Ergosteroids: VI. Metabolism of dehydroepiandrosterone by rat liver in vitro: a liquid chromatographic–mass spectrometric study

Because relatively large amounts of dehydroepiandrosterone (DHEA) are required to demonstrate its diverse metabolic effects, it is postulated that this steroid may be converted to more active molecules. To search for the possible receptor-recognized hormones, DHEA was incubated with whole rat liver homogenate and metabolite appearances were studied by LC–MS as a function of time to predict the sequence of their formation. An array of metabolites has been resolved, identified and characterized by highly specific and accurate technique of LC–MS, and several of these steroids were analyzed quantitatively. Their identities were established by comparison with pure chemically synthesized compounds and by chemical degradation of isolated fractions. In the present study, we have reasonably established that DHEA was converted to 7α-OH-DHEA, 7-oxo-DHEA, and 7β-OH-DHEA in sequence. These metabolites were further reduced at position 7 and/or 17 to form their respective diols and triols, which were also sulfated at 3β-position. DHEA and its 7-oxygenated derivatives were also converted to their respective 3β-sulfate esters. Several of these steroids are being reported for the first time. 16α-Hydroxy-DHEA, androst-5-ene-3β,16α,17β-triol, androst-4-ene-3,17-dione, 11-hydroxyandrost-4-ene-3,17-dione, androst-5-ene-3,17-diol and testosterone were also identified and characterized. In all, 19 metabolites of DHEA are being reported in this extensive study. We have also detected the formation of 12 additional metabolites including several conjugates, which are the subject of current investigation.