Anna Andersone

Bacteria and viruses' potential collaboration has been reported to result in enhanced infection pathogenesis. New antimicrobial agents are necessary, but stronger synthetic antibiotics cause more severe side effects. The relevance of natural agents has increased in the post-COVID-19 period also due to COVID-induced cytokine storm, causing severe complications. This study aimed to evaluate Aronia melanocarpa branches for producing anti-SARS-CoV-2, anti-inflammatory, and antimicrobial preparations, and their synergistic activity with antibiotics. Biomass water and water-ethanol extracts were analyzed for total polyphenols, tannins, individual compounds (UHPLC-MS/MS), content of functional OH groups. Anti-SARS-CoV-2 activity was tested using SARS-CoV-2 (2019-nCoV) Inhibitor Screening ELISA Kit, anti-inflammatory activity - in peripheral blood mononuclear cells (PBMNC) under normal and inflammatory conditions; antimicrobial and synergistic efficacy with antibiotics were tested against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Oligomeric proanthocyanidins were dominant compounds in the extracts, with the highest concentration in autumn samples (35% per dry extract). The extracts and oligomeric proanthocyanidins were effective in inhibiting the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein and regulating inflammatory processes caused by viral and bacterial infections, including the reduction of IL-6 and regulation of IL-10 secretion. Proanthocyanidins and extracts exhibited significant anti-biofilm activities and showed synergistic activity with antibiotics.

This study aimed to evaluate the potential of branches of black chokeberry, sea buckthorn, and black currant as raw materials for the development of pharmacologically active compounds, primarily oligomeric proanthocyanidins (OPCs), as they exhibit a broad spectrum of biological activities, including antioxidant, antimicrobial, anti-inflammatory, anticancer, etc. Branch biomass collected in spring and autumn of 2023–2025 was analyzed for its functional group profile and used for the isolation of OPCs with ethanol, an ethanol–water mixture (1:1, v/v), and an ethanol–acetone–water mixture (4:1:5, v/v/v). The highest yield of OPCs (up to 14% of DB) was achieved using the ethanol–acetone–water solvent mixture. Using LC-MS/MS, the OPC composition was analyzed and found to consist of dimers (m/z 577), trimers (m/z 865), and tetramers (m/z 1153). The maximum OPC content was observed in autumn samples. Mechanical pretreatment enhanced OPC accessibility by disrupting cell walls and increasing particle surface, facilitating release from the matrix and yielding up to 1.2-fold more OPCs than from untreated biomass. Quantification of 22 elements in the biomass by ICP-MS revealed low levels of toxic metals along with the presence of nutritionally relevant elements. Therefore, from a chemical safety perspective, biomass can be considered suitable for use as a source of OPCs.

Fruit shrubs’ lignocellulosic biomass remaining as waste after harvesting and/or after pruning is an underutilized, little-explored bioresource. Sea buckthorn (Hippophae rhamnoides L.), aronia (Aronia melanocarpa) and blackcurrant (Ribes nigrum) berries are rich in biologically active compounds, so these shrubs’ woody biomass derivatives are prospective investigation objects. The influence of pre-treated biomass, extracts, and purified proanthocyanidins on the oxidative stability of lipid-based systems was studied by accelerated oxidation method. Emulsion stability, antimicrobial activity against bacteria that causes acne—Cutibacterium acnes; contaminating wounds; skin care products—Streptococcus pyogenes, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus cereus; cytotoxicity and phototoxicity of extracts and proanthocyanidins on HaCaT human keratinocytes were tested. The study established that biomass, lipophilic extracts obtained using liquefied hydrofluorocarbon, and hydrophilic extracts obtained by aqueous ethanol increased oxidative stability of lipid-based formulations. Compounds with skin-protecting properties were detected. Sea buckthorn and aronia hydrophilic extracts and proanthocyanidins had the highest antimicrobial activity. Low phototoxicity was revealed, emphasizing safety and applicability in topical formulations; human HaCaT keratinocyte viability was the best with aronia extracts, but none of the other samples decreased cell viability by more than 50%. It was proven that agro-waste biomass is a prospective source of multifunctional ingredients for cosmetic and pharmaceutical topical formulations.

