Bioactive Composition and In Vitro Antioxidant Properties of Wild Blackberry (Rubus spp.) and Blueberry (Vaccinium spp.) Populations

This study comparatively evaluated the phenolic profiles and antioxidant capacities of wild blackberry (Rubus spp., n = 5) and blueberry (Vaccinium spp., n = 4) fruits naturally grown in the high-altitude Akılbaba Region (Giresun) of the Eastern Black Sea region (Türkiye). Methanolic extracts of fresh fruits were assessed for total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities using, the ferric reducing antioxidant power (FRAP) and DPPH assays, while individual phenolic compositions were quantified against 25 standards using RP-HPLC-PDA. The mean TPC and TFC values were determined as 4.49 ± 0.29 mg GAE/g FW and 0.06 ± 0.03 mg QE/g FW for blackberry, and 5.86 ± 1.25 mg GAE/g FW and 0.47 ± 0.13 mg QE/g FW for blueberry, respectively. Regarding antioxidant activity, FRAP values were determined as 96.08 ± 9.92 µmol FeSO4∙7H2O E/g FW for blackberry and 95.30 ± 13.26 µmol FeSO4∙7H2O E/g FW for blueberry samples. In the chromatographic analysis, blackberry was primarily distinguished by substantial concentrations of ellagic and gallic acids, while blueberry was characterized by chlorogenic acid as the major phenolic constituent. In contrast, chrysin and pinocembrin were detected as common flavonoid markers in all samples. Overall, although these two wild berry groups exhibited marked differences in their individual phenolic profiles, their antioxidant responses were assay-dependent, with comparable FRAP values but significantly stronger DPPH radical-scavenging activity in blackberry.