Grape seed extract has been proven to exert anticancer effects on different
tumors. These effects are mainly ascribed to
catechin and
procyanidin content. Analytical studies demonstrated that
grape seed extract composition is complex and it is likely other components could exert
biological activities. Using cell count and flow cytometry assays, we evaluated the
cytostatic and apoptotic effects produced by three different grape seed extracts from Italia, Palieri and Red Globe cultivars, on Caco2 and HCT-8
colon cancer cells. These effects were compared to those induced by
epigallocatechin and
procyanidins, alone or in association, on the same cell lines. All the extracts induced growth inhibition and apoptosis in Caco2 and HCT-8 cells, along the intrinsic apoptotic pathway. On both cell lines, growth inhibition induced by Italia and Palieri grape seed extracts was significantly higher than that it has been recorded with
epigallocatechin,
procyanidins and their association. In Caco2 cells, the extract from Red Globe cultivar was less effective in inducing growth inhibition than
procyanidins alone and in association with
epigallocatechin, whereas, in HCT-8 cells, only the association of
epigallocatechin and
procyanidins triggers a significant proliferation decrease. On both cell lines, apoptosis induced by Italia, Palieri and Red Globe grape seed extracts was considerably higher than has been recorded with
epigallocatechin,
procyanidins and their association. These data support the hypothesis by which other compounds, present in the grape seed extracts, are likely to enhance the anticancer effects.