Factors Affecting Antioxidant and Anticancer Properties of Berry Fruits

Shiow Y. Wang, Fruit Laboratory, BARC, ARS, U. S.  Department of Agriculture, Beltsville, Maryland 20705-2350, USA. E-mail: wangs@ba.ars.usda.gov

      Berry fruits have been shown to contain high levels of antioxidant compounds such as carotenoids, vitamins, phenols, flavonoids, dietary glutathionine, and endogenous metabolites.  Many factors affect antioxidant levels in berry fruits.  These factors include genotype variation and maturity, pre-harvest conditions (climate, temperature, and light), culture practices, post-harvest handling and processing.  These antioxidants can act as free radical scavengers, peroxide decomposers, singlet and triplet oxygen quenchers, enzyme inhibitors, and synergists. The various antioxidant components found in berry fruits may provide protection against cancer and heart disease, in addition to a number of other health benefits. Discussion will be made on some strategies for establishing a new research and production paradigm such as improving selection criteria among different horticultural cultivars, and improving pre-harvest conditions and post-harvest handling to enhance nutrient quality.  Evidence will also be presented on the prevention and inhibition of tumor growth by fruit extracts and bioactive compounds isolated from fruits.

Berry fruit extracts (BEs) or bioactive compounds (BCs) isolated from berry fruits significantly inhibited activator protein-1 (AP-1), nuclear factor-KappaB (NF-kB), and mitogen-activated protein kinases (MAPKs) signaling induced by UV or 12-O-tetradecanolyphorbol-13-acetate (TPA).  Furthermore, BEs and BCs inhibited TPA-induced neoplastic transformation in JB6 cells. In vivo studies indicated that BCs decreased the number of nonmalignant and malignant skin tumors per mouse induced by TPA in 7, 12-dimethylbenz (a) anthracene-initiated mouse skin.  In HL-60 cells, BEs and BCs specifically induced apoptosis and differentiation, but had no effect on normal rat blood PMNs or lung alveolar macrophages.  BEs or BCs inhibited proliferation of A549 cells, a human lung cancer cell line. Animal studies indicated that BCs reduced the size of A549 tumor xenograft growth and significantly inhibited metastasis of A549 tumor xenograft in athymic nude mice.  Further mechanistic studies suggested that BCs inhibited migration and invasion of A549 cells.  All these data suggest that BCs may function as a potential chemopreventive and chemotherapeutic agent with little cytotoxicity to normal tissue.  These results also suggest that the chemopreventative effects of berry fruits may be through their antioxidant properties by blocking reactive oxygen species-mediated AP-1, NF-kB, and MAPK activation.

Keywords: Antioxidants, preharvest and postharvest factors, anticancer

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