Vol 23, No 1 (2023)
Articles
Preparation of new substituted imidazolone derivatives based on 1-(2-oxo-2-phenylethylidene)pyrrolo[3,2,1-ij]quinolin-2-ones
Abstract
This work demonstrates the possibility of obtaining new biologically active molecules containing a privileged imidazolone fragment by the Brønsted acid-catalyzed reaction of 1,3-dimethylurea with 1-(2-oxo-2-phenylethylidene)pyrrolo[3,2,1-ij]quinolin-2-ones. The presence of an active oxoylidene system in ones makes it possible to introduce these compounds into cyclization reactions with various binucleophilic agents. The choice of such an N,N-binucleophile as 1,3-dimethylurea allowed us to obtain a number of new 1-(oxoimidazolyl)pyrrolo[3,2,1-ij]quinolin2-ones in a process carried out at refl ux in acetonitrile and a tenfold excess of 1,3-dimethylurea via p-toluenesulfonic acid catalysis. It has been found that 1-(oxoimidazolyl)pyrrolo[3,2,1-ij]quinolin-2-ones in solution undergo keto-enol tautomerism. This is evidenced by the duplication of characteristic proton signals and the presence of the hydroxyl group proton signal in the region of 4.95 ppm in the 1 H NMR spectrum of the obtained compounds. Also, based on the experimental data, we have presented a possible reaction mechanism. It is assumed that the reaction proceeds through consistent intermolecular addition of 1,3-dimethylurea to 1-phenacylidenepyrrolo[3,2,1-ij]quinolin-2-ones with intramolecular cyclization, followed by elimination of a water molecule.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):4-10
4-10
4-Ethoxymethylene-2-phenyl-5(4H)-oxazolone in reactions with various heterocyclic amines
Abstract
The analysis of the literature data has showed that there is no information on the behavior in 5(4H)-oxazolones with amines under the conditions of a sealed vessel reactor, which makes it possible to obtain heterocyclic systems with diff erent amines. We have developed and presented an easy, fast, reliable and innovative method for the preparation of a new series of compounds with synthetic and biological potential, based on the interaction of 4-ethoxymethylene-2-phenyl-5(4H)-oxazolone and heterocyclic amines with diff erent ring sizes and sets heteroatoms using a sealed vessel reactor. Based on the results obtained, it has been found that the transformation proceeds by the mechanism of nucleophilic addition of Michael. The scheme of the conducted interaction has been discussed. Initially, the amino group of the amine used is attacked at the exocyclic C=C bond of the initial substrate, ethoxymethylenexazolone, proceeding with the elimination of a well-leaving ethoxy group in the form of an ethanol molecule, which leads to the fi nal 4-hetarylaminomethylidene derivatives of oxazol-5(4H)-one. In the course of the work, it has been found that the use of a sealed vessel reactor makes it possible to reduce the time of transformations, to achieve an increase in selectivity and yields of target products compared to the usual type of activation of the reaction mixture, such as boiling in ethanol. It has been shown that not only the type of activation, but also the nature of the solvent used aff ects the rate of the reaction. It has been found that under these conditions the transfor mation proceeds with the preservation of the oxazol-5(4Н)-one ring. Control over the course of reactions, determination of individuality and identifi cation of the obtained compounds have been carried out by TLC, elemental analysis, IR-, NMR spectroscopy.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):11-17
11-17
Free-radical graft copolymerization acrylamide, 2-sodium 2-acrylamido-2-methylpropane sulfonic onto chitosan
Abstract
The method presents obtaining hydrosoluble graft copolymer of complicated structure based on сhitosan, acrylamide (AM), sodium 2-acrylamido-2-methylpropane sulfonic (АМPS-Na) in order to obtain fl ocсulant which is resistant to salt of transition metals and heat temperature, and in order to use it as a reagent for oil production processes. The obvious advantages of this copolymer can be attributed to its biodegradation due to inclusion of a biopolymer into the composition of the copolymer, which is important for the preservation of ecology, and effi ciency of its synthetic analogues. The graft copolymerization acrylamide and sodium 2-acrylamido-2-methylpropane sulfonic onto active sites of chitosan has been performed under condition of high concentration monomers in nitrogen atmosphere using combined initiator system of complex composition under the following order monomers [АА]>[АМПС-Na]. Kinetic study of graft copolymerization has been carried out using thermometry methods. Attempts have been made to describe mathematically the reaction of graft monomers АM and АМPS-Na onto chitosan. The IR spectra analysis of copolymers has been carried out. The study of reaction rate and molecular characteristics of synthesized copolymers has been conducted under changing concentration of chitosan, monomers, ratio components of the initiator system and reaction temperature during synthesis. It has been determined that the averaged energy activation of copolymerization reaction was in the range of reaction temperature 10–25°С. Molecular composition and proposed structure of the grafted copolymers have been determined by the results of viscosity and sedimentation analysis. The results of this study allow to obtain grafted copolymers with specifi ed properties and structure to use them in such areas as sewage and industrial water treatment and mineral industry.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):18-27
