Testosterone metabolism revisited: discovery of new metabolites

Profiling Urinary Sulfate Metabolites With Mass Spectrometry

The study of urinary phase II sulfate metabolites is central to understanding the role and fate of endogenous and exogenous compounds in biological systems. This study describes a new workflow for the untargeted metabolic profiling of sulfated metabolites in a urine matrix. Analysis was performed using ultra-high-performance liquid chromatography-high resolution tandem mass spectrometry (UHPLC-HRMS/MS) with data dependent acquisition (DDA) coupled to an automated script-based data processing pipeline and differential metabolite level analysis. Sulfates were identified through k-means clustering analysis of sulfate ester derived MS/MS fragmentation intensities. The utility of the method was highlighted in two applications. Firstly, the urinary metabolome of a thoroughbred horse was examined before and after administration of the anabolic androgenic steroid (AAS) testosterone propionate. The analysis detected elevated levels of ten sulfated steroid metabolites, three of which were identified and confirmed by comparison with synthesised reference materials. This included 5α-androstane-3β,17α-diol 3-sulfate, a previously unreported equine metabolite of testosterone propionate. Secondly, the hydrolytic activity of four sulfatase enzymes on pooled human urine was examined. This revealed that Pseudomonas aeruginosa arylsulfatases (PaS) enzymes possessed higher selectivity for the hydrolysis of sulfated metabolites than the commercially available Helix pomatia arylsulfatase (HpS). This novel method provides a rapid tool for the systematic, untargeted metabolic profiling of sulfated metabolites in a urinary matrix.

Recent advances in identifying and utilizing metabolites of selected doping agents in human sports drug testing

Probing for evidence of the administration of prohibited therapeutics, drugs and/or drug candidates as well as the use of methods of doping in doping control samples is a central assignment of anti-doping laboratories. In order to accomplish the desired analytical sensitivity, retrospectivity, and comprehensiveness, a considerable portion of anti-doping research has been invested into studying metabolic biotransformation and elimination profiles of doping agents. As these doping agents include lower molecular mass drugs such as e.g. stimulants and anabolic androgenic steroids, some of which further necessitate the differentiation of their natural/endogenous or xenobiotic origin, but also higher molecular mass substances such as e.g. insulins, growth hormone, or siRNA/anti-sense oligonucleotides, a variety of different strategies towards the identification of employable and informative metabolites have been developed. In this review, approaches supporting the identification, characterization, and implementation of metabolites exemplified by means of selected doping agents into routine doping controls are presented, and challenges as well as solutions reported and published between 2010 and 2020 are discussed.

Metabolomic signatures in elite cyclists: differential characterization of a seeming normal endocrine status regarding three serum hormones

INTRODUCTION

Serum phenotyping of elite cyclists regarding cortisol, IGF1 and testosterone is a way to detect endocrine disruptions possibly explained by exercise overload, non-balanced diet or by doping. This latter disruption-driven approach is supported by fundamental physiology although without any evidence of any metabolic markers.

OBJECTIVES

Serum samples were distributed through Low, High or Normal endocrine classes according to hormone concentration. A ¹H NMR metabolomic study of 655 serum obtained in the context of the longitudinal medical follow-up of 253 subjects was performed to discriminate the three classes for every endocrine phenotype.

METHODS

An original processing algorithm was built which combined a partial-least squares-based orthogonal correction of metabolomic signals and a shrinkage discriminant analysis (SDA) to get satisfying classifications. An extended validation procedure was used to plan in larger size cohorts a minimal size to get a global prediction rate (GPR), i.e. the product of the three class prediction rates, higher than 99.9%.

RESULTS

Considering the 200 most SDA-informative variables, a sigmoidal fitting of the GPR gave estimates of a minimal sample size to 929, 2346 and 1408 for cortisol, IGF1 and testosterone, respectively. Analysis of outliers from cortisol and testosterone Normal classes outside the 97.5%-confidence limit of score prediction revealed possibly (i) an inadequate protein intake for outliers or (ii) an intake of dietary ergogenics, glycine or glutamine, which might explain the significant presence of heterogeneous metabolic profiles in a supposedly normal cyclists subgroup.

CONCLUSION

In a next validation metabolomics study of a so-sized cohort, anthropological, clinical and dietary metadata should be recorded in priority at the blood collection time to confirm these functional hypotheses.

Identification of Trenbolone Metabolites Using Hydrogen Isotope Ratio Mass Spectrometry and Liquid Chromatography/High Accuracy/High Resolution Mass Spectrometry for Doping Control Analysis

