Analysis of accumulation patterns and preliminary study on the condensation mechanism of proanthocyanidins in the tea plant [Camellia sinensis].
Analysis of accumulation patterns and preliminary study on the condensation mechanism of proanthocyanidins in the tea plant [Camellia sinensis].
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茶树原花青素积累规律分析及缩合机制初步研究
DOI：
10.1038/srep08742
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发表时间：
2015-03-04
影响因子：
4.6
通讯作者：
Xia T
中科院分区：
文献类型：
--
作者：
Jiang X;Liu Y;Wu Y;Tan H;Meng F;Wang YS;Li M;Zhao L;Liu L;Qian Y;Gao L;Xia T
本研究采用水解和硫解实验、NP-HPLC、HPLC-ESI-MS、MALDI-TOF-MS、1H-NMR和13 C-NMR等技术对茶树不同器官中的原花青素进行了定性和定量分析。结果表明，在叶片中，三羟基、顺式和没食子酰化的黄烷-3-醇是主要的单体儿茶素单元，当聚合度大于5时，（表）儿茶素是黄烷-3-醇聚合物的主要单元。在根中，PA被发现是丰富的和表儿茶素形成的寡聚和聚合PA的主要延伸单位。为了了解原花青素聚合的机理，研究了黄烷-3-醇的自缩合反应。结果表明，在弱酸性和弱碱性条件下，以原花青素B2和单体黄烷-3-醇（表儿茶素或儿茶素）为底物或仅以原花青素B2为底物时，在茶树提取物和非酶体外分析中均检测到相同的三聚体（m/z 865）。这表明原花青素B2不仅可以释放出碳正离子作为亲电性的上位单元，而且本身也可以直接作为亲核性的下位单元，在体外或体内形成原花青素三聚体。
In the present study, proanthocyanidins were qualitatively and quantitatively identified using hydrolysis and thiolysis assays, NP-HPLC, HPLC-ESI-MS, MALDI-TOF-MS,1H-NMR and13C-NMR techniques in different organs of tea plants. The results showed that in leaves, the tri-hydroxyl,cis- and galloylated flavan-3-ols were the main monomeric catechins units and (epi)catechin was found to be the major unit of polymeric flavan-3-ols when the degree of polymerization was greater than five. In roots, the PAs were found to be abundant and epicatechin formed the predominant extension unit of oligomeric and polymeric PAs. In order to understand the mechanism of proanthocyanidins polymerization, auto-condensation of the flavan-3-ols was investigated. The results showed that the same trimers (m/z865) were detected in the extracts of tea plants and in the non-enzymaticin vitroassay, in weak acid as well as weak alkaline solutions at room temperature, when the substrates used were either procyanidin B2 and monomeric flavan-3-ols (epicatechin or catechin), or only procyanidin B2. This suggested that procyanidin B2 not only released carbocation as electrophilic upper units, but also could be used as nucleophilic lower units directly itself, to form the procyanidin trimerin vitroorin vivo.
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影响因子：
7.4
作者：
Abrahams, S;Tanner, GJ;Ashton, AR
通讯作者：
Ashton, AR
影响因子：
7.4
作者：
Hancock, Kerry R.;Collette, Vern;Rasmussen, Susanne
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Rasmussen, Susanne
影响因子：
6.1
作者：
Gu, LW;Kelm, M;Prior, RL
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Prior, RL
影响因子：
3.8
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HASLAM, E;OPIE, CT;PORTER, LJ
通讯作者：
PORTER, LJ
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7.4
作者：
Ferrer, I;Thurman, EM;Fernandez-Alba, AR
通讯作者：
Fernandez-Alba, AR