Novel nontoxic mitochondrial probe for confocal fluorescence microscopy.

We propose a 2,5-Bis[1-(4-N-methylpyridinium)ethen-2-yl)]-N-methylpyrrole ditriflate (PEPEP) as a novel nontoxic, nonpotentiometric mitochondrial probe for confocal fluorescence microscopy. PEPEP is a representative chromophore of a large family of heterocyclic fluorescent dyes that show fluorescence emission in aqueous media and great DNA affinity. We check its cytotoxicity and intracellular localization in mammalian and yeast cell cultures. We demonstrate that PEPEP is a very efficient dye for fluorescence confocal microscopy and a valuable alternative to the most frequently used mitochondrial stains.