Home – Home – Jornals – Chemistry for Sustainable Development 2023 number 4

Biosimilarity and pharmacokinetic descriptors were obtained using SwissADME and ADMETlab 2.0 web services. Analysis of the obtained descriptors shows that, according to Lipinski's rule, quinoxalyl hydrazones of 2-hydroximino-1,3-dioxocompounds may be promising candidates for drug development for oral administration. Analysis of the pharmacokinetic descriptors of the structures studied shows that, according to the in silico predictions, the compounds can penetrate the blood-brain barrier, be absorbed in the gastrointestinal tract, bind to plasma proteins, be rapidly eliminated from target cells and inhibit CYP3A4, CYP1A2, CYP2C19 and CYP2D6 isoenzymes. The antioxidant activity of quinoxalyl hydrazone derivatives with different benzoyl, ester and acetyl moieties has been studied. Pharmacological screening of the obtained compounds was performed in vitro in the model of Fe²⁺-induced lipid peroxidation. The data of pharmacological screening indicate clearly pronounced inhibition of lipid peroxidation in the system of yolk lipoproteins by the compounds obtained, which indicates a significant contribution of quinoxalone scaffold in the manifestation of antioxidant properties. Variations in the structure of the starting 1,3-dicarbonyl compounds did not result in significant changes in the antioxidant activity of the obtained hydrazones. The compounds obtained can be promising compounds with marked antioxidant activity for further in vivo studies, including investigation of acute and chronic toxicity. The leading compound is tolyl-substituted quinoxalyl hydrazone IIb.

The validation of a standard certified method for measuring the mass fraction of oil products in soils and bottom sediments by IR spectrometry for measuring the content of oil products in sorbent samples based on ash and slag waste from thermal power engineering, and changes in the method of sample preparation in order to improve the metrological characteristics of the method are proposed. To calculate the metrological characteristics of the method to be validated, 48 measurements were carried out according to the recommendations set out in RMG 61-2010 (Appendix E). The assessment of the repeatability index was carried out according to the Cochran criterion. Grubbs statistics were used to evaluate the intralaboratory precision index. The correctness score was determined using a two-sample Student's t -test. The assessment of the accuracy indicator was performed by the selective relative standard deviation of the measurement results of the control sample. Quality indicators of the standard methodology PND F 16.1:2.2.22-98 (2005 edition): repeatability rate 8 %; index of intralaboratory precision 10 %; correctness score 15 %; accuracy rate 25 %. Quality indicators of the method being validated: repeatability rate 2.7 %; index of intralaboratory precision 2.7 %; correctness score 1.3 %; accuracy rate 5.3 %. The measurement results obtained using the developed validated method for measuring the oil product content in the samples of modified sorbent based on ash and slag wastes are more reproducible in terms of repeatability and precision, as well as more correct and accurate in comparison with the results obtained when measuring using the standard PND F method 16.1:2.2.22-98 (2005 edition).

The effect of basalt fibres on the rheometric, physical-mechanical, performance and dynamic (vibration absorbing) properties of rubber used for rail fastenings is investigated. The rubber mixture based on butadiene-methylstyrene (SKMS-30ARK), isoprene (SKI-3) and butadiene-nitrile (SKN 2655) caoutchoucs contained also vulcanising agents (sulphur, N,N′ -dithiodimorpholine, tetramethylthiuram disulphide), vulcanisation accelerator ( N-cyclohexyl-2-benzothiazole sulphenamide), vulcanisation activators (zinc oxide, stearic acid), softeners (industrial oil I-12A, rosin), antioxidants ( N-phenyl- N'-isopropyl-para-phenylenediamine, wax ZV-P, acetonanil N), fillers (kaolin, carbon black of N 220 and P 514 grades, silicon dioxide Zeosil 1165 MP) and other ingredients. The strength properties and hardness of the vulcanisates are observed to increase with an increase in the content of basalt fibres in the rubber mixture. Basalt fibres reduce changes in the elastic-strength parameters of vulcanisates after daily thermal aging in air and under the action of the standard petroleum fluid SZhR-1. The improved dynamic (vibration damping) properties are exhibited by vulcanised rubber containing 12.0 phr basalt fibres.

