Evaluation of Anthocyanin Profiling, Total Phenolic and Flavonoid Content, and Antioxidant Activity of Korean Rubus Accessions for Functional Food Applications and Breeding

The Rubus genus includes numerous berry species known for their rich phytochemical content and antioxidant properties. However, comparative evaluations of wild and cultivated Rubus germplasms in East Asia remain limited. This study aimed to identify superior resources with potential for use in functional foods and breeding through integrated phytochemical and antioxidant profiling. Fifteen accessions collected across Korea were assessed for fruit coloration, total phenolic content (TPC), total flavonoid content (TFC), five antioxidant activities (DPPH, ABTS⁺, superoxide, ferric-reducing activity power, and Fe²⁺ chelation), and anthocyanin composition by high-performance liquid chromatography‒Mass spectrometry. The TPC ranged from 1.03 to 7.54 mg g⁻¹ of frozen fruit, and TFC ranged from 2.75 to 7.52 mg g⁻¹ of frozen fruit, with significant differences among accessions (p < 0.05). Black-colored fruits such as R. coreanus and R. ursinus varieties exhibited high anthocyanin levels (approximately total 471 and 316 mg g⁻¹ extracts, respectively), with cyanidin-O-hexoside and cyanidin-3-O-glucoside being the dominant pigments. However, the antioxidant performance of these accessions varied. A wild R. crataegifolius (no. 9, resource F) showed the highest TPC and ranked within the top five in multiple antioxidant assays, despite its moderate anthocyanin content. Correlation analysis revealed that TPC and TFC were significantly associated with antioxidant activity (p < 0.05) but not directly with anthocyanin content. These results suggest that antioxidant potential is influenced by a broader spectrum of phenolic compounds, rather than anthocyanins alone. These findings underscore the need to look beyond visual traits and focus on biochemical evidence when selecting elite Rubus accessions.