Characterisation of steroids in wooden crates of veal calves by accelerated solvent extraction (ASE) and ultra-high performance liquid chromatography coupled to triple quadrupole mass spectrometry (U-HPLC-QqQ-MS-MS)

Formation of Δ(1) and Δ(6) testosterone metabolites by human hepatocytes

The existence of urinary testosterone (T) metabolites conjugated with cysteine has been recently reported. The formation of a ring double bond by a phase I metabolic transformation and the subsequent nucleophilic conjugation with glutathione was proposed as a putative metabolic pathway for the occurrence of these metabolites in urine. The main goal of the present study was to confirm the first step of the postulated pathway. For that purpose, human hepatocyte cells systems were incubated with a pure T standard. The cell culture supernatants were analyzed by liquid chromatography coupled to mass spectrometry using a selected reaction monitoring method. Major T metabolites such as androsterone and 4-androstene-3,17-dione, together with the recently reported Δ(1) and Δ(6) metabolites were simultaneously quantified. The formation of 1,4-androstadien-3,17-dione, 4,6-androstadien-3,17-dione, 17β-hydroxy-4,6-androstadien-3-one and 17β-hydroxy-1,4-androstadien-3-one (boldenone) after incubation of T in hepatocyte cell cultures was demonstrated by comparing the retention times and the ion ratios of the metabolites with those obtained by analysis of commercial standards. Thus, the formation of double bonds Δ(1) and Δ(6) by hepatic phase I metabolism of T was confirmed. Analogously to T, this pathway might also be present in other steroids, opening the possibility of targeting additional biomarkers.

Endogenous boldenone-formation in cattle: alternative invertebrate organisms to elucidate the enzymatic pathway and the potential role of edible fungi on cattle's feed

Although beta-boldenone (bBol) used to be a marker of illegal steroid administration in calves, its endogenous formation has recently been demonstrated in these vertebrates. However, research on the pathway leading to bBol remains scarce. This study shows the usefulness of in vivo invertebrate models as alternatives to vertebrate animal experiments, using Neomysis integer and Lucilia sericata. In accordance with vertebrates, androstenedione (AED) was the main metabolite of beta-testosterone (bT) produced by these invertebrates, and bBol was also frequently detected. Moreover, in vitro experiments using feed-borne fungi and microsomes were useful to perform the pathway from bT to bBol. Even the conversion of phytosterols into steroids was shown in vitro. Both in vivo and in vitro, the conversion of bT into bBol could be demonstrated in this study. Metabolism of phytosterols by feed-borne fungi may be of particular importance to explain the endogenous bBol-formation by cattle. To the best of our knowledge, it is the first time the latter pathway is described in literature.