Antioxidant activity is an important characteristic of plant extracts The paper presents the results of research the antioxidant properties and the total content of polyphenolic components of extracts from wood greenery of fir (Abies sibirica), spruce (Picea abies) and pine (Pínus sylvéstris), obtained by an environmentally friendly emulsion method using an aqueous alkaline solution as an extractant, were determined. The total content of phenolic components was determined using the Folin-Ciocalteu reagent, the total content of flavonoids was determined by a complexation reaction with aluminum chloride, and the total antioxidant activity was determined using the phosphomolybdate method. It is established that emulsion extracts of coniferous wood greenery have antioxidant activity, and an assessment was made of changes in the activity of the extracts during storage.
This article presents a comparative analysis of the chemical composition, biological activity, and applications of two main types of products derived from Melissa officinalis: essential oil and extracts. Our analysis reveals the complementarity of their properties, which is critical for product selection based on the intended application. The essential oil, rich in volatile terpenoids (citral, citronellal), exhibits pronounced antimicrobial (antibacterial, antifungal) activity and sedative effects upon inhalation. Conversely, the extracts primarily contain non-volatile phenolic compounds (rosmarinic acid, flavonoids) and triterpenes, demonstrating strong antioxidant, anti-inflammatory, neuroprotective, and anxiolytic activities when administered orally. Both products are active against herpes simplex virus and possess spasmolytic properties. Toxicity studies on animal models indicate moderate acute toxicity of the essential oil and very low toxicity of aqueous extracts; however, hydrosolvent extracts at high doses can cause liver and kidney damage, highlighting the dependence of safety on the extraction method. Aqueous extracts of Melissa did not show genotoxic or teratogenic effects. In the food industry, essential oil is used as a flavoring agent and potential preservative, often employing encapsulation technologies to improve stability. Extracts are applied as functional ingredients in supplements and fortified products to impart antioxidant and calming properties, requiring standardization and addressing issues of bioavailability and regulatory approval.
The genus Populus L. (Salicaceae family) is widespread in Europe and Asia and prefers a warm and moderately cold climate more often for growing. Poplar plants have a rich chemical composition and contain mainly compounds of a phenolic nature: simple phenols, phenolic carboxylic acids and their derivatives, phenylpropanoids, including hydroxycinnamic acids, flavonoids, including flavanones (dominated by compounds pinocembrin, pinostrobin), flavanonols, flavones, flavonols, chalcones and dihydrochalcones. The component composition of the buds of the genus Populus L. it is very complex and is specific to each species. Moreover, the amount of phenolic compounds depends on the geographical region of growth, climate, sampling time, as well as on the chosen solvent and extraction method. Due to their rich component composition of biologically active compounds, the kidneys of five species of the genus Populus L. are included in the State Pharmacopoeia of the Russian Federation and are used as a remedy with antimicrobial, antifungal and anti-inflammatory effects. One of the promising species of the genus Populus L. is the red-nerved poplar (Populus rubrinervis Hort. Alb.), whose buds reach a length of up to 14 mm. Previously, we found antimicrobial, antifungal and diuretic properties for water-alcohol extracts of the buds of the Populus rubrinervis. In addition, the TLC method detected pinostrobin in the alcoholic extraction of the buds of this plant, and also determined the quantitative content of phenolic compounds in the studied raw materials – 6.91%. Eight compounds were isolated for the first time by methods of circulating chloroform extraction (Soxlet apparatus) and subsequent adsorption column chromatography on silica gel of chloroform extraction from the buds of Populus rubrinervis: pinostrobin (5-hydroxy-7-methoxyflavanone), pinocembrin (5,7-dihydroxyflavanone), alpinone (3,5-dihydroxy-7-methoxyflavanone), pinobanksin (3,5,7-trihydroxyflavanone), rhamnocitrin (3,5,4'-trihydroxy-7-methoxyflavone), 2',6'-dihydroxy-4'-methoxychalcone, 2',4',6'-trihydroxychalcone and cinnamic acid. The obtained compounds were characterized using UV, 1H NMR, 13C NMR spectroscopy and mass spectrometry. It was determined, that the flavonoids are the dominant phenolic components of the raw materials of the studied plant.
