VII Congress of Russian Biophysicists-2023, Krasnodar, Russia.

This special issue of Biophysical Reviews contains the materials presented at the VII Congress of Biophysicists of Russia, held from 17 to 23 April in Krasnodar. We believe that we have managed to prepare a selection of articles that well reflects the current state of biophysical science in Russia and its place in the world science. The VII Russian Congress on Biophysics was held in Krasnodar in April 2023, continuing the tradition of the series of biophysics conferences held every 4 years.

Positive (Regulatory) and Negative (Cytotoxic) Effects of Dinitrosyl Iron Complexes on Living Organisms.

The proposed in our studies mechanism of dinitrosyl iron complex (DNIC) formation through the main step of disproportionation of two NO molecules in complex with Fe2+ ion leads to emergence of the resonance structure of dinitrosyl-iron fragment of DNIC, [Fe2+(NO)(NO)]. The latter allowed suggesting capacity of these complexes to function as donor of both neutral NO molecules as well as nitrosonium cations (NO), which has been demonstrated in experiments. Analysis of biological activity of DNICs with thiol-containing ligands presented in this review demonstrates that NO molecules and nitrosonium cations released from the complexes exert respectively positive (regulatory) and negative (cytotoxic) effects on living organisms.

An open call for contributions to a special issue of highlighting the research themes of VII Congress of Russian Biophysicists 2023.

We announce a call for contributions to a Special Issue of associated with the VII Congress of Russian Biophysicists (to be held in Krasnodar, Russia, 17-23 April 2023). The Congress is the main biophysical meeting held within Russia and is organized every four years. The Congress will focus on both the physical principles and mechanisms of biological processes occurring at different levels of structural organization, from molecular to cellular to organism and to population levels.

Physico-Chemistry of Dinitrosyl Iron Complexes as a Determinant of Their Biological Activity.

In this article we minutely discuss the so-called "oxidative" mechanism of mononuclear form of dinitrosyl iron complexes (M-DNICs) formations proposed by the author. M-DNICs are proposed to be formed from their building material-neutral NO molecules, Fe ions and anionic non-thiol (L) and thiol (RS) ligands based on the disproportionation reaction of NO molecules binding with divalent ion irons in pairs. Then a protonated form of nitroxyl anion (NO) appearing in the reaction is released from this group and a neutral NO molecule is included instead.

Nitrosonium Cation as a Cytotoxic Component of Dinitrosyl Iron Complexes with Thiol-containing Ligands (based on the Experimental Work on MCF7 Human Breast Cancer Cell Culture).

Here we demonstrate that binuclear dinitrosyl iron complexes with thiol-containing ligands (glutathione and mercaptosuccinate, B-DNIC-GSH and B-DNIC-MS, respectively) exert cytotoxic effects on MCF7 human breast cancer cells. We showed that they are mediated by nitrosonium cations released from these complexes (NO). This finding is supported by the cytotoxic effect of both B-DNICs on MCF7 cells evidenced to retain or was even promoted in the presence of N-Methyl-D-glucamine dithiocarbamate (MGD).

How is Nitric Oxide (NO) Converted into Nitrosonium Cations (NO) in Living Organisms? (Based on the Results of Optical and EPR Analyses of Dinitrosyl Iron Complexes with Thiol-Containing Ligands).

The present work provides theoretical and experimental foundations for the ability of dinitrosyl iron complexes (DNICs) with thiolcontaining ligands to be not only the donors of neutral NO molecules, but also the donors of nitrosonium cations (NO) in living organisms ensuring S-nitrosation of various proteins and low-molecular-weight compounds. It is proposed that the emergence of those cations in DNICs is related to disproportionation reaction of NO molecules, initiated by their binding with Fe ions (two NO molecules per one ion). At the same time, possible hydrolysis of iron-bound nitrosonium cations is prevented by the electron density transition to nitrosonium cations from sulfur atoms of thiol-containing ligands, which are included in the coordination sphere of iron.

What is the Mechanism of Nitric Oxide Conversion into Nitrosonium Ions Ensuring S-Nitrosating Processes in Living Organisms.

