Comparison of phenolic composition and antioxidant properties of two native Chilean and one domestic strawberry genotypes

The phenolic composition of extracts from the forms chiloensis and patagonica of Fragaria chiloensis were compared with that of the commercial strawberry Fragaria × ananassa cv. Chandler by high performance liquid chromatography with diode-array detector (HPLC–DAD) and high performance liquid chromatography with electrospray ionization mass spectroscopy detector (HPLC–ESI–MS). The phenolic constituents in the three species were mainly proanthocyanidins, hydrolysable tannins, anthocyanins and flavonol glycosides. In both native strawberry species the main flavonol glycoside was quercetin 3-O-glucuronide and the minor anthocyanins identified were cyanidin-malonyl-glucoside and pelargonidin-malonyl-glucoside. The highest anthocyanin content was found in the commercial red strawberry while ellagic acid was the main phenolic in the native white strawberry. From the methanolic fruit extract of the native Chilean strawberry Fragaria chiloensis ssp. chiloensis f. chiloensis four known antioxidants were isolated by selective fractionation using the bleaching of the free radical scavenger 1,1-diphenyl-2-picrylhydrazyl (DPPH) as the guiding assay. The antioxidant properties (measured as the bleaching of the DPPH radical) were determined for methanol extracts of the three fruits, for fractions of F. chiloensis ssp. chiloensis f. chiloensis, and for the isolated compounds cyanidin-3-glucoside, pelargonidin-3-glucoside, quercetin-3-glucuronide and ellagic acid. This study allows a clear chemical differentiation between the commercial strawberry and the Chilean white strawberry.