For the first time, various fractions of polysaccharide complexes were isolated from the grains of a local and three introduced South Korean cultivars of Panicum miliaceum. Their qualitative and quantitative monosaccharide compositions were determined. The isolated fractions were represented by water-soluble polysaccharides (1.0–22.0%), pectic substances (5.5–21.0%), and hemicelluloses (9.0–15.5%). The main monosaccharides were identified as Glc, Man, Ara, Xyl, Rha, Gal, and UAc, indicating the structural diversity of the isolated compounds. The antimicrobial activity of the obtained fractions was studied: water-soluble polysaccharides from the Yongyang cultivar and pectic substances from Suwon 5 F2 exhibited pronounced antimicrobial activity against Pseudomonas aeruginosa (strain No. 003841/114), comparable to that of cefazolin. The obtained results confirm the potential of P. miliaceum polysaccharides as a source of natural biologically active compounds.
The paper studies the process of thermal decomposition of buckwheat husk using thermogravimetry, FTIR spectroscopy and kinetic analysis. The process of thermal decomposition at three heating rates of 5, 10 and 20 °C/min consists of the stages of drying, removal of volatile substances and carbonization. Most of the gaseous products (CO2, CO) were released at the main stage of pyrolysis at a decomposition temperature of 270–440 °C, which was accompanied by the greatest mass loss. To calculate the kinetic parameters of thermal decomposition of buckwheat husk, the Ozawa-Flynn-Wall integral isoconversion method was used, and the Coates-Redfern method was used to determine the decomposition mechanism. The average values of activation energy for heating rates of 5, 10 and 20 °C/min were 29.88–37.04 kJ/mol. It was found that thermochemical destruction of buckwheat husk is best described by a model of chemical reaction of the first and second order. The relationship between the parameters of the kinetic triplet was studied by the Kriging method and visualized as three-dimensional surfaces.
A method for quantitative determination of succinic and caffeic acids in leaves of mint variety Metelitsa by HPLC with UV- and MS-detection was developed. It was found that the HPLC-UV method is applicable only for the determination of caffeic acid, while HPLC-MS methods in two different modes of ion registration - selected ion monitoring (SIM) and selected reaction monitoring (MRM), can be used to determine the concentrations of both types of acids - succinic and caffeic acids. When analyzing complex mixtures, to which the analyzed plant extracts belong, the MRM mode should be preferred as a more selective and sensitive method. Foliar use of 0.1% aqueous succinic acid solution during the vegetative growth phase of mint plants to regulate their growth and development resulted in a 20 and 43% increase in the biomass of 1 mint plant and inflorescence, respectively, compared to the control. The use of caffeic acid solution of two concentrations (0.01 and 0.1%) as a growth regulator did not cause such a result – a decrease in biomass of one plant and inflorescence by 9–8% and 3%, respectively, was observed. Treatment of mint plants with succinic acid caused an increase in the concentration of this metabolite in leaves - more than 20 times. While at foliar use of caffeic acid the content of this metabolite in mint leaves remained at the level of control. To increase the yield of mint variety Metelitsa in the phase of vegetative growth it is recommended to use foliar treatment with 0.1% solution of succinic acid.
The phenolic components of the leaves of P. vera L., growing in the Bostanlyk district of the Tashkent region of the Re-public of Uzbekistan, were studied for the first time. The raw materials were collected in September 2022, after the pistachio fruits were harvested. 1 kg of air-dried crushed leaves of the plant was treated with chloroform, then extracted three times with 70% aqueous acetone, followed by evaporation of the acetone, treatment of the aqueous residue with ethyl acetate, concentration of the ethyl acetate fraction, and precipitation of the concentrate with chloroform, the amount of polyphenols was obtained. The yield was 12% of the air-dry weight of the raw material. Column chromatography on naked powder was used for the preliminary sepa-ration of polyphenols. The column was washed successively with diethyl ether, water, pure acetone and 60% aqueous acetone. For the first time, phenoloxy acids, flavonoids and gallotannins were isolated from this plant using column chromatography. The main components of P. vera leaves turned out to be gallotannins (45-47% by weight of the total polyphenols). Identification of the isolated compounds was carried out using thin layer chromatography, high performance liquid chromatography and mass spec-trometry. As a result of the studies, it was established that pistachio leaves contain quercetin – 3-O-(2′′-galloyl)-β-D-glucopyranoside, myricetin-3-O-β-(6′-galloyl)-galactopyranoside, 1,2,6-tri-O-galloyl-β-D-glucopyranose, 1,2,4,6-tetra-galloyl-β-D-glucopyranose, 1,2,3,4,6-penta-O-galloyl-β-D-glucose, 3-O-digalloyl-1,2,4,6-tetra-O-galloyl-β-D-glucose, 3,6-bis-O-digalloyl-1,2,4-tri-O-galloyl-β-D-glucose, gallic acid, 1,2,3,6-tetra-O-galloyl-β-D-glucopyranose, 1-O-galloyl-2,3-hexahydroxydiphenoyl-α-D-glucopyranose, 1,3,6-tri-O-galloyl-β-D-glucopyranose.
