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首页> 美国卫生研究院文献>Scientific Reports >Analysis of accumulation patterns and preliminary study on the condensation mechanism of proanthocyanidins in the tea plant Camellia sinensis
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Analysis of accumulation patterns and preliminary study on the condensation mechanism of proanthocyanidins in the tea plant Camellia sinensis

机译：茶树原花色素的积累模式分析及缩合机理的初步研究

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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, and 13C-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/z 865) were detected in the extracts of tea plants and in the non-enzymatic in vitro assay, 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 trimer in vitro or in vivo.
机译：在本研究中，通过水解和硫解测定，NP-HPLC，HPLC-ESI-MS，MALDI-TOF-MS， 1 H-NMR和 13定性和定量鉴定原花青素。茶树不同器官中的 C-NMR技术。结果表明，在叶片中，三羟基，顺式和没食子的黄烷-3-醇是主要的儿茶素单元，而（表）儿茶素被认为是聚合的黄烷-3-醇的主要单元。聚合度大于5。在根部，发现PA含量很高，而表儿茶素形成了低聚和聚合PA的主要延伸单元。为了理解原花色素聚合的机理，研究了黄烷-3-醇的自缩合。结果表明，当所用底物为室温时，在室温下在弱酸和弱碱性溶液中，在茶树提取物中和非酶体外测定中也检测到相同的三聚体（m / z 865）。原花青素B2和单体flavan-3-ols（表儿茶素或儿茶素），或仅原花青素B2。这表明原花青素B2不仅释放出碳阳离子作为亲电子的上位单元，而且本身也可以直接用作亲核的下位单元，从而在体外或体内形成原花青素三聚体。

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