Comparative study of polyphenolic content and antioxidant capacity in fruits of Arbutus unedo, A. andrachne and their natural hybrid A.× andrachnoides

Abstract

Fruits of the three Arbutus species native in the Eastern Mediterranean region, i.e. Arbutus andrachne, A. unedo and their natural hybrid A. × andrachnoides, collected from two different regions in Greece (Kalamos and Varympompi), were analysed comparatively in order to determine their phenolic profile and measure the antioxidant activity using two different single electron transfer-based assays, ferric reducing ability (FRAP) and 2,2-diphenylpicrylhydrazil radical scavenging capacity (DPPH). The pomological characteristics of the hybrid were similar to A. andrachne, while A. unedo had about 2.0-2.5 times larger fruits, with 20% more moisture being 175% heavier. All three species and their biotypes from the two areas had high phenolic content and antioxidant properties and were clearly pulled in different groups. Total flavanols scored a very strong correlation to antioxidant capacity. Highest total flavanols concentrations were found in A. andrachne fruits, while the hybrid had similar concentrations with A. unedo. In samples from Kalamos, concerning condensed tannins, total flavones, flavonols, phenolics and antioxidant capacity FRAP, as well as total anthocyanin and delphinidin 3-O-galactoside, the hybrid presented average values compared to the two parental species, while A. andrachne had the highest values. A strong correlation was found between ortho-diphenols and total soluble solids, as well as of total phenolics and flavonoids with total anthocyanins. The polyphenolic content and the antioxidant capacity varied in different biotypes. A. andrachne biotype from Kalamos showed the highest antioxidant capacity and anthocyanin potential. All A. unedo biotypes and A. × andrachnoides from Varympompi showed higher concentrations of ascorbic acid compared to the other biotypes.