[The Redox-Catalytic Properties of Cobalamins].

Vitamin B12, or cobalamin, is essential for normal body function and is used in the therapies of different diseases. Vitamin B12 has anti-inflammatory and antioxidant properties that can play an important role in the prevention of some diseases. On the other hand, it has been reported that vitamin B12 in combination with such reducing agents as ascorbate (vitamin C) and thiols showed prooxidant activity. This review provides information on the roles of vitamin B12 in diseases accompanied by inflammation and oxidative stress and the effects of vitamin B12 administrated alone and in combinations with different reducing agents such as ascorbate and thiols on oxidative stress. In addition, the mechanisms of prooxidant actions of combinations of vitamin B12 with these reducing agents depending on the form of vitamin B12 (hydroxocobalamin and cyanocobalamin) are discussed. Understanding the mechanisms of prooxidant action of vitamin B12 is necessary for developing strategies for therapeutic administration of vitamin B12.

Hydroxycobalamin catalyzes the oxidation of diethyldithiocarbamate and increases its cytotoxicity independently of copper ions.

It is known that some metals (Cu, Zn, Cd, Au) markedly increase the toxic effect of thiocarbamates. It was shown in the present study that hydroxycobalamin (a form of vitamin B12, HOCbl), which incorporates cobalt, significantly enhances the cytotoxicity of diethyldithiocarbamate (DDC), decreasing its IC50 value in tumor cells three to five times. The addition of HOCbl to aqueous DDC solutions accelerated the reduction of oxygen. No hydrogen peroxide accumulation was observed in DDC + HOCbl solutions; however, catalase slowed down the oxygen reduction rate. Catalase as well as the antioxidants N-acetylcysteine (NAC) and glutathione (GSH) partially inhibited the cytotoxic effect of DDC + HOCbl, whereas ascorbate, pyruvate, and tiron, a scavenger of superoxide anion, had no cytoprotective effect. The administration of HOCbl into DDC solutions (> 1 mM) resulted in the formation of a crystalline precipitate, which was inhibited in the presence of GSH. The data of UV and NMR spectroscopy and HPLC and Mass Spectrometry (LC/MS) indicated that the main products of the reaction of DDC with HOCbl are disulfiram (DSF) and its oxidized forms, sulfones and sulfoxides. The increase in the cytotoxicity of DDC combined with HOCbl occurred both in the presence of Cu2+ in culture medium and in nominally Cu-free solutions, as well as in growth medium containing the copper chelator bathocuproine disulfonate (BCS). The results indicate that HOCbl accelerates the oxidation of DDC with the formation of DSF and its oxidized forms. Presumably, the main cause of the synergistic increase in the toxic effect of DDC + HOCbl is the formation of sulfones and sulfoxides of DSF.

[Collagen and Taxifolin-based Material: Production and Properties].

The possibility of producing the material based on collagen and biologically active polyphenol taxifolin was explored, and the properties of the material were studied. The data on the dynamics of the release of polyphenol chemically linked to collagen are represented, and the metal-reducing activity of polyphenol released from the gel is determined. The effect of taxifolin, taxifolin glutarate and gel containing polyphenol on the production of reactive oxygen species by neutrophils stimulated with phorbol myristate acetate was examined. It was shown that polyphenol released from the gel material exerts antioxidant and metal-reducing properties, suggesting that unoxidized polyphenol linked to collagen.

Skin regeneration after chemical burn under the effect of taxifolin-based preparations.

We studied the effect of liposome preparation containing taxifolin oligomers and taxifolin conjugates with carbonyl compounds on skin regeneration after chemical burn. The preparations containing flavonoid conjugates intensified regeneration processes and reparation of hair follicles and sebaceous glands after chemical burn. The preparation based on taxifolin conjugate with acetaldehyde was most effective; its activity was comparable with that of the wound-healing preparation Olasol. Taxifolin conjugates with carbonyl compounds can be used for the creation of combined wound- and burn-healing preparations.

Effects of a nanocomplex containing antioxidant, lipid, and amino acid on thermal burn wound surface.

Dihydroquercetin (flavonoid of plant origin) immobilized with an amino acid in lecithin nanoparticles promotes reduction of inflammatory reactions in the wound after thermal burn. The use of a liposomal complex in burn injury stabilizes endogenous antioxidant system and limits the secondary necrotic zone in the wounds. The treatment was associated with intensification of skin regeneration processes and reparation of hairy follicles and sebaceous glands.

Effect of liposomes containing antioxidant, phospholipid, and amino acid on skin regeneration after chemical burn.

Liposomes containing natural flavonoid dihydroquercetin, phospholipid lecithin, and zwitterionic amino acid glycine were used for the therapy of glacial acetic acid-induced chemical burn. No inflammatory reaction was observed in the region of wound. The area of postburn injury did not increase in time. Planimetry and histological studies showed that improved skin regeneration was accompanied by repair of hair follicles and sebaceous glands.

Changes in the ultrastructure and function of goldfish Mauthner neurons in the presence of 3,4-dihydro-2(1H)-pyrimidinethione.

The behavioral effects of 3,4-dihydro-2(1H)-pyrimidinethione (DPT, a pyrimidine derivative), which is used as a test system for detecting tumor growth, on the ultrastructure and function of Mauthner neurons (MN), were studied in goldfish. Application of DPT to MN was found to lead to increased resistance of neurons to exhaustive stimulation, which was accompanied by increases in the sizes of actin-containing membrane desmosome-like contacts, along with the formation of bundles of actin stress fibers; these effects are similar to those previously reported with dopamine. The similarity of the morphofunctional changes in MN on exposure to an artificial chemical substance for which there are no membrane receptors and dopamine itself suggests that they have trophic effects on the stabilization and polymerization of cytoskeletal actin due to direct penetration into postsynaptic neurons.

Distribution of DNA, proteins, and lipids in cells of the olfactory bulb in rats of different ages.

Luminescence and absorption stains specific for DNA (acridine orange, ethidium bromide), proteins (silver nitrate), and lipids (Sudan III) were used to study the distribution of DNA, proteins, and lipids in sections of the olfactory bulb in rats, studies being performed after fixation of brains with paraformaldehyde. DNA was found to be more abundant in the glomerular cell layer than the mitral cell layer. Higher quantities of DNA were present in the granular layer, located beneath the mitral layer. The characteristics of cell layers in the olfactory bulb were studied in rats aged two days and one month. There were differences between the layers of rats of different ages in terms of the content and distribution of DNA, though there were no differences in the total protein or lipid contents. Glomeruli were immature in two-day-old rats.