Galinsoga parviflora Cav. (Asteraceae family) is a segetal-ruderal species, introduced from Peru and spread throughout the territory of Ukraine, the European and other continents. In our country, it is a dangerous invasive species that litters crops and natural biomes. Simultaneously, G. parviflora is an edible plant that is used in traditional medicine in some countries, and there are some results of scientific research that testify to the effectiveness of its use as a medicinal plant material with anti-inflammatory, wound-healing, hypotensive, hemostatic, cytotoxic properties and others. Since the G. parviflora species is morphologically variable, there is a need to study its chemical composition and properties before using it, in particular as a medicinal plant raw material or for other purposes. The phytochemical investigation of aqueous and aqueous ethanolic extracts of G. parviflora herb resulted in the identification of several groups of biologically active compounds. Most of them are polyphenols, flavonoids, carotenoids – have high antioxidant activity, and therefore can cause antibacterial effects. The aim of the study was to collect G. parviflora plants, prepare extracts from the above-ground part (grass) and determine the content of polyphenolic compounds, flavonoids, carotenoids, as well as the antibacterial activity of the prepared extracts. In extracts of the G. parviflora herb collected in the vicinity of Lviv, the content of polyphenols was determined at the level of 4.38–7.71 mg·g-1 of dry mass (DM) in terms of gallic acid, the content of flavonoids at the level of3.56–7.27 mg·g-1 of DM in terms of quercetin, and carotenoids – 10.95 ± 0.5 μg · g-1 of DM. Studies of the antibacterial activity of ethanolic and aqueous-ethanolic extracts of the herb G. parviflora against test cultures of Escherichia coli and Bacillus brevis, conducted using the well method, allowed to establish that the extract prepared with 20 % aqueous ethanol most strongly inhibits the growth of the studied cultures. Strong statistically significant relationships were established between the zones of inhibition of E. coli and flavonoids – p < 0.001.Key words: Galinsoga parviflora Cav., aqueous and aqueous-ethanolic extracts, antibacterial activity

Vorobets N., Yavorska H. Gallant soldier – a promising raw material with antibacterial properties. Sci. Bull. Uzhorod Univ. (Ser. Biol.). 2025; 58: 82-87. https://doi.org/10.32782/1998-6475.2025.58.12