Bioconversion of genistein to(–)-5-hydroxy-equol by a newly isolated cock intestinal anaerobic bacterium

一株新分离鸡肠道厌氧细菌将染料木素转化为左旋-5-羟基-雌马酚（英文）

A newly isolated bacterium, named as AUH-JLC257, was found to be capable of bioconverting isoflavone genistein to 5-hydroxy-equol under anaerobic conditions. The metabolite 5-hydroxy-equol was identified by using UV spectrum, electrospray ionization mass spectrometry （ESI-MS） as well as IH and 13C NMR analyses. Chiral stationary-phase high-performance liquid chromatography analysis and specific rotation examination demonstrated that the bio-synthesized 5-hydroxy-equol was just （-）-5-hydroxy-equol. The average bioconverting rate was 83.1%, and the strain AUH-JLC257 could efficiently transform genistein at a maximal substrate concentration of 0.6 mmol/L. We, for the first time, showed that the bio-synthesized 5-hydroxy-equol had 1,1-diphenyl-2-picrylhydrazyl （DPPH） radical-scavenging activity at concentrations as low as 3.3μmol/L. In addition, the 16S rRNA gene sequence （1401 bp） of the bacterium strain AUH-JLC257 showed the highest similarity （99.27%） to that of Slackia equolifaciens strain DZE.

本研究从鸡新鲜粪样中分离得到一株能在厌氧条件下将大豆异黄酮染料木素转化为5-羟基-雌马酚的棒状严格厌氧细菌,我们将其命名为AUH-JLC257。通过ESI质谱、核磁共振氢谱和碳谱等对产物5-羟基-雌马酚进行了结构鉴定。通过手性高效液相色谱检测和旋光测定发现生成的5-羟基-雌马酚仅为左旋-5-羟基-雌马酚。菌株AUH-JLC257能高效转化底物染料木素的最大浓度为0.6 mmol/L,平均转化率为83.1%。通过本研究首次发现生成的5-羟基-雌马酚在3.3μmol/L浓度下仍表现出对二苯代苦味酰基自由基(DPPH)的清除能力。通过16S rR NA基因序列比对,菌株AUH-JLC257与菌株Slackia equolifaciens strain DZE相似性最高,相似性为99.27%。