LIGNAN AND ISOFLAVONOID CONJUGATES IN HUMAN URINE

Lignans and isoflavonoids are two groups of diphenolic phytoestrogens of plant origin which have gained increasing interest because of their possible cancer protective properties. High excretion of these compou nds occur in populations at low risk of breast, prostate and colon can cer consuming either high amounts of whole-grain (lignans and some iso flavonoids) or soy products (isoflavonoids and some lignans). We deter mined the pattern of conjugation of the phytoestrogens in four urine s amples from vegetarian or semivegetarian women and in two samples from men. Seven compounds were investigated: enterodiol, enterolactone, ma tairesinol, daidzein, equol, genistein and O-desmethylangolensin. The fractions quantified are the free fraction, mono- and disulfate, as we ll as the mono-, di- and sulfoglucuronide fractions. For the fractiona tion and purification we used ion-exchange chromatography and the dete rmination of the concentrations of each compound in all fractions was done by isotope dilution gas chromatography-mass spectrometry (GLC-MS) using deuterated internal standards of all diphenols. More than 60% o f all compounds determined, occurred in the monoglucuronide fraction. Daidzein, enterodiol and equol are excreted to a relatively high exten t as sulfoglucuronides and genistein as diglucuronide. We conclude tha t the general pattern of lignan and isoflavonoid conjugates in urine i s similar to that of endogenous estrogens.