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Prodelphinidin trimers and characterization of a proanthocyanidin oligomer from Cistus albidus.
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2003
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BiologyMedicinal ChemistryBioorganic ChemistryBiochemistryNatural SciencesHigher Oligomeric FractionNatural Product BiosynthesisOrganic ChemistryPhytochemicalCistus AlbidusChemical BiologyPharmacologyProdelphinidin TrimersProanthocyanidin OligomerPhytochemistryAir-dried HerbNatural Product Synthesis
Two new natural prodelphinidin trimers have been isolated from the air-dried herb of Cistus albidus, epigallocatechin-(4beta --> 8)-gallocatechin-(4alpha --> 8)-catechin and epigallocatechin-(4beta --> 8)-gallocatechin-(4alpha --> 8)-gallocatechin in addition to catechin, gallocatechin and thirteen known proanthocyanidins. The structures were determined on the basis of 1D- and reverse 2D-NMR (HSQC, HMBC) experiments of their peracetylated derivatives, MALDI-TOF-MS and by acid-catalysed degradation with phloroglucinol. A more abundant higher oligomeric proanthocyanidins fraction was also isolated and its chemical constitution studied by 13C-NMR. The mean molecular weight of the higher oligomeric fraction was estimated to be 6-7 flavan-3-ol-units.