18-27
Thin layer chromatography of some statins in aqueous organic mobile phases modified with buff er solutions
Abstract
The influence of a number of factors on the chromatographic properties of statins (atorvastatin, rosuvastatin, simvastatin) in normal-phase and reverse-phase chromatography modes has been studied by the method of the thin-layer chromatography (TLC) in order to select the most effective analytical systems for the total and separate determination of statins in pharmaceuticals. The study has been performed by ascending TLC on commercial plates with polar, weakly polar, and nonpolar phases. Efficiency and selectivity of chromatographic separation of statins have been established: the nature of the stationary phase (SF), the nature of the mobile phase (MF), the nature and concentration of the organic solvent of the mobile phase, the ionic strength of the solution. It has been revealed that the most effective SF are the reverse-phase plates RP-18, on which statins are separated with a high value of the number of theoretical plates (N) and the lowest value of the height of the equivalent theoretical plate (H). From organic solvents, the aprotic solvent acetonitrile turned out to be effective, which in the MF of the acetonitrile –water composition (70:30) gives the best results of chromatographic separation of statins. It has been found that with an increase in the ionic strength of the solution in the range of 0.1–1.5 mol (KCl), the mobility of statins changes slightly, which is accompanied by a significant blurring of chromatographic zones and deterioration of statin separation, and therefore no strong electrolyte was introduced in further studies. Binary mixtures of atorvastatin and simvastatin have been separated under selected optimal conditions. It has been found that the greatest selectivity of separation is observed in the MF acetonitrile – phosphate buffer (70:30) at pH 3. Quantitative determination of atorvastatin in «Atorvastatin-OBL», «Liprimar» and «Tulip» drugs has been carried out to optimize the chromatography conditions. The correctness and reliability of the determination has been established using the standard drug atorvastatin, Sr did not exceed 0.01–0.02.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):28-38
28-38
Electroanalytic properties of unmodified and polyaniline-modifi ed planar sensors sensitive to doxycycline
Abstract
Doxycycline has a wide range of antimicrobial and anti-infl ammatory properties and is used to treat various infectious diseases. Spectroscopic, chromatographic, electrochemical, immunoassay and other methods are used to determine tetracycline antibiotics in various objects. Planar sensors allow express detection of antibiotics in small sample volumes. Planar potentiometric sensors based on ion associations doxycycline – tetraphenylborate (Copt = 2–3%), modifi er – polyaniline, for the quantitative determination of doxycycline have been developed. It has been found that for non-modifi cated sensors, the linearity intervals of electrode functions are 1×10 -4 – 5×10 -3 M, Cmin – 5,0×10-5 M, angular coeffi cients – 50±2 mV/pC, response time – 25 s. It is shown that the introduction of a modifi er into the carbon-containing ink of sensors leads to the stabilization of their potential, to an increase in the angular coeffi cients of electrode functions (56±1), reduced response time (20 s) and reduced detection limit (4.0 ×10-5 M). It is shown that the introduction of the modifi er into the carbon-containing ink of the sensors leads to stabilization of their potential, to an increase in the angular coeffi cients of electrode functions (56±1), a decrease in response time (20 seconds) and a decrease in the detection limit (4.0 ×10-5 M). Doxycycline sensitive sensors have selectivity to the base ion (Ki/j < < 1) and inorganic cations (Ki/j (K+) = 0.61; Ki/j (Na+) = 0,01; Ki/j (Mg 2+) = 0,01; Ki/j (Ca2+) = 0.09), and indicate the possibility of determining doxycycline in human biological fl uids. Against the background of oral liquid, the angular coeffi cients of electrode functions (45±1 mV/pS) decrease, which is associated with the background infl uence of oral liquid. The developed planar sensors are used to determination doxycycline in medicinal and biological media.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):39-50
39-50
Determination of atmospheric air pollution by physical and chemical characteristics of snowmelt
Abstract
