Activity of stabilized vegetable extracts against oxidative stress and beta amyloid toxicity

Free radicals are known to play significant roles in many chronic pathologies as cardiovascular diseases, inflammatory processes, some cancer forms and aging. Concerning the latter both reactive oxygen (ROS) and nitrogen (RNS) species are suspected to be involved in the onset and development of neurodegenerative diseases as Alzheimer's disease (AD) characterized by selective neuronal death. In AD the beta-amyloid peptide, the major protein component of plaques, exert an active role in producing neurodegeneration when aggregated into fibrils. Different mechanisms underlie the toxic effects of this peptide including dysregulation of the normal redox state of neurons and generation of ROS. Among different strategies to contrast beta-amyloid toxicity one possible approach for therapeutic intervention in AD may be the use of antioxidant drugs. Vegetables and fruits are an important natural source od antioxidants and epidemiological data suggest that dietary antioxidants exert protective actions versus chronic pathologies probably in relation to components as vitamin C and E, flavonoids and anthocyanins. Within this context we tested the hypothesis that stabilized vegetal extracts found to have significant antioxidant activity in vitro, may also demonstrate protective properties against beta-amyloid induced cellular toxicity. We used a screening cellular model (human neuroblastoma celles IMR32) where beta-amyloid toxicity was tested using either beta-amyloid (1-42) or beta-amyloid (23-35) in comparison with known ROS generating systems such as H2O2/Fe2+, ascorbi acid/Fe2+, measuring cell viability by MTT assay, LDH leakage and fluorescent microscopy. In this system various stabilized vegetable extracts active against ROS generating systems have been tested and showed protective activities without intrinsic cellular toxicity at dilution factors ranging from 100 to 10000 fold relative to pure extract. Further fractionation of the most active exracts may lead to the identification of novel dietary compounds/mixtures with significant antioxidant potential.