Covalent anthocyanin-flavonol complexes from the violet-blue flowers of Allium 'Blue Perfume'

Norio Saito, Maiko Nakamura, Koichi Shinoda, Naho Murata, Toshinari Kanazawa, Kazuhisa Kato, Kenjiro Toki, Hiroko Kasai, Toshio Honda, Fumi Tatsuzawa

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5 Citations (Scopus)

Abstract

Three covalent anthocyanin-flavonol complexes (pigments 1-3) were extracted from the violet-blue flower of Allium 'Blue Perfume' with 5% acetic acid-MeOH solution, in which pigment 1 was the dominant pigment. These three pigments are based on delphinidin 3-glucoside as their deacylanthocyanin and were acylated with malonyl kaempferol 3-sophoroside-7-glucosiduronic acid or malonyl-kaempferol 3-p-coumaroyl-tetraglycoside-7-glucosiduronic acid in addition to acylation with acetic acid. By spectroscopic and chemical methods, the structures of these three pigments 1-3 were determined to be: pigment 1, (6 I-O-(delphinidin 3-O-(3 I-O-(acetyl)-β- glucopyranoside I)))(2 VI-O-(kaempferol 3-O-(2 II-O-(3 III-O-(β-glucopyranosyl V)-β- glucopyranosyl III)-4 II-O-(trans-p-coumaroyl)-6 II-O-(β-glucopyranosyl IV)-β-glucopyranoside II)-7-O-(β-glucosiduronic acid VI))) malonate; pigment 2, (6 I-O-(delphinidin 3-O-(3 I-O-(acetyl)-β- glucopyranoside I)))(2 VI-O-(kaempferol 3-O-(2 II-O-β-glucopyranosyl III)-β-glucopyranoside II)-7-O-(β-glucosiduronic acid VI))); and pigment 3, (6 I-O-(delphinidin 3-O-(3 I-O-(acetyl)-β- glucopyranoside I)))(2 VI-O-(kaempferol 3-O-(2 II-O-(3 III-O-(β-glucopyranosyl V)-β- glucopyranosyl III)-4 II-O-(cis-p-coumaroyl)-6 II-O-(β-glucopyranosyl IV)-β-glucopyranoside II)-7-O-(β-glucosiduronic acid VI))) malonate. The structure of pigment 2 was analogous to that of a covalent anthocyanin-flavonol complex isolated from Allium schoenoprasum where delphinidin was observed in place of cyanidin. The three covalent anthocyanin-flavonol complexes (pigment 1-3) had a stable violet-blue color with three characteristic absorption maxima at 540, 547 and 618 nm in pH 5-6 buffer solution. From circular dichroism measurement of pigment 1 in the pH 6.0 buffer solution, cotton effects were observed at 533 (+), 604 (-) and 638 (-) nm. Based on these results, these covalent anthocyanin-flavonol complexes were presumed to maintain a stable intramolecular association between delphinidin and kaempferol units closely related to that observed between anthocyanin and hydroxycinnamic acid residues in polyacylated anthocyanins. Additionally, an acylated kaempferol glycoside (pigment 4) was isolated from the same flower extract, and its structure was determined to be kaempferol 3-O-sophoroside-7-O-(3-O-(malonyl)-β- glucopyranosiduronic acid).

Original languageEnglish
Pages (from-to)99-108
Number of pages10
JournalPhytochemistry
Volume80
DOIs
Publication statusPublished - 2012 Aug
Externally publishedYes

Keywords

  • Alliaceae
  • Allium 'Blue Perfume'
  • Anthocyanin and flavonols disubstitute malonate
  • Delphinidin 3-glucoside kaempferol 3-glycoside-7-glucosiduronic acids and malonic acid
  • Flower color
  • Intramolecular copigmentation

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Plant Science
  • Horticulture

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