Vol 24, No 4 (2024)
Chemistry
Excitation energy transfer in europium complexes with doxycycline in the presence of surfactant micelles and silver nanoparticles
Abstract
Doxycycline is a broad-spectrum tetracycline antibiotic used to treat infections in humans and in veterinary medicine as a prophylactic drug and growth stimulant. For this reason, residual amounts of antibiotics in milk, meat and other food products can cause resistance and the development of allergies. In this regard, constant monitoring of residual contents of tetracyclines in food products, environmental objects, and biological fl uids is required. The purpose of this work was to study the eff ect of spherical silver nanoparticles and surfactant micelles on the intensity of sensitized fl uorescence of europium ion complexes with doxycycline and to develop a new sensitive and simple method for the fl uorimetric determination of doxycycline in solutions. As a result of the simultaneous infl uence of the energy of an external excitation source and the surface plasmon resonance of silver nanoparticles on doxycycline, the intensity of its fl uorescence increases. The probability of the ligand transition to the excited state increases signifi cantly, which contributes to the most effi cient implementation of intramolecular excitation energy transfer in the Eu3+ complex with doxycycline. We have shown that in the presence of silver nanoparticles and Eu3+ ions, the fl uorescence intensity of an analytical system containing doxycycline increases 125 times. In the presence of the nonionic surfactant Tween-80, the sensitized fl uorescence signal of the Eu3+ chelate with doxycycline increases by more than 19 times. Solubilization of the components of the analytical reaction into micelles of surfactants helps to change their protolytic properties, dehydration, increase the stability of the complexes, and the effi ciency of intramolecular energy transfer. In the combined presence of Tween-80 surfactant micelles and silver nanoparticles, an additional 27-fold increase in the fl uorescence intensity of the metal ion chelate with doxycycline is observed. Based on the conducted research, a method for the fl uorimetric determination of doxycycline using Tween-80 micelles, silver nanoclusters and Eu3+ ions in natural water has been proposed. The range of detectable concentrations is 1.0·10-7–1.0·10-5 M, detection limit (Limit of Detection) 6.0·10-8М (3 σ). The correctness of the defi nition has been controlled by the “entered–found” method.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2024;24(4):364-373
364-373
Some cyano-substituted spiro-linked pyrazolines and pyrrolidines with antimicrobial activity
Abstract
This work summarizes one-pot synthetic approaches to spiro-fused (di)azoles, which are promising in terms of studying biological activity. Proposed approaches involve condensation reactions of (hetero)cyclic ketones, methylene active moieties, and N-nucleophiles, occurring under mild conditions by both stepwise and concerted mechanisms. The antimicrobial activity of signals from the proposed approaches of cyanosubstituted spiro-membered pyrazolines and pyrrolidines against gram-negative (P. aeruginosa, E. coli) and gram-positive (S. aureus) losses has been studied (EC50 determination (μg/ml)).The well-known component of broad-spectrum antimicrobial drugs, ciprofl oxacin, has been used as a control. It has been found that 3-amino-2-(4-nitrophenyl)-1,2-diazaspiro[4.5]dec-3-ene-4-carbonitrile exhibits the greatest inhibitory eff ect against selected gram-negative bacteria. In this case, the phenyl substituent at the second nitrogen atom of the pyrazoline ring plays an important role, since its replacement with an aroyl fragment reduces the studied eff ect by several tens of times, regardless of the type of the second ring. Substituted spiroindolinopyrrolizidinedicarbonitriles, containing cyano groups at the 2nd carbon atom of the pyrrolizidine ring and a phenyl substituent at the fi rst, also exhibit a moderate and high inhibitory eff ect. For pairs with the same type of substituent position, compounds containing a 3,4 Cl2 substituent in the phenyl fragment have the greatest antimicrobial activity.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2024;24(4):374-379
374-379
Methods for calculating specifi c electrical conductivity of the LiF+NaF mixtures melt
Abstract
The calculation of the specifi c electrical conductivity of lithium and sodium fl uorides mixtures melts is presented. The Iinterest in the LiF–NaF system melts is determined by their practical signifi cance. Melts of LiF+NaF mixtures are used in heat-storing compositions and in metallurgy. They are part of various multicomponent systems. The specifi c electrical conductivity calculation by isoconcentration, isothermal and interpolation methods is given for LiF+NaF mixtures melts of various compositions using known reference data for the temperature range 1020...1340 K. A calculation has been performed for the eutectic composition. The resulting analytical equations have been used to describe and calculate the specifi c electrical conductivity of the eutectic mixture for