Yu. A. Gracheva

Effect of Organotin Compounds and Their Complexes with Phosphatidylcholine on Peroxide Oxidation of Lipid Structural Fragments

Oxidation of a lipid structural fragment, oleic acid, in the presence of a series of organotin compounds and their complexes with phosphatidylcholine was studied at 25, 37, 65, and 95°C. At a nearly physiological temperature, acceleration of hydroperoxide accumulation in the presence of these complexes was observed. At 65°C, addition of organotin derivatives leads to increase in the initial rate of hydroperoxide accumulation, but the kinetic curves acquire an S-like character as the reaction progresses. These data indicate that the rate of decomposition of hydroperoxides exceeds the rate of their accumulation. In the presence of 2,6-di-tert-butylphenol as antioxidant, the promoting effect of organotin compounds disappears. A possible reaction mechanism and the role of radical species arising from dissociation of the CÄSn bond are discussed.

Synthesis and antioxidant activity of new organotin compounds containing a 2,6-di-tert-butylphenol moiety

ISSN 00125008, Doklady Chemistry, 2013, Vol. 451, Part 1, pp. 177–180.

Complexes of organotin compounds with bis- and trisphosphonate derivatives of 2,6-di-tert-butylphenol having antioxidant activity

Complexes of organotin compounds R2SnCl2 with bisand trisphosphonate derivatives of 2,6-di-tert-butyl-4-methylphenol (ionol) were synthesized. X-ray diffraction studies were carried out for some of them. The redox properties of the synthesized compounds were characterized by cyclic voltammetry. Antioxidant/prooxidant activity of the complexes was studied using a new electrochemical method based on measuring the rate of hydrogen atom transfer to the stable radical 2,2´-diphenyl-1-picrylhydrazyl (DPPH). The data obtained were compared with the results of studying activity of the compounds during lipid peroxidation (LP) in biological samples. A correlation is observed between the results on antioxidant activity obtained by electrochemical DPPH test and using biological samples. Unlike the initial organotin compounds, the synthesized complexes have antioxidant activity, whereas phosphorus-containing phenols exhibit the properties of efficient antioxidants and chelating agents.

Synthesis of new sulfur-containing derivatives of furanoallocolchicinoids

Reaction of hydroxyl-containing heterocyclic colchicinoids with S-nucleophiles led to the formation of furanoallocolchicinoid sulfides in a high yield.

Dual Effect of Organomercury Compounds on Peroxide Oxidation of Oleic Acid

Oxidation of oleic acid with atmospheric oxygen in the presence of HgCl2 and various organo- mercury compounds (methylmercury iodide, isopropylmercury bromide, n-hexylmercury bromide, phenylmercury bromide, diphenylmercury, p-tolylmercury bromide, bis-p-tolylmercury) was studied. Mercury compounds exert a dual effect on accumulation of oleic acid hydroperoxide in the temperature range 20-90°C. Below 50°C, the concentration of the hydroperoxides formed in the presence of mercury compounds is lower, and at higher temperatures, higher than in the experiments performed without mercury compounds. Comparison of the concentrations of oleic acid hydroperoxides with those of their transformation products, carbonyl compounds, determined spectrophotometrically, shows that actually organomercury compounds and HgCl2 accelerate peroxide oxidation at all the studied temperatures. Decreased accumulation of peroxides below 50°C is apparently due to the fact that the rate of their reaction with organomercury compounds is higher than the rate of their formation.

Ways of Decreasing the Oxidative Stress Promoted by Organomercury Compounds

The oxidative stress of an organism resulting in metabolism disorder is related to the peroxide oxidation of lipids (POL) and to changes in the structure of cell membranes [1]. Detailed studies of POL processes showed that a number of exogenous agents exist, for example, metal salts and organic radicals, which promote the formation of hydroperoxides or carbonyl compounds, which are products of their decomposition, and accumulation of these products in the cell [2]. In addition, assays carried out for the whole organism indicate that toxic organomercury compounds RHgX and R 2 Hg are accumulated in cell membranes due to their lipophilic properties and accelerate POL [3, 4]. However, scarcity of the available data on the mechanism of toxic action of RHgX and R 2 Hg at the molecular level do not allow one to propose a general concept for the choice of detoxifying agents. Currently, thio derivatives and complexones [5], for example, 2,3-dimercaptopropanol and calcium disodium ethylenediaminetetraacetate, are used most often as detoxifying agents against mercury poisoning. The action of these agents is based on the binding of Hg atoms to give Hg‐S or Hg‐O bonds; however, it does not imply the possibility of deactivation of the reactive C-centered organic radicals resulting from the homolytic cleavage of the Hg‐C bond, which inevitably accompanies the involvement of RHgX and R 2 Hg in biochemical redox and radical processes.

One-Pot Synthesis of 2-Alkylsulfanyldihydrofuran Derivatives from Tetracyanocyclopropyl Ketones

Successive treatment of 3-acylcyclopropane-1,1,2,2-tetracarbonitriles with sodium hydrogen carbonate and alkylmercaptan in water environment results in the formation of 2-(5-amino-2-aryl-2-alkyl-sulfanyl-4-cyano-2,3-dihydrofuran-3-ylidene)propanedinitriles.

Synthesis and study of new phenolic antioxidants with nitroaromatic and heterocyclic substituents

New polyfunctional aromatic, nitroaromatic, and heterocyclic compounds linked to the 2,6-di-tert-butylphenol moiety via –NH–, –C(O)NH–, –S–, or–C=N– spacers were synthesized. These structures provide intramolecular charge transfer (ICT) and exhibit antioxidant activity. The structures of the new compounds were established by X-ray diffraction. The novel compounds were evaluated for antioxidant activity using the DPPH assay. The presence of the 2,4,6-trinitrophenyl moiety in combination with the –NH– spacer leads to a considerable increase in the antioxidant activity of 2,6-di-tert-butylphenols. These compounds are also weak lipoxygenase inhibitors. The results of this study provide an opportunity to search for new types of antioxidants with ICT.

Reaction of 1-(tetracyanocyclopropyl)alkanones with sodium and potassium hydroxides

Enolizable 1-(tetracyanocyclopropyl)alkanones reacted with aqueous alkali metal hydroxides to give, depending on the alkali concentration, 2-(5-amino-2-alkylidene-4-cyano-2,3-dihydrofuran-3-ylidene)-propanedinitriles or 2-(4-alkyl-3-amino-2-cyano-5-oxo-cyclopent-2-en-1-ylidene)propanedinitriles.

Organometallic derivatives of 2,6-di-tert-butylphenols as specific inhibitors of methyl oleate oxidation

Abstract2,6-Di-tert-butylphenols containing the Pt—SnCl3 and Pt—GeCl3 groups in the para position exert a dual effect on the oxidation of methyl oleate by molecular oxygen. Initially, these compounds act as antioxidants producing the corresponding phenoxyl radicals whose decomposition is accompanied by elimination of SnCl2 and GeCl2, which are oxidation promoters.