Doping control analysis of seven bioactive peptides in horse plasma by liquid chromatography–mass spectrometry

The sensitive detection of low molecular mass peptide drugs in dried blood spots by solid-phase extraction and LC-HRMS

Dried blood spot (DBS) technique has become a new popular topic in anti-doping field in recent years due to its advantages of sample stability and easy operation. It can be employed as a supplementary method to routine urine analysis. However, the small volume of DBS samples (usually 10-20 μL) significantly reduces the application value of this technique. Therefore, the development of sensitive detection methods for the analysis of prohibited substances in DBS is particularly important. In this study, based on the characteristics of low molecular mass peptide (LMMP) drugs, systematic optimization strategies were utilized for the first time to establish a sensitive detection method for LMMPs in DBS. Without using DMSO to enhance mass spectrometry ionization efficiency of peptides, the limits of detection (LOD) ranged between 0.05 and 3.74 ng/mL, significantly better than the previously reported method (0.5-20 ng/mL). This method was validated according to the guidelines of the World Anti-Doping Agency (WADA), and corresponding post-administration study was conducted, demonstrating that the method could be applied to routine analysis of LMMP drugs in DBS. Moreover, since DMSO is not involved, this method also has the potential to simultaneously detect both LMMP and small molecular drugs.

Doping control analysis of small peptides in human urine using LC-HRMS with parallel reaction monitoring mode: screening and confirmation

This study described a reliable analytical method, which combines solid-phase extraction (SPE) with liquid chromatography-high resolution mass spectrometry (LC-HRMS) employing the parallel reaction monitoring (PRM) mode, for screening 41 small peptides and 3 non-peptide growth hormone secretagogues in human urine. Additionally 36 small peptides and 3 non-peptide growth hormone secretagogues were also confirmed in the same way. For the whole screening procedure, the PRM mode was applied to the HRMS detection of small peptides, which reduces the background noise from matrix compounds to a large extent and thus improves the selectivity and reliability of the peptide analytes. Meanwhile, competent chromatographic separation was achieved within a total runtime of 14 minutes, indicating an improvement in the detection efficiency. Moreover, the PRM mode could also be applied to the confirmation procedure due to its strong identification power with a low risk of generating false positives or negatives and good selectivity. Validation was performed according to the relevant World Anti-Doping Agency (WADA) criteria, including selectivity and reliability, limit of detection (LOD), limit of identification (LOI), recovery, extraction stability and carryover. The LODs of the peptide analytes ranged between 0.20 ng mL^-1 and 0.92 ng mL^-1 in urine, while their LOIs ranged between 0.20 ng mL^-1 and 2.00 ng mL^-1, which met the corresponding Minimum Required Performance Levels (MRPLs) as defined by WADA. The developed method furnished the rapid and sensitive detection of small peptides in urine for more than 5000 samples with no false-positive or false-negative, indicating that it is an eligible method for doping control analysis.

A comprehensive study on the performance of different retention mechanisms in sport drug testing by liquid chromatography tandem mass spectrometry

Anti-doping substances listed by the World Anti-Doping Agency (WADA) include hundreds of compounds of very different physico-chemical properties. Anti-doping control laboratories need to screen all these substances in the so-called Initial Testing Procedures (ITPs) what is very challenging from an analytical point of view. ITPs are mostly based on reversed-phase (RP) liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) using C18 columns, which feature poor retention and peak tailing for polar and basic compounds, respectively. While studies on this field dealing with the comparison of stationary phases are focused on certain chemical classes, this research provides a wide multi-target approach. For this purpose, a representative group of 93 anti-doping agents (log P from -2.4 to 9.2) included in ten different classes of prohibited substances was selected. A comprehensive study on the performance of six columns and four eluents on different separation parameters (retention factors, asymmetry factors, co-elutions, total run times) and matrix effects (signal enhancement or suppression) was performed for LC-MS/MS-based ITPs. Columns working in both RP [C18, C8, phenyl hexyl (PH), pentafluorophenyl (PFP) and mixed-mode hydrophilic/RP (HILIC-RP)) and hydrophilic (HILIC)] modes were investigated. Eluents contained methanol or acetonitrile as organic modifiers, with or without the addition of ammonium acetate. The best column-mobile phase binomial for ITPs was PFP using water-methanol (0.1% formic acid) as eluent, while HILIC was the best option for highly polar non-aromatic anti-doping agents, which were poorly addressed by PFP. Excellent good peak shapes and relative acceptable matrix interferences were obtained for HILIC-RP, which was tested for the first time for the analysis of anti-doping agents, although the number of compounds eluting too fast was too high. On the whole, the alkyl phase C18 showed the worst performance and although C8 and PH were better, their performance did not surpass that of PFP. Possible retention mechanisms underlying separation in the different stationary phases were discussed. This research provides valuable information to anti-doping control labs for improving LC-MS/MS-based ITPs and it proposes PFP as a suitable alternative to the already established C18.

