The Content of Certain Groups of Phenolic Compounds and the Biological Activity of Extracts of Various Halophyte Parts of (L.) Griseb. and L. at Different Levels of Soil Salinization.

Halophyte plants are known for their resistance to harsh environmental conditions associated with excess salts in their habitats. Their resistance to salinization is due, among other things, to their high ability to detoxify free radicals, owing to the relatively high content of antioxidants. On the coast of the Baltic Sea and in the lagoons, there are several rare halophyte species included in the Red Book of the Kaliningrad Region (Russia) and the Baltic region, such as (L.) Griseb. and L. The aim of the research was to study the accumulation of certain groups of phenolic compounds in different parts of and plants under conditions of weak and strong soil salinity, as well as to analyze the antioxidant, antibacterial, and fungicidal activity of extracts of the studied plant species. The present study showed an increase in total phenolic content in the roots and shoots of and the shoots of in response to increased soil salinity. At the same time, the total content of flavonoids in all the studied parts of the two plant species remained unchanged. However, the content of individual flavonoids (hesperetin, epicatechin, apigenin derivative, luteolin derivative) in increased, for there was a tendency to reduce the content of flavonoids in roots and shoots with an increase in soil salinity. There was an increase in the total content of hydroxycinnamic acids in the roots of , as well as an increase in the content of protocatechuic acid in the roots and shoots of . A positive relationship was established between the antioxidant activity of root extracts and the total content of phenolic compounds, as well as shoots extracts and the total content of phenolic compounds. Extracts of showed no antibacterial activity against and , and weak fungicidal activity of stem extracts and inflorescences grown on soils, with high levels of salinities, was detected against . The extracts of roots and shoots from showed weak antimicrobial and fungicidal activity.