Secondary metabolites and bioactivity of sweet cherry...and others

Consumption of fruits and vegetables has been associated with several benefits for human health, their regular consumption has been associated with a reduced risk of a number of chronic diseases. In fact, food provides bioactive compounds with a known activity in health promotion and disease prevention. We found, through NMR spectroscopy and HPLC-DAD analysis, that the metabolomic composition of sweet cherry fruits vary substantially among 18 different cultivars analyzed (Marostica PGI zone). Data revealed that the main polyphenolic compounds in the fruits were anthocyanins, hydroxycinnamic acid and flavonoids with strong differences between cultivar. For example, the Sandra tardiva cultivar accumulated higher levels of cyanidins whereas Grace star cultivar show low abundance of this pholyphenols. Furthermore, many sweet cherry metabolites possess antioxidant activity, so we investigate the in vitro antioxidant properties of fruit extracts using ABTS and FRAP assays. The two assays gave similar results and in general we found that in vitro antioxidant activity correlates mainly with the anthocyanin and quercetin content. To investigate in more details antioxidant properties, artificial simplified phytocomplexs were made to mimic the composition of Sandra Tardiva, Sandra and Grace Star cultivars on the basis of their pholyphenols content. We found that anthocyanins, quercetins and ascorbic acid, when mixed together at the same concentrations found in the Sandra Tardiva extracts, displayed strong synergistic antioxidant activity in the FRAP assay. However when the same components were mixed in the proportions found in the Sandra and Grace Star cultivars, the effects were additive rather than synergistic In order to gain the in vivo antioxidant activity of the cherry fruits we tested their antioxidant activity in a cellular model. THP-1 cell line were incubated with Sandra Tardiva, Sandra and Grace Star extracts and the antioxidant activity was evaluated by flow cytometry. The intracellular reactive oxygen species (ROS) were detected using the ROS-sensitive fluorescent dye, H2DCFDA that upon cleavage of acetate groups by intracellular esterases and oxidation is converted to the highly fluorescence DCF. Our results shows a reduced emission of fluorescence in cell-treated with cherry extracts suggesting an antioxidant effect due to accumulation of antioxidant metabolites of cherry fruits. To investigate the absorption of cherry metabolites and their potential role in the oxidative stress protection, cell incubated with Sandra Tardiva, Sandra and Grace were analysed in mass spectromery. Following the treatment with cherry extract many of principal metabolites of cherry, such as cyanidin 3-O-glucoside, feruilc acid and coumaroyl quinic acid were found able to penetrate cell membranes. Nowadays we are interested in studying the effects of several fruits and raw vegetables on monoamine oxidase, that are responsible for the degradation of neurotransmitters in the central nervous system, in order to evalutate antidepressant like-activity of their metabolites.