Establishment of a post-race biomarkers database and application of pathway analysis to identify potential biomarkers in post-race equine plasma

In the context of doping control, conventional direct chemical testing detects only a limited scope of target substances in equine biological samples. To expand the ability to detect doping agents and their detection windows, metabolomics has recently become a common approach for monitoring alteration of biomarkers caused by doping agents in relevant metabolic pathways. In horse racing, remarkable changes in metabolic profiles between the rest state and racing are likely to affect the identification of doping biomarkers. Previously, we reported a limited number of significantly upregulated metabolites after racing, based on a non-targeted metabolomics approach using out-of-competition and post-race equine plasma samples. In this study, we performed a more thorough analysis of the data set, using pathway analysis to establish a post-race biomarkers database (PBD) that includes upregulated and downregulated metabolites, their fold changes, and relevant pathways, with the main objective of improving our understanding of changes in physiological status related to horse racing. Statistical analysis of the PBD revealed that two peak combinations of pentadecanoyl carnitine/galactosylglycerol (P/G) and heptadecanoyl carnitine/galactosylglycerol (H/G) could be used as potential biomarkers for the discrimination of the rest and post-race groups. To demonstrate the applicability of the PBD, we validated the post-race biomarkers P/G and H/G (highly involved in lipid metabolism) by a single-blind test. This strategy, which combines establishment of a biomarker database with pathway analysis, represents a powerful tool for discovering potential doping biomarkers in the future.

Doping detection in animals: A review of analytical methodologies published from 1990 to 2019

Despite the impressive innate physical abilities of horses, camels, greyhounds, or pigeons, doping agents might be administered to these animals to improve their performance. To control these illegal practices, anti-doping analytical methodologies have been developed. This review compiles the analytical methods that have been published for the detection of prohibited substances administered to animals involved in sports over 30 years. Relevant papers meeting the search criteria that discussed analytical methods aiming to detect and/or quantify doping substances in animal biological matrices published from 1990 to 2019 were considered. A total of 317 studies were included, of which 298 were related to horses, demonstrating significant advances toward the development of doping detection methods for equine sports. However, analytical methods for the detection of doping agents in sports involving other species are lacking. Due to enhanced accuracy and specificity, chromatographic analysis coupled to mass spectrometry detection is preferred over immunoassays. Regarding biological matrices, blood and urine remain the first choice, although alternative biological matrices, such as hair and feces, have been considered. With the increasing number and type of drugs used as doping agents, the analytes addressed in the published papers are diverse. It is very important to continue to detect and quantify these drugs, recognizing those that are most frequently used, in order to punish the abusers, protect animals' health, and ensure a healthier and genuine competition.

Doping control analysis of small peptides: A decade of progress

Small peptides are handled in the field of sports drug testing analysis as a separate group doping substances. It is a diverse group, which includes but is not limited to growth hormone releasing-factors and gonadotropin-releasing hormone analogues. Significant progress has been achieved during the past decade in the doping control analysis of these peptides. In this article, achievements in the application of liquid chromatography-mass spectrometry-based methodologies are reviewed. To meet the augmenting demands for analyzing an increasing number of samples for the presence of an increasing number of prohibited small peptides, testing methods have been drastically simplified, whilst their performance level remained constant. High-resolution mass spectrometers have been installed in routine laboratories and became the preferred detection technique. The discovery and implementation of metabolites/catabolites in testing methods led to extended detection windows of some peptides, thus, contributed to more efficient testing in the anti-doping community.