The component composition of essential oil (EO) obtained by hydrodistillation, as well as hexane extract of the roots of the plant Perovskia scrophulariifolia Bunge, collected in the Samarkand region of the Republic of Uzbekistan, was studied. Using GC-MS, 43 compounds were identified in the EO, which is 90.5% of the total amount of EO, while in the hexane extract – 21 substances, which make up 73.6% of the total amount of the extract. Oxidized sesquiterpenes (40.5%) and sesquiterpenes (31.4%) predominate in the EO, while the main components of the hexane extract are oxidized diterpenes (43.0%). The dominant components of the EO are aromadendrene (16.1%), caryophyllene (10.1%), valerenal (7.0%), spathulenol (5.6%), hydroxyeremophilone (5.6%), ledol (5.0%), aristo-1(10)-en-9-ol isovaleric acid ester (4.6%), sclareol (4.2%) and eremophilone (4.1%). The major components of the hexane extract are bis(2-ethylhexyl) ester of 1,4-benzenedicarboxylic acid (19.4%), ferruginol (12.9%), sclareol (6.5%), 9,10-dimethoxy-1,2,3,4-tetrahydro-1,4-ethanoanthracene (6.1%) and 1b,4b-epoxy-6-hydroxy-a-homo-5,7,9-estratrien-17-one (5.6%). Five individual phenolic compounds were isolated from various fractions of the methanol extract of P. scrорhulariifоlia roots and identified with cryptotanshinone, rosmarinic and caffeic acids, D-pinitol and β-sitosterol based on 1H, 13C NMR, HSQC and HMBC spectra. The antibacterial and antifungal activity of rosmarinic acid and hexane extract of roots was studied in vitro using the disk diffusion method in agar. It was found that B. subtilis, S. aureus and P. aeruginosa are sensitive to the studied samples, with the greatest antibacterial effect observed for rosmarinic acid against the gram-positive bacterium S. aureus.
For the first time, a comprehensive study was conducted on the proteins of the plant Rindera cyclodonta and the press cake remaining after alkaloid extraction. A comparative analysis was performed using methods such as polyacrylamide gel electrophoresis (PAGE), infrared spectroscopy, scanning electron microscopy (SEM), amino acid analysis, and elemental composition analysis. Structural and compositional changes in proteins after alkaloid removal were established, and features of the amino acid profile were identified. The obtained data expand the knowledge about the chemical composition of R. cyclodonta and can be used to assess the potential for utilizing plant raw materials. The article presents results on the total protein content: 8.9% in sample I (initial plant material) and 6.7% in sample II (press cake after alkaloid extraction). Electrophoretic analysis of proteins in both R. cyclodonta samples was conducted using PAGE conditions. Differences in the molecular mass of protein fractions were found, confirming the presence of low-molecular-weight subunits and high-molecular-weight components. Additionally, amino acid analysis, IR spectroscopy, SEM, and elemental composition analysis were carried out. Amino acid analysis of samples I and II revealed quantitative differences in the concentrations of individual amino acids. The total amino acid content in the samples was 81.360 mg/g and 82.130 mg/g, respectively, indicating similar overall amino acid profiles; however, the distribution of specific amino acids varied significantly. Scanning electron microscopy revealed microstructural differences in the plant tissue surfaces. Sample I had a more ordered surface, while Sample II showed loose and less organized structures, which may correlate with differences in protein composition. An analysis of functional groups based on characteristic absorption bands was also performed. The data confirm the presence of biologically active compounds in the samples. This study helps characterize the chemical composition of the plant and contributes to further pharmacological analysis. Using energy-dispersive spectroscopy (EDS), the presence of both organic elements (C, O, N) and inorganic components (Ca, Mg, S, Fe, etc.) was established, reflecting structural features and the possible degree of protein mineralization. The comparative characterization of the two samples revealed differences in nitrogen, sulfur, and trace element contents, which may be due to tissue specificity and extraction methods.
