Kaede Protein Chromophore Analogue as a Tool for Simultaneous Selective Staining of the Nucleus and Mitochondria

Objective: Synthesis of a new series of fluorescent dyes based on Kaede chromophore moiety for selective mitochondria and nucleus staining. Methods: [3+2]-cycloaddition of carboxyimidate to aromatic imines. Reaction of arylidene imidazolone with BBr3 followed by treatment with aqueous HF was used in synthesis of difluoroboranyl compound. Condensation of corresponding aromatic aldehydes with active methyl group of arylidene-imidazolone was used for Kaede chromophore analogues synthesis. UV-VIS spectroscopy and fluorimetry was used to study optical properties of new chromophores. The widefield fluorescence microscopy was used for imaging of cellular structures. Results and Discussion: We discovered that 5-((Z)-4-(dimethylamino)-3-hydroxybenzylidene)-3-methyl-2-((E)-2-(pyridin-4-yl)vinyl)-3,5-dihydro-4H-imidazol-4-one can act as a fluorogen for mitochondria and nucleus. Conclusions: We created a series of three new arylidene imidazolone fluorogens and showed that compound can be used as a dye for mitochondria and nucleus in widefield fluorescence microscopy.