New technique to isolate anthocyanins from Delaware grapes by forming an aluminium complex using a Discovery DPA-6S

An aluminium complex of crude Delaware grape anthocyanins, bearing an ortho-dihydroxyl group on the B ring and/or a p-coumaroyl group as an ester with flavocommelin, was formed and isolated by ethanol precipitation. Using a Discovery DPA-6S short column, selected anthocyanins were isolated to give cyanidin 3-glucoside (Cy3G, 48.2% yield with 95.2% purity) and cyanidin 3-(6-O-p-coumaroylglucoside) (Cy3-pC·G, 44.9% yield with 91.4% purity) from natural Delaware grape skin extracts without ODS-HPLC column chromatography. DPPH radical scavenging activity of the complex pigment was 3.4 ± 0.10 μmol TE/mg. Moreover, isolated pure anthocyanins from the complex pigment showed significantly higher DPPH radical scavenging activity [4.5 ± 0.08 μmol TE/mg (Cy3G) and 4.5 ± 0.04 μmol TE/mg (Cy3-pC·G), (p<0.05)].