Polyphenol contents, antioxidant activities, and anti-cancer cell proliferation properties at each stage of fruit development in intersectional hybrids between highbush blueberry and shashanbo (Vaccinium bracteatum Thunb.)

BACKGROUND: In blueberries, the total polyphenol contents, total anthocyanin contents, and antioxidant activities of fruits in blueberries and their relatives are becoming important targets for breeders. Recently, intersectional hybrids between Japanese wild species Shashanbo and highbush blueberry were produced using polyploid breeding for the first time. However, the polyphenol contents, antioxidant activities, and anti-cancer cell proliferation properties of the fruits of these intersectional hybrids have not been studied sufficiently. OBJECTIVE: The objectives of this study were to determine the anthocyanin contents, polyphenol contents, and antioxidant activities at each stage of fruit development in intersectional hybrids, and to examine the effects of the fruit extracts on anti-cancer cell proliferation properties using human promyelocytic leukemia (HL-60) cells. METHODS: Freeze-dried fruit samples of three intersectional hybrids and their parents at five developmental stages were used to evaluate their polyphenol contents, anthocyanin contents, and levels of two types of antioxidant activities (DPPH and ORAC). The anti-cancer cell proliferation properties of each extract were also evaluated according to the survival rate of HL-60 cells. RESULTS: The total polyphenol contents in fruits of the intersectional hybrids gradually decreased as the fruits grew, but the contents increased slightly at the mature stage. Meanwhile, the total anthocyanin contents increased strongly to the mature stage. In addition, the fruit extract of intersectional hybrid JM1 was found to be more effective for inhibiting the growth of HL-60 human leukemia cells in vitro. Total polyphenol content correlated highly with antioxidant activities and anti-cancer cell proliferation properties. CONCLUSIONS: We clarified that the intersectional hybrids had produced have abundant bioactive compounds, high levels of antioxidant activities, and anti-cancer cell proliferation properties. The results proved the effectiveness of the use of Japanese wild Vaccinium species for the strategic breeding of blueberries with high levels of bioactive compounds.