The manuscript explores the valorization of forest logging residues, collected during forest management operations between summer 2023 and spring 2025 in mixed deciduous and coniferous forests, as a raw material for producing valuable bioactive products. These products offer a sustainable alternative to synthetic pesticides and fertilizers. Seven batches of biomass, comprising understory trees and branches from deciduous (mainly aspen, birch, and grey alder) and coniferous (mainly Scots pine) species, were collected during different seasons, crushed, and extracted using an ethanol–water solution. The yield of hydrophilic extracts containing proanthocyanidins (PACs) ranged from 18 to 25% per dry biomass. The highest PACs concentration (42% of extract dry mass) was found in small branches with a high bark content. The extracts and PACs at concentrations of 6.25–12.50 mg mL⁻¹ showed fungicidal activity against several pathogenic fungi, including Botrytis cinerea Pers., Mycosphaerella sp. Johanson, Heterobasidion annosum (Fr.) Bref., and Heterobasidion parviporum Niemelä & Korhonen. Residual biomass after extraction, enriched with sea buckthorn berry pomace and a siliceous complex, was characterized and evaluated for its impact on the growth of Scots pine seedlings and selected agricultural crops. Results from forest and agricultural field trials in 2023–2025 confirmed a positive effect of the fertilizer on crop yield and quality at a low application rate (40 kg ha⁻¹ per crop). Fertilizer increased the yield of radish, dill, potatoes, and wheat by up to 44% (highest for potatoes and dill) compared to the reference, confirming its agronomic value.

The aim of research was to evaluate the impact of low rates of application of environmentally friendly organo-mineral soil amendments on yields components (number of productive tillers m2, 1000 grain weight, grain number per ear), grain yield and yield quality of spring and winter wheat under organic farming conditions. Soil amendments were obtained based of forest logging residues - lignocellulosic biomass, after isolation of polyphenols by water extraction and enrichment with silicon (Si), included the content of polyphenolic compounds. The soil amendments were used for seed material treatment. Field experiments were carried out in the certified organic farming field. The control variant and organo-mineral soil amendments, containing inorganic oligomer in various mass ratios (three variants) were tested. The varieties (spring wheat ‘Robijs’, winter wheat ‘Edvins’), certified for growing under organic farming conditions, were used in trial. It was shown that the treatment of seed material with organo-mineral soil amendments increased the number of productive tillers as well as have a beneficial effect on the yield (the increase till 21.6% compared to the control) but decreased the number of grains per ear of spring wheat, depending on concentration of inorganic oligomers). In variant with the highest tested concentration of inorganic oligomer, a trend towards yield growth for winter wheat can be observed. The obtained results show that the treatment of seed material with promotes plant growth and development, researches should be continued.

Blackcurrant (Ribes Nigrum L.) is one of the most common shrubs in Latvia, in addition to fruits and leaves, twigs cut in spring and autumn are rich in oligomeric polyphenols - proanthocyanidins, which have powerful antioxidant, antimicrobial, anti-inflammatory properties. The yield of proanthocyanidin-containing extracts ranged from 12 to 22%/DM. At the same time, the twigs cut in autumn were richer in proanthocyanidin than in spring. The strong antimicrobial properties of the extracts showed their effectiveness against a wide range of bacteria, which makes the extracts promising for use in medicine and the food industry. All extracts introduced into the lipid-based cosmetic cream showed antioxidant activity comparable to reference samples. This indicates the potential for using these extracts as active ingredients in cosmetics aimed at protecting the skin from the negative effects of free radicals. The results obtained open up new opportunities for developing innovative cosmetic formulations with improved antioxidant properties that help slow down the ageing process of the skin and maintain its health. The use of blackcurrant twigs is a sustainable and cost-effective source of valuable bioactive compounds.

