Variability of phenolic compounds in berries of  Actinidia arguta Miq. and Actinidia kolomikta Maxim.

Growing consumer demand for nutritious and health-beneficial fruits has stimulated research aimed at identifying and evaluating new superfruits. Furthermore, underutilized native and introduced berry species are increasingly recognized as promising sources of vitamins and other valuable bioactive compounds. In the present study, five cultivars of Actinidia kolomikta together with five cultivars and hybrids of Actinidia arguta from the Actinidia Lindl. germplasm collection maintained at the Botanical Garden of Vytautas Magnus University were investigated. The qualitative and quantitative composition of phenolic compounds was determined using ultra-high-performance liquid chromatography coupled with mass spectrometry (UHPLC-MS). The results revealed that berries of A. kolomikta accumulated significantly higher amounts of total flavonoids, hydroxycinnamic acid derivatives, and proanthocyanidins than those of A. arguta. Comprehensive UHPLC-ESI-MS/MS analysis enabled the identification of the major classes of phenolic compounds, including flavan-3-ols, flavones, flavonols, and hydroxycinnamic acids. Variations in antioxidant activity, as determined by the CUPRAC, FRAP, and ABTS•+ assays, were closely associated with cultivar-specific characteristics. The phenolic compounds identified in this study exhibit considerable potential for further scientific research as well as practical applications because of their beneficial effects on human health. Despite the observed differences, berries of both cold-hardy kiwifruit species were confirmed to be rich natural sources of antioxidants. Additional studies are required to clarify the role of these secondary metabolites in plant defence mechanisms and to determine their contribution to resistance against fungal pathogens, bacterial diseases, and insect pests. The significant biochemical differences observed among the investigated cultivars also enabled the identification of promising donor genotypes with valuable biochemical traits for use in future kiwifruit breeding programs.