In this work, screening studies of the cytotoxic effect of chlorins with fragments of di-, tri-, and pentaethylene glycol at the macrocycle periphery in relation to HeLa, A549, and HT29 cells were performed. It is shown that, despite different hydrophobicity, all the compounds studied have a comparable photodynamic effect. The conjugate of chlorin e6 with pentaethylene glycol, which has the lowest tendency to association among the studied compounds with tropism for low density lipoproteins and the best characteristics of the formation of molecular complexes with Tween 80, has a significant difference in dark and photoinduced toxicity (ratio IC50(dark)/IC50(photo) approximately 2 orders of magnitude for all cell lines), which allows to hope for a sufficiently large "therapeutic window". A study of the interaction of this compound with HeLa cells shows that the substance penetrates the cell and, after red light irradiation induces ROS appearance inside the cell, associated, apparently, with the photogeneration of singlet oxygen. These data indicate that photoinduced toxic effects are caused by damage to intracellular structures as a result of oxidative stress. Programmed type of cell death characterized with caspase-3 induction is prevailing. So, the conjugate of chlorin e6 with pentaethylene glycol is a promising antitumor PS that can be successfully solubilized with Tween 80, which makes it suitable for further in vivo studies.

A water-soluble monocationic chlorin photosensitizer for antimicrobial photodynamic therapy of superficial localized infections has been proposed. The antimicrobial activity of this compound against planktonic forms of nosocomial antibiotic-resistant gram-negative pathogens, Pseudomonas aeruginosa, Enterobacter cloacae, and Acinetobacter baumannii, has been studied in comparison with the activity of the photosensitizer Fotoran e(6), widely used in the clinical photodynamic therapy of tumors. It has been shown that both photosensitizers possess low dark toxicity; however, the light toxicity of the monocationic chlorin is higher by several orders of magnitude, and it can be proposed as a new agent for the antimicrobial photodynamic therapy.

Interactions of cationic and anionic chlorin photosensitizers (PSs) for photodynamic therapy with the potential delivery vehicle, the micellar surfactant Tween 80, were studied by spectrophotometric and fluorescence titration. The formation of PS—Tween 80 complexes in an aqueous solution was demonstrated. Two binding modes of the macrocycles to surfactant micelles, each with its own binding constant and stereochemistry of interactions, are observed in the spectrophotometric titration curves. Regardless of the sign and magnitude of the charge of the PS molecule, water-soluble chlorin macroheterocycles are located in the outer layer of the micelle surrounded by polar oxyethylene groups, into which hydrated iodide ions can penetrate. Cationic PSs were found to be, in general, more accessible to the quencher.

Aggregation studies of a photosensitizer (PS), tricationic chlorin (H2Chl3+), and its interaction with passive delivery vehicles Tween 80 and polyvinylpyrrolidone (PVP) in aqueous solutions have been carried out using 1D and 2D NMR spectroscopy, which has been shown to be a powerful tool for detecting both nanoaggregates at about 10–3 mole/kg and associates formed in solutions of H2Chl3+ at PS concentration lower by two orders of magnitude. NMR spectroscopy also can be used to identify molecular fragments of PS responsible for aggregation. The addition of solubilizers Tween 80 and PVP leads to the destruction of the PS nanoaggregates and formation of stable complexes with potential carriers, while the associated forms of the macrocycle may be retained in the solution. These results are consistent with the adsorption, fluorescence, and dynamic light scattering data. The molecular complex of water-soluble H2Chl3+ ions with the PVP macromolecule in aqueous solution is additionally stabilized by hydrogen bonding of the amide NH proton of the photosensitizer and oxygen atom of the polymer carbonyl group.

