Cancer-preventive activities of secondary metabolites from leaves of the bilberry Vaccinium smallii A. Gray.

Ten secondary metabolites including flavonoids (1-8), caffeic (9) and chlorogenic (10) acids were structurally identified from the extract of Sakhalin bilberry Vaccinium smallii leaves and studied in vitro as potential cancer-preventive agents. The results showed that compounds 1-10 inhibited EGF-induced neoplastic transformation of mouse JB6 Cl 41 P+ cells in soft agar with an inhibition concentration (INCC50) of 20-80 µm. Moreover, all these natural products were non-toxic against JB6 Cl 41 P+ cells up to a concentration of 200 µm.