title: Structure of anthocyanin from the blue petals of Phacelia campanularia and its blue flower color development.
abstract: The dicaffeoyl anthocyanin, phacelianin, was isolated from blue petals of Phacelia campanularia. Its structure was determined to be 3-O-(6-O-(4'-O-(6-O-(4'-O-beta-d-glucopyranosyl-(E)-caffeoyl)-beta-d-glucopyranosyl)-(E)-caffeoyl)-beta-d-glucopyranosyl)-5-O-(6-O-malonyl-beta-d-glucopyranosyl)delphinidin. The CD of the blue petals of the phacelia showed a strong negative Cotton effect and that of the suspension of the colored protoplasts was the same, indicating that the chromophores of phacelianin may stack intermolecularly in an anti-clockwise stacking manner in the blue-colored vacuoles. In a weakly acidic aqueous solution, phacelianin displayed the same blue color and negative Cotton effect in CD as those of the petals. However, blue-black colored precipitates gradually formed without metal ions. A very small amount of Al(3+) or Fe(3+) may be required to stabilize the blue solution. Phacelianin may take both an inter- and intramolecular stacking form and shows the blue petal color by molecular association and the co-existence of a small amount of metal ions. We also isolated a major anthocyanin from the blue petals of Evolvulus pilosus and revised the structure identical to phacelianin.
authors.affiliation: Graduate School of Human Informatics, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
authors.forename: Mihoko
authors.initials: M
authors.lastname: Mori
authors.forename: Tadao
authors.initials: T
authors.lastname: Kondo
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Toki
authors.forename: Kumi
authors.initials: K
authors.lastname: Yoshida
mesh_terms: D000872:Anthocyanins / Q000737:chemistry* / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D003116:Color; D035264:Flowers / Q000737:chemistry*; D029522:Hydrophyllaceae / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010858:Pigmentation / Q000502:physiology*
chemical_list: D000872:Anthocyanins