Ursolic acid and its esters: occurrence in cranberries and other Vaccinium fruit and effects on matrix metalloproteinase activity in DU145 prostate tumor cells.

Background: Ursolic acid and its cis- and trans-3-O-p-hydroxycinnamoyl esters have been identified as constituents of American cranberries (Vaccinium macrocarpon), which inhibit tumor cell proliferation. Since the compounds may contribute to berry anticancer properties, their content in cranberries, selected cranberry products, and three other Vaccinium species (V. oxycoccus, V.