Variations in antioxidant capacity and phenolics in leaf extracts isolated by different polarity solvents from seven blueberry (Vaccinium L.) genotypes at three phenological stages

Antioxidant potential of blueberry leaves of seven genotypes (Vaccinium corymbosum, V. angustifolium, and hybrids) harvested at three phenological stages from three different bushes was evaluated by total phenolic content (TPC), ABTS and DPPH radical scavenging capacity, ferric reducing antioxidant power, and oxygen radical absorbance capacity (ORAC). The leaves were consecutively extracted with hexane (He), acetone (Ac), and methanol/water (Me/W). The extracts isolated with higher polarity solvents were stronger antioxidants. Remarkable variations in antioxidant capacity were observed depending on harvesting stage, genotype, and individual bushes. TPC was in the ranges of 29–143 (He), 87–312 (Ac), 85–333 (Me/W) mg GAE/g, ORAC—2633–10170 (Ac), 1517–13302 (Me/W) μmol trolox eqv/g. In general Putte, Northland and Gila genotypes demonstrated higher antioxidant capacity than Bluecrop, Dixi, Gretha, and Northblue. Phytochemical composition of selected samples was screened by UPLC/MS2; six previously not reported in blueberries leaves compounds were identified. In conclusion, this study demonstrated that blueberry leaves are a good source of natural antioxidants and valuable polyphenolic compounds, which could find various applications.