Division of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey GU27XH, UK.
Arch Biochem Biophys. 2010 Sep 1;501(1):73-8. doi: 10.1016/j.abb.2010.02.009. Epub 2010 Feb 25.
The catabolism by human fecal microflora of pure procyanidin B2 ((-)-epicatechin-4beta-->8-(-)-epicatechin) has been investigated using a static in vitro culture model. For the first time, 24 catabolites were detected by LC-MS(n) with M(r) greater than 290 indicating that they could not have formed from just one of the epicatechin units in the procyanidin structure. Structures have been assigned on the basis of the fragmentation in the ion trap mass spectrometer and with regard to catabolic pathways known to occur in fecal microorganisms. Twenty of these 'dimeric' catabolites produced fragment ions characteristic of flavanols and/or proanthocyanidins. One catabolite was identified tentatively as either 6- or 8-hydroxy-procyanidin B2. Thirteen were characterized as having been microbially reduced in at least one of the epicatechin units. Five contained an apparently unmodified epicatechin unit but in at least one case this was shown to consist of the B-ring of the "upper" epicatechin unit and the A-ring of the "lower". These 'dimeric' catabolites were detected up to 9h after the start of the incubation and collectively accounted for approximately 20% of the substrate.
采用静态体外培养模型研究了人粪便微生物对纯原花青素 B2((-)-表儿茶素-4β→8-(-)-表儿茶素)的分解代谢作用。首次通过 LC-MS(n) 检测到 24 种分子量大于 290 的代谢产物，表明它们不可能仅由原花青素结构中的一个表儿茶素单元形成。根据在离子阱质谱仪中的碎裂和粪便微生物中已知的代谢途径，对结构进行了分配。其中 20 种“二聚体”代谢产物产生了黄烷醇和/或原花青素的特征片段离子。一种代谢产物被暂定鉴定为 6-或 8-羟基原花青素 B2。13 种被鉴定为至少在一个表儿茶素单元中被微生物还原。其中 5 种含有一个明显未修饰的表儿茶素单元，但在至少一种情况下，这被证明是由“上”表儿茶素单元的 B 环和“下”表儿茶素单元的 A 环组成。这些“二聚体”代谢产物在孵育开始后 9 小时内被检测到，总共占底物的约 20%。
