This paper examines the elicitor effect of yeast extract (YE) in various concentrations (200–1000 mg/L) on the accumulation of phenolic compounds (PC) in flowering flax ( Linum grandiflorum Desf.) cells cultured in vitro and their antiradical activity. It is established that the total PС content and the content of phenylpropanoids increase in the cell culture, especially at high YE concentrations in the medium (500 and 1000 mg/L). The antiradical activity of flax culture extracts remains in most cases at the control level. Therefore, the elicitation of flowering flax in vitro cultures by YE activates the PC biosynthesis resulting in the accumulation of these secondary metabolites, while the antiradical activity of cell culture extracts does not decrease compared to the control level.

Introduction. Plant tissue cultures are potential producers of biologically active plant metabolites, which include various phenolic compounds that can be used to maintain human health. In most cases, their accumulation is lower than in the initial explants, which requires a search for factors and influences to intensify this process. In this case, it is very promising to use the precursors of their biosynthesis as potential “regulators" of the for-mation of various metabolites. The aim of the study was to study the effect of L-phenylalanine (FA, 3 mM), trans-cinnamic acid (CC, 1 mM) and naringenin (NG, 0.5 mM), as com-ponents of various stages of phenolic metabolism, on the accumulation of various classes of phenolic compounds, including phenylpropanoids and flavanols, in callus cultures of the tea plant (Camellia sinensis L.): a strain of "Kimyn" and "Local population". Material and methods: The object of the study was callus cultures of tea plants of leaf origin grown for 7 days on a liquid nutrient medium of Heller basic composition (control) or enriched with L-phenylalanine (3 mM), trans-cinnamic acid (1 mM) or naringenin (0.5 mM). The morphophysiological parameters of the cullus (color, density, water content), the amount of polyphenols and flavans in them were ana-lyzed. Results. According to the data obtained, the action of NG led to a significant increase in the accumulation of phenylpropanoids and flavanols in two strains of tea culture. Whereas FA contributed to a sharp increase in the content of phenylpropanoids only, which is more pronounced in the "Kimyn" strain. Thus, the most effective "regulators" of the accumulation of phenolic compounds are FA and NG. At the same time, the trends in the accumu-lation of various polyphenols were similar for both cultures, however, in the case of the "Wormwood" strain, the response was more pronounced. Conclusion. The study demonstrates the significant biotechnological potential of phenolic precursors as regulators of the accumulation of polyphenols in the callus cultures of the tea plant. The effect of their action depends on both the compound used and the strain of the tea plant. The results ob-tained open up prospects for the development of effective biotechnological approaches to the regulation of the accumulation of pharmacologically val-uable secondary metabolites of a phenolic nature in in vitro cultures of higher plants.

The effect of different concentrations of cadmium (Cd, 42–126 µM) on the antioxidant system of in vitro cultures of Rhododendron japonicum was studied. A decrease in the activity of superoxide dismutase, one of the main high-molecular antioxidants, was shown in heterotrophic calli grown on media with increasing concentrations of the pollutant, and an increase in photomyxotrophic cultures. The accumulation of low molecular weight phenolic antioxidants in them in most cases increased. The results obtained indicate changes in the antioxidant status of callus cultures of Rh. japonicum grown on media with Cd and the important role of antioxidant enzymes and low molecular weight antioxidants in maintaining their viability.