IN-VITRO ANTICANCER ACTIVITY OF FRUIT EXTRACTS FROM VACCINIUM SPECIES

Fruit extracts of four Vaccinium species (lowbush blueberry, bilberry, cranberry, and lingonberry) were screened for anticarcinogenic compou nds by a combination of fractionation and in vitro testing of their ab ility to induce the Phase II xenobiotic detoxification enzyme quinone reductase (QR) and to inhibit the induction of ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine synthesis, by the tumor promoter phorbol 12-myristate 13-acetate (TPA). The crude extracts, an thocyanin and proanthocyanidin fractions were not highly active in QR induction whereas the ethyl acetate extracts were active QR inducers. The concentrations required to double QR activity (designated CDqr) fo r the ethyl acetate extracts of lowbush blueberry, cranberry, lingonbe rry, and bilberry were 4.2, 3.7, 1.3, and 1.0 mu g tannic acid equival ents (TAE), respectively, Further fractionation of the bilberry ethyl acetate extract revealed that the majority of inducer potency was cont ained in a hexane/chloroform subfraction (CDqr = 0.07 mu g TAE). In co ntrast to their effects on QR, crude extracts of lowbush blueberry, cr anberry, and lingonberry were active inhibitors of ODC activity. The c oncentrations of these crude extracts needed to inhibit ODC activity b y 50% (designated IC50) were 8.0, 7.0, and 9.0 mu g TAE, respectively. The greatest activity in these extracts appeared to be contained in t he polymeric proanthocyanidin fractions of the lowbush blueberry, cran berry, and lingonberry fruits (IC50 = 3.0, 6.0, and 5.0 mu g TAE, resp ectively). The anthocyanidin and ethyl acetate extracts of the four Va ccinium species were either inactive or relatively weak inhibitors of ODC activity. Thus, components of the hexane/chloroform fraction of bi lberry and of the proanthocyanidin fraction of lowbush blueberry, cran berry, and lingonberry exhibit potential anticarcinogenic activity as evaluated by in vitro screening tests.