Communication. Detection of equol in the steroid fraction from sturgeon (Acipenser baeri) plasma using capillary gas chromatography-mass spectrometry
Equol, which is a derivative of the vegetal isoflavone formononetin and obtained by bacterial degradation in the digestive tract of mammals fed on a vegetal diet, has been detected in the plasma of sturgeon fed on a soya-based fish diet. Such a compound, which is a structural analogue of certain sexual steroids, e.g., estradiol, has been demonstrated to have an estrogenic activity in several mammals and as such it could also be responsible for the secretion of vitellogenin by hepatocytes in male sturgeons. A combined analytical procedure involving several liquid chromatographic separations and capillary gas chromatography-mass spectrometry with chemical ionisation led to the detection of equol in estradiol extracts from fish plasma.