Two highly invasive plant species, Lysimachia vulgaris and Lythrum salicaria are well-known for its anti-inflammatory, hemostatic, and antidiaroic activity. These plants are most widespread on the territory of Euroasia, where their traditional medicinal use has been reported. Due to their invasiveness, they are undesirable plants in  other parts of the world. Till this day, many studies were conducted regarding the biological and pharmacological activity of L. salicaria. In this study, the polyphenol content of plant extracts was examined using the Folin-Ciocalteou method. Antioxidant activity of selected plant species was also determined, using DPPH and FRAP methods. Extracts of different polarities were prepared using methanol, water, and acetone. Extraction was performed by maceration and ultrasonic extraction. The results of the study show that both plant species possess antioxidant activity. Lythrum salicaria extracts show a significant polyphenol content and antioxidant capacity, with results notably higher than the results of studies conducted so far. The different antioxidant activity of the prepared extracts confirms the influence of solvents and extraction methods on the utilization of the antioxidant potential of plants. Additionally, for the aqueous extracts prepared by ultrasonic extraction method, an in vitro study of antibacterial activity was conducted. Both plant species show antibacterial activity, with an emphasis on the very strong antibacterial activity of L. salicaria extracts against selected bacterial strains.

Tussilago farfara L., also known as coltsfoot, is a plant that has been used since ancient times to relieve coughs. Subsequently, the effectiveness of coltsfoot in the treatment of bronchial asthma, pneumonia and other respiratory diseases was established. In this research, the antioxidant and antimicrobial activity of different coltsfoot extracts was analyzed. The antioxidant activity was monitored through the DPPH radical inhibition efficiency and the extract's reducing ability. Antibacterial activity was tested using the diffusion technique. Tussilago farfara L. extracts showed extremely high antioxidant activity in in vitro conditions. The highest antioxidant capacity was found in extracts prepared by mixing water and organic solvents. High antibacterial activity was found for ethanolic, acetone and aqueous-ethanolic extracts of coltsfoot.

Telekia speciosa (Schreb.) Baumg., Asteraceae, is widespread in Eastern and Central Europe and the Balkan Peninsula. Previous phytochemical investigations have revealed T. speciosa as a rich source of sesquiterpene lactone -isoalantolactone, especially in its underground parts. The aim of the present study was to analyze the essential oils from aerial and underground parts of T. speciosa and investigate their antimicrobial activity. Chemical composition of essential oils was determined by GC-FID/MS method leading to the identification of 67 compounds in total, with 15.77 % oxygenated monoterpenes, 7.77 % sesquiterpene hydrocarbons, 49.14 % oxygenated sesquiterpenes, and 12.37 % other compounds from aerial parts, and 3.80 % oxygenated monoterpenes, 3.13 % sesquiterpene hydrocarbons, 90.33 % oxygenated sesquiterpenes from underground parts essential oil. The main components from aerial parts were (E)-nerolidol (11.54 %) and caryophyllene oxide (10.54 %), while isoalantolactone was the predominant component from essential oil underground parts (83.41 %). The minimum inhibitory concentration (MIC), minimum bactericidal/fungicidal concentration of the essential oils were evaluated against six strains of bacteria and two strains of fungus using in vitro microdilution method. Both oils presented antimicrobial properties against pathogens Staphylococcus aureus, Bacilus cereus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. Inhibition of growth of tested microorganisms by T. speciosa underground parts essential oil was achieved with MICs ranging from 1.0 to 11.0 mg mL -1 , while MICs of aerial parts essential oil varied from 4.0 to 30.0 mg mL -1 . The obtained results contribute to the knowledge of antimicrobial properties of T. speciosa, which support traditional uses underground parts of the plant.