Isolation of an anaerobic intestinal bacterium capable of cleaving the C-ring of the isoflavonoid daidzein

Arch Microbiol. 2002 Jul;178(1):8-12. doi: 10.1007/s00203-002-0414-6. Epub 2002 Apr 16.


Colonic bacteria were screened for bacteria involved in the conversion of phytoestrogens. A gram-positive anaerobic bacterium, strain HGH 136, capable of conversion of the isoflavonoid daidzein, was isolated and identified as a Clostridium sp. The bacterium cleaved the C-ring of daidzein to produce O-demethylangolensin ( O-Dma). This compound was identified by comparison of the HPLC retention time and UV spectrum of the metabolite with chemically synthesized O-Dma. The identity of the metabolite was confirmed by liquid chromatography-mass spectrometry and NMR using synthetic O-Dma as a standard. The bacterium incubated with synthetic dihydrodaidzein also produced O-Dma. After 3 days of incubation, 28% of added daidzein and 12% of added dihydrodaidzein were converted to O-Dma. This is the first study in which an anaerobic bacterium involved in the ring cleavage of daidzein to produce O-Dma has been identified.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacteria, Anaerobic / isolation & purification*
  • Bacteria, Anaerobic / metabolism
  • Carbon / chemistry
  • Carbon / metabolism*
  • Chromatography, High Pressure Liquid
  • Humans
  • Intestines / microbiology*
  • Isoflavones / chemistry
  • Isoflavones / metabolism*
  • Phylogeny
  • RNA, Ribosomal, 16S / analysis


  • Isoflavones
  • RNA, Ribosomal, 16S
  • daidzein
  • Carbon