Here, I present the data testifying that the conversion of free radical NO molecules to nitrosonium ions (NO), which are necessary for the realization of one of NO biological effects (S-nitrosation), may occur in living organisms after binding NO molecules to loosely bound iron (Fe ions) with the subsequent mutual one-electron oxidation-reduction of NO molecules (their disproportionation). Inclusion of thiol-containing substances as iron ligands into this process prevents hydrolysis of NO ions bound to iron thus providing the formation of stable dinitrosyl iron complexes (DNIC) with thiol ligands. Such complexes act in living organisms as donors of NO and NO, providing stabilization and transfer of these agents via the autocrine and paracrine pathways.

Protective Effect of Dinitrosyl Iron Complexes with Glutathione in Red Blood Cell Lysis Induced by Hypochlorous Acid.

Hypochlorous acid (HOCl), one of the major precursors of free radicals in body cells and tissues, is endowed with strong prooxidant activity. In living systems, dinitrosyl iron complexes (DNIC) with glutathione ligands play the role of nitric oxide donors and possess a broad range of biological activities. At micromolar concentrations, DNIC effectively inhibit HOCl-induced lysis of red blood cells (RBCs) and manifest an ability to scavenge alkoxyl and alkylperoxyl radicals generated in the reaction of HOCl with -butyl hydroperoxide.

The Inhibiting Effect of Dinitrosyl Iron Complexes with Thiol-containing Ligands on the Growth of Endometrioid Tumours in Rats with Experimental Endometriosis.

The possibility that binuclear dinitrosyl iron complexes with glutathione and cysteine (DNIC-GSН and B-DNIC-Cys) have a strong cytotoxic effect on the growth of endometrioid tumours (EMT) in rats with surgically induced experimental endometriosis established in our previous studies has been supported with experimental data. The increase in the DNIC-GSН or B-DNIC-Cys dose from 10 (in our previous studies) to 20 μmol/kg (after i/p administration to experimental rats) fully suppressed the growth of uterine tissues implanted onto the inner surface of the abdominal wall. At 2 μmol/kg DNIC-GSН, the median value of EMT volume increased from 0 to 15 mm, while the mean size of EMT-from 55 to 77 mm (data from EMT measurements in 10 experimental rats).

Is it possible to combine photodynamic therapy and application of dinitrosyl iron complexes in the wound treatment?

We have studied the effect of interactions between dinitrosyl iron complexes with thiol-containing ligands (DNIC-TL) and diglucamine salt of chlorine e6 (photoditazine, PD) on the rate of photosensitized oxidation of a model organic substrate - tryptophan - in the presence and absence of an amphiphilic polymer, Pluronic F127, as well as on the DNIC-TL and PD photostability. Using EPR and UV spectroscopy, we determined the rate constants for photodegradation of mono- and dinuclear DNIC-TL and PD, respectively. The presence of the photosensitizer and Pluronic F127 has been shown to have a negligible effect on the rate of photodestruction of mono- and dinuclear DNIC-TL, taking into account the changing DNIC-TL and PD concentrations in the photoexcitation conditions.

Physicochemical parameters of NO-containing gas flow affect wound healing therapy. An experimental study.

Therapy of wounds and inflammatory diseases with NO-containing gas flows (NO-CGF) has proved to be effective in a longterm clinical practice. Plasma-chemical generation of nitric oxide occurs from atmospheric air in Plason device. For the purpose of modification and improvement of NO-therapy, effects of various physicochemical parameters of the NO-CGF on inflammatory and reparative processes in wounds were studied.

EPR Characterization of Dinitrosyl Iron Complexes with Thiol-Containing Ligands as an Approach to Their Identification in Biological Objects: An Overview.

The overview demonstrates how the use of only one physico-chemical approach, viz., the electron paramagnetic resonance method, allowed detection and identification of dinitrosyl iron complexes with thiol-containing ligands in various animal and bacterial cells. These complexes are formed in biological objects in the paramagnetic (electron paramagnetic resonance-active) mononuclear and diamagnetic (electron paramagnetic resonance-silent) binuclear forms and control the activity of nitrogen monoxide, one of the most universal regulators of metabolic processes in the organism.

