Characterization of Acylated Anthocyanins in Callus Induced From Storage Root of Purple-Fleshed Sweet Potato, Ipomoea batatas L

Four anthocyanins were isolated from a highly pigmented callusinduced from the storage root of purple-fleshed sweet potato(Ipomoea batatas L) cultivar Ayamurasaki. Theanthocyanins were respectively identified as cyanidin3-O-(2-O-(6-O-(E)-caffeoyl-β-D-glucopyranosyl)-β-D-glucopyranoside)-5-O-β-D-glucopyranoside, cyanidin3-O-(2-O-(6-O-(E)-p-coumaroyl-β-D-glucopyranosyl)-6-O-(E)-caffeoyl-β-D-glucopyranoside)-5-O-β-D-glucopyranoside, cyanidin3-O-(2-O-(6-O-(E)-p-coumaroyl-β-D-glucopyranosyl)-6-O-(E)-p-coumaroyl-β-D-glucopyranoside)-5-O-β-D-glucopyranoside, and peonidin3-O-(2-O-(6-O-(E)-p-coumaroyl-β-D-glucopyranosyl)-6-O-(E)-p-coumaroyl-β-D-glucopyranoside)-5-O-β-D-glucopyranoside by chemical and spectroscopic analyses. These anthocyanins wereexamined with respect to the stability in neutral aqueous solutionas well as the radical scavenging activity against the1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. These acylatedanthocyanins exhibited both higher stability and higher DPPHradical scavenging activity than corresponding nonacylatedcyanidin and peonidin 3-O-sophoroside-5-O-glucosides.