Trenbolone is a synthetic anabolic-androgenic steroid, which has been misused for performance enhancement in sports. The detection of trenbolone doping in routine sports drug testing programs is complex as methods utilizing gas chromatography/mass spectrometry are complicated by unspecific derivatization products and artifacts, and liquid chromatography/mass spectrometry-based assays have shown to allow for comparably high limits-of-detection only. The number of previously reported metabolites in human urine is limited, and most analytical methods rely on targeting epitrenbolone, trenbolone glucuronide, and epitrenbolone glucuronide. In order to probe for the presence of additional trenbolone metabolites and to re-investigate the metabolism, an elimination study was conducted. One single dose of 10 mg of 5-fold deuterated trenbolone was administered to a healthy male volunteer and urine samples were collected for 30 days. For sample processing, published protocols were combined considering unconjugated, glucuronic acid-, sulfo- and alkaline-labile conjugated steroid metabolites. The sample preparation strategy consisted of solid-phase extractions, liquid-liquid extractions, metabolite de-conjugation, HPLC fractionation, and derivatization. Analytical methods included gas chromatography/thermal conversion/hydrogen isotope ratio mass spectrometry combined with single quadrupole mass spectrometry as well as liquid chromatography/high accuracy/high resolution mass spectrometry of the hydrolyzed and non-hydrolyzed samples. Twenty deuterium-labeled metabolites were identified including glucuronic acid-, sulfo- and potential cysteine-conjugates, and characterized by parallel reaction monitoring experiments yielding corresponding product ion mass spectra. Main metabolites were attributed to trenbolone-diol and potential trenbolone-diketone derivatives excreted as glucuronic acid and sulfo-conjugated analytes with detection windows of 5, respectively 6 days. Further characterization was conducted with pseudo MS3 experiments of the intact conjugates and by comparison of resulting product ion mass spectra with reference material.

Metabolomic response to coffee consumption: application to a three-stage clinical trial

BACKGROUND

Coffee is widely consumed and contains many bioactive compounds, any of which may impact pathways related to disease development.

OBJECTIVE

To identify individual metabolite changes in response to coffee.

METHODS

We profiled the metabolome of fasting serum samples collected from a previously reported single-blinded, three-stage clinical trial. Forty-seven habitual coffee consumers refrained from drinking coffee for 1 month, consumed four cups of coffee/day in the second month and eight cups/day in the third month. Samples collected after each coffee stage were subject to nontargeted metabolomic profiling using UPLC-ESI-MS/MS. A total of 733 metabolites were included for univariate and multivariate analyses.

RESULTS

A total of 115 metabolites were significantly associated with coffee intake (P < 0.05 and Q < 0.05). Eighty-two were of known identity and mapped to one of 33 predefined biological pathways. We observed a significant enrichment of metabolite members of five pathways (P < 0.05): (i) xanthine metabolism: includes caffeine metabolites, (ii) benzoate metabolism: reflects polyphenol metabolite products of gut microbiota metabolism, (iii) steroid: novel but may reflect phytosterol content of coffee, (iv) fatty acid metabolism (acylcholine): novel link to coffee and (v) endocannabinoid: novel link to coffee.

CONCLUSIONS

The novel metabolites and candidate pathways we have identified may provide new insight into the mechanisms by which coffee may be exerting its health effects.

Evaluation of markers out of the steroid profile for the screening of testosterone misuse. Part II: Intramuscular administration

In the fight against doping, the introduction of alternative markers to the steroid profile can be considered as an effective approach to improve the screening capabilities for the detection of testosterone (T) misuse. The aim of this study was to evaluate the potential of several T metabolites (cysteinyl conjugated and glucuronoconjugated resistant to enzymatic hydrolysis) to detect both the transdermal and the intramuscular administration of T. In Part I of the study, we studied the potential of these metabolites for the detection of T transdermal administration. Results revealed that resistant glucuronides can be a suitable complement to the current steroid profile. In this, Part II, dedicated to the intramuscular administration, we studied the potential of cysteinyl conjugated, resistant glucuronoconjugated and 1-cyclopentenoylglycine (1-CPG) for the detection of a single intramuscular injection of T cypionate. Possible differences in the excretion profile of all markers were explored between individuals with low basal (n=6) and medium basal (n=6) values of the testosterone/epitestosterone ratio (T/E). The results showed that all tested markers presented low intra-individual stability in basal conditions. Despite this, all glucuronoconjugated markers and 1-CPG, but not the cysteinyl conjugated markers, provided detection windows that were similar or longer than those obtained by markers currently included in the steroid profile. Based on the results obtained from the 2 parts of this study and from previously reported data, the potential applicability and the limitations of including these markers in the steroid profile are discussed.

Evaluation of markers out of the steroid profile for the screening of testosterone misuse. Part I: Transdermal administration

Although the introduction by the World Anti-Doping Agency (WADA) of the steroid module of the athlete biological passport (ABP) marked an important step forward in the screening of testosterone (T) misuse, it still remains one of the most difficult challenges in doping control analysis. The urinary determination of alternative markers has been recently reported as a promising tool for improving the screening of T oral administration. However, their evaluation for other, commonly used, administration routes is still required. The main goal of this study is the evaluation of the potential of 2 groups of metabolites (cysteinyl conjugated and glucuronoconjugated) after transdermal and intramuscular administration of T. Their suitability was evaluated in individuals with both low basal (L-T/E) and medium basal (M-T/E) values of T/E. In this Part I, we evaluated the urinary excretion profile of these 2 groups of T metabolites after the administration of 3 doses of T gel to 12 volunteers (6 L-T/E and 6 M-T/E) for 3 consecutive days. For this purpose, 9 different concentration ratios (5 cysteinyl conjugated and 4 glucuronoconjugated markers) were studied. Both, the intra-individual variability and the detection windows (DW) obtained by each ratio were evaluated. Cysteinyl conjugates showed a general low intra-individual variability and DWs that were shorter than any other tested marker. Despite the relatively large intra-individual variability, the DWs reached by glucuronoconjugates (2-3 days) were similar to those obtained by markers currently included in the ABP. Overall; this evaluation advises for the introduction of additional glucuronoconjugated markers in the screening of transdermal T administration.