Physicochemical and pharmacological properties of the humic substances from the Kansk-Achinsk coal basin, the Pereyaslovskoe deposit, have been studied. The presence of polycyclic aromatic structures and aliphatic fragments with various functional groups as substituents (carboxyl, carbonyl and quinoid, phenolic, alcoholic, ether and ester, amino and amide) was established by means of UV, IR, ¹³C NMR spectroscopy, fluorimetry, and elemental analysis. It has been determined using HPLC that coal humic substances are highly hydrophilic polydisperse biopolymers with medium molecular weights. According to the indicator of microbiological purity (category 3B), the content of microorganisms does not exceed the indicators required by the State Pharmacopeia of the Russian Federation (SPh XIV edition). The content of radionuclides, toxic metals (lead, cadmium, mercury, arsenic) corresponds to the norms (according to SPh XIV edition). The presence of 11 essential elements has been established. The studied humic substances belong to the V class of hazard (low-hazard substances, according to GOST 32644-2014), do not have allergising properties and cytotoxic effect within a broad concentration range. Antioxidant, immunotropic, cytoprotective properties were established in the studies of specific pharmacological activity with various experimental models. The ability to inhibit free radicals such as hydroxyl radical (HO^•) and superoxide-anion radical (O₂^-•) should be noted, as these radicals are able to bypass the endogenous antioxidant defense systems of the body. It is concluded that the studied humic substances of the Kansk-Achinsk coal basin, the Pereyaslovskoe deposit, are safe and effective biologically active substances of natural origin for use as a promising biologically active substance in the food and pharmaceutical industries.

Bashkir linden honey is known not only for its unique aroma and delicate taste, but also for its medicinal antibacterial properties. One of the components responsible for the bactericidal properties of honey is hydrogen peroxide, which is formed as a result of enzymatic oxidation of glucose to gluconic acid by glucose oxidase, the enzyme produced by bees. However, there are no data in the literature on the studies of the peroxide antibacterial properties of Bashkir honey. The present study deals with the quantitative determination of the hydrogen peroxide content in Bashkir linden honey collected from various natural and agricultural zones of the Republic of Bashkortostan. According to the results of the melissopalynological analysis, all the studied 39 honey samples are floral monofloral linden honey. The concentration of hydrogen peroxide in all samples ranges within 0-51.97 mg/kg · h. The high diversity in the sensitivity of the investigated strains of opportunistic microorganisms Staphylococcus aureus , Escherichia coli and Pseudomonas aeruginosa to the tested samples of linden honey suggests the presence of both peroxide and non-peroxide mechanisms of antibacterial activity. Non-peroxide antibacterial activity can be represented by the honey components of bee, plant and microbial origin: organic acids, antimicrobial proteins and peptides, as well as bacteriocins.

The influence of low molecular weight nitrogenous bases (by the example of quinoline) on the composition and colloidal stability of asphaltenes in solutions and oil dispersed systems is investigated. The objects of study were model oil systems with the basic nitrogen content of 1.0-3.0 wt. %, obtained by mixing the original oil and quinoline. The content of basic nitrogen (N_bas) was determined using the method of non-aqueous potentiometric titration. Analysis of the colloidal stability of asphaltenes in solutions and oil systems was carried out by spectrophotometry. It is shown that the content of asphaltenes in oil systems is reduced by 0.22 wt. % with an increase in the content of basic nitrogen (quinoline) up to 3 wt. %. At the same time, the content of resins increases by almost 8 wt. %. With an increase in the content of quinoline in oil systems, the proportion of basic nitrogen in the asphaltenes isolated from them increases from 1.71 to 3.60 wt. %, which indicates the active participation of quinoline in the formation of supramolecular structures of asphaltenes during their precipitation with n-hexane. The presence of low molecular weight nitrogenous bases (quinoline) in oil contributes to a significant increase in the growth rate of aggregates and a decrease in the colloidal stability of oil systems.

The content of phenolic compounds (flavonols, flavans (catechins), tannins), polysaccharides (pectins, protopectins), tetraterpenes (carotenoids) and the antioxidant activity have been studied in Inula helenium L., Antennaria dioica (L.) Graertn., Ligularia macrophylla (Ledeb.) DC Echinacea purpurea (L.) Moench. cultivated in Western Siberia. Flavonol content in the leaves and inflorescences of the studied species of the Asteraceae family was determined to be 0.75-1.98 wt. %, the maximum amount was detected in the inflorescences of I. helenium. Tannins are present in the amount of 9.62-14.86 wt. %, the maximum content is observed in the leaves of A. dioica and inflorescences of E. purpurea. The amount of catechins ranges from 0.02 ( A. dioica, L. macrophylla ) to 0.13 wt. % ( E. purpurea, I. helenium ). Pectins are present at the level of 1.20 %, somewhat lower content is detected in the leaves of I. helenium and inflorescences of L. macrophylla (0.43 and 0.59 wt. %, respectively), a fairly high content of protopectins (7.89-11.88 %) in the leaves and inflorescences of the studied species exhibits no significant differences. The concentration of carotenoids in the leaves and inflorescences of L. macrophylla is almost at the same level, while in I. helenium and E. purpurea it is significantly higher in leaves, in A. dioica - in inflorescences. The indicators of the total content of phenolic antioxidants in the leaves and inflorescences of I. helenium, A. dioica, and L. macrophylla have no significant differences. According to the results of a comparison of the antioxidant capacity of the studied extracts by means of DPPH, the highest radical-binding activity is exhibited by the extracts from the leaves of I. helenium (0.46 mg/mL) and inflorescences of A. dioica (0.47 mg/mL), somewhat lower activity is exhibited by the extracts of E. purpurea (0.70-0.92 mg/mL) and L. macrophylla (1.00-1.25 mg/mL).

