Flower colors and flavonoids in the cultivars of Lobelia erinus L. (Campanulaceae)

摘要

Four new acylated anthocyanins were isolated from the violet-blue and purple-violet flower cultivars of Lobelia erinus L., along with five known anthocyanins and two known flavones. The four novel acylated anthocyanins were determined to be delphinidin 3-O-[6-O-(4-O-(trans-p-coumaroye-alpha-rhamnopyranosyl)-beta-glucopyranoside]-5-O-[6-O-(malonyl)-beta-glucopyranoside]-3'-O-[6-O-(trans caffeoyl)-beta-glucopyranoside]-5'-O-(beta-glucopyranoside) (2), delphinidin 3-O-[6-O-(4-O-(cis-p-coumaroyl)-alpha-rhamnopyranosyl)-beta-glucopyranoside]-5-O-[6-O-(malonyl)-beta-glucopyranoside]-3',5'-di-O-[6-O-(trans-caffeoyl)-beta-glucopyranosidel(5), cyanidin 3-O-[6-O-(4-O-(trans-p-coumaroyl)-alpha-rhamnopyranosyl)-beta-glucopyranosidel-5-O-[6-O-(malonyl)-beta-glucopyranoside] -3'-O-[6-O-(trans-caffeoye-beta-glucopyranosidel (7), and cyanidin 3-O-[6-O-(4-O-(trans-p-coumaroye-alpha-rhamnopyranosyl)-beta-glucopyranosidel-5-O-[6-O-(malonyl)-beta-glucopyranoside]-3'-O-[6-O-(trans-feruloyl)-beta-glucopyranosidel (9), using chemical and spectroscopic methods. Using spectroscopy, the visible absorption curves obtained from fresh violet-blue and purple-violet petals indicated the presence of poly acylated anthocyanins in these plants. Two strong absorption maxima from seven violet-blue cultivars were observed at 614 and 570 nm, which included delphinidin based poly acylated anthocyanins, and two absorption maxima from two purple-violet cultivars were observed at 588 and 552 nm, which were included cyanidin based poly acylated anthocyanins. The violet-blue cultivars contained pigment 4 as a major anthocyanin and purple-violet cultivars contained pigment 7 as a major anthocyanin. All cultivars contained apigenin 7-rutinoside (F2) as a major flavone in their petals. The spectra of purified pigments 4 and 7 in pH 5.0 buffer solution and the spectra obtained by adding F2 to respective solutions containing pigments 4 and 7 showed nearly identical curves, respectively. Moreover, under the same pH conditions, the spectra of pigments 4 and 7 and the spectra of violet-blue and purple-violet petals showed nearly identical curves, respectively. These results suggested that the violet-blue and purple-violet flower cultivars containing poly acylated anthocyanins are affected by intramolecular co-pigmentation under weak acid conditions but are not affected by intermolecular co-pigmentation.