From an economic and ecological standpoint, it is crucial to investigate the biologically active compounds of mistletoe plants, which are currently discarded by pruning urban mistletoe-infested trees. In the present study, the content of phenolic compounds, triterpenic and organic acids, as well as the antioxidant activity of the extracts of various mistletoe organs (leaves, stems, and fruits) collected from the most infested tree species were investigated. The mistletoe samples collected from Betula pendula, Acer platanoides, Crataegus monogyna, and Sorbus aucuparia showed the highest content of phenolic acids and flavonoids as well as antioxidant activity, as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and ferric reducing/antioxidant power (FRAP) assays. The leaves and stems of mistletoe from Tilia cordata were characterized by a high content of triterpenic acids (oleanolic, ursolic, and betulinic). The leaves and fruits of mistletoe plants from Populus nigra and Salix alba contained a high concentration of organic acids, particularly succinic and citric acids. Compared to stem and leaf extracts, the antioxidant activity of the mistletoe fruit extracts was 1.5-3 times higher. The obtained results indicate that mistletoe is a valuable raw material and can be used as a source of phenolic compounds and triterpenic and organic acids, as well as for producing extracts with antioxidant properties.
Keywords: biological active compounds; hemiparasitic plants; medicinal plants; plant–plant interactions; raw material; secondary metabolites.