Elucidation of the biosynthetic pathways of boldenone in the equine testis.

This study investigates the biological pathways through which boldenone, an anabolic-androgenic steroid banned in horse racing, is naturally produced in the testis of uncastrated male horses, aiding in the distinction between doping and natural occurrence.

Introduction of the Research

• This study revolves around boldenone, an anabolic-androgenic steroid, which is found naturally in the urine of intact male horses and is outlawed in equine sports because of its performance-enhancing effects.
• The researchers aimed to gather evidence to help differentiate between doping cases and natural production of boldenone. As the testis is believed to be a source of this substance, the researchers focused their study on the biosynthetic pathways of boldenone creation within the equine testis.

Methodology

• Qualitative analysis was carried out on extracts of equine testicular homogenates (tissue mixtures obtained from testes of three horses). The testicular extracts were either left unmodified or were spiked with potential precursors of boldenone.
• The researchers utilized liquid chromatography tandem mass spectrometry (LC-MS/MS) and LC high resolution mass spectrometry (LC-HRMS), techniques commonly used for compound identification and quantification. Both underivatised and derivatised samples were analyzed.

Findings

• The researchers found traces of boldenone and boldienone, another naturally occurring steroid, in the equine testis. This was established by the analysis of non-spiked testicular tissue samples.
• Also, when the homogenates were incubated with deuterium or carbon isotopes labeled testosterone and androstenedione, matching stable isotope analogues of boldenone and boldienone were produced.
• A steroid named 2-hydroxyandrostenedione was also noticed, suggesting that this steroid might act as an intermediate compound in the biosynthetic process.

Conclusion

• The study concluded that boldenone and boldienone are naturally synthesized in equine testis via a process that involves a conversion of testosterone and androstenedione.
• But for a more comprehensive understanding of the pathways involved in these transformations, further research is needed, incorporating additional test subjects and more rigorous enzyme kinetic experiments.
• Moreover, pure reference standards for 2-OH androstenedione isomers, a potential intermediate compound in the biosynthetic process, would be needed for better characterization of the pathways involved in these transformations.