Abstract：
:Boldenone is an anabolic-androgenic steroid that is prohibited in equine sports. Urine from the uncastrated male horse contains boldenone that is thought to be of endogenous origin and thus a threshold ('cut-off') concentration has been adopted internationally for free and conjugated boldenone to help distinguish cases of doping from its natural production. The testis is likely to be a source of boldenone. Qualitative analysis was performed on extracts of equine testicular homogenates (n = 3 horses) incubated non-spiked and in the presence of its potential precursors using liquid chromatography tandem mass spectrometry (LC-MS/MS) and LC high resolution mass spectrometry (LC-HRMS). Samples were analysed both underivatised and derivatised to increase the certainty of identification. In addition to previously reported endogenous steroids, analysis of non-spiked testicular tissue samples demonstrated the presence of boldenone and boldienone at trace levels in the equine testis. Incubation of homogenates with deuterium or carbon isotope labelled testosterone and androstenedione resulted in the matching stable isotope analogues of boldenone and boldienone being formed. Additionally, deuterium and carbon labelled 2-hydroxyandrostenedione was detected, raising the possibility that this steroid is a biosynthetic intermediate. In conclusion, boldenone and boldienone are naturally present in the equine testis, with the biosynthesis of these steroids arising from the conversion of testosterone and androstenedione. However, additional work employing larger numbers of animals, further enzyme kinetic experiments and pure reference standards for 2-OH androstenedione isomers would be required to better characterize the pathways involved in these transformations.
journal_name
Steroidsjournal_title
Steroidsauthors
Viljanto MJ,Kicman AT,Walker CJ,Parkin MC,Wolff K,Pearce CM,Scarth Jdoi
10.1016/j.steroids.2019.03.011subject
Has Abstractpub_date
2019-06-01 00:00:00pages
79-91eissn
0039-128Xissn
1878-5867pii
S0039-128X(19)30062-5journal_volume
146pub_type
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