Detection of bioactive peptides including gonadotrophin-releasing factors (GnRHs) in horse urine using ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC/HRMS)

The use of bioactive peptides as a doping agent in both human and animal sports has become increasingly popular in recent years. As such, methods to control the misuse of bioactive peptides in equine sports have received attention. This paper describes a sensitive accurate mass method for the detection of 40 bioactive peptides and two non-peptide growth hormone secretagogues (< 2 kDa) at low pg/mL levels in horse urine using ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC/HRMS). A simple mixed-mode cation exchange solid-phase extraction (SPE) cartridge was employed for the extraction of 42 targets and/or their in vitro metabolites from horse urine. The final extract was analyzed using UHPLC/HRMS in positive electrospray ionization (ESI) mode under both full scan and data independent acquisition (DIA, for MS² ). The estimated limits of detection (LoD) for most of the targets could reach down to 10 pg/mL in horse urine. This method was validated for qualitative detection purposes. The validation data, including method specificity, method sensitivity, extraction recovery, method precision, and matrix effect were reported. A thorough in vitro study was also performed on four gonadotrophin-releasing factors (GnRHs), namely leuprorelin, buserelin, goserelin, and nafarelin, using the S9 fraction isolated from horse liver. The identified in vitro metabolites have been incorporated into the method for controlling the misuse of GnRHs. The applicability of this method was demonstrated by the identification of leuprorelin and one of its metabolites, Leu M4, in urine obtained after intramuscular administration of leuprorelin to a thoroughbred gelding (castrated horse).

A comprehensive approach to detecting multitudinous bioactive peptides in equine plasma and urine using hydrophilic interaction liquid chromatography coupled to high resolution mass spectrometry

Bioactive peptides possess pharmacological effects and can be illicitly used in sports. To deter such misuse, an untargeted method using high resolution mass spectrometry (HRMS) has been developed for comprehensive detection of multitudinous exogenous peptides in equine plasma and urine. Forty-four peptides were extracted using mixed-mode solid-phase extraction (SPE) from plasma and urine, separated with a hydrophilic interaction liquid chromatography (HILIC) column, and detected on an HRMS instrument. Ammonium formate as a mobile phase additive had effects on HILIC retention and charge state distribution of the peptides. The acetonitrile percentage in the reconstitution solution affected the solubility of peptide neat standards and peptides in plasma and urine extracts differently. The stability of the peptides in plasma at ambient temperature was assessed. The limit of detection (LOD) was 10-50 pg/mL for most of the peptides in plasma, and ≤ 500 pg/mL for the remaining. LOD was 100-400 pg/mL for the majority of the analytes in urine, and ≤ 4000 pg/mL for the others. The method was used successfully to analyze incurred plasma and urine samples from research horses administered dermorphin. Even in the absence of reference standards, dermorphin metabolites (aFGYPS-NH₂ , YaFG, and YaF) were identified. These results demonstrate that data generated with this method can be retrospectively reviewed for peptides that are unknown at the time of sample analysis without requiring re-analysis of the sample. This method provides a powerful novel tool for detection of numerous bioactive peptides and their metabolites in equine plasma and urine for doping control.

Doping control analysis of 46 polar drugs in horse plasma and urine using a 'dilute-and-shoot' ultra high performance liquid chromatography-high resolution mass spectrometry approach