Polysaccharide components were isolated from the aerial part of Tribulus terrestris, including 7.7% water-soluble polysaccharides, 6.5% pectins and 13.4% hemicellulose. Analysis of the monosaccharide composition revealed the absence of mannose in any of the constituent polysaccharides. The major monosaccharides of the water-soluble polysaccharides were galactose, glucose and arabinose, together with traces of xylose and 25–30% uronic acid. For the purified polysaccharide, the monosaccharide composition consisted of arabinose, glucose and galactose in a ratio of 1 : 2.2 : 3.3. The pectins extracted from the aerial part of Tribulus terrestris were cream-coloured with a yellowish tinge. These pectins were characterised by a high content of galactose, glucose, arabinose, rhamnose, traces of xylose and 50% uronic acid. It was found that the pectins from the aerial part of Tribulus terrestris are highly esterified (the degree of esterification (λ) is 88.0%), with the main chain composed of α-1,4-galacturonan, with the neutral sugars occupying a peripheral position with respect to the main chain. The monosaccharide composition of the two hemicelluloses indicates the presence of galactose, glucose, arabinose, xylose, rhamnose and 55–60% uronic acid.
The article presents the results of testing the concepts of the dual nature of the mass transfer mechanism in a supercritical fluid extraction process for binary systems of types I-II phase behavior using the example of the problem of isolating acetone from its aqueous solution. It has been established that the opinion on the preference of distillation separation in comparison with the possibilities of the extraction process implemented in supercritical fluid conditions is incorrect and is caused by imperfect ideas and underestimation of the possibilities of the extraction process. The expediency of using the supercritical fluid extraction process as applied to systems of types I-II phase behavior in the context of the problem of separating mixtures of fatty acid esters is substantiated. The results of an experimental study of the phase behavior of the binary mixture "CO2-ethyl ester of oleic acid" carried out at T = 313.15 K are presented. For the system under consideration, type I-II phase behavior is established. Also presented are the results of the experimental implementation of the supercritical fluid extraction process as applied to the problem of concentrating ethyl ester of palmitic acid in a mixture with ethyl ester of oleic acid. The original approach to concentration is efficient and is characterized by a sufficiently high dynamics of the separation process and can be applied to a wide range of systems, including fatty acids themselves.
This article examines the dynamics of fatty oil accumulation in spring rapeseed seeds of the Sibirsky, Nadezhdy 92, and 595 varieties, grown in the Krasnoyarsk forest-steppe during the period of intensive seed ripening (August–September 2025), as well as the dynamics of higher fatty acid accumulation in the oil. It was found that oil content increases continuously during seed ripening, reaching 39.9–43.3%. The highest oil content was found in the seeds of the Sibirsky spring rapeseed variety. Using chromatographic mass spectrometry (CMS), conditions were selected for the complete separation of all oil acids as methyl esters on a non-polar capillary column. The following acids were found to be present in all rapeseed varieties studied: palmitic, stearic, oleic, linoleic, eicosenoic, eicosanoic, and erucic. A significant increase in oleic acid content and a decrease in erucic acid content were observed at the end of ripening. Based on their erucic acid content, the rapeseed oil of the studied varieties is classified as edible oil.
The component composition of extractive substances extracted from the aboveground part of aniseed lofant grown in Khakassia with water and water-alcohol extractants with ethanol content of 20, 40, 70, 95% ethanol was studied by HPLC with UV detection. Rosmarinic acid, luteolin and quercetin were identified as the main components in the extracts. The total content of phenolic components was 9.0% of the initial sample in the case of 70% ethanol was used as an extractant. Data on the antiradical activity (ARA) of the extractive substances were obtained in a model reaction of the obtained extracts with a solution of 2,2-diphenyl-1-picrylhydrazyl (DPPH). The extracts were obtained at a hydromodulus of 1 : 100, and to determine the ARA they were diluted another 100 times. The ARA value was determined by the decrease of the 517 nm band characteristic of DPPH over 30 minutes. It was found that the ARA of the 20% extract had the maximum value, reaching a value of 37.6%, even at the specified dilution.
