of desire benefit to quantify and monitor the CYP1A-involved biological behaviors in physiological conditions. The assay in real living samples (Human liver microsomes) further proved the analytical utility of the probe. Finally, the cytotoxicity assay and confocal fluorescence imaging demonstrated that this probe was of great promise for detecting the activity of endogenous CYP1A in human living cells.