Acylated delphinidin glycosides from violet and violet-Blue flowers of clematis cultivars and their coloration

Abstract

Three new acylated delphinidin glycosides, delphinidin 3-O-β- [(2"-trans-caffeoylglucopyranosyl)-(1→2)-(6"- succinylgalactopyranoside)]-7-O-β- glucopyranoside (1), delphinidin 3-O-β-[(2"-trans-caffeoylglucopyranosyl)-(1→2) -(6"-trans-caffeoyl-tartaroyl-malonylgalactopyranoside)]-7-O-β- glucopyranoside (2), and delphinidin 3-O-β-[(2"-trans- caffeoylglucopyranosyl)-(1→2)-(6"-trans-caffeoyl-tartaroyl- malonylgalactopyranoside)]-3'-O-β- glucuronopyranoside (3), were isolated from the violet and violet-blue sepals of Clematis cultivars 'Jackmanii Superba' and 'Fujimusume'. The chemical structures of the isolated anthocyanins were determined by LC-MS, characterization of hydrolyzates, and UV, 1H and 13C NMR spectroscopy. The visible absorption spectra of these anthocyanins were compared with those of fresh sepals and crude extracts in pH 5.1 buffer solution. In addition, the co-pigment effect with some kaempferol glycosides and caffeoylglucose was examined.