title: Isolation of bilberry anthocyanidin 3-glycosides bearing ortho-dihydroxyl groups on the B ring by forming an aluminum complex and their antioxidant activity.
abstract: Bilberry anthocyanin bearing an ortho-dihydroxyl group on the B ring was selectively isolated by complex formation with flavocommelin and aluminum ions (Al(3+)). The interaction between the anthocyanins, flavocommelin, and Al(3+) might have happened in a manner similar to rigid supramolecules, such as commelinin, protocyanin, and other complex pigments. Complex blue pigment (CP, 8.85 ± 0.26 mg) with Al(3+) was formed from 18.6 mg (15 μmol) of bilberry pigment, 18.2 mg (30 μmol, 2.0 equiv) of flavocommelin, and 0.03 mL of 0.5 M aluminum chloride aqueous solution (15 μmol, 1.0 equiv), yielding 36.5 ± 0.7% recovery of anthocyanins in the complex after precipitation by ethanol. Consequently, anthocyanins bearing ortho-dihydroxyl groups on the B rings (delphinidin 3-glycosides, cyanidin 3-glycosides, and petunidin 3-glycosides) predominating (98.0 ± 0.2%) in the complex were selectively isolated in a dose-dependent manner by the addition of Al(3+), increasing the antioxidative activity of the mixture of anthocyanins.
authors.affiliation: United Graduate School of Agricultural Sciences, Ehime University, 3-5-7 Tarumi, Matsuyama 790-8566, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Asada
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Tamura
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D000872:Anthocyanins / Q000737:chemistry / Q000302:isolation & purification*; D000975:Antioxidants / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry*; D029800:Vaccinium myrtillus / Q000737:chemistry*
chemical_list: D000872:Anthocyanins; D000975:Antioxidants; D006027:Glycosides; D000535:Aluminum