temperatures 5°, 10°, 50°, 75°, 100° above the liquidus. The specifi c electrical conductivity of the eutectic mixture melt is calculated on isotherms by interpolation for the isoconcentration dependences of hypoeutectic and hypereutectic mixtures. Isotherms of electrical conductivity (1020...1340 K) of melts depending on the content of LiF and NaF components are described by a third-degree polynomial. Depending on the temperature, the coeffi cients in the resulting equation change linearly. A comparison has been made of the values of specifi c electrical conductivity ϰ(LiF+NaF), calculated from the obtained equations. The description of ϰ(LiF+NaF) by isoconcentration and isothermal methods has showed satisfactory convergence of calculation results and makes it possible to calculate the specifi c electrical conductivity of LiF+NaF mixtures melts of any given composition, including eutectic.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2024;24(4):380-391
380-391
Graft polymerization of methacrylic and acrylic acids on preirradiated polyethylene fi lm and evaluation of strength characteristics of graft copolymers
Abstract
Membranes on the basis of synthetic and modifi ed natural polymeric substrates are widely used in separation and fi ltration processes and as conductive or isolating media. Grafting acrylic monomers onto polymeric substrates is an eff ective method of their production. Polyethylene, a synthetic polymer, has high strength properties, thermal and chemical resistance, which makes it a good substrate for various products. The objective of this work was producing ion exchange grafted fi lms on the basis of preirradiated polyethylene grafted with methacrylic and acrylic acids, and regulation of their properties during synthesis. Methacrylic and acrylic acids have been grafted onto preirradiated polyethylene fi lm (thickness 30±5 μm) in concentrated solutions with a monomer content up to 45 wt.% in the presence of iron (II) ions at temperatures within 90–97 °C. The concentration of the monomers, initiators, additives of modifi ers and the reaction temperature have been varied. The kinetics of grafting polymerization, grafting degree and the degree of swelling in an electrolyte have been studied by a gravimetric method. The infl uence of the nature of grafted monomers, the concentration of components and modifi ers on the above quantities and mechanical properties of the grafted fi lms have been established. Our modifi ed fi lms have been characterized by FTIR spectroscopy, chemical elemental analysis, scanning electron microscopy (the relief and surface morphology), and their mechanical properties have been assessed by the uniaxial tensile method. The study of the resulting ion exchange composites for the purpose of further application in the technology of treating waste and industrial waters from polyvalent metals and as ion conducting media will be carried out in the future.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2024;24(4):392-401
392-401
Influence of time factor on adhesion and electrosurface properties of conductor and dielectric after plasma chemical activation of surface
Abstract
The paper presents the results of measuring the surface adhesion fi gures of a dielectric (non-foiled glass-cloth-base laminate) and a conductor (foiled glass-cloth-base laminate) obtained by the adhesive tape tear-off method, as well as the surface potential depending on the time of storage of samples in natural conditions after activation of their surface by plasma-chemical etching. The obtained dependences are complex declining functions of time. We have attributed the jump in the adhesion fi gures of the activated surface, compared to the unactivated surface, immediately after its activation to the acquisition of a developed morphology by the surface, and the jump in the potential to the acquisition of surface charge. On the obtained dependences we have selected the initial and fi nal areas, which we have approximated by empirical linear equations. By the intersection of the approximating lines we have determined the conditional times of transition from the initial fast-declining section to the fi nal slow-declining section. It has turned out that these times coincide for time dependences of the adhesion fi gures and potential for both studied samples. A correlation between the parameters of the equations for the adhesion fi gures and surface potential is shown. An attempt is made to explain the observed dependences by the acquisition of electric charge by the surface and adsorption of substance from the environment.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2024;24(4):402-414
402-414
Biology
Results of monitoring of reintroduced populations of Calophaca wolgarica in the Saratov region
Abstract