Researchers from various countries are engaged in the search for biologically active substances with antioxidant properties. Medicinal plants are among the most accessible sources of such substances. One such source is the species of the genus Arctium L. The most widespread species of this genus in Russia is Arctium tomentosum Mill., which has also been introduced into industrial cultivation. Research on wild and cultivated varieties of Arctium tomentosum is scarce or entirely absent. The dominant groups of biologically active substances in the leaves of cultivated Arctium tomentosum include polysaccharides, hydroxycinnamic acids, tannins, and triterpenoid saponins, with peak accumulation (excluding polysaccharides) occurring in mid-summer. The dominant groups of compounds in liquid and dry extracts are the same as in the raw plant material. Chlorogenic acid is predominant in all extracts, while 4-caffeoylquinic acid is detected only in the 70% liquid extract. The 70 and 40% extracts from the leaves exhibit high antioxidant and antiradical activity compared to the aqueous extract, containing significantly higher concentrations of hydroxycinnamic acids, coumarins, carotenoids, and chlorophyll. The obtained results highlight the potential for further research into ethanol-based extraction complexes from A. tomentosum leaves as a source for creating agents with complex, including antioxidant, effects.
Currently, fluff cellulose (fluff-cellulose) is used as a raw material for the production of sanitary and hygienic products (SHP). In Russia, SHP is purchased abroad, mainly in the USA. In the United States, it is obtained from completely bleached sulfate cellulose from southern pine wood. In connection with the above, the purpose of this study is to find a technological solution for the production of fluff cellulose with properties similar to imported analogues. A method for obtaining fluff pulp by the traditional (wet) molding method has been experimentally developed. Fluff cellulose material was obtained using the traditional fiber milling method. When using industrial pulp, it is necessary to solve the problem of restoring and developing the capillary-porous structure of wood pulp, which it lost during drying of commercial pulp, activating the surface and preserving the length of the cellulose fiber. All this forms the basis for obtaining fluff cellulose material with the required hydrophilicity. The study of the regularities of the pulp preparation process, its regulation, and the creation of physico-chemical modification bases determine the relevance of this work: obtaining fluff-cellulose. The purpose of the work: to carry out and justify the modification of wood pulp by physico-chemical methods to obtain fluff material with improved moisture absorption (fluff-cellulose).
The global production of polymers produced is about 438 million tons per year, of which about 40% are packaging materials. The vast majority in it falls on non-biodegradable polymeric materials from petrochemical raw materials. Many polymer products are disposable, end up in landfills within a month after manufacture and are not recycled further. The situation has been exacerbated by the Covid'19 pandemic. Improper collection, storage and disposal of single-use plastics are a major sources of environmental pollution. Unrecycled plastic accumulates in the world's oceans and on land, and is broken down by environmental factors into micro- and nanoplastics. These particles end up in water, air, plants and through the food chain into the human body, where they are toxic to various life support systems. The use of partially biodegradable polyalkanoate polymers for packaging does not avoid problems with the formation of nanoparticles due to their long biodegradation times. The review considers the main results in the field of production and properties of biodegradable packaging materials and protective films for food products based on polymers of natural origin - chitosan and starch. The main problem with polysaccharide films is brittleness. In this regard, the review highlights the characteristics and achievements of their modification with TiO2 particles. Inclusion of small amounts of TiO2 in polysaccharides provides high physical and mechanical properties of films, light protection properties, and antibacterial activity and is safe for products.
The article summarizes the literature data on the use of waste from the processing of seeds and components of sunflower (Helianthus annuus L.) biomass as sorption materials for the extraction of various pollutants from aquatic environments. It briefly presents information on the volumes of sunflower seed cultivation in the Russian Federation. It presents data on the composition of cake, meal and husk of sunflower seeds and biomass components. It is shown that the mass fraction of crude fiber, according to various sources, ranges from 17.09 to 30.1%, which determines the high sorption properties of the material, and in the husk of sunflower seeds the proportion of crude fiber reaches 67%. It briefly presents information on the ways of their use in various sectors of the national economy. It was revealed that the greatest number of publications are devoted to the use of sunflower seed husk (SSH) as a sorbent for the removal of pollutants from model and real wastewater. The article presents information on the possibility of extracting chromium (VI), copper (II), iron (III), nickel (II), lead (II), zinc (II) and other ions using sunflower seed processing products. Cases of extracting organic compounds from solutions, such as dyes, petroleum products and other organic substances, are described. Data on the values of the maximum sorption capacity and the efficiency of extracting pollutants from LSP and plant stems are presented. It is determined that adsorption isotherms are well described in most cases by the Langmuir and Freundlich models, and the kinetics of the processes in the overwhelming majority of cases obeys the pseudo-second-order model.
