title: Endogenous boldenone-formation in cattle: alternative invertebrate organisms to elucidate the enzymatic pathway and the potential role of edible fungi on cattle's feed.
abstract: 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.
authors.affiliation: Ghent University, Faculty of Veterinary Medicine, Research Group of Veterinary Public Health and Zoonoses, Laboratory of Chemical Analysis, Salisburylaan 133, B-9820 Merelbeke, Belgium. Karolien.Verheyden@UGent.be
authors.forename: K
authors.initials: K
authors.lastname: Verheyden
authors.forename: H
authors.initials: H
authors.lastname: Noppe
authors.forename: H
authors.initials: H
authors.lastname: Zorn
authors.forename: F
authors.initials: F
authors.lastname: Van Immerseel
authors.forename: J
authors.initials: J
authors.lastname: Vanden Bussche
authors.forename: K
authors.initials: K
authors.lastname: Wille
authors.forename: K
authors.initials: K
authors.lastname: Bekaert
authors.forename: C R
authors.initials: CR
authors.lastname: Janssen
authors.forename: H F
authors.initials: HF
authors.lastname: De Brabander
authors.forename: L
authors.initials: L
authors.lastname: Vanhaecke
mesh_terms: D045930:Anabolic Agents / Q000378:metabolism*; D000735:Androstenedione / Q000378:metabolism; D000821:Animal Feed / Q000382:microbiology*; D023401:Animal Use Alternatives / Q000379:methods*; D000818:Animals; D053898:Biosynthetic Pathways; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D003445:Crustacea / Q000378:metabolism; D004175:Diptera / Q000378:metabolism; D005658:Fungi / Q000378:metabolism*; D007814:Larva / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D010840:Phytosterols / Q000378:metabolism; D020076:Pleurotus / Q000378:metabolism; D015813:Substance Abuse Detection / Q000662:veterinary; D053719:Tandem Mass Spectrometry; D013739:Testosterone / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D045930:Anabolic Agents; D010840:Phytosterols; D013739:Testosterone; D000735:Androstenedione; C013915:boldenone