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Characterization of Proanthocyanidin Oligomers of Ephedra sinica

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Title: Characterization of Proanthocyanidin Oligomers of Ephedra sinica
Authors: Orejola, Joanna / Matsuo, Yosuke / Saito, Yoshinori / Tanaka, Takashi
Issue Date: 6-Aug-2017
Publisher: Multidisciplinary Digital Publishing Institute (MDPI)
Citation: Molecules, 22(8), 1308; 2017
Abstract: Ephedra sinica, an important plant in Chinese traditional medicine, contains a complex mixture of proanthocyanidin oligomers as major constituents; however, only the minor components have been chemically characterized. In this study, oligomers with relatively large molecular weights, which form the main body of the proanthocyanidin fractions, were separated by adsorption and size-exclusion chromatography. Acid-catalyzed degradation in the presence of mercaptoethanol or phloroglucinol led to the isolation of 18 fragments, the structures of which were elucidated from their experimental and TDDFT-calculated ECD spectra. The results indicated that (−)-epigallocatechin was the main extension unit, while catechin, the A-type epigallocatechin–gallocatechin dimer, and the A-type epigallocatechin homodimer, were identified as the terminal units. Among the degradation products, thioethers of gallocatechin with 3,4-cis configurations, a B-type prodelphinidin dimer, a prodelphinidin trimer with both A- and B-type linkages, and a prodelphinidin dimer with an α-substituted A-type linkage were new compounds. In addition, a phloroglucinol adduct of an A-type prodelphinidin dimer, a doubly-linked phloroglucinol adduct of epigallocatechin, and a unique product with a flavan-3-ol skeleton generated by the rearrangement of the aromatic rings were also isolated.
Keywords: Ephedra sinica / proanthocyanidin / oligomer / thiolysis / phloroglucinolysis / TDDFT / ECD
URI: http://hdl.handle.net/10069/37779
DOI: 10.3390/molecules22081308
Rights: © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Type: Journal Article
Text Version: publisher
Appears in Collections:Articles in academic journal

Citable URI : http://hdl.handle.net/10069/37779

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