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.