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The influence of low temperature and storage time on the antioxidant capacity of standard solutions and apple and orange extracts was evaluated. In addition, the effects of ascorbic acid (AA) addition to the fruit extracts in terms of antioxidant capacity, AA content and soluble and hydrolyzable polyphenol contents were also analysed. Polyphenol contents in both apple and orange extracts were stable during storage period, which reflected also in the antioxidant capacity stability. Freezing at −18 °C did not result in different retention rates for polyphenols, AA and antioxidant capacity when compared to freezing at −70 °C. However, vitamin C content in orange juice, without AA addition, slightly increased along the experimental period (10 days). Thus, this study shows that it may not be necessary to measure the antioxidant capacity immediately after the preparation of fruit extracts or antioxidant standard solutions. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the influence of the in vitro gastrointestinal digestion of yerba mate extract on the cellular antioxidant activity (CAA) and cytotoxic and antiproliferative action toward HepG2 cells. The total reducing substances, isolated phenolic acids, total flavonoids and total antioxidant activity of the yerba mate extract decreased significantly after in vitro digestion. The digested extract promoted lower CAA and inhibition of HepG2 cell proliferation when compared to the non-digested extract ( P < 0.05). No significant difference was observed in the cytotoxicity assay. Dose–response correlations were found for both yerba mate extracts for CAA, antiproliferative activity and cytotoxicity. The simulated gastrointestinal digestion of yerba mate extract promoted a significant decrease in the phytochemical content, total antioxidant activity, CAA and inhibition of HepG2 cell proliferation. Nevertheless, digested yerba mate extract still has considerable CAA and antiproliferative activity, which merits further investigation in in vivo studies. [ABSTRACT FROM AUTHOR]