To obtain a good harvest, regular pruning of fruit trees and bushes is necessary, which results in the accumulation of piles of cut twigs. These twigs are underutilized and form a large number of agricultural waste. Finding a use for this lignocellulosic biomass is necessary for the sustainable use of resources, as well as for creating additional income for berry growers and rural workers. The purpose of the research was to evaluate the potential of branches of various fruit trees and shrubs as a source of valuable oligomeric polyphenolic compounds – proanthocyanidins, which have a wide range of biologically active properties, including antioxidant, antibacterial, anti-inflammatory, anticancer, etc. Hydrophilic extracts of twigs of sea buckthorn (Hippopae rhamnoides L.), black chokeberry (Aronia melanocarpa), black currant (Ribes nigrum L.), red currant (Ribes rubrum), gooseberry (Grossulariaceae), quince (Cydonia oblonga), raspberry (Rubus L.), and grape (Vitis vinifera) were studied for the first time. The main process for isolating proanthocyanidins from the twigs is the extraction by ethanol-water solutions. The amount of extractive substances in the branches containing proanthocyanidins varied from 6 to 28% per DM. The highest content of proanthocyanidins was found in black chokeberry, quince, and sea buckthorn. The proanthocyanidins isolation from hydrophilic extracts was carried out by Sephadex LH-20. The antimicrobial activity of dominant hydrophilic extracts and purified oligomeric proanthocyanidins was studied against eleven pathogenic bacteria and fungus: Pseudomonas syringae pv. syringae, Erwinia rhapontici, Fusarium culmorum, Verticillium dahlia, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Bacillus cereus, Candida albicans and Cutibacterium acnes. The MIC and MBC/MFC of extracts ranged from 2 to 6 mg/mL. The antimicrobial activity of purified proanthocyanidins was 10 times higher than that of the extracts.

The purpose of this work was to evaluate the impact of low rates of application of environmentally friendly organo-mineral soil amendments on grown under organic farming conditions dill’s green mass yield and it’s composition, including the content of polyphenolic compounds. Soil amendments were obtained based on forest logging residues – lignocellulosic biomass, after isolation of polyphenols by water-ethanol extraction and enrichment with silicon (Si)-containing inorganic oligomer in various mass ratios. Lignocellulosic biomass is rich in polyphenols which can damage the functionality of the bacterial cell membranes thus inhibiting the growth of soil microorganisms. Polyphenols can be isolated from the lignocellulosic substrate and evaluated in further studies for their potential to protect plants from pathogenic microorganisms. The influence of the prepared soil amendments on soil microorganisms was tested. Field experiments were carried out in a certified biological field intended for scientific purposes. It was shown that soil amendments have a beneficial effect on the yield (42%) and a slight influence on the composition of dill at low amendment application rates. The addition of soil amendments also contributed to insignificant changes in the amount of polyphenols. The soil amendments didn’t influence the soil microorganisms under study. The results confirmed the ability of the soil amendments based on the forest logging residues to activate dill growth.

Aronia melanocarpa is a hardy berry-producing shrub that demands low maintenance and can grow on almost any type of soil. Since the best fruits can be obtained on the branches younger than 7 years, pruning of 1/3 of the shrub is usually performed each winter or after flowering, and also to remove damaged or overgrown branches. For sustainable production of Aronia melanocarpa berries, it is necessary to find a rational use for this pruning lignocellulosic biomass. Some studies available for Aronia melanocarpa berries show that they are very rich in various biologically active substances with proven functional and pharmacological activities including anti-inflammatory, antioxidant, and antimicrobial properties. The chemical composition of Aronia melanocarpa branches is currently almost unknown. The study aimed to evaluate the composition and potential of chokeberry branches as a source of polyphenols. General chemical characterization of the biomass was carried out using the method of analytical pyrolysis. Extraction of branch biomass was carried out using aqueous alcohol solutions. Quantitative analysis of the extracts showed a large amount of oligomeric proanthocyanidins. The most suitable extractant was determined to obtain the highest yield of the dominant polyphenols in the hydrophilic extract. The antioxidant activity of the hydrophilic extracts as well as antibacterial activity against six pathogenic bacteria was evaluated. The results showed the high potential of chokeberry lignocellulosic biomass as a source of valuable biologically active compounds for the creation of preparations for the healthcare, nutrition industry, and cosmetics.