For 11 years, the staff of the Scientifi c Research Center “Botanical Garden” of SSU named after N.G. Chernyshevsky have been reintroducing a rare protected plant, Calophaca wolgarica (L. fi l.) DC., into potentially suitable places in the Saratov Region. This species is considered extinct in the region. Restoration of the species in the Saratov Region will expand its range, increase the biodiversity of the local fl ora and enrich biogeocenoses. Seed material for the reintroduction of C. wolgarica was collected from natural cenopopulations in the Volgograd Region. In 2013–2015 the seeds were sown in Voskresensky (near the village of Ershovka) and Krasnoarmeysky (the villages of Kamenka, Mordovo, Rogatkino, Belogorskoye) districts of the Saratov right bank, in Perelyubsky (the village of Kutseba), Pugachevsky (near the village of Maksyutovo), Fyodorovsky (the village of Dolina) districts of the left bank. In 2020, sowing was carried out in Pugachevsky (the villages of Maksyutovo, Solyanka) and Yershovsky (the village of Novorozhenka) districts. Seedlings were planted in Krasnoarmeysky district (the villages of Rogatkino, Kamenka), but they died in the year of planting. The seeds germinated in Pugachevsky, Fyodorovsky, Yershovsky and Krasnoarmeysky districts. To analyze the results of C. wolgarica reintroduction in the Saratov region, the dynamics of the number of individuals, their ontogenetic and vitality structure were assessed in the created populations. The vitality structure was analyzed for individuals whose ontogenetic state was predominant in terms of numbers for a specifi c year of observations. According to the results of the studies conducted in the period from 2016 to 2024, out of six districts selected as sites for the reintroduction of C. wolgarica, three – Pugachevskiy, Fyodorovsky and Yershovsky – are suitable for the growth of this species, and reintroduction is promising here. In two reintroduction populations from Pugachevskiy and Fyodorovsky districts, some of the plants have reached the generative period. These populations are potentially capable of self-sustaining. The most favorable habitats for C. wolgarica are located in the Pugachevskiy district.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2024;24(4):415-429
415-429
Phylogeographic characterization of scorpions of the genus Mesobuthus Vachon, 1950
Abstract
The study of zoogeographic characteristics in combination with the use of modern methods for assessing phylogenetic relationships allowed us to examine in detail the phylogeographic structure in scorpions of the genus Mesobuthus. In this work, to assess phylogenetic relationships, we used the decoded sequences of the COI gene fragment obtained by the team of authors in collaborative work and deposited in the Genbank database (NCBI). Previously published results of zoogeographic studies, due to the lack of data on the distribution of species of this genus, did not fully refl ect the zoogeographic structure of the genus Mesobuthus. Therefore, the previously typifi ed ranges of some species of the genus Mesobuthus were revised in this work. For this purpose, specimens from the collection of the Zoological Institute of the Russian Academy of Sciences were studied. To establish the zoogeographic position of the genus Mesobuthus, the biogeographic zoning of the Palaearctic, proposed by Emelyanov A. F. and Krivokhatsky V. A., was chosen. According to the results of the study, fi ve species groups (phillipsii, kirmanensis, eupeus, afghanus, thersites) were identifi ed in the genus Mesobuthus using phylogenetic analysis. The zoogeographic analysis identifi ed two clusters consisting of eight elemental faunas. In addition, transition zones between the North Central Asian and Iranian-Mekranian elemental faunas, as well as between the Khorasan-Girkan and South Turkana-Afghan elemental faunas were identifi ed. In this study, based on the dates obtained, it was found that in scorpions of the genus Mesobuthus, the hypothetical center of origin coincides with the modern chorological center, which is the Iranian-Mekranian elemental fauna. Phylogenetic relationships between fi ve groups of species prove that the genus Mesobuthus spread from the Iranian-Mekranian elemental fauna to the north, forming the other elemental faunas. Also, it is established that the main processes of Mesobuthus genus faunagenesis fall on the period from the middle Miocene to the late Pliocene.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2024;24(4):430-438
430-438
Photostimulation as a therapy method for spinal cord contusion while asleep and awake
Abstract
Traumatic spinal cord injury is one of the most complex problems in modern medicine, characterized by a signifi cant number of severe consequences and complications, development of traumatic spinal cord disease with a complex of structural and functional disorders leading to limited self-care and mobility, persistent endocrine shifts and changes in internal organs and systems, loss of control of pelvic functions, high mortality rates, and an extremely high level of social and psychological maladaptation of patients. Taking into account the fact that lymphatic drainage processes in the brain are activated during sleep, attention was given to comparing the eff ects of phototherapy of injured spinal cord in mice receiving treatment while asleep or awake. Photobiomodulation therapy was used as an anti-infl ammatory and non-invasive treatment with minimal side eff ects. In the course of the study we established the presence of lymphatic structures in the animals’ spinal cord tissues. In a number of phototherapeutic eff ects during sleep we observed the following: improvement of morphological parameters of spinal cord tissues and activation of lymphatic drainage processes in the spinal cord.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2024;24(4):439-447
