A newellagitannin dimer named euscaphinin was isolated from the leaves of Euscaphis japonica (THUNB.) KANITZ. The structure of this dimer was determined on the basis of spectroscopic and chemical evidence. The resulting structure indicated that it was produced by intermolecular C-O oxidative coupling between the galloyl groups of molecules of 1(beta)-O-galloyl pedunculagin, the major ellagitannin of
In the research on ellagitannin metabolism, two unique dehydroellagitannins, carpinins E (1) and F (2), bearing dehydrohexahydroxydiphenoyl (DHHDP) and hydrated biscyclohexenetrione dicarboxyl ester (HBCHT) groups, were isolated from young leaves of Carpinusjaponica. Upon heating in H2O or treatment with pH 6 buffer at room temperature, 1 and 2 afforded the reduction product 3, isocarpinin A, with
在鞣花单宁的代谢的研究,两个独特dehydroellagitannins,carpinins E(1)和F(2),轴承dehydrohexahydroxydiphenoyl(DHHDP)和水合biscyclohexenetrione二羧基酯(HBCHT)基团,是从嫩叶分离鹅耳枥粳稻。在 H 2 O 中加热或在室温下用 pH 6 缓冲液处理后,1和2提供还原产物3,异果皮素 A,带有 ( R )-六羟基二苯甲酰基 (HHDP) 基团,表明 ( S )-DHHDP 组。这得益于产量增加3在 pH 6 的缓冲溶液中,表没食子儿茶素-3 - O-没食子酸酯 ( 15 )共存,伴随着15的氧化。相比之下,用抗坏血酸处理1和2产生了4,carpinin A,具有 ( S )-HHDP 组。在与抗坏血酸一起加热时,HBCHT 基团也被还原为 ( S )-HHDP 基团,并且2转化为 2,3;4,6-bis(
Stability and Oxidation Products of Hydrolysable Tannins in Basic Conditions Detected by HPLC/DAD-ESI/QTOF/MS
作者:Anu Tuominen、Terhi Sundman
DOI:10.1002/pca.2456
日期:2013.9
Hydrolysabletannins occur in plants that are used for food or medicine by humans or herbivores. Basicconditions can alter the structures of tannins, that is, the oxidation of phenolic groups can lead to the formation of toxic quinones. Previously, these labile quinones and other oxidationproducts have been studied with colorimetric or electron paramagnetic resonance methods, which give limited information