title: Heterogeneity of the interflavanyl bond in proanthocyanidins from natural sources lacking C-4 (C-ring) deoxy flavonoid nucleophiles.
abstract: The proanthocyanidin pool in the floral kingdom usually involves the presence of carbon-carbon bonds linking predominantly flavan-3-ol constituent moieties. Such an ensemble of flavan-3-ol units originates via electrophilic aromatic substitution of flavan-4-yl carbocations (or their equivalents) derived from flavan-4-ols and/or flavan-3,4-diols and the nucleophilic centers of the m-oxygenated A-rings of flavan-3-ol nucleophiles. In the absence of these potent flavan-3-ol nucleophiles with their aptitude for the formation of carbon-carbon bonds, alternative centers emerge as participants in interflavanyl bond formation. Such a phenomenon is demonstrated for the distribution of various profisetinidin-, prorobinetinidin-, proguibourtinidin-, promelacacinidin- and proteracacinidin-type pro- and leuco-anthocyanidins in several southern hemisphere heartwood species.
authors.affiliation: Department of Pharmacognosy, School of Pharmacy, The University of Mississippi, University, MS 38677, USA. dferreir@olemiss.edu
authors.forename: Daneel
authors.initials: D
authors.lastname: Ferreira
authors.forename: Jannie P J
authors.initials: JP
authors.lastname: Marais
authors.forename: Desmond
authors.initials: D
authors.lastname: Slade
mesh_terms: D002244:Carbon / Q000737:chemistry; D005419:Flavonoids / Q000737:chemistry; D015394:Molecular Structure; D044945:Proanthocyanidins / Q000737:chemistry*
chemical_list: D005419:Flavonoids; D044945:Proanthocyanidins; D002244:Carbon