The article presents data on the content of biologically active compounds and the total activity of phenolic antioxidants in the leaves and inflorescences of the valuable forage plant Trifolium pannonicum Premier cultivar grown in different agroclimatic subareas of the Novosibirsk region – moderately warm, moist and moderately warm, not sufficiently moist. It is shown that, depending on the plant growth, biologically active substances are synthesized in differently: the content of flavonols, catechins, carotenoids and pectin substances is 1.1–1.6 times higher in plants from a more humid area. Tannins maximally (up to 17.43%) accumulate in the leaves of T. pannonicum, grown in an area with insufficient moisture. All samples of T. pannonicum variety Premier are characterized by high antioxidant activity of ethanol extracts from leaves and inflorescences (1.50–2.20 mg/g). The maximum of the total activity of antioxidants was found in the inflorescences of T. pannonicum from an area with insufficient moisture. Plant material T. pannonicum variety Premier is characterized by a fairly high content of biologically active substances.

The article presents Dara on the content of biologically active compounds (BAC) and the total phenolic antioxidants activity (TPA) evaluated for leaves and inflorescences of eight species from the Rosaceae family: Padus avium, Malus baccata, Alhemilla vulgaris, Potentilla inquinans, Filipendula vulgaris, F. palmata, Sanguisorba officinalis, S. alpina. It was determined that leaves and inflorescences contain flavonols, catechins, tannins, carotenoids, saponins, pectin substances. Usually, woody plants tend to accumulate less BAC and TPA than herbs. The highest level of flavonols and tannins was registered in inflorescences of F. vulgaris (12.25% and 45.02 %). The content of pectin substances was quite high, with the biggest share of protopectins (4.4-10.65%). The maximum quantity of catechins (4.76%) was found in the leaves of F. palmata, saponins – in the inflorescences of M. baccata (20.77%). The highest content of carotenoids was found in the leaves of plants, most notably in P. inquinans (1.00 mg/g). The highest antioxidant activity was recorded for water-ethanol extracts from inflorescences (up to 7.77 mg/g) and leaves (2.11 mg/g) of F. vulgaris and A. vulgaris plants due to increased content of phenolic compounds, in particular flavonols and tannins, compared to the other species.