In order to develop the technology of eudialyte concentrate processing based on the use of sorption conversion, the patterns of metal extraction from sulphocationites saturated in the process and the regeneration of sulphocationite and solutions used for desorption for reuse are investigated. The compositions of saturated sorbents containing alkaline metals (sodium, potassium), alkaline earth and rare earth metals, titanium, zirconium (hafnium), niobium (tantalum), aluminium, iron, manganese, natural radionuclides are presented. Desorption with various solutions is investigated. It is found that niobium (tantalum) is most difficult to desorb. It is recommended to carry out two-stage desorption at a temperature of 20 ^oC: at first, desorption with a 5 M NaCl solution, in which the majority of metals contained in the sorbent are converted into solution, and then desorption of zirconium and niobium with a 1 M Н₂С₂О₄ solution. The issues of further processing of the obtained desorbates are considered. In accordance with previous studies, the impurity cake containing thorium, iron, aluminium, titanium is precipitated and separated from desorbates based on a 5 M NaCl solution through fractional neutralization, initially to pH 4, then the concentrate of rare earth elements is separated by neutralization to pH 7.5, and, finally, at pH ≥ 10, alkaline earth metals and manganese. Zirconium (hafnium) - niobium concentrate is precipitated from desorbates based on 1 M Н₂С₂О₄ solution through neutralization with NaOH to pH 10, and then zirconium (hafnium) is leached from it using Na₂CO₃ solution. It is stressed that the sorbent in the H⁺-form is formed after desorption with a 1 M Н₂С₂О₄ solution, which allows using it repeatedly to decompose eudialyte concentrate by sorption conversion. It is shown that the 1 M Н₂С₂О₄ solution can be regenerated by electrodialysis from the Na₂С₂О₄ solution obtained by precipitation of the collective zirconium (hafnium) - niobium concentrate.

The results of studies on the development of technologies for the utilisation of silica sols formed during eudialyte concentrate processing by means of sorption conversion are presented. As promising areas, the following directions have been proposed and studied: additional extraction of valuable metals from silica sols by sorption with sulphocationite; silica sol separation into silica-enriched silica gel and silica-depleted acid solution by successive freezing and thawing of the initial silica sol; the use of silica contained in silica sols to obtain wollastonite. The percentage of rare metals that can be absorbed by sulphocationite from silica sols obtained at a temperature of 80°C - the optimum temperature for the decomposition of eudialyte concentrate by sorption conversion - is found to be (%) 58.6-70.3 Ti, 46-50 Zr, 24.7-29.9 Hf, 23.5-34.7 Nb, while sodium remains in silica sol. The low degree of filling of the sorption exchange capacity of the sulphonic cation exchanger allows it to be additionally saturated in the process of sorption conversion. It is shown that the concentration of SiO₂ reached 33.0 g/L in silica gels obtained by successive freezing and thawing of silica sols. The specific effective radioactivity of silica gels is low, which allows them to be used in the production of civil building materials. Acid solutions depleted in silica, the volume of which was 72.5-81.2 % of the volume of the initial silica sols, contain up to (%) 78.3 Ti, 56 Zr, 45.1 Hf, 76.4 Nb, 92.2 Na, 100 Th, 100 U, and only 1.1-3.6 SiO₂. Such solutions after additional strengthening are suitable for reuse for the decomposition of eudialyte concentrate. The possibility of obtaining wollastonite from silica sol based on nitric acid solution without the use of autoclave equipment has been experimentally proven. The ways of regeneration of the mother liquor obtained after precipitation of the wollastonite precursor are discussed.

