Effects of solvents and extraction methods on the content and antiradical activity of polyphenols from fruits Actinidia arguta, Crataegus monogyna, Gaultheria procumbens and Schisandra chinensis.

BACKGROUND In line with the current tendency towards the production of the so-called safe foods, the use of environmentally-friendly methods for the extraction of polyphenols from fruits has been sought. Citric acid is a good solvent in the preparation of phenolic compounds for the food and pharmaceutical industries because it is a natural antioxidant and is non-toxic for the environment. Furthermore, new sources of polyphenols from fruit of orchard plants that are less known in Poland have been looked for. The aim of this study was  to assess the content and antiradical activity of polyphenolic compounds in fruit extracts, depending on the extraction method employed. In addition, the yield of extraction processes was assessed. METHODS The experimental materials were fruits of the following plants: Actinidia arguta, Crataegus monogyna, Gaultheria procumbens, Schisandra chinensis. For the extraction, aqueous solutions of citric acid (CAE) and methanol (ME) were used. The following were determined in fruit extracts: the content of total phenols (TP) and anthocyanins (A), and antiradical activity (DPPH and ABTS). RESULTS In general, the C. monogyna fruit extracts were distinguished by the highest TP and A content. The TP and A content was significantly higher in fruit extracts obtained with the CAE method than in the ones produced with the ME method. The highest mean A/TP ratio was determined for S. chinensis fruit extracts. The antiradical activity (DPPH and ABTS) in fruit extracts did not depend on an extraction method, but on fruit species. Overall, a higher yield of extraction processes was achieved for the CAE method than for the ME method. CONCLUSIONS The present study indicates that the selected extraction methods are able to obtain polyphenolic extracts from fruits with a high antiradical activity and high yield. The use of citric acid in order to extract polyphenols from fruits may be an alternative to the conventional extraction method, while being eco-friendly and more effective than the latter.