ИСТИНА

IntroductionPhotodynamic therapy, commonly applied to treat skin cancer, is based on activation of photosensitizers (PS) by lightdelivery to generate reactive oxygen species, basically singlet oxygen (SO), damaging cell membraneMethodsWe studied in vitro the processes involved in photodynamic therapy on a model bilayer lipid membranes (BLM)by measuring the boundary potential applying the Intramembrane Field Compensation (IFC) Method (Sokolov andKuzЃfmin, Biofizika, 25:170, 1980). IFC method allowed to monitor binding of PS on BLM and damage of targetmolecules (TM) of SO under illumination. di-4-ANEPPS was used as TM since it adsorbs on BLM creating a dipolepotential. The rate of TM oxidation was calculated from the kinetics of the potential drop under illumination and itsrestoration in darkResults and DiscussionWe studied the adsorption and photodynamic efficiency of newly synthesized positively charged porphyrins, namelyb-imidazolyl substituted porphyrin and itЃfs Zn(II) and In(III) complexes; and two phosphorus (V) complexes of meso-(p-pyridyl)-triphenylporphyrin bearing hydroxyl and ethoxyl axial ligands. We observed the adsorption of these PS onBLM by measuring the boundary potential change, which was proportional to the logarithm of concentrations of eachcompound. To evaluate their photodynamic efficiency, we determined the rate of oxidation (R) of TM adsorbed eitherin the same or opposite surface of the BLM where molecules of PS were adsorbed. Similar R values were obtainedsuggesting equal distribution of SO between two sides of BLM.ConclusionsThe adsorption of PS compounds on BLM was found to be a main factor influencing on the photodynamic efficiencyof the porphyrin-based PS used in this study.AcknowledgementsThis work was supported by the Russian Foundation of Basic Research (N 19-04-00694a) and the Ministry ofEducation and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUSTЃбMISiSЃв (‡‚ „K4-2017-053).