Evaluation of two glucuronides resistant to enzymatic hydrolysis as markers of testosterone oral administration

Testosterone (T) has traditionally been the most commonly reported doping agent by doping control laboratories. The screening of T misuse is performed by the quantification of six endogenous androgenic steroids and the ratio T/E included in the Athlete Biological Passport (ABP). The inclusion of additional metabolites can improve the screening capabilities of ABP. In this study, the potential of 3α-glucuronide-6β-hydroxyandrosterone (6OH-Andros3G) and 3α-glucuronide-6β-hydroxyetiocholanolone (6OH-Etio3G) as markers of T oral administration was evaluated. These glucuronides have been shown to be resistant to enzymatic hydrolysis and their quantification by means of liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was reported as the only way to obtain feasible results. Urine samples were collected from five volunteers before and after the oral administration of 40mg of T undecanoate and were analyzed by a LC-MS/MS method recently developed. Concentration of 6OH-Andros3G and 6OH-Etio3G compounds and those of the glucuronides of T (TG), epitestosterone (EG), androsterone and etiocholanolone were established and different concentration ratios were calculated. The detection windows (DWs) for the T administration obtained by each selected ratio were compared to the one of TG/EG. The results showed that four out of the nine tested markers presented DWs much larger for all volunteers than those obtained by the World Anti-Doping Agency established T/E marker or other alternative markers. The 6OH-Andros3G/EG, 6OH-Etio3G/EG, 6OH-Andros3G/TG and 6OH-Etio3G/TG markers were able to identify the T abuse up to 96h after the administration, extending our detection capability for the misuse up to 84h more than the classic marker. The importance of these markers was also highlighted by their prolonged capacity to detect the T misuse in the case of one volunteer whose TG/EG barely exceeded his individual threshold. As a consequence, the four markers presented in this study seem to have an exceptional potential as biomarkers of T oral administration.

Current LC-MS methods and procedures applied to the identification of new steroid metabolites

The study of the metabolism of steroids has a long history; from the first characterizations of the major metabolites of steroidal hormones in the pre-chromatographic era, to the latest discoveries of new forms of excretions. The introduction of mass spectrometers coupled to gas chromatography at the end of the 1960's represented a major breakthrough for the elucidation of new metabolites. In the last two decades, this technique is being complemented by the use of liquid chromatography-mass spectrometry (LC-MS). In addition of becoming fundamental in clinical steroid determinations due to its excellent specificity, throughput and sensitivity, LC-MS has emerged as an exceptional tool for the discovery of new steroid metabolites. The aim of the present review is to provide an overview of the current LC-MS procedures used in the quest of novel metabolic products of steroidal hormones and exogenous steroids. Several aspects regarding LC separations are first outlined, followed by a description of the key processes that take place in the mass spectrometric analysis, i.e. the ionization of the steroids in the source and the fragmentation of the selected precursor ions in the collision cell. The different analyzers and approaches employed together with representative examples of each of them are described. Special emphasis is placed on triple quadrupole analyzers (LC-MS/MS), since they are the most commonly employed. Examples on the use of precursor ion scan, neutral loss scan and theoretical selected reaction monitoring strategies are also explained.

Advances in bioanalytical techniques to measure steroid hormones in serum

Steroid hormones are measured clinically to determine if a patient has a pathological process occurring in the adrenal gland, or other hormone responsive organs. They are very similar in structure making them analytically challenging to measure. Additionally, these hormones have vast concentration differences in human serum adding to the measurement complexity. GC–MS was the gold standard methodology used to measure steroid hormones clinically, followed by radioimmunoassay, but that was replaced by immunoassay due to ease of use. LC–MS/MS has now become a popular alternative owing to simplified sample preparation than for GC–MS and increased specificity and sensitivity over immunoassay. This review will discuss these methodologies and some new developments that could simplify and improve steroid hormone analysis in serum.

Urinary cysteinyl progestogens: Occurrence and origin

The presence of two cysteinyl progestogens, 16-cysteinyl-progesterone (16-Cys-Prog) and 16-cysteinyl-pregnenolone (16-Cys-Preg), in human urine is described for the first time. Their occurrence was unequivocally confirmed by comparison with synthesized material by using mass spectrometric detectors. Several experiments were performed in order to clarify their origin. The adrenal origin of both 16-Cys-Prog and 16-Cys-Preg can be inferred from the increase in their concentrations after ACTH stimulatory test, together with their circadian variation similar to the one observed for cortisol. Moreover, the notable increase in excretions of 16-Cys-Prog during the luteal phase of the menstrual cycle points towards an ovarian production for this progestogen. However, the analysis of samples during the course of two pregnancies revealed that, in spite of the large amounts of progesterone produced during gestation, the human placenta lacks the capacity to make 16-Cys-Prog. The adrenal and ovarian origin has been further indicated by the absence of both metabolites in samples collected from a subject with bilateral adrenalectomy and hypogonadotrophyic hypogonadism. Regarding liver action, in vitro studies with hepatocytes and progesterone indicate that, although the liver is able to metabolize progesterone to 6-dehydroprogesterone, it has not the enzymatic machinery for the generation of 16-dehydroprogesterone. Taken together, these results open the possibility for a noninvasive test for the simultaneous evaluation of progesterone biosynthesis in different organs.

Effects of resistance training on testosterone metabolism in younger and older men

This study investigated the effects of resistance training (RT) on the metabolism of testosterone (T) in younger (n=5, 28±3yrs.) and older (n=8, 70±2yrs.) men. Experimental heavy resistance exercises (5×10RM leg presses) were performed before and after a 12-month of RT. No age differences were found in the production or metabolic clearance rate of T (determined by stable isotope dilution method), skeletal muscle androgen receptor content or serum LH concentrations due to acute or chronic RT. The T production capacity response to gonadotropin stimulation and the concentrations of the urinary T metabolites (androsterone and etiocholanolone) were lower in the older compared to younger men (p<0.05-0.01). This study further showed that RT may have acute effect on T production and clearance rates, while the exercise-induced increases in serum T appeared to be induced by decreased metabolic clearance rate of T. Attenuated T production capacity and urinary excretion of T metabolites in older men may reflect the known reduction in testicular steroidogenesis upon aging. No changes were observed in T metabolism due to RT indicating a homeostatic stability for this hormone in men of different ages.

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.

Detection and characterization of prednisolone metabolites in human urine by LC-MS/MS

Glucocorticosteroids are prohibited in sports when used by systemic administrations (e.g. oral), whereas they are allowed using other administration ways. Strategies to discriminate between administrations routes have to be developed by doping control laboratories. For this reason, the metabolism of prednisolone (PRED) was studied using liquid chromatography coupled to tandem mass spectrometry. A single oral (10 mg) dose of PRED was administered to two healthy male volunteers. Urine samples were collected up to 6 days after administration. Samples were hydrolyzed with β-glucuronidase and subjected to liquid-liquid extraction with ethyl acetate in alkaline conditions. The extracts were analyzed by liquid chromatography coupled to tandem mass spectrometry. Precursor ion scan methods (m/z 77, 91, 105, 121, 147 and 171) in positive ionization and neutral loss scan methods (76 and 94 Da) in negative ionization modes were applied for the open detection of PRED metabolites. Using these methods, PRED parent compound plus 20 metabolites were detected. PRED and 11 metabolites were characterized by comparison with standards of the compounds (PRED, prednisone, 20β-dihydro-PRED and 20α-dihydro-PRED, 20β-dihydro-prednisone and 20α-dihydro-prednisone, 6β-hydroxy-PRED and 6α-hydroxy-PRED, 20β isomers and 20α isomers of 6β,11β,17α,20,21-pentahydroxypregnan-1,4-diene-3-one, 6α,11β,17α,20β,21-pentahydroxypregnan-1,4-diene-3-one and Δ(6) -PRED). Using mass spectrometric data, feasible structures were proposed for seven of the remaining nine detected metabolites, including several 6-hydroxy-metabolites. Eleven of the characterized metabolites have not been previously described. Maximum excretion rates for PRED metabolites were achieved in first 24 h; however, most of the metabolites were still detectable in the last collected samples (day 6).

Detection and characterization of triamcinolone acetonide metabolites in human urine by liquid chromatography/tandem mass spectrometry after intramuscular administration

RATIONALE

Glucocorticosteroids are prohibited in sports when used by systemic administrations (e.g. intramuscular, IM), whereas they are allowed using other ways of administration. Strategies to discriminate between administrations routes have to be developed by doping control laboratories. For this reason, the metabolism of triamcinolone acetonide (TA), one of the most used glucocorticosteroids, was studied using liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS).

METHODS

Urine samples obtained after IM administration of TA were analyzed using two sample treatments: (a) hydrolysis with β-glucuronidase enzymes and liquid-liquid extraction under alkaline conditions, and (b) liquid-liquid extraction under acidic conditions. The extracts were analyzed by LC/MS/MS.

RESULTS

TA, commercially available metabolites (6β-hydroxytriamcinolone acetonide, 6β-OH-TA, and triamcinolone), and their C20-reduced derivatives showed characteristic fragmentation behavior. Besides common product ions and neutral losses for corticosteroids containing fluorine, additional characteristic neutral losses (58 Da, loss of acetone; 44 Da, loss of acetaldehyde) were observed in positive electrospray ionization. Based on that behavior, two complementary approaches were applied to detect TA metabolites: (a) open detection by precursor ion and neutral loss scan methods and (b) targeted detection by selected reaction monitoring methods (SRM) containing theoretical ion transitions of the potential metabolites. Two main compounds, TA and 6β-OH-TA, and nine minor potential metabolites, were detected by open screening methods. Using SRM, two additional metabolites were detected. Some of the metabolites were characterized using reference standards and, for the rest of metabolites, feasible structures were proposed based on mass spectrometric data.

CONCLUSIONS

Metabolites resulting from hydroxylation in C-6, oxidation of the 11-hydroxyl group, reduction of the Δ(4) double bond and oxidation of the side chain were detected. Some of them have not been previously described. Excretion profiles of the detected metabolites after IM administration are presented.

Evaluation of urinary excretion of androgens conjugated to cysteine in human pregnancy by mass spectrometry

Alterations in the maternal excretion of steroids during pregnancy are not restricted to the production of progesterone and estriol by the fetoplacental unit. Although there is a lack of longitudinal data on urinary androgen concentrations during pregnancy, some studies revealed that modifications in the excretions of androgens might be significant. Recently, several testosterone metabolites excreted as cysteine conjugates have been reported in human urine. We conducted a longitudinal study on androgens conjugated with cysteine and major androgens and estrogens excreted as glucuronides in three pregnant women by mass spectrometric techniques. The urinary concentrations obtained in samples weekly collected during each of the three trimesters and samples collected before pregnancy were compared. Results showed a significant increase in urinary estrogens and norandrosterone and a moderate decrease in the urinary concentrations for most of the androgens. The most significant exception to this behavior was the rise observed for epitestosterone glucuronide when comparing basal levels with the first trimester. Cysteinyl conjugates of testosterone metabolites showed a different behavior. Whereas 4,6-androstanedione remained almost constant through the three trimesters, and Δ(6)-testosterone decreased as the majority of androgens, the excretion profile of 1,4-androstanedione notably increased, reaching a maximum at the third trimester. Alterations in the steroid profile are used in doping control analysis for the screening of endogenous anabolic androgenic steroid misuse. In this study, the main parameters proposed for doping control have been determined for basal samples and samples collected in the first trimester and they have been compared. In spite of the limited number of cases, significant variations have been found in all pregnancies studied. These alterations have to be taken into consideration if anabolic steroids are included into the Athlete Biological Passport. This article is part of a Special Issue entitled 'Pregnancy and Steroids'.

Current status and bioanalytical challenges in the detection of unknown anabolic androgenic steroids in doping control analysis

Androgenic anabolic steroids (AAS) are prohibited in sports due to their anabolic effects. Doping control laboratories usually face the screening of AAS misuse by target methods based on MS detection. Although these methods allow for the sensitive and specific detection of targeted compounds and metabolites, the rest remain undetectable. This fact opens a door for cheaters, since different AAS can be synthesized in order to evade doping control tests. This situation was evidenced in 2003 with the discovery of the designer steroid tetrahydrogestrinone. One decade after this discovery, the detection of unknown AAS still remains one of the main analytical challenges in the doping control field. In this manuscript, the current situation in the detection of unknown AAS is reviewed. Although important steps have been made in order to minimize this analytical problem and different analytical strategies have been proposed, there are still some drawbacks related to each approach.

The influence of androgenic steroid hormones on female aggression in 'atypical' mammals

Dimorphism on dominance and agonistic behaviour in mammals tends to be strongly biased toward males. In this review, we focus on a select few species of mammals in which females are as or more aggressive than males, and/or are dominant to males, and explore the role of androgenic hormones in mediating this important difference. While the data are not as clear-cut as those published on traditional laboratory mammals, our review highlights important endocrine substrates for both organizational and activational influences of steroids on female aggressive behaviour. We highlight areas in which further observations and experiments are crucial, especially the potential facilitative effects of androgens on female aggression. Finally, new and innovative techniques, including molecular genetics and receptor pharmacology, portend important insights into the ways in which androgenic hormones regulate aggressive behaviour in 'atypical' female mammals.

Molecular docking simulation studies on potent butyrylcholinesterase inhibitors obtained from microbial transformation of dihydrotestosterone

BACKGROUND

Biotransformation is an effective technique for the synthesis of libraries of bioactive compounds. Current study on microbial transformation of dihydrotestosterone (DHT) (1) was carried out to produce various functionalized metabolites.

RESULTS

Microbial transformation of DHT (1) by using two fungal cultures resulted in potent butyrylcholinesterase (BChE) inhibitors. Biotransformation with Macrophomina phaseolina led to the formation of two known products, 5α-androstan-3β,17β-diol (2), and 5β-androstan-3α,17β-diol (3), while biotransformation with Gibberella fujikuroi yielded six known metabolites, 11α,17β-dihydroxyandrost-4-en-3-one (4), androst-1,4-dien-3,17-dione (5), 11α-hydroxyandrost-4-en-3,17-dione (6), 11α-hydroxyandrost-1,4-dien-3,17-dione (7), 12β-hydroxyandrost-1,4-dien-3,17-dione (8), and 16α-hydroxyandrost-1,4-dien-3,17-dione (9). Metabolites 2 and 3 were found to be inactive, while metabolite 4 only weakly inhibited the enzyme. Metabolites 5-7 were identified as significant inhibitors of BChE. Furthermore, predicted results from docking simulation studies were in complete agreement with experimental data. Theoretical results were found to be helpful in explaining the possible mode of action of these newly discovered potent BChE inhibitors. Compounds 8 and 9 were not evaluated for enzyme inhibition activity both in vitro and in silico, due to lack of sufficient quantities.

CONCLUSION

Biotransformation of DHT (1) with two fungal cultures produced eight known metabolites. Metabolites 5-7 effectively inhibited the BChE activity. Cholinesterase inhibition is among the key strategies in the management of Alzheimer's disease (AD). The experimental findings were further validated by in silico inhibition studies and possible modes of action were deduced.

Detection, synthesis and characterization of metabolites of steroid hormones conjugated with cysteine

The occurrence of several polyunsaturated testosterone related compounds (including 4,6-androstadien-3,17-dione and 4,6-androstadien-17β-ol-3-one) in urine after alkaline treatment of the sample has been recently reported. Although several experiments seem to indicate that they are testosterone metabolites, their origin is still unknown. In this study, it is demonstrated that these metabolites are produced from the degradation of cysteine conjugates. Several testosterone metabolites conjugated with cysteine have been synthesized and characterized by NMR techniques. Their detection in human urine has been performed by LC-MS/MS. The acquisition of several transitions in the SRM mode and the comparison between ion ratios and retention times allowed for the unequivocal confirmation of the presence of cysteine conjugates in urine. The analysis of urine samples collected after testosterone administration confirmed that synthesized cysteine conjugates are testosterone metabolites. The fact that these conjugates result in polyunsaturated compounds in urine after alkaline treatment was demonstrated by fraction collection and alkaline treatment of each fraction. Besides, the presence of these metabolites was also confirmed in human plasma. The formation of these metabolites implies an unreported metabolic biotransformation: 6,7-dehydrogenation as phase I metabolism followed by conjugation with glutathione and subsequent transformation to cysteine conjugates. Finally, the existence of similar metabolites for cortisol and progesterone was also confirmed by LC-MS/MS indicating that the presented metabolic pathway is not exclusively active in androgens, but common to progestagens and glucocorticoids.

Alternative long-term markers for the detection of methyltestosterone misuse

Methyltestosterone (MT) is one of the most frequently detected anabolic androgenic steroids in doping control analysis. MT misuse is commonly detected by the identification of its two main metabolites excreted as glucuronide conjugates, 17α-methyl-5α-androstan-3α,17β-diol and 17α-methyl-5β-androstan-3α,17β-diol. The detection of these metabolites is normally performed by gas chromatography-mass spectrometry, after previous hydrolysis with β-glucuronidase enzymes, extraction and derivatization steps. The aim of the present work was to study the sulphate fraction of MT and to evaluate their potential to improve the detection of the misuse of the drug in sports. MT was administered to healthy volunteers and urine samples were collected up to 30days after administration. After an extraction with ethyl acetate, urine extracts were analysed by liquid chromatography tandem mass spectrometry using electrospray ionisation in negative mode by monitoring the transition m/z 385 to m/z 97. Three diol sulphate metabolites (S1, S2 and S3) were detected. Potential structures for these metabolites were proposed after solvolysis and mass spectrometric experiments: S1, 17α-methyl-5β-androstan-3α,17β-diol 3α-sulphate; S2, 17β-methyl-5α-androstan-3α,17α-diol 3α-sulphate; and S3, 17β-methyl-5β-androstan-3α,17α-diol 3α-sulphate. Synthesis of reference compounds will be required in order to confirm the structures. The retrospectivity of these sulphate metabolites in the detection of MT misuse was compared with the obtained with previously described metabolites. Metabolite S2 was detected up to 21days after MT administration, improving between 2 and 3 times the retrospectivity of the detection compared to the last long-term metabolite of MT previously described, 17α-hydroxy-17β-methylandrostan-4,6-dien-3-one.

New potential markers for the detection of boldenone misuse

Boldenone is one of the most frequently detected anabolic androgenic steroids in doping control analysis. Boldenone misuse is commonly detected by the identification of the active drug and its main metabolite, 5β-androst-1-en-17β-ol-3-one (BM1), by gas chromatography-mass spectrometry (GC-MS), after previous hydrolysis with β-glucuronidase enzymes, extraction and derivatization steps. However, some cases of endogenous boldenone and BM1 have been reported. Nowadays, when these compounds are detected in urine at low concentrations, isotope ratio mass spectrometry (IRMS) analysis is needed to confirm their exogenous origin. The aim of the present study was to identify boldenone metabolites conjugated with sulphate and to evaluate their potential to improve the detection of boldenone misuse in sports. Boldenone was administered to a healthy volunteer and urine samples were collected up to 56h after administration. After a liquid-liquid extraction with ethyl acetate, urine extracts were analysed by liquid chromatography tandem mass spectrometry (LC-MS/MS) using electrospray ionisation in negative mode by monitoring the transition of m/z 365-350, specific for boldenone sulphate. Boldenone sulphate was identified in the excretion study urine samples and, moreover, another peak with the same transition was observed. Based on the MS/MS behaviour the metabolite was identified as epiboldenone sulphate. The identity was confirmed by isolation of the LC peak, solvolysis and comparison of the retention time and MS/MS spectra with an epiboldenone standard. These sulphated metabolites have not been previously reported in humans and although they account for less than 1% of the administered dose, they were still present in urine when the concentrations of the major metabolites, boldenone and BM1, were at the level of endogenous origin. The sulphated metabolites were also detected in 10 urine samples tested positive to boldenone and BM1 by GC-MS. In order to verify the usefulness of these new metabolites to discriminate between endogenous and exogenous origin of boldenone, four samples containing endogenous boldenone and BM1, confirmed by IRMS, were analysed. In 3 of the 4 samples, neither boldenone sulphate nor epiboldenone sulphate were detected, confirming that these metabolites were mainly detected after exogenous administration of boldenone. In contrast, boldenone sulphate and, in some cases, epiboldenone sulphate were present in samples with low concentrations of exogenous boldenone and BM1. Thus, boldenone and epiboldenone sulphates are additional markers for the exogenous origin of boldenone and they can be used to reduce the number of samples to be analysed by IRMS. In samples with boldenone and BM1 at the concentrations suspicion for endogenous origin, only if boldenone and epiboldenone sulphates are present, further analysis by IRMS will be needed to confirm exogenous origin.

Identification of budesonide metabolites in human urine after oral administration

Budesonide (BUD) is a glucocorticoid widely used for the treatment of asthma, rhinitis, and inflammatory bowel disease. Its use in sport competitions is prohibited when administered by oral, intravenous, intramuscular, or rectal routes. However, topical preparations are not prohibited. Strategies to discriminate between legal and forbidden administrations have to be developed by doping control laboratories. For this reason, metabolism of BUD has been re-evaluated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with different scan methods. Urine samples obtained after oral administration of 3 mg of BUD to two healthy volunteers have been analyzed for metabolite detection in free and glucuronide metabolic fractions. Structures of the metabolites have been studied by LC-MS/MS using collision induced dissociation and gas chromatography-mass spectrometry (GC/MS) in full scan mode with electron ionization. Combination of all structural information allowed the proposition of the most comprehensive picture for BUD metabolism in humans to this date. Overall, 16 metabolites including ten previously unreported compounds have been detected. The main metabolite is 16α-hydroxy-prednisolone resulting from the cleavage of the acetal group. Other metabolites without the acetal group have been identified such as those resulting from reduction of C20 carbonyl group, oxidation of the C11 hydroxyl group and reduction of the A ring. Metabolites maintaining the acetal group have also been identified, resulting from 6-hydroxylation (6α and 6β-hydroxy-budesonide), 23-hydroxylation, reduction of C6-C7, oxidation of the C11 hydroxyl group, and reduction of the C20 carbonyl group. Metabolites were mainly excreted in the free fraction. All of them were excreted in urine during the first 24 h after administration, and seven of them were still detected up to 48 h after administration for both volunteers.

Using complementary mass spectrometric approaches for the determination of methylprednisolone metabolites in human urine

RATIONALE

The metabolism of methylprednisolone is revisited in order to find new metabolites that could be important for distinguishing between different routes of administration. Recently developed liquid chromatography/tandem mass spectrometry (LC/MS/MS) strategies for the detection of corticosteroid metabolites have been applied to the study of methylprednisolone metabolism.

METHODS

The structures of these metabolites were studied using two complementary mass spectrometric techniques: LC/MS/MS in product ion scan mode with electrospray ionization and gas chromatography/mass spectrometry (GC/MS) in full scan mode with electron ionization. Metabolites were also isolated by semipreparative liquid chromatography fractionation. Each fraction was divided into two aliquots; one was studied by LC/MS/MS and the other by GC/MS after methoxyamine-trimethylsilyl derivatization.

RESULTS

The combination of all the structural information allowed us to propose a comprehensive picture of methylprednisolone metabolism in humans. Overall, 15 metabolites including five previously unreported compounds have been detected. Specifically, 16β,17α,21-trihydroxy-6α-methylpregna-1,4-diene-3,11,20-trione, 17α,20β,21-trihydroxy-6α-methylpregna-1,4-diene-3, 11-dione, 11β,17α,21-trihydroxy-6α-hydroxymethylpregna-1,4-diene-3,20-dione, 11β,17α,20ξ,21-tetrahydroxy-6α-hydroxymethylpregna-1,4-diene-3-one, and 17α,21-dihydroxy-6α-hydroxymethylpregna-1,4-diene-3,11,20-trione are proposed as feasible structures for the novel metabolites. In addition to the expected biotransformations: reduction of the C20 carbonyl, oxidation of the C11 hydroxy group, and further 6β-hydroxylation, we propose that hydroxylation of the 6α-methyl group can also take place.

CONCLUSIONS

New metabolites have been identified in urine samples collected after oral administration of 40 mg of methylprednisolone. All identified metabolites were found in all samples collected up to 36 h after oral administration. However, after topical administration of 5 g of methylprednisolone aceponate, neither the parent compound nor any of the metabolites were detected.

