Antioxidant properties and electrochemical activity of anthocyanins and anthocyanidins in mulberries

This study analyzed the anthocyanin content and antioxidant properties of five mulberry ( Morus spp. ) varieties, including black ( M. nigra ), red ( M. rubra ) and white ( M. alba ) types. Anthocyanins were extracted and analyzed using HPLC–MS, which revealed four major pigments: cyanidin-3-glucoside, cyanidin-3-rutinoside, cyanidin-3,5-diglucoside and pelargonidin-3-glucoside. Total anthocyanins were significantly higher in black mulberries Bom irangi (185 mg/100 g) and Kalmi (158 mg/100 g) compared to 28–60 mg/100 g in other varieties, consistent with their dark fruit color. Electrochemical analysis by cyclic voltammetry showed oxidation peak potentials (E pa ) of key anthocyanins: + 368 mV for cyanidin; + 830 mV for cyanidin-3-glucoside; and + 912 mV for pelargonidin-3-glucoside. Lower E pa indicates easier oxidation and greater antioxidant activity. DPPH radical scavenging assays revealed strongest potency for Bom irangi (EC50 42 μg/mL) and Kalmi (EC50 58 μg/mL), again due to high anthocyanin levels. Further, a negative correlation (R 2  = 0.923) was demonstrated between E pa values and EC50, proving excellent predictive ability of electrochemical data for estimating antioxidant capacity. Cyanidin with lowest E pa (+ 368 mV) and highest hydroxylation exhibited strongest activity (EC50 35 μg/mL). Overall, the study successfully demonstrated the antioxidant potential of mulberry anthocyanins, especially from black varieties, using advanced analytical strategies.