439-447
Study of the influence of various physiologically active substances on changes in the lipid composition and phospholipase activity of damaged somatic nerves
Abstract
The changes in lipid composition and phospholipase activity in damaged somatic nerves were studied against the background of the action of potassium hyaluronate and insulin-like growth factor-1. It has been shown that nerve cutting is accompanied by an increase in phospholipase A2 activity, resulting in an accumulation of lysophospholipids and free fatty acids, as well as an increase in phosphatidylinositol levels and a decrease in diacylglycerol content, which is most likely due to inactivation of phosphoinositide-specifi c phospholipase C against the background of injury to the nerve conductor. The introduction of potassium hyaluronate and insulin-like growth factor-1 enhances the recovery processes in the injured nerve conductor, however, the mechanisms of their action remain diff erent. According to the literature data and the results of our own research, the action of potassium hyaluronate and insulin-like growth factor-1 is realized as a result of the launch of signaling pathways associated with the regulation of the activity of enzymes from the phospholipase family. At the same time, our data on a decrease in the activity of phospholipase A2 and the absence of signifi cant changes in the level of phosphatidylinositol and diacylglycerol indicate that potassium hyaluronate most likely exerts its eff ect through the PL A2 -mediated pathway. In addition, it was shown that against the background of the action of IGF-1, an intensifi cation of phosphoinositide metabolism is observed, which is explained by the activation of phosphoinositidespecifi c phospholipase C. According to the literature, the launch of the phospholipase C-mediated mechanism is accompanied by the formation of components of the phosphatidylinositol 3-kinase signaling pathway involved in stimulation of the expression of various transcription factors necessary for axonal regeneration and restoration of the functioning of injured nerve conductors.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2024;24(4):448-460
448-460
Ektacytometry: Characterization of erythrocytes of residents of KhMAO-Yugra treated with natural zeolites
Abstract
The effect of a diet containing natural zeolite (clinoptilolite) on the deformability of red blood cells of volunteers of both sexes, of a wide age range living in KhMAO-Yugra (Khanty-Mansiysk), was studied. Natural zeolites, according to literature data, have antioxidant, membrane-protective and hematostimulating properties. It has been shown that the use of zeolite powder by volunteers for 30 days causes an increase in the erythrocyte deformability index (determined by laser diff ractometry) compared to measurements taken before the start of the study. Such changes were the result of a signifi cant increase in erythropoiesis and a decrease in lipoperoxidation processes. The results obtained indicate the multifaceted role of zeolites in ensuring the normal functioning of the human body living in areas with uncomfortable climatic and geographical conditions.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2024;24(4):461-472
461-472
Ecology
On the status of plant populations in the South of the Middle Volga region (Russia) from the Annexes of the “Convention on International Trade in Endangered Species of Wild Fauna and Flora”
Abstract
The article provides information on the current status of populations of 29 plant species from the Orchidaceae family in the south of the Middle Volga region (within the Penza, Samara and Ulyanovsk regions) from Annex II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES): Cephalanthera longifolia (L.) Fritsch, Cephalanthera rubra (L.) Rich., Corallorhiza trifida Chatel., Cypripedium calceolus L., Cypripedium guttatum Sw., Cypripedium macranthos Sw., Cypripedium ventricosum Sw., Dactylorhiza fuchsii (Druce) Soo, Dactylorhiza incarnata (L.) Soo, Dactylorhiza maculata (L.) Soo, Dactylorhiza russowii (Klinge) Holub, Dactylorhiza viridis (L.) R. M. Bateman, Pridgeon et M. W. Chase, Epipactis atrorubens (Hoffm.) Besser, Epipactis helleborine (L.) Crantz, Epipactis palustris (L.) Crantz, Epipogium aphyllum Sw., Goodyera repens (L.) R. Br., Gymnadenia conopsea (L.) R. Br., Hammarbya palu dosa (L.) Kuntze, Herminium monorchis (L.) R. Br., Liparis loeselii (L.) Rich., Malaxis monophyllos (L.) Sw., Neotinea ustulata (L.) R. M. Bateman, Pridgeon et M. W. Chase, Neottia nidus-avis (L.) Rich., Neottia ovata (L.) Bluff et Fingerh., Orchis militaris L., Platanthera bifolia (L.) Rich., Platanthera chlorantha (Custer) Rchb., Ponerorchis cucullata (L.) X. H. Jin, Schuit. et W. T. Jin.
Izvestiya of Saratov University. New series. Series: Chemistry. Biology. Ecology. 2024;24(4):473-480
473-480