Localization and Biological Activities of Bioflavonoids from Taxus canadensis Marshall

Relict yew plants (Taxus L.) are not only ornamental plants with valuable wood but also have the ability to synthesize the unique compound taxol, which is successfully used in the treatment of cancer due to its powerful cytotoxic effect. Due to the presence of taxol, all parts of yew plants are extremely poisonous, but there have been cases where animals have eaten yew cones without fatal consequences. The biosynthesis of taxol is carried out due to the interaction of the isoprenoid and phenolic pathways of the secondary metabolism of plants. Despite the close attention of researchers to the peculiarities of taxol metabolism, there is very little data on the tissue and intracellular localization of both taxols and phenolic compounds in yew plants. Polyphenols are known to be physiologically active mediators involved in respiration, photosynthesis, plant growth and development, as well as in the process of in vitro dedifferentiation. Since Taxus is a relict species and has a limited and hard-to-reach range in nature, technologies that allow yew plants to be restored without removing plant material from the natural environment are of great practical importance: overcoming deep physiological dormancy of seeds, microclonal reproduction and initiation of plant growth. In vitro cultures are possible sources of biologically active and medicinal products. The aims and objectives of this study are to determine the characteristics of the formation and localization of phenolic compounds with high biological activity in various organs of plants of the genus Taxus and to determine the biological activity of ethanolic extracts from this plant. The objects of this study were the generative organs of Taxus canadensis, collected during the entire growing season (April–October) from plants growing in the Moscow region. The localization of various classes of polyphenols was determined by histochemical methods using light microscopy. Histochemical studies have shown the abundant presence of polyphenols in yew megastrobiles, microstrobiles, cones, seeds and aril. Ethanolic plant extracts were used to determine the biological activity. Flavans were dominant in the aril at various stages of vegetation, which was confirmed by our biochemical and histochemical studies. Extractive substances of T. canadensis show high antibacterial activity, especially in its shoot extracts. Ethanolic extracts from plant shoots showed greater biological activity than seed extracts. Aril extracts had the lowest cytotoxicity.