The state of the environment in cities is determined by the degree of pollution of individual components of the environment. Geochemical anomalies in urban agglomerations are often formed in pollution depositing media such as soil, snow cover, bottom sediments. The purpose of the study is environmental monitoring of anthropogenic impact in diff erent areas of Smolensk and Vyazma according to the physical and chemical characteristics of melted snow. Snow was chosen as the object of the study, because it accumulates many substances entering the atmosphere, and subsequently can become a source of secondary pollution of the soil cover, underground and surface waters. The study determined organoleptic parameters (smell, color, turbidity, the presence of sediment in melt water), chemical parameters (the number of suspended particles, pH, total rigidity and mineralization, the amount of organic substances).The presence of chloride ions (Cl- ), sulfate ions (SO4 2-), nitrate ions (NO3-), nitrite ions (NO2 - ), bicarbonate ions (HCO3 - ) and ions of some heavy metals (Pb2+, Cu2+, Fe3+) have been determined. Bioindication of the studied samples on watercress has been carried out in parallel. A low level of air pollution in Smolensk and Vyazma has been established. The greatest contribution to the formation of the level of pollution in the cold period of the year is made by suspended substances, iron and manganese compounds in concentrations exceeding the maximum permissible concentration. The concentration of impurities depends on the distance from large industrial objects, automobile and railway objects, sanitary and technical condition and cleaning regime of the territory. The courtyard territories of Smolensk and Vyazma are the cleanest. The largest part of snow pollution is provided by the thermoelectric power stations and transport. Samples taken near car parks, railway tracks and near the thermoelectric power stations were the most unfavorable.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):51-61
51-61
Acid extraction of radionuclides from soil samples using autoclave decomposition
Abstract
The specifi cs of the nuclear tests carried out on the territory of the former Semipalatinsk test site (STS) led to the emergence of various sites that diff er in levels of radioactive contamination and radionuclide composition. This also led to a signifi cant diff erence in the solubility of radioactive particles. Traditionally, the “Experimental Field” testing ground was characterized by the presence of sparingly soluble, vitrifi ed particles, which was determined by the features inherent in ground tests of nuclear weapons, namely, the interaction of the high-temperature explosion region with soil particles. The presence of such sparingly soluble particles in the soil cover makes it impossible to use 6–8 М HCl and 7–8 М HNO3 solutions which are most often used radiochemical analysis to determine the content of 90Sr and 239+240Pu. This paper considers methods for the acid extraction of anthropogenic radionuclides from soils of the STS using autoclaving. The aim of the research is to develop a method for the acid extraction of anthropogenic radionuclides from enlarged soil samples using autoclave decomposition. A blank soil sample was used to determine the optimal autoclave decomposition parameters; to test the acid extraction method, a soil sample was taken from the territory of the “experimental fi eld” testing ground. The radionuclide 137Cs has been used as the most optimal indicator of acid extraction due to its strong fi xation on clay and mineral soil particles and ease of detection by the gamma radiation. Autoclave decomposition has been carried out by dissolving the studied samples in a mixture of mineral acids (HCl, HNO3, HF, H2SO4). The specifi c activity of radionuclide has been determined on a BE3830 gamma spectrometer with a high-purity germanium detector (Canberra, USA), the amount of undecomposed soil residue has been determined gravimetrically (PA214C analytical balance, Ohaus, USA). The data obtained indicate that the most complete extraction of 137Cs occurs when using concentrated HF solutions (individually or in a mixture with other mineral acids). The degree of extraction of 137Cs varied from 85 to 100%. The worst results have been shown by the use of a mixture of acids 3HCl:HNO3. In this case the degree of extraction of 137Cs did not exceed 20%. The effi ciency of decomposition of soil samples weighing 10 g with a concentrated solution of HF at a temperature of 120 to 160 ºC was ≥95%.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):62-69
62-69
Study of adsorption of cadmium ions from solutions on natural and modifi ed diatomites
Abstract