The high sensitivity of ultra high performance liquid chromatography coupled with high resolution mass spectrometry (UHPLC-HRMS) allows the identification of many prohibited substances without pre-concentration, leading to the development of simple and fast 'dilute-and-shoot' methods for doping control for human and equine sports. While the detection of polar drugs in plasma and urine is difficult using liquid-liquid or solid-phase extraction as these substances are poorly extracted, the 'dilute-and-shoot' approach is plausible. This paper describes a 'dilute-and-shoot' UHPLC-HRMS screening method to detect 46 polar drugs in equine urine and plasma, including some angiotensin-converting enzyme (ACE) inhibitors, sympathomimetics, anti-epileptics, hemostatics, the new doping agent 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), as well as two threshold substances, namely dimethyl sulfoxide and theobromine. For plasma, the sample (200μL) was protein precipitated using trichloroacetic acid, and the resulting supernatant was diluted using Buffer A with an overall dilution factor of 3. For urine, the sample (20μL) was simply diluted 50-fold with Buffer A. The diluted plasma or urine sample was then analysed using a UHPLC-HRMS system in full-scan ESI mode. The assay was validated for qualitative identification purpose. This straightforward and reliable approach carried out in combination with other screening procedures has increased the efficiency of doping control analysis in the laboratory. Moreover, since the UHPLC-HRMS data were acquired in full-scan mode, the method could theoretically accommodate an unlimited number of existing and new doping agents, and would allow a retrospectively search for drugs that have not been targeted at the time of analysis.

Qualitative identification of growth hormone-releasing hormones in human plasma by means of immunoaffinity purification and LC-HRMS/MS

The use of growth hormone-releasing hormones (GHRHs) is prohibited in sports according to the regulations of the World Anti-Doping Agency (WADA). The aim of the present study was to develop a method for the simultaneous detection of four different GHRHs and respective metabolites from human plasma by means of immunoaffinity purification and subsequent nano-ultrahigh performance liquid chromatography-high resolution/high accuracy (tandem) mass spectrometry. The target analytes included Geref (Sermorelin), CJC-1293, CJC-1295, and Egrifta (Tesamorelin) as well as two metabolites of Geref and CJC-1293, which were captured from plasma samples using a polyclonal GHRH antibody in concert with protein A/G monolithic MSIA™ D.A.R.T.'S® (Disposable Automation Research Tips) prior to separation and detection. The method was fully validated and found to be fit for purpose considering the parameters specificity, linearity, recovery (19-37%), lower limit of detection (<50 pg/mL), imprecision (<20%), and ion suppression/enhancement effects. The analytes' stability and metabolism were elucidated using in vitro and in vivo approaches. EDTA blood samples were collected from rats 2, 4, and 8 h after intravenous administration of GHRH (one compound per test animal). All intact substances were detected for at least 4 h but no anticipated metabolite was confirmed in laboratory rodents' samples; conversely, a Geref metabolite (GHRH3-29) was found in a human plasma sample collected after subcutaneous injection of the drug to a healthy male volunteer. The obtained results demonstrate that GHRHs are successfully detected in plasma using an immunoaffinity-mass spectrometry-based method, which can be applied to sports drug testing samples. Further studies are however required and warranted to account for potential species-related differences in metabolism and elimination of the target analytes.

Generation of 2,000 breast cancer metabolic landscapes reveals a poor prognosis group with active serotonin production

A major roadblock in the effective treatment of cancers is their heterogeneity, whereby multiple molecular landscapes are classified as a single disease. To explore the contribution of cellular metabolism to cancer heterogeneity, we analyse the Metabric dataset, a landmark genomic and transcriptomic study of 2,000 individual breast tumours, in the context of the human genome-scale metabolic network. We create personalized metabolic landscapes for each tumour by exploring sets of active reactions that satisfy constraints derived from human biochemistry and maximize congruency with the Metabric transcriptome data. Classification of the personalized landscapes derived from 997 tumour samples within the Metabric discovery dataset reveals a novel poor prognosis cluster, reproducible in the 995-sample validation dataset. We experimentally follow mechanistic hypotheses resulting from the computational study and establish that active serotonin production is a major metabolic feature of the poor prognosis group. These data support the reconsideration of concomitant serotonin-specific uptake inhibitors treatment during breast cancer chemotherapy.

Current trends in mass spectrometry of peptides and proteins: Application to veterinary and sports-doping control

Detection of misuse of peptides and proteins as growth promoters is a major issue for sport and food regulatory agencies. The limitations of current analytical detection strategies for this class of compounds, in combination with their efficacy in growth-promoting effects, make peptