Comparison of the use of mass spectrometry and methylene unit values in the determination of the stereochemistry of estranediol, the major urinary metabolite of 19-nortestosterone in the horse

New oxymesterone metabolites in human by gas chromatography-tandem mass spectrometry and their application for doping control

Oxymesterone (17α-methyl-4, 17β-dihydroxy-androst-4-ene-3-one) is one of the anabolic androgenic steroids (AAS) banned by the World Anti-Doping Agency (WADA). The biotransformation of oxymesterone is performed in vitro by human heptocytes and human urinary metabolic profiles are investigated after single dose of 20 mg to two adult males as well. Cell cultures and urine samples were hydrolyzed by β-glucuronidase, extracted, and reacted with N-Methyl-N-trimethylsilyltrifluoroacetamide (MSTFA), ammonium iodide (NH4 I), and dithioerythritol. After derivatization, a gas chromatography triple quadruple tandem mass spectrometry (GC-MS/MS) using full scan and MS/MS modes was applied. The total ion chromatographs of the blank and the positive samples are compared, and 7 new metabolites were found. In addition to the well-known 17-epioxymesterone, oxymesterone is metabolized by 4-ene-reduction, 3-keto-reduction, 11β-hydroxylation, and 16ξ-hydroxylation. Based on the behavior of the MS/MS results of product ion and precursor ion modes, a GC-MS/MS method has been developed monitoring these metabolites. The structures of metabolite 2 and 4 are tentatively identified as 17α-methyl-3β, 17β-dihydroxy-5α-androstane-4-one and 17α-methyl-3α, 4ξ, 17β-trihydroxy-5α-androstane, respectively. Detection of oxymesterone using new metabolites M2 and M4 can extend the detection window up to 4 days since the parent steroid was not detectable. Copyright © 2015 John Wiley & Sons, Ltd.

Metabolism of norethisterone in the greyhound

RATIONALE

Norethisterone has been used as a successful oral contraceptive in humans for many years. It was recently permitted for use as an oestrus suppressant in racing greyhounds. To monitor the use of norethisterone as part of a routine drug surveillance programme, knowledge of its metabolism was required to enable detection.

METHODS

Gas chromatography/mass spectrometry and selective derivatisation techniques have been used to identify urinary metabolites of norethisterone following oral administration to the greyhound. Metabolites were extracted using solid-phase and liquid-liquid extraction techniques.

RESULTS

Several metabolites were identified, including reduced, mono-, di- and trihydroxylated steroids. The major metabolites observed were 17α-ethynyl-5β-estrane-3α,17β-diol, 17α-ethynyl-5α-estrane-3β,17β-diol, three 17α-ethynylestranetriol stereoisomers and two 17α-ethynylestranetetrol stereoisomers. The major metabolites were predominantly excreted as glucuronic acid conjugates and detection of the administration of norethisterone was possible for up to 8 days post-dose using the methods described. The nandrolone metabolites, 19-norepiandrosterone, estranediol and 19-noretiocholanolone, were also identified in the post-administration samples collected up to 8 h after dosing the treated animals.

CONCLUSIONS

The urinary metabolites identified in this study have further increased the knowledge of steroid metabolism in the greyhound, providing information to support routine drug testing programmes for greyhound racing.

Easy stereoselective synthesis of 5α-estrane-3β,17α-diol, the major metabolite of nandrolone in the horse

5α-Estrane-3β,17α-diol is the major metabolite of nandrolone in horse urine. The presence of 5α-estrane-3β,17α-diol in female and gelding urines is prohibited by Racing Rules and its natural presence in male urine led regulation authorities to establish a concentration threshold of 45 ng/mL. This paper describes a rapid, simple and stereoselective synthesis of 5α-estrane-3β,17α-diol, providing horseracing laboratories with an essential reference material for their antidoping performance.

Metabolism of anabolic steroids and their relevance to drug detection in horseracing

The fight against doping in sport using analytical chemistry is a mature area with a history of approximately 100 years in horseracing. In common with human sport, anabolic/androgenic steroids (AASs) are an important group of potential doping agents. Particular issues with their detection are extensive metabolism including both phase I and phase II. A number of the common AASs are also endogenous to the equine. A further issue is the large number of synthetic steroids produced as pharmaceutical products or as 'designer' drugs intended to avoid detection or for the human supplement market. An understanding of the metabolism of AASs is vital to the development of effective detection methods for equine sport. The aim of this paper is to review current knowledge of the metabolism of appropriate steroids, the current approaches to their detection in equine sport and future trends that may affect equine dope testing.

Some aspects of doping and medication control in equine sports

This chapter reviews drug and medication control in equestrian sports and addresses the rules of racing, the technological advances that have been made in drug detection and the importance of metabolism studies in the development of effective drug surveillance programmes. Typical approaches to screening and confirmatory analysis are discussed, as are the quality processes that underpin these procedures. The chapter also addresses four specific topics relevant to equestrian sports: substances controlled by threshold values, the approach adopted recently by European racing authorities to control some therapeutic substances, anabolic steroids in the horse and LC-MS analysis in drug testing in animal sports and metabolism studies. The purpose of discussing these specific topics is to emphasise the importance of research and development and collaboration to further global harmonisation and the development and support of international rules.

Progesterone-transforming enzyme activity in the hypothalamus of the male rat

The aim of the present study was to assess the activities of the progesterone (Pr) transforming enzyme systems 3alpha-oxidoreductase (3alpha-OR), 5alpha-reductase (5alpha-R) and 20alpha-oxidoreductase (20alpha-OR) in the hypothalamus of the male rat, at different stages of sexual maturation and following castration and adrenalectomy. Special attention was paid to transformation to 3alpha-reduced compounds previously shown to inhibit FSH synthesis and secretion. Homogenates of hypothalamic tissue were incubated with 14C-progesterone. Pr-metabolites were isolated, identified by gas chromatography/mass-spectrometry (GC/MS) and measured by liquid scintillation counting (LSC). In adult rats a ratio of 6:2.5:1 for 5alpha-R:3alpha-OR:20alpha-OR enzyme- activities was found. The hypothalamic 5alpha-R and particularly 3alpha-OR activities were considerably higher before puberty (10-20 day old rats) than in adulthood. Adrenalectomy in adult rats resulted in an increased activity of the three enzyme systems. No significant changes were seen following castration. Among the isolated metabolites, 3alpha-hydroxy-pregn-4-en-20-one (3alpha-Pr) and 3alpha-hydroxy-5alpha-pregnane-20-one (5alpha,3alpha-Pr) were identified. Conversion to both these neurosteroids was considerably higher during prepuberty than in adulthood. The finding that before puberty the hypothalamus has a markedly increased capacity to convert Pr to 3alpha-reduced compounds, such as 3alpha-Pr, known to effectively inhibit FSH release, warrants further research into the mechanisms regulating the hypothalamic formation of biologically active Pr derivatives and their role in the regulation of gonadotropin secretion.

Evidence for the presence of endogenous 19-norandrosterone in human urine

In 1997, in the scope of antidoping control in sport, a not inconsiderable number of urine analysed by official laboratories revealed the presence of 19-nortestosterone (19-NT: 17beta-hydroxyestr-4-en-3-one) metabolites: 19-norandrosterone (19-NA: 3alpha-hydroxy-5alpha-estran-17-one) and 19-noretiocholanolone (19-NE: 3alpha-hydroxy-5beta-estran-17-one). These repeated results on a short period of time generated some investigations and especially the verification of the possible production of these metabolites by an unknown endogenous route in adult entire male. Some experiences were led on different persons known to be non-treated with steroids and more precisely with nandrolone. Extractive methods were developed focusing on their selectivity, i.e. searching to eliminate at best matrix interferences from the target analytes. Gas chromatography coupled to mass spectrometry (quadrupole and magnetic instruments) was used to detect, identify and quantify the suspected signals. Two types of derivatization (TMS and TBDMS), a semi-preparative HPLC as well as co-chromatography proved unambiguously the presence, in more than 50% of the analysed urine (n = 40), of 19-NA at concentrations between 0.05 and 0.60 ng/ml. 19-NE was not detected with the developed methods (LOD<0.02 ng/ml). Experiments led on athletes showed that after a prolonged intense effort, the 19-NA concentration can be increased by a factor varying between 2 and 4. Even if some complementary researches have to be done in order to determine the maximal physiological level of 19-NA and 19-NE, these results should considerably change the strategy of antidoping laboratories.

The methyl-5 alpha-dihydrotestosterones mesterolone and drostanolone; gas chromatographic/mass spectrometric characterization of the urinary metabolites

Before including the detection of the methyl-5 alpha-dihydrotestosterones mesterolone (1 alpha-methyl-17 beta-hydroxy-5 alpha-androstan-3-one) and drostanolone (2 alpha-methyl-17 beta-hydroxy-5 alpha-androstan-3-one) in doping control procedures, their urinary metabolites were characterized by gas chromatography/mass spectrometry. Several metabolites were found after enzymatic hydrolysis and conversion of the respective metabolites to their trimethylsilyl-enol-trimethylsilyl ether derivatives. The major metabolites of mesterolone and drostanolone were identified as 1 alpha-methyl-androsterone and 2 alpha-methyl-androsterone, respectively. The parent compounds and the intermediate 3 alpha,17 beta-dihydroxysteroid metabolites were detected as well. The reduction into the corresponding 3 beta-hydroxysteroids was a minor metabolic pathway. All metabolites were found to be conjugated to glucuronic acid.

Detection of 19-nortestosterone and its urinary metabolites in miniature pigs by gas chromatography-mass spectrometry

The metabolism of 19-nortestosterone was investigated in a miniature non-castrated male pig (boar), in a castrated pig (barrow) and in a female pig (sow). Urine samples were taken before and at regular intervals after the injection of 100 mg of Laurabolin (nortestosterone laurate). The sample clean-up consists in preliminary solid-phase extraction, followed by high-performance liquid chromatographic purification and fractionation. Finally, gas chromatography-mass spectrometry is used to identify the 19-nortestosterone metabolites.