Contreras-Domínguez Monica, Guyot Sylvain, Marnet Nathalie, Le Petit Jean, Perraud-Gaime Isabelle, Roussos Sevastianos, Augur Christopher
IRD-Unité BioTrans, IMEP, Boîte 441, Fac. Sci. & Tech. St. Jérôme, Université Paul Cézanne, Av. Escadrille Normandie-Niemen, F-13397 Marseille Cedex 20, France.
Biochimie. 2006 Dec;88(12):1899-908. doi: 10.1016/j.biochi.2006.07.011. Epub 2006 Aug 7.
Aspergillus fumigatus was able to grow on apple-purified procyanidins (PCs). PCs concentration decreased 30% over the first 60 h of liquid fermentation. The mean degree of polymerization (DPn) of apple-purified PCs increased from 8 to 15 during the fermentation. A fungal enzyme extract from the liquid fermentation was used to study procyanidin B2 [(-)-epicatechin-(4beta-8)-(-)-epicatechin] degradation. The major degradation product (PB2-X) had a retention time of 10.5 min and a molecular mass at m/z 609. High-performance liquid chromatography/multiple fragment mass spectrometry (HPLC/MS(n)) was used for the structural characterization of PB2-X as well as that of thiolysis-treated PB2-X. Twelve fragment ions at m/z 565, 547, 457, 439 (two fragment ions), 421, 413, 377, 395, 351, 287 and 277 were completely identified. It was therefore deduced that the terminal unit of procyanidin B2 dimer was modified by an oxygenase from A. fumigatus leaving the extension unit intact. In addition, FT-IR analysis confirmed a lactone formation in (-)-epicatechin moiety involved in oxidative degradation. Two reaction schemes were postulated for the interpretation of the results.
烟曲霉能够在苹果纯化的原花青素（PCs）上生长。在液体发酵的前60小时内，PCs浓度下降了30%。发酵过程中，苹果纯化PCs的平均聚合度（DPn）从8增加到15。利用液体发酵得到的真菌酶提取物研究原花青素B2 [(-)-表儿茶素-(4β-8)-(-)-表儿茶素] 的降解。主要降解产物（PB2-X）的保留时间为10.5分钟，分子量为m/z 609。采用高效液相色谱/多片段质谱（HPLC/MS(n)）对PB2-X以及硫解处理后的PB2-X进行结构表征。完全鉴定出了m/z 565、547、457、439（两个碎片离子）、421、413、377、395、351、287和277处的12个碎片离子。因此推断，烟曲霉的加氧酶修饰了原花青素B2二聚体的末端单元，而延伸单元保持完整。此外，傅里叶变换红外光谱（FT-IR）分析证实，参与氧化降解的(-)-表儿茶素部分形成了内酯。为解释这些结果提出了两个反应方案。
