Human gut microbiota has become the subject of extensive research in recent years and our knowledge of intestinal bacteria and their potential functional capacity is rapidly growing. The microbial community commonly referred to our hidden metabolic organ due to influence on human health, including host metabolism, physiology, nutrition, and immune functions. There are some reports that the functions of intestinal bacteria to host. Recent studies of intestinal bacteria have been mostly focused on metagenomics that is sequence microbial communities. But, metagenomic study cannot give us basic information like stereochemical metabolic pathway. So, for the functional study of microbial community composed with thousands species, the functional study of individual microbes is necessary. Stereochemical course of daidzein reduction into (3R)-dihydrodaidzein by the human intestinal anaerobic bacterium Coprobacillus strain MRG-1 was studied. (3S)-dihydrodaidzein was converted to (3S)-equol via (3S,4R)-tetrahydrodaidzein by the human intestinal anaerobic bacterium Eggerthella strain Julong 732. The isomerization of (3R)-dihydrodaidzein to (3S)-dihydrodaidzein was also successfully observed. To elucidate the biosynthetic pathway of (3S)-equol, the absolute configurations of dihydrodaidzein and tetrahydrodaidzein were determined with synthesized each stereoisomer which was separated by semi-preparative chiral column chromatography, and characterized by NMR spectroscopy and circular dichroism spectroscopy based on semi-empirical experiments.

Isoflavone metabolism leading by the human intestinal bacteria

249th National Meeting (2015)

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