The search for new technologies for the purification of natural and waste water does not lose its relevance. Biologically, heavy metals are among the most dangerous pollutants. The highest toxicity among them has cadmium, causing serious environmental problems during technogenic pollution of the aquatic environment, and its extraction is an urgent task. The analysis of foreign studies on the extraction of cadmium ions is carried out. The adsorption of cadmium has been studied by many authors and described in many works on kaolin oxides / iron hydroxides, in contrast to siliceous rocks. In this work, the use of the sorption method is proposed for the purification of wastewater from ions of heavy metals. The aim was to study the sorption activity of diatomite in relation to cadmium ions. The studies have been carried out under static conditions. The processes of physicochemical modification of diatomite for the extraction of cadmium ions from aqueous solutions have been investigated. The influence of time and pH on the value of sorption has been studied. The optimal conditions for sorption extraction have been determined. Adsorption isotherms have been constructed, and quantitative characteristics of the values of adsorption of cadmium ions on the surface of modified sorbents have been obtained. The fundamental possibility of using diatomites for the purification of cadmium-containing wastewater has been assessed. Based on the data obtained, it can be concluded that acid activation does not promote adsorption (even negative adsorption is observed), which confirms the mobility of cadmium in the low pH region, it can be assumed that only an increase in alkalinity to the possibility of formation of hydroxocadmium (CdOH)+. Thermal, shows stable adsorption in relation to Cd+2, which suggests the possibility of using such activation of cadmium diatomite and other metals, that is, with complex pollution.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):70-76
70-76
Study of patterns of accumulation of the most dangerous ecotoxicants in wild medicinal plant raw materials of various ecotopes of the Voronezh region
Abstract
Voronezh region is one of the most important areas of agriculture and crop production. The purpose of the study was to study the patterns of accumulation of the most dangerous heavy metals in wild medicinal plant raw materials of various ecotopes of the Voronezh region. The accumulation of heavy metals (lead, mercury, cadmium, nickel, copper, zinc, cobalt, chromium) and arsenic was studied, using an example of 10 types of medicinal plant raw materials, which were produced in 51 ecotopes of the Voronezh region. When analyzing the average values of the accumulation coeffi cients of heavy metals and arsenic by all studied types of medicinal plant raw materials, it is possible to build up a series of decreases in the total average accumulation effi ciency of the determined elements for these plants, which is as follows: zinc> copper > cadmium > cobalt > nickel > arsenic > chromium > lead > mercury. When analyzing the values of accumulation coeffi cients, rows of decreasing effi ciency of accumulation of elements in all types of medicinal plant raw materials studied are constructed. A detailed analysis of the characteristics of the accumulation of heavy metals and arsenic from soils in medicinal plant raw materials showed the presence of aclose positive relationship between concentrations in soil and plants for most of the determined elements, which indicates the predominant contamination of plant raw materials through the soil.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):77-85
77-85
Gold nanostars as a photoagent under the antimicrobial action of infrared (808 nm) laser radiation
Abstract
Gold nanostars with an average core diameter of 122,2 nm and a spike length of 114,6 nm were synthesized and characterized at a concentration of 5,36×1010 pcs/ml with an absorption maximum of 840 nm. Gold nanostars were coated with thiolated polyethylene glycol, its amount was about 8×104 molecules per 1 particle and about 4,4×1015 molecules/ml in the colloid. The zeta potential of gold nanostars coated with PEG-SH was −2.3 mV. The combined eff ect of gold nanostars and low-intensity infrared (808 nm) laser radiation on the bacteria Staphylococcus aureus 209 P and Escherichia coli 113-13 has been studied. Incubation of suspensions of microorganisms in the presence of nanoparticles without access to light did not lead to a signifi cant reduction in the number of bacteria. Irradiation for 30 min of bacterial suspensions containing nanoparticles caused the death of 39% of the S. aureus population and 80% of the E. coli population. During the thermometry of the studied suspensions, it was found that the temperature increase is dose-dependent. The increase in temperature of the control samples that did not contain photothermal agents did not exceed 1 °C in both cases throughout the entire time of the experiment. For suspensions of bacteria (equally S. aureus and E. coli) incubated with gold nanostars during irradiation, an increase in temperature indicators, on average, by 4 °C was revealed. The more pronounced antibacterial activity of the combination of gold nanostars and infrared (808 nm) laser radiation against E. coli can also be explained by the greater sensitivity of gram-negative microorganisms to photothermal exposure.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):86-93
86-93
Molecular mechanisms of the opening of the blood-brain barrier in rodents by means of sound