Study of plasma-chemical NO-containing gas flow for treatment of wounds and inflammatory processes.

This work is aimed at exhaustive and detailed study of chemical, physical and physico-chemical characteristics of NO-containing gas flow (NO-CGF) generated by a plasma-chemical generator of Plason device, which has been used in medical practice for more than 15 years for effectively healing wound and inflammatory conditions with exogenous nitric oxide (NO-therapy). Data was obtained on spatial structure of the gas flow, and values of its local parameters in axial and radial directions, such as nitric oxide content, velocity, temperature and mass flow density of nitric oxide, providing altogether the effectiveness of treatment by the exogenous NO-therapy method, were determined experimentally and by computations. It was demonstrated that plasma-chemical synthesis of NO from atmospheric air in a low direct current (DC) arc provides a high mass flow of nitric oxide at the level of 1.

Dinitrosyl iron complexes with natural thiol-containing ligands in aqueous solutions: Synthesis and some physico-chemical characteristics (A methodological review).

Two approaches to the synthesis of dinitrosyl iron complexes (DNIC) with glutathione and l-cysteine in aqueous solutions based on the use of gaseous NO and appropriate S-nitrosothiols, viz., S-nitrosoglutathione (GS-NO) or S-nitrosocysteine (Cys-NO), respectively, are considered. A schematic representation of a vacuum unit for generation and accumulation of gaseous NO purified from the NO admixture and its application for obtaining aqueous solutions of DNIC in a Thunberg apparatus is given.

The binuclear form of dinitrosyl iron complexes with thiol-containing ligands in animal tissues.

It has been established that treatment of mice with sodium nitrite, S-nitrosoglutathione and the water-soluble nitroglycerine derivative isosorbide dinitrate (ISDN) as NO donors initiates in vivo synthesis of significant amounts of EPR-silent binuclear dinitrosyl iron complexes (B-DNIC) with thiol-containing ligands in the liver and other tissues of experimental mice. This effect is especially apparent if NO donors are administered to mice simultaneously with the Fe-citrate complex. Similar results were obtained in experiments on isolated liver and other mouse tissues treated with gaseous NО in vitro and during stimulation of endogenous NO synthesis in the presence of inducible NO synthase.

Dinitrosyl iron complexes with thiol-containing ligands as a "working form" of endogenous nitric oxide.

The material presented herein is an overview of the results obtained by our research team during the many years' study of biological activities and occurrence of dinitrosyl iron complexes (DNIC) with thiol-containing ligands in human and animal organisms. With regard to their dose dependence and vast diversity of biological activities, DNIC are similar to the system of endogenous NO, one of the most universal regulators of biological processes. The role of biologically active components in DNIC is played by their iron-dinitrosyl fragments, [Fe(NO)2], endowed with the ability to generate neutral NO molecules and nitrosonium ions (NO(+)).

The hypotensive effect of the nitric monoxide donor Oxacom at different routs of its administration to experimental animals.

Earlier it has been found that the hypotensive drug Oxacom containing binuclear dinitrosyl iron complexes (B-DNIC) with glutathione can effectively decrease, as a nitric monooxide (NO) donor, the mean arterial pressure (МАР) in rats upon intravenous bolus injection in the form of an aqueous solution (Chazov et al., 2012). The aim of this study was to investigate the hypotensive effects of Oxacom administered to experimental rats by intravenous, intramuscular, subcutaneous, intraperitoneal, intragastric, rectal routes.

Dinitrosyl iron complexes with glutathione incorporated into a collagen matrix as a base for the design of drugs accelerating skin wound healing.

Composites of a collagen matrix and dinitrosyl iron complexes with glutathione (DNIC-GS) (in a dose of 4.0 μmoles per item) in the form of spongy sheets (DNIC-Col) were prepared and then topically applied in rat excisional full-thickness skin wound model. The effects of DNIC-Col were studied in comparison with spontaneously healing wounds (SpWH) and wounds treated with collagen sponges (Col) without DNIC-GS.

The effect of dinitrosyl iron complexes with glutathione and S-nitrosoglutathione on the development of experimental endometriosis in rats: a comparative studies.

