Oxidative conversion of B- to A-type procyanidin trimer: Evidence for quinone methide mechanism
Oxidative conversion of B- to A-type procyanidin trimer: Evidence for quinone methide mechanism
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DOI：
10.1016/j.foodchem.2014.01.018
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发表时间：
2014-07-01
期刊：
影响因子：
8.8
通讯作者：
Li, Yiming
中科院分区：
文献类型：
--
作者：
Chen, Liang;Yuan, Pulong;Li, Yiming
植物中存在两种主要类型的原花青素低聚体(A型和B型)。以前的研究表明，B型原花青素二聚体可以通过氧化转化为A型二聚体。然而，这一机制缺乏实验证据。本文研究了B型原花青素三聚体原花青素C-1(PC-1)转化为A型肉桂单宁B-1(CTB-1)的条件，包括温度、pH值和四种催化剂。催化剂包括DPPH、O-2(-)、多酚氧化酶和黄嘌呤氧化酶。结果表明，温度和pH对转化率有显著影响。对于相同的产物，自由基和氧化物酶都能加快转化率，但转化率没有增加。此外，还讨论了CTB-1连续氧化产物(P_1-P_4)的分离和鉴定。这些结果表明，植物中B-原花青素向A-原花青素的氧化转化可能涉及自由基驱动的过程或酶催化的自由基反应。(C)2014爱思唯尔有限公司。保留所有权利。
Two main types of procyanidin oligomers (A-type and B-type) are present in plants. Previous studies revealed that B-type procyanidin dimers can be converted into A-type dimers by oxidation. However, the mechanism lacks experimental proof. In this study, the conditions of a B-type procyanidin trimer, procyanidin C-1 (PC-1), conversion to A-type cinnamtannin B-1 (CTB-1), including temperature, pH value and four catalysts were investigated. The catalysts include DPPH, O-2(-), polyphenol oxidase and xanthine oxidase. Results show that the conversion is significantly affected by temperature and pH. Both free radicals and oxidases accelerate the conversion rate with the same products but show no increase in conversion ratio. Moreover, the isolation and identification of continuous oxidation products (P 1-P 4) from CTB-1 are discussed here. These results demonstrate that the oxidative conversion of B- to A-procyanidins in plants might involve a free radical-driven process or an enzyme-catalyzed free radical reaction via a quinone methide mechanism. (C) 2014 Elsevier Ltd. All rights reserved.