In this experimental work the acute toxicity of a chemically modified derivative of the natural pigment chlorophyll a called monocationic chlorin e6, which is a promising photosensitizer (PS) for antimicrobial and antitumor photodynamic therapy, was studied using white rats. The advantages of the PS under investigation are an intense absorption in the long-wavelength region of the visible spectrum, a sufficiently high quantum yield of singlet oxygen generation, pronounced amphiphilic properties along with an appropriate solubility in water, and a high level of photocytotoxic- ity in relation to both malignant HeLa cells and antibiotic-resistant hospital strains of E. сoli bacteria., P. aerugenosa and others. It has been shown that the value of LD50 of the considered PS can be calculated as the value of 100 mg/kg. In the reproduced experimental model of acute toxicity, pathomorphological changes in the vital organs of laboratory animals indicate a pronounced vasopathic effect of the drug with the development of cerebral edema and respiratory distress syndrome, which have become the main signs of thanatogenesis.

Purpose: to study the effectiveness of photodynamic therapy in combination with diathermoelectroconization in the treatment of cervical intraepithelial neoplasia and cervical cancer.Materials and methods. The study included 108 patients aged 33.13 ± 1.18 years. Human papillomavirus was detected in all patients. The study group consisted of 62 patients with cervical diseases. The fi rst subgroup included 28 patients with moderate to severe cervical intraepithelial neoplasia and pT1AN0M0 cervical cancer who underwent diathermoelectroconization and photodynamic therapy. The second subgroup included 34 patients with severe cervical intraepithelial neoplasia who underwent only cervical diathermoelectroconization. The control group included 46 patients with unchanged cervix. To carry out fl uorescent diagnostics and photodynamic therapy, the patients of the fi rst subgroup were intravenously injected with a solution of photosensitizer “Fotoditazin” (“Vetagrand”, Russia) at a dose of 0.8–1.2 mg/kg. Three hours later, using the AFS device (“Polironik”, Russia), fl uorescent diagnostics was performed followed by photodynamic therapy with an ALHT-ELOMED laser (“Elomed”, Russia) in continuous mode. The wavelength was 662 nm, the output power – 3 W, the radiation dose – 200–300 J/cm2 for the cervix and 100–125 J/cm2 – for the cervical canal. All patients underwent complex antiviral therapy.Results. All patients after photodynamic therapy showed complete eradication of human papillomavirus and regression of cervical intraepithelial neoplasia. Morphological studies have shown that the effectiveness of combined treatment of moderate and severe cervical intraepithelial neoplasia, reaching 100 %, was higher than with the use of diathermoelectroconization alone (95 %). There were no recurrences of cervical intraepithelial neoplasia and cervical cancer after combined treatment.Conclusion. Photodynamic therapy of cervical intraepithelial neoplasia and cervical cancer is a highly effective method.

The interaction of the dicationic photosensitizers (PSs) of the porphyrin {13(3),17(3)-bis-N-(2-N',N',N'-trimethylammonioethylamide) diiodide of deuteroporphyrin-IX} and chlorin {3(1),3(2)-bis-(N,N,N-trimethylammoniomethyl)-13(1)-N-methylamide-15(2),17(3)-dimethyl ester of chlorin e 6 diiodide} types with a nonionic surfactant Tween 80 (a potential delivery means) in the region of spherical micelles was studied by spectrophotometric and fluorescent titration. It was found that stable PS–Tween 80 complexes formed, with two binding modes with their own interaction constants and stoichiometry revealed on the titration curves; the most probable reasons for this are discussed. It was concluded that PS molecules lie in the outer layer of the micelle, where they are surrounded by polar oxyethylene groups and where hydrated iodide ions can penetrate. In the presence of various electrolytes, the size of Tween 80 micelles changed, which was detected by dynamic light scattering.

Dark and photoinduced toxicity of several novel and previously described derivatives of chlorin e 6 with tetraalkylammonium substituents differing from each other in number of cationic groups and their location in the macrocycle were studied in HeLa cells and mammalian erythrocytes.The optimal design of cationic derivatives of chlorin e 6 that provides the most efficient photodynamic effect was shown to require the localization of cationic substituents in the same part of the molecule.In combination with the hydrophobicity of the chlorin macrocycle, it increases the amphiphilic properties of the whole molecule and enhances its interaction with biomembranes.

