neochlorogenic acid, and rosmarinic acid (max. 724.2, 482.7, 154.7 mg/100 g DW, respectively). Of the examined materials, A. arbutifolia leaves were characterized by the highest total phenolics content (9148.2 mg gal. ac. Eq./100 g DW) and showed the highest antioxidant activity in DPPH and FRAP assays. The results demonstrate that fruits of A. arbutifolia and A. ×prunifolia are a rich source of antioxidants and can be used as plant raw materials, alternatively to A. melanocarpa berries. Leaves of the investigated species are of potential therapeutic and dietary interest because of their high flavonol and phenolic acid content.

In order to find new sources of natural antioxidants, the antioxidant potential of 70% methanolic extracts from the inflorescences and leaves of 16 species from the genus Sorbus s.s. was evaluated using two complementary in vitro test systems: the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging assay and the AAPH [2,2′-azobis-(2-amidinopropane)dihydrochloride]-induced linoleic acid (LA) peroxidation test. The radical-scavenging capacities of the extracts towards the DPPH radical were in the range of 0.25−0.86 millimolar Trolox® equivalents/g dry weight. They were significantly correlated (r = -0.8089, p < 0.001) with the results of the LA-peroxidation test, indicating the Sorbus extracts to be universal antioxidants. Significant linear correlations were also found between the different antioxidant potentials and total phenolic contents as estimated by the Folin-Ciocalteu method and further verified by serial determinations of proanthocyanidins, chlorogenic acid isomers and flavonoids (|r| in the range of 0.71−0.95, p < 0.001). Cluster analysis of the data matrix identified the ten samples (inflorescences of S. aucuparia, S. pohuashanensis, S. decora, S. koehneana, S. commixta, S. gracilis, and S. sitchensis, and the leaves of S. wilfordii, S. pogonopetala, and S. gracilis) exhibiting the highest antioxidant activity and total phenolic levels and therefore the greatest potential as effective sources for natural health products.

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The essential oils from seeds of nine Abies koreana specimens have been studied using GC-MS-FID and NMR methods, leading to the determination of 96 volatiles, which constituted over 99% of the oils. The hydrodistilled oils of fresh, resinous scent were isolated with yields in the range of 3.8-8.5%. The results showed that the essential oil of Korean fir seeds contained 70-95% monoterpenes and 1-20% oxygenated monoterpenes as the dominant groups. The numerous sesquiterpenes, diterpenes and their oxygenated derivatives constituted only 2-8% of the oil. The major component of the seed essential oil was limonene (41-72 g/100g); the laevorotary form of this terpene predominated. A. koreana seeds seem to be a rich source of both essential oil and (-)-limonene, whose average enantiomeric excess was above 95%.

Although interactions between alien and native plant species are well studied, data on interactions between two co-existing alien species with respect to their invasibility are scarce. The aims of this study were (1) to evaluate three factors shaping abundance of the alien shrub species Cornus alternifolia: abundance of another alien (invasive) shrub species (Prunus serotina), type of tree stand (coniferous vs. broadleaved) and distance to propagule sources and (2) to assess the potential dispersal distance of the species studied. Densities of both species were assessed within 194 experimental plots (located in experimental plantations of trees) in Rogów Arboretum (Central Poland). P. serotina occurred on 79 and C. alternifolia on 33 of the 194 plots. The furthest distance of C. alternifolia from the propagule source was 338 m. C. alternifolia reached higher densities in coniferous than broadleaved tree stands. Density of C. alternifolia depended on tree stand type and distance from the propagule source, but did not depend on density of P. serotina. Density of C. alternifolia decreased with increasing distance from the propagule source; however, this relationship was modified by the type of tree stand: densities were lower in broadleaved than in coniferous stands. The presence of the invasive species seems to neither facilitate nor limit the dispersal distance of C. alternifolia, as these two species differ in shade tolerance. The study also provided the first information about C. alternifolia potential invasiveness, because earlier this species was noticed only as casually escaping from cultivation in Slovakia.