Abstract
In this study, in experiments on 35 healthy male mice of the C57BL/6 line weighing 25±3 g, it was shown that loud sound/music for 2 hours causes a temporary increase in the permeability of the blood-brain barrier (BBB) in rodents. To investigate changes in the permeability of the blood-brain barrier, the molecular mechanisms responsible for its discovery were investigated using laser speckle-contrast imaging of regional cerebral blood fl ow (rCBF), immunohistochemical analysis and biochemical analysis of adrenaline in blood plasma. With a sound-dependent increase in the permeability of the blood-brain barrier, there was a decrease in signal intensity from CLND-5, Occ, JAM and an increase in the signal from ZO-1. However, after 4 hours, the signal intensity from the studied proteins was restored, which may be due to their internalization. The results of the study of the eff ects of music and sound on of BBB in the intact brain require a revision of traditional knowledge about the barrier functions of the brain and open up new opportunities for non-invasive drug delivery strategies. They also may off er some insight into the etiology of brain disorders that follow inadvertent or deliberate exposure to very loud sounds, i.e. battle or rock concerts.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):94-103
94-103
Colormetric system for monitoring the growth of microalgae Dunaliella salina under laboratory conditions
Abstract
The brackish microalgae Dunaliella salina, being an extremophilic halophyte, is a promising object for biotechnological production. The aim of this work is to develop a methodology for non-destructive control of the development of a microalgae culture under conditions of balanced growth during periodic cultivation on plates. Before the start of the experiment, the microalgae culture was synchronized. The quantitative content of chlorophylls a and b, as well as carotenoids, was determined spectrophotometrically in alcohol extracts. During cultivation, time-lapse images were recorded on a smartphone camera. The basis of the colorimetric evaluation is the analysis of the time series of images in the RGB color model. It is shown that the ratio of colors correlates to a high degree with the content of the determined main plant pigments – chlorophylls and carotenoids, and with the data of spectrophotometric measurements of live suspensions. The changes in the blue channel are the most pronounced, the least being in the green channel. The logarithm of color intensity is linearly dependent on the degree of dilution of the culture. The developed method for real-time monitoring of the development dynamics of the D. salina microalgae culture makes it possible to build growth curves and solve multiparametric problems to optimize the cultivation of microalgae, including when working with large arrays of samples.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):104-109
104-109
The ecological and coenotic features of plant communities containing Colchicum bulbocodium subsp. versicolor (Colchicaceae) in the Lower Volga region
Abstract
The article presents a phytocoenotic description of 23 plant communities with Colchicum bulbocodium subsp. versicolor studied during the period of mass fl owering in 2014–2018. It was found that, across the Lower Volga region, the studied communities with C. bulbocodium subsp. versicolor are mostly confi ned to the slopes of south- and east-facing arroyos and more seldom to the southern and northern hill slopes, plains, arroyo and liman bases, and fl oodmeadows. During the period of mass fl owering, 207 vascular plants were detected in the studied communities. Every community description included 9 to 36 species. Biological diversity was assessed with the Shannon index and polydominance index; the degree of dominance was measured with the Simpson index. The species similarity of the communities was evaluated through pairwise comparison with the Jaccard coeffi cient. It was revealed that C. bulbocodium subsp. versicolor occurs in communities varying in diversity and species composition. The subspecies is not confi ned to specifi c phytocoenoses. It usually grows on rich and, more seldom, fairly rich and slightly saline soils. Their alluviality is more often weak rather than moderate. Watering usually corresponds to the dry steppe or semi-desert climate type, rarely to the middle steppe type, being moderately variable and in some cases highly variable. The impact of grazing is usually weak, but it is either moderate or strong in some communities. The communities with C. bulbocodium subsp. versicolor are dominated by hemicryptophytes: mostly tap-root, short-rhizome and long-rhizome herbaceous perennials. In phytocoenotic terms, most species belong to the zonal type of vegetation, namely steppe vegetation. The participation of meadow species is prominent. The share of weed species is rather high, which indicates a signifi cant anthropogenic load on the studied communities.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2023;23(1):110-123
110-123