Heterogeneity of the interflavanyl bond in proanthocyanidins from natural sources lacking C-4 (C-ring) deoxy flavonoid nucleophiles |
| |
Authors: | Ferreira Daneel Marais Jannie P J Slade Desmond |
| |
Institution: | Department of Pharmacognosy, School of Pharmacy, The University of Mississippi, University, MS 38677, USA. dferreir@olemiss.edu |
| |
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. |
| |
Keywords: | Acacia caffra Acacia fasciculifera Acacia galpinii Acacia mearnsii (black wattle) Acacia melanoxylon Burkea africana Colophospermum mopane Guibourtia coleosperma Nelia meyeri Peltophorum africanum Prosopis glandulosa Robinia pseudacacia Leguminosae Aizoaceae Proanthocyanidins Leucoanthocyanidins Proteracacinidins Promelacacinidins |
本文献已被 ScienceDirect PubMed 等数据库收录! |