Gas chromatography coupled to mass spectrometry-based metabolomic to screen for anabolic practices in cattle: identification of 5α-androst-2-en-17-one as new biomarker of 4-androstenedione misuse

The use of anabolic steroids as growth promoters for meat-producing animals is banned within the European Union. However, screening for the illegal use of natural steroid hormones still represents a difficult challenge because of the high interindividual and physiological variability of the endogenous concentration levels in animals. In this context, the development of untargeted profiling approaches for identifying new relevant biomarkers of exposure and/or effect has been emerging for a couple of years. The present study deals with an untargeted metabolomics approach on the basis of GC-MS aiming to reveal potential biomarkers signing a fraudulent administration of 4-androstenedione (AED), an anabolic androgenic steroid chosen as template. After a sample preparation based on microextraction by packed sorbent, urinary profiles of the free and deglucurono-conjugates urinary metabolites were acquired by GC-MS in the full-scan acquisition mode. Data processing and chemometric procedures highlighted 125 ions, allowing discrimination between samples collected before and after an administration of 4-AED. After a first evaluation of the signal robustness using additional and independent non-compliant samples, 17 steroid-like metabolites were pointed out as relevant candidate biomarkers. All these metabolites were then monitored using a targeted GC-MS/MS method for an additional assessment of their capacity to be used as biomarkers. Finally, two steroids, namely 5α-androstane-3β,17α-diol and 5α-androst-2-en-17-one, were concluded to be compatible with such a definition and which could be finally usable for screening purpose of AED abuse in cattle.

Recent developments in MS for small molecules: application to human doping control analysis

Recent developments in MS for the detection of small molecules in the context of doping control analysis are reviewed. Doping control analysis is evolving together with MS, which is the technique of choice in order to accomplish the analytical requirements in this field. Since these analytical requirements for the detection of a doping agent depend on the substance, in the first section we review the different scenarios. The commonly established approaches, together with their achievements and drawbacks are described. New developments in hyphenated MS techniques (both GC–MS/MS and LC–MS/MS) concerning interfaces and analyzers are mentioned. The use (or potential use) of these developments in order to minimize the limitations of the commonly established approaches in the doping control field is discussed. Finally, a brief discussion about trends and remaining limitations is presented.

Challenges and benefits of endogenous steroid analysis by LC–MS/MS

Quantification of endogenous hormonal steroids and their precursors is essential for diagnosing a wide range of endocrine disorders. Historically, these analyses have been carried out using immunoassay, but such methods are problematic, especially for low-concentration analytes, due to assay interference by other endogenous steroids. MS offers improved specificity over immunoassay and can be highly sensitive. GC–MS, with use of stable isotopically labeled internal standards, is considered the ‘gold standard’ method for serum steroid analysis. GC–MS is the method of choice for profiling steroid metabolites in urine, but these techniques are not appropriate for routine use in clinical laboratories owing to a need for extensive sample preparation, as well as analytical expertise. LC–MS/MS compares well to GC–MS in terms of accuracy, precision and sensitivity, but allows simplified sample preparation. While most publications have featured only one or a limited number of steroids, we consider that steroid paneling (which we propose as the preferred term for multitargeted steroid analysis) has great potential to enable clinicians to make a definitive diagnosis. It is adaptable for use in a number of matrices, including serum, saliva and dried blood spots. However, LC–MS/MS-based steroid analysis is not straightforward, and understanding the chemical and analytical processes involved is essential for implementation of a robust clinical service. This article discusses specific challenges in the measurement of endogenous steroids using LC–MS/MS, and provides examples of the benefits it offers.

Alternative markers for the long-term detection of oral testosterone misuse

The screening of testosterone misuse in the doping control field is normally performed by the measurement of the ratio between the concentrations of testosterone and epitestosterone excreted as glucuronides (T/E). Despite the satisfactory results obtained with this approach, the measurement of T/E presents some limitations like the long-term detection of oral testosterone administration. Recently, several testosterone metabolites released after basic treatment of the urine have been reported (androsta-1,4-dien-3,17-dione, androsta-4,6-dien-3,17-dione, 17β-hydroxy-androsta-4,6-dien-3-one and 15-androsten-3,17-dione). In the present work, the usefulness of these metabolites for the detection of oral testosterone misuse has been evaluated and compared with the conventional T/E measurement. For this purpose, 173 urine samples collected from healthy volunteers were analysed in order to obtain reference concentrations for the four metabolites released after alkaline treatment. On the other hand, urine samples collected from five volunteers before and after testosterone undecanoate administration were also analysed. Concentrations of androsta-4,6-dien-3,17-dione and 17β-hydroxy-androsta-4,6-dien-3-one showed a similar behaviour as the T/E, allowing the detection of the misuse for several hours after administration. More promising results were obtained by quantifying androsta-1,4-dien-3,17-dione and 15-androsten-3,17-dione. The time in which the concentrations of these analytes could be differentiated from the basal level was between 3 and 6 times longer than the obtained with T/E, as a result, an improvement in the detection of testosterone abuse can be achieved. Moreover, several ratios between these compounds were evaluated. Some of them improved the detection of testosterone misuse when comparing with T/E. The best results were obtained with those ratios involving androsta-1,4-dien-3,17-dione.