An economically viable and environmentally friendly method is proposed for recycling the wastes from electrical discharge cutting of the blanks obtained by the spark plasma sintering of a powdered composition based on zirconium diboride with the addition of silicon carbide, lanthanum and yttrium oxides. The wastes are ground in a flow-type centrifugal mill TsEM-7-1, and the product of milling is further consolidated by spark plasma sintering. The microstructure and phase composition of the sintered materials made from initial powder composition and the powder obtained by grinding the ceramic wastes from final machining of finished products are investigated. It is shown that the largest pieces in the wastes that cannot be ground in the mill are to be crushed preliminarily to enhance the yield of ground powder. The absence of differences in the phase composition of initial and processed powder mixtures and blanks made of them has been revealed, which demonstrates the possibility of repeated use of the wastes for spark plasma sintering of the materials formed from ceramic powders based on zirconium diboride, for the purpose of decreasing the consumption of initial components.

The features of the molecular and supramolecular structure of brown and bituminous coals at different metamorphisms stages have been determined using a complex of methods: IR spectroscopy, X-ray diffraction, the kinetics of swelling in solvents, and sorption of molecular iodine. The relations of the supramolecular structure of coals with the indicators of molecular composition are established, the evolution of coal structure in the series of metamorphism, the mechanisms of transport of solvent molecules into the volume of the organic mass of various coals are considered.

The published data are considered, and the technological aspects of a promising industrial process for the chlorine-free production of alkoxysilanes from silicon dioxide are analysed. Particular attention is paid to key issues that have not yet been considered in the literature. It is shown that the raw material base for the synthesis of alkoxysilanes can be expanded at the expense of microsilica, waste from the production of silicon and ferrosilicon. It has been experimentally confirmed that potassium hydroxide used as a catalyst for the synthesis of alkoxysilanes can be recovered and returned to the process. It has been established that the products of tetramethoxysilane (Si(OMe)₄) synthesis from silicon dioxide and dimethyl carbonate contain 55 components (among them, 45 high-boiling ones have not been identified). The main impurities in the reaction products are MeOH, CH₂O, MeOMe, and (MeO)₃SiOSi(OMe)₃. Technological prospects for the process of obtaining Si(OMe)₄ from industrial wastes are considered.

The regularities of ethoxylation of benzoic acid derivatives during interaction with polyethylene glycol through mechanochemical solid-phase synthesis in a vibrating apparatus have been studied. The conditions for carrying out mechanochemical reactions to increase the conversion degree of initial reagents into reaction products are analysed. The products of ethoxylation are characterized by IR spectroscopy, acid-base potentiometric titration, tensiometry, and dilatational rheology. It has been established that the degree of starting reagents conversion into ethoxylation products depends on the nature of the substituent and its position in the benzene ring. The degree of conversion into reaction products is higher for ortho-substituted derivatives of benzoic acid. It is shown that the salts of ethoxylated derivatives of benzoic acid exhibit pronounced surfactant properties at the air - solution interface.

The distribution of the 1^st hazard class substances and trace elements in the natural waters of the Novosibirsk urban agglomeration is investigated. A substantial role in water pollution is played in the study area not only by a large number of vehicles but also industrial enterprises. The composition of natural waters is determined as mainly hydrocarbonate calcium and hydrocarbonate calcium-magnesium, with total dissolved solids varying from 127 to 910 mg/dm³, and silicon concentration 0.14-11.61 mg/dm³. The geochemical setting changes from reducing (Eh -164.3 mV) to oxidizing (Eh 442.1 mV), pH 6.9-8.8 with O₂(sol.) content 0.48-20.28 mg/dm³. Within the city of Novosibirsk, excesses of background values for 33 elements were revealed; the concentrations of the first hazard class substances are, mg/dm³: Be (6.4·10^-6)-(1.4·10^-4), As 0.0003-0.26, Hg (8.33·10^-7)-(2.3·10^-4), Tl (6.2·10^-7)-(8.2·10^-5), U (1.3·10^-5)-0.21. The activity of radon, established in the natural waters of the city of Novosibirsk, varies from 1 to 1570 Bq/dm³. The waters under active anthropogenic load are mainly the river waters of the Inya, the Eltsovka the 2^nd, the Plyushchikha, the Eltsovka, the Kamyshenka, and the Ob. In groundwater samples, excesses over the actual normative documents and maximum permissible levels were revealed in the well in Kirov settlement (Mn - by a factor of 14, Fe - 10, As - 5), and in the Topol Gardeners Non-Commercial Partnership (Mn - by a factor of 59, Fe - 94, and As - 27).