Identification of Flavonoid Pigments and Coloration Mechanisms in the Bluish-purple Flowers of <i>Platycodon grandiflorus</i> (Jacq.) A. DC. (Campanulaceae)

We investigated bluish-purple Platycodon grandiflorus flowers for yet unidentified flavonoid-related compounds and their flower coloration mechanisms. identified a new polyacylated anthocyanin, delphinidin 3-O-[6-O-(α-rhamnopyranosyl)-β-glucopyranoside]-7-O-[6-O-(4-O-(6-O-(4-O-(6-O-(4-O-(β-glucopyranosyl)-trans-caffeoyl)-β-glucopyranosyl)-trans-caffeoyl)-β-glucopyranosyl)-trans-caffeoyl)-β-glucopyranoside] (3) as the minor anthocyanin component along with four known anthocyanins, flavones, chlorogenic acid. The major of P. is platyconin. While platyconin has two caffeic acids linked in series via glucose molecules at 7-position delphinidin, 3 three delphinidin. To investigate effects number aromatic acyl groups on bluing stability, color stability diluted aqueous solution (5 × 10−5 M) weak acidic condition (pH 5.7, same pH petal sap) were compared those Results showed that even if bound there was no further or stabilizing to platyconin, but tendency toward weakening intensity observed. Investigation change content developmental stages 3-rutinoside-7-glucoside, which deacylated form first accumulated up sufficient amounts bud stage, followed by an increase content. At petals not purple violet, except veins, despite presence good amount indicating 3-rutinoside-7-glucoside present some colorless state.