Phytochemicals from the roots of northern highbush blueberry (Vaccinium corymbosum)

Growing evidence from many in vitro studies suggest that plants produce secondary metabolites which may have potential physiological properties. The northern highbush blueberry (Vaccinium corymbosum L.) plant is commercially cultivated for its valuable dark-blue fruit, which has been extensively researched and has been shown to contain phenolic compounds recognized to have positive health benefits. Thus, an evaluation of other parts of the plant, that as of yet have not been investigated, could be worthwhile. There may be undiscovered bioactive compounds within the roots of this plant that may contribute to the improvement of human health. This rationale supports further research and investigation into the roots of the plant. A preliminary study showed that the crude extract of the blueberry roots showed antioxidant activity. Using various chromatographic methods and spectroscopic techniques, the blueberry root compounds were isolated, fractionated and analyzed. Six compounds were identified by 1H and 13C NMR and mass spectrometry data. Three lignans, which were never previously reported in the blueberry plant, were identified as nudiposide, lyoniside, and ssioriside; one phenolic acid; sinapic acid glucoside, and two catechins; epigallocatechin (EGC) and dulcisflavan. The isolated compounds were evaluated for inhibitory effect on α-glucosidase and tyrosinase. Of the six compounds evaluated, ssioriside was a moderate inhibitor of α-glucosidase (IC50 = 650µM) and epigallocatechin showed weak tyrosinase enzyme inhibition activity (IC50 = 2001µM)