The red clover isoflavone irilone is largely resistant to degradation by the human gut microbiota.
Intestinal bacteria may influence bioavailability and physiological activity of dietary isoflavones. We therefore investigated the ability of human intestinal microbiota to convert irilone and genistein in vitro. In contrast to genistein, irilone was largely resistant to transformation by fecal slurries of ten human subjects. The fecal microbiota converted genistein to dihydrogenistein, 6'-hydroxy-O-desmethylangolensin, and 2-(4-hydroxyphenyl)-propionic acid. However, considerable interindividual differences in the rate of genistein degradation and the pattern of metabolites formed from genistein were observed. Only one metabolite, namely dihydroirilone, was formed from irilone in minor amounts. In further experiments, Eubacterium ramulus, a prevalent flavonoid-degrading species of the human gut, was tested for transformation of irilone. In contrast to genistein, irilone was not converted by E. ramulus. Irilone only differs from genistein by a methylenedioxy group attached to the A-ring of the isoflavone skeleton. This substitution obviously restricts the degradability of irilone by human intestinal bacteria.
Braune
Annett
A
Department of Gastrointestinal Microbiology, German Institute of Human Nutrition Potsdam-Rehbrücke, 14558 Nuthetal, Germany. braune@dife.de
Maul
Ronald
R
Schebb
Nils Helge
NH
Kulling
Sabine E
SE
Blaut
Michael
M
D000328:Adult; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000378:metabolism* / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid; D019587:Dietary Supplements; D005051:Eubacterium / Q000378:metabolism; D005243:Feces / Q000382:microbiology*; D005260:Female; D005285:Fermentation; D008401:Gas Chromatography-Mass Spectrometry; D019833:Genistein / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D006801:Humans; D007529:Isoflavones / Q000737:chemistry / Q000378:metabolism* / Q000493:pharmacokinetics; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010936:Plant Extracts / Q000737:chemistry; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D029921:Trifolium / Q000737:chemistry*; D055815:Young Adult
D000972:Antineoplastic Agents, Phytogenic; D007529:Isoflavones; D010936:Plant Extracts; C530234:irilone; D019833:Genistein