Equol: pharmacokinetics and biological actions.
Equol [7-hydroxy-3-(4'-hydroxyphenyl)-chroman], an isoflavan produced by intestinal bacteria in response to soy isoflavone intake in some but not all humans, exhibits a wide range of biological properties. It exists as the diastereoisomers S-(-)equol and R-(+)equol. Intestinal bacteria produce exclusively S-(-)equol, which has selective affinity for estrogen receptor (ER)-beta. The evidence is conflicting on whether there is an advantage to producing S-(-)equol in response to soy isoflavone intakes, but the ability to now synthesize these diastereoisomers opens the way for future clinical trials to directly examine their potential in a number of hormone-dependent conditions. In this review, the plasma and urinary pharmacokinetics of S-(-)equol and R-(+)equol are reviewed and summarized, and some of the more recent evidence supporting potential biological effects of S-(-)equol is considered.
Setchell
Kenneth D R
KD
Pathology and Laboratory Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA. kenneth.setchell@cchmc.org
Clerici
Carlo
C
D000818:Animals; D001419:Bacteria / Q000378:metabolism; D001711:Biotransformation; D060754:Equol; D006801:Humans; D007422:Intestines / Q000382:microbiology; D007529:Isoflavones / Q000737:chemistry / Q000493:pharmacokinetics* / Q000494:pharmacology*; D013237:Stereoisomerism
C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D007529:Isoflavones; D060754:Equol