A comprehensive study of four classes of aromatic macroheterocycles - N-substituted, isomeric, contracted and inverted porphyrin analogues - was carried out using a combination of spectral and thermal, conductometric and quantum-chemical methods. It was shown that inverted porphyrinoids and meso-substituted corroles have a pronounced chemical activity of NH bonds, which is appeared in the ability of these compounds to interact with a weak electron donors B to form acid-basic molecular complexes like HnPn center dot B with unaccomplished proton transfer. It was concluded that the tendency of porphyrinoids to molecular complexation with electron donors is controlled by the combination of a few factors, as an increase in a K-system polarization of the molecule, a decrease in its aromaticity and an ability to form solvent-dependent tautomeric forms. It was demonstrated for the first time that the innercyclic NH-proton as part of molecular complex forms an intermolecular hydrogen bond with the electron-donor center of molecule B yielding unaccomplished acid-base interaction. NH-active forms of the inverted analog of porphyrin and corrole are formed in polar electron-donor media, for example, in N,N-dimethylformamide solutions. Molecular complexes formed under these conditions, similarly to 1 : 1 electrolytes, demonstrate concentration dependences of the enthalpy of dissolution, as well as a shift and broadening of proton NH signals in the H-1 NMR spectrum. However, they do not show a change in the specific electrical conductivity of the medium in comparison with a pure solvent. This indicates the presence of Hbound forms, rather than anionic particles in solutions of these porphyrinoids.

The method of photodynamic therapy (PDT), which is used both for the treatment of oncological diseases and as an alternative to antibiotic therapy of resistant bacterial and fungal infections, needs a photosensitizer (PS) in the drug dosage form in non-aggregated state. Aggregation of PS reduces the quantum yield of reactive oxygen species (ROS), the time of circulation of pigments in the bloodstream, their tropism to atypical cells, and, hence, the effectiveness of PDT. In this work, we studied the aggregation state of potential PSs based on chlorin e6 containing fragments of antibacterial drugs Miramistin and Dioxidin in aqueous solutions of ethanol, as well as the biocompatible micellar surfactant Tween 80. The best way to study the aggregation of macrocycles of the chlorin series in aqueous ethanol solutions is a combination of absorption spectroscopy and dynamic light scattering methods, which makes it possible to draw conclusions about the formation of aggregated forms of different types in the system. Presumably, the introduction of additional fragments of antibacterial drugs into the structure of a potential photosensitizer bring a positive effect on APDT, despite the fact that such hydrophobic PSs in aqueous solutions of ethanol and Tween 80 are aggregated not only at therapeutic concentrations, but also in more dilute solutions. The binding constants of PS-surfactant were determined spectrophotometrically. The probable depth of PS localization in a micelle was estimated by the method of fluorescence quenching. The size of their aggregates in aqueous solutions was determined by the method of dynamic light scattering. It has been suggested that even with large excess of surfactants in relation to PS, the latter can be found not only inside of the micelle formed, but in a free aggregated form. It was shown that the use of Tween 80 makes it possible to achieve only partial disaggregation of the hydrophobic macrocyclic PSs studied.

The electronic absorption spectra of cationic forms of porphyrinoids in acetonitrile or benzene with the addition of acetic or trifluoroacetic acid have been studied and the values of the acid-base interaction constants have been calculated. The order of changes in the basicity of the studied compounds obtained from spectrophotometric, quantum-chemical (DFT, B3LYP, and CC-pVDZ using NBO analysis), and thermodynamic data have been consistent.

Thermogravimetry and quantum chemistry, including NBO analysis, are used to study the thermal stability and NH acidity of single and double protonated forms of tetrapyrrole macroheterocyclic ligands (porphyrins, their inverted and N-substituted analogs, and corroles). The temperature ranges of the destruction of porphyrinium acetates and trifluoroacetates, the enthalpies of evaporation of acid molecules from the crystalline phase, and the composition of cationic salts are calculated. The structures of protonated forms of macrocycles are optimized. The energies of porphyrin–acid interaction and the values of charge transfer ​​during the formation of bonds are calculated.