Synthesis and characterization of the reactivity of new far-red fluorescent dyes and a boronate probe containing a tricyanopyrroline skeleton

Abstract

Probes that exhibit turn-on fluorescence in the far-red region (600–750 nm) are in high demand because their use causes minimal autofluorescence and cellular damage. Here, we present a practical microwave-assisted synthesis of dyes containing a tricyanopyrroline (TCP) unit and a new boronate probe based on the TCP chemical scaffold. The proposed microwave-assisted method performs better in an eighteenth of the time than condensation in ethanol. We also present the simple methodology to detect peroxynitrite using the TCP-BOR redox probe in three different ways. First, the TCP-OH dye, which absorbs far-red light, is a major oxidation product that can be used for fluorescent detection. Second, peroxynitrite-specific products, nitrated TCP-NO2, and reduced TCP-H derivatives can easily be detected and quantified with HPLC due to a significant difference in the position of their absorption bands. Furthermore, the EPR signal recording of the spin adducts of the phenyl radical formed in the reaction of TCP-BOR with peroxynitrite and mass spectrometric analyses of these adducts can also be used to confirm the oxidation of the probe by peroxynitrite. TCP-OH was also detected in macrophages RAW 264.7 activated for the ONOO− production.