Difference Analysis in Antioxidant Activity and Composition of Pigments from Pink and Black Peanut Seed Coat

To have a deep understanding of the difference in antioxidant activity and composition of the seed coat pigments between pink and black peanuts, the composition of seed coat pigments from pink and black peanuts were analyzed by UPLC-Q-TOF-MS. Catechin, two dimer, one trimer and two tetramers of proanthocyanidins were identified in the pink peanut coat, while two cyanidin, four delpinidin besides dimer, trimer and tetramers of proanthocyanidins were identified in black peanuts seed coat. The antioxidant activity of pink and black peanut seed coat pigment were determined by spectrophotometry. The results showed that the antioxidant activity of pink peanut seed coat pigments was (17.46+1.88) U/mg. the antioxidant activity of black peanut seed coat pigments was (23.77+1.58) U/mg;the semi-inhibitory effect IC₅₀ of black peanut seed coat pigments on hydroxyl radicals and superoxide anions were 0.58 and 1.79, respectively, and that of red peanut seed coat pigments on hydroxyl Semi-inhibitory IC₅₀ of oxygen anion were 0.39 and 1.41 mg/mL. Its compounds and antioxidant activity had obvious differences. The total antioxidant activity of black peanut was stronger than that of pink peanut, while the ability of inhibiting hydroxyl radical and superoxide anion was weaker than that of pink peanut.