Antioxidant properties of polyphenolic extracts from chokeberry, blackcurrant, blackberry, and raspberry fruits

Abstract

Berry fruits are valuable source of polyphenolic compounds, which show high biological activity. They are characterized by great diversity in structure and antioxidant properties. The main phenolic compounds found in investigated fruits from Rosaceae family are: p-coumaric, caffeic and ferulic acids; anthocyanins, mainly cyaniding-3-glucoside derivatives; flavonols, commonly quercetin, myrycetin and kaempferol, and flavanols like (+) catechin and (-) epicatechin. In some species, in raspberry and blackberry for example, ellegic acid derivatives (hydrolysable tannins) are found in large quantities. In other ones, e.g. in chokeberry and blackberry, hydroxycinnamic acid derivatives such as chlorogenic and neochlorogenic acids dominate. Large variations in quality and quantity of phenolic compounds in fruits may explain their different antioxidant properties. The aim of this study was investigation of antioxidant activity of phenolic compounds in extracts obtained from chokeberry (CB), blackcurrant (BC), blackberry (BB), and raspberry (RB). The determination of total phenolic and anthocyanins content as well as ABTS test, were done in four fractions obtained with methanol (WA), ether (WB), ethyl acetate (WC) and water (WD). The richest in phenolic compounds were blackcurrant extracts (31-331 mg/g), then extracts from chokeberry (20-197 mg/g), raspberry (22-210 mg/g), and blackberry (46-113 mg/g). The highest content was determined in WB fraction (BC, CB, RB) and WC fraction (CB, BB). Total antioxidant activity against ABTS^·+ radical cation decreased in order: CB >BC >BB > RB. The most active were ether (WB) and acetate (WC) fractions, which contain the majority of phenolic compounds. The correlation coefficient between total phenolic content and ABTS test was high (r = 0.94).