Effects of Extracts of Apple Peel from Organically and Integrated Production Cultivated Apples and Ursolic Acid on Cancer Cell Proliferation

The effects of extract of apple peel, 'Aroma', organically cultivated or cultivated according to integrated production, on cell proliferation in vitro of colon cancer HT29 cells and breast cancer MCF-7 cells, were investigated. Different sequences of solvents were used, and the inhibiting effect on cancer cell proliferation of the different extracts was investigated. The solvents used were ethanol, methanol, DMSO and hexane in different sequences. The extracts decreased the proliferation of both HT29 and MCF-7 cells, the effect was different for the different extracts, and ethanol showed the highest inhibition effect. The inhibiting effect of the extracts also varied between both apple production methods, and extracts from peels of organically produced apples showed in some cases higher inhibition effects, while sometimes no differences were found. In addition, as ursolic acid, a component of apple peel, has been proposed to inhibit cancer cell proliferation, the inhibiting effect of pure ursolic acid on cancer cell proliferation was compared with the effect of the apple peel solvent fraction with the highest ursolic acid concentration. The inhibiting effect was higher in the apple fraction extract than in pure ursolic acid. Further, a range of different apple cultivars, integrated production and organically cultivated, were analysed by HPLC for their content of ursolic acid to investigate possible differences in concentrations.