10-N-Nonyl Acridine Orange Dye as a Fluorescent Indicator of the Effect of the Antiseptic Octenidine on the Membranes of Rhodobacter sphaeroides Chromatophores

Abstract

Increasing volumes of produced antiseptics and disinfectants, which are widely used in medicine, veterinary medicine, the food industry, and everyday life, can pose a serious environmental problem after use. Previously, when studying the action of a number of antiseptics at micromolar concentrations, the authors identified disturbances in the functioning of photosynthetic membranes and phototransforming pigment-protein complexes isolated from them in various representatives of photosynthetic organisms. In this work, to determine the sensitivity of photosynthetic membranes to the action of the cationic antiseptic octenidine, chromatophores of the purple nonsulfur bacteria Rhodobacter sphaeroides labeled with the fluorescent dye 10-N-nonyl acridine orange (NAO) were used. It was shown that the binding of NAO to chromatophores is accompanied by a shift in the maximum emission of the dye from 525 to 640 nm. The “red” fluorescence of NAO associated with chromatophores turned out to be sensitive to the effect of increasing concentrations of octenidine on photosynthetic membranes. Concentrations of the antiseptic at which it leads to degradation of chromatophore structures and a change in the aggregative state of NAO, which can be detected by enhanced “green” fluorescence in the emission spectra of the dye, were established. The properties of NAO as a fluorescent indicator of the functional state of photosynthetic membranes and potential changes that can occur in such systems under the influence of the cationic antiseptic are discussed.