Main Components of Anthocyanins and Their Antioxidant Activities in Black Corn Grain

Purpose To identify the main components of anthocyanins (ACs) in black corn grain, and to study the antioxidant activity of different anthocyanin fractions.

Methods ACs was extracted from corn grain using acidic methanol, and purified by open column chromatography, obtaining different fractions. Five different ACs fractions were selected, and the chemical structure of ACs in the fractions was identified by ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS), and the antioxidant activity of each fraction was measured.

Results Black corn grain contained more than 22 kinds of ACs, including six kinds of cyanidinoside, six kinds of pelargonidinoside, five kinds of peonins, one kind of delphinin and one kind of petunin, and three kinds of unknown structures. Black corn ACs had antioxidant activity, but its ability to scavenge free radicals in the original solution was extremely significantly lower than that of vitamin C (Vc), and the difference in total antioxidant capacity was significant with Vc. The antioxidant activity of purified ACs was enhanced, and the antioxidant activity of some fractions were significantly stronger than that of Vc.

Conclusion A total of 19 kinds of ACs were identified from the extract and purified fractions of ACs in black corn grain using UPLC-MS. Among them, cyanidin-3-O-(6-O-acetylgalactoside), pelargonidin-3-O-(6-O-acetylgalactoside), delphinidin-3-O-rutinoside, pelargonidin-3-O-(6-O-succinylglucoside), peonidin-3-O-(6-O-acetylglucoside), peonidin-3-O-(2,6-O-methylmalonylglucoside), petunidin-3-O-glucoside, peonidin-3-O-(2-O-methylglucoside) were identified in black corn grain for the first time. The ACs in black corn grain have strong antioxidant activity and are closely related to the components and composition of ACs. After purification, although the components of its original solution are reduced, the antioxidant activity is enhanced.