In this study, the heterogeneous sulfation of low molecular weight chitosan (LMWC, Mw = 12.2 kDa, DP = 73, PDI = 1.25) using sulfuric acid in isopropanol medium was systematically investigated. A series of sulfated chitosan derivatives were synthesized under varying reaction parameters, including temperature (-30 to +5 °C), time (1–24 h), and H₂SO₄ molar ratios (1.0–8.0 mmol/mmol GlcNU). The molecular characteristics of the obtained products varied within a wide range: DP = 58-73, DS = 0.026–1.289, sulfur content = 0.51–14.16%, SO3Na = 1.64–45.58%, with yields ranging from 10.12% to 80.12%. FTIR spectroscopy confirmed successful sulfation through characteristic -SO3- absorption bands at 1220, 1060, 987, and 814 cm-1, indicating that sulfation predominantly occurred at the C-6 position of glucosamine residues via hydroxyl and amino groups. The optimal reaction conditions were determined to be 4.0 mmol/mmol H2SO4 per glucosamine unit at -20 °C for 12 hours, ensuring high DS values and minimal depolymerization. Elemental analysis supported FTIR findings and showed high correlation between reaction variables and functional group incorporation. These results demonstrate that controlled heterogeneous sulfation of LMWC in isopropanol is an effective method to produce water-soluble, highly substituted chitosan derivatives with preserved backbone integrity. The obtained derivatives are promising for further biomedical applications such as drug delivery, anticoagulant formulations, and bioactive coatings. This study provides a clear understanding of how reaction parameters influence structural and functional outcomes in chitosan sulfation chemistry.
The leading theory explaining the negative impact of various factors on the body is currently considered to be the theory of oxidative stress. A way to combat this phenomenon is the use of antioxidants. Numerous methods and approaches for determining antioxidants have been described in the literature. However, there is still no generally accepted approach to determining and assessing the amount of antioxidants in plant samples, as plants are complex in composition, including the composition of reducing substances. Therefore, it is reasonable to describe the analytical results comprehensively. Therefore, the aim of this study was to employ several methods for determining antioxidants: spectrophotometry with the Folin-Ciocalteu reagent, coulometric titration with iodine, and stripping voltammetry in alcohol extracts after and without boiling, but with the addition of hydrochloric acid to the extracting solution. Samples of needles from various representatives of the Pinaceae family were used as the object of study. A stripping voltammetric method for the determination of antioxidants in aqueous-alcoholic extracts of fir needles in a phosphate buffer solution at pH 6.8 with the addition of hydrogen peroxide as a model reactive oxygen species was tested and validated. The method allows for obtaining results both in terms of an antioxidant standard and as equivalent volumes of the studied extracts per mass of inactivated hydrogen peroxide. All plant samples were found to contain significant amounts of biologically active substances, with extracts from Hemlock (Pseudotsuga menziesii) exhibiting the highest antioxidant properties, polyphenol content, and ascorbic acid content. A close correlation was observed between the total antioxidant content and the amount of polyphenolic compounds in the samples.
Currently, there is a growing interest in preparations made from lignin, due to their various useful properties. These include biodegradability, biocompatibility, harmlessness, and a wide range of biological activities. For the first time, the fundamental possibility of using exogenous lignin to protect aquatic plant organisms from the negative effects of copper ions has been demonstrated in this work. Lignin from ledum (Ledum palustre L.) was tested as a chemoprotective agent. Presents the results of a study on the biological activity of isolated lignin on a laboratory culture of duckweed (Lemna minor L.) under the influence of a copper stress factor. During the experiments, we established the values of biomarkers for plant well-being (growth rate, level of damage, frond area, content of malondialdehyde and chlorophyll) and found that water-soluble lignin from ledum was not toxic to plant organisms. Preliminary cultivation of plants in aqueous lignin-containing media increased the total frond area, had a positive effect on growth rate, and reduced the level of damage to duckweed in copper-containing aqueous media. It was concluded that pre-treating duckweed with water-soluble lignin would increase the plant's resistance to copper stress. The data obtained confirm the opinion about the adaptive and protective properties of lignin under the influence of stress factors of various nature.