It has been established that intraperitoneal bolus administration of S-nitrosoglutathione (GS-NO) (12.5μmoles/kg; 10 injections in 10 days), beginning with day 4 after transplantation of two 2-mm autologous fragments of endometrial tissue onto the inner surface of the abdominal wall of rats with surgically induced (experimenta) endometriosis failed to prevent further growth of endometrioid (EMT) and additive tumors, while treatment of animals with dinitrosyl iron complexes (DNIC) with glutathione (12.5μmoles/kg, 10 injections in 10 days) suppressed tumor growth virtually completely.

Redox activities of mono- and binuclear forms of low-molecular and protein-bound dinitrosyl iron complexes with thiol-containing ligands.

EPR, optical, electrochemical and stopped-flow methods were used to demonstrate that Fe(NO)2 fragments in paramagnetic mononuclear and diamagnetic binuclear forms of dinitrosyl iron complexes with glutathione are reversibly reduced by a two-electron mechanism to be further transformed from the initial state with d(7) configuration into states with the d(8) and d(9) electronic configurations of the iron atom. Under these conditions, both forms of DNIC display identical optical and EPR characteristics in state d(9) suggesting that reduction of the binuclear form of DNIC initiates their reversible decomposition into two mononuclear dinitrosyl iron fragments, one of which is EPR-silent (d(8)) and the other one is EPR-active (d(9)). Both forms of DNIC produce EPR signals with the following values of the g-factor: g⊥=2.

Dinitrosyl iron complexes with glutathione suppress experimental endometriosis in rats.

Dinitrosyl iron complexes (DNIC) with glutathione exert a cytotoxic effect on endometrioid tumours in rats with surgically induced experimental endometriosis. Intraperitoneal treatment of rats (Group 1) with DNIC (12.5μmoles/kg, daily, for 12 days), beginning with day 4 after the surgical operation (implantation of two 2mm-thick uterine fragments onto the abdominal wall) followed by 14-day keeping of animals on a standard feeding schedule (without medication) resulted in complete inhibition of the growth of endometrioid implants (EMI) in the majority of experimental animals.

A simple protocol for the synthesis of dinitrosyl iron complexes with glutathione: EPR, optical, chromatographic and biological characterization of reaction products.

The diamagnetic binuclear form of dinitrosyl iron complexes (B-DNIC) with glutathione can be easily synthesized in the air at ambient temperature. The synthetic protocol includes consecutive addition to distilled water of glutathione, which decreases the pH of the test solution to 4.0, a bivalent iron salt (e.

Redox conversions of dinitrosyl iron complexes with natural thiol-containing ligands.

Using the electron paramagnetic resonance (EPR) and optical spectrophotometric methods, it has been established that biologically active, water-soluble dinitrosyl iron complexes (DNIC) with glutathione are predominantly represented by the diamagnetic binuclear form (B-DNIC) even in the presence of a 10-fold excess of glutathione non-incorporated into DNIC at neutral pH. With the increase in рН to 10-11, B-DNIC are fully converted into the paramagnetic mononuclear form (М-DNIC) with a characteristic EPR signal at g⊥=2.04, g‖=2.

Dinitrosyl iron complexes with glutathione as NO and NO⁺ donors.

It has been found that heating of solutions of the binuclear form of dinitrosyl iron complexes (B-DNIC) with glutathione in a degassed Thunberg apparatus (рН 1.0, 70°С, 6 h) results in their decomposition with a concomitant release of four gaseous NO molecules per one B-DNIC. Further injection of air into the Thunberg apparatus initiates fast oxidation of NO to NO₂ and formation of two GS-NO molecules per one B-DNIC.

Hypotensive effect of Oxacom® containing a dinitrosyl iron complex with glutathione: animal studies and clinical trials on healthy volunteers.

A comparative study of hypotensive effects of binuclear forms of dinitrosyl iron complexes (DNICs) with glutathione, S-nitrosoglutathione (GS-NO) and sodium nitrite (NaNO(2)) on rats has been carried out. The latter appeared to be the least efficient, viz., mean arterial pressure (MAP) decreased by 10 and 30 mmHg at 25 and 100 μmoles/kg of NaNO(2).