Full length articleCharacterization and purification of anthocyanins from black peanut (Arachis hypogaea L.) skin by combined column chromatography

•Composition of anthocyanins and flavonols in black peanut skin was identified.•An efficient method was developed for the purification of anthocyanins.•Two pure monomeric anthocyanins were isolated from black peanut skin extracts.•Chemical structure was identified for cyanidin-3-O-sophoroside.

Black peanut skins as a byproduct from peanut industry contain abundant anthocyanins, evaluated as 8.61 ± 0.27 mg/g dry black peanut skins, are currently poorly exploited. In this work, four anthocyanins and three major flavonols were detected and identified by HPLC-PDA-ESI-MS/MS from the acidified water extract of black peanut skins of Arachis hypogaea L. After preliminary removal of flavonols by ethyl acetate (EtOAc), further purification of the anthocyanins was conducted using a combination of Amberlite XAD-7HP and ODS-AQ-HG column chromatography methods. Two most abundant monomeric anthocyanins cyanidin-3-O-sophoroside (5.77 ± 0.42 mg) and cyanidin-3-O-sambubioside (4.10 ± 0.17 mg) were eventually obtained from 2 g dry black peanut skins, and their purities were determined by HPLC-PDA as 97.29% and 98.28% at the yields of 87.47% and 64.27% on the basis of their total amount in the crude extracts, respectively. These sequential treatments can be easily adapted to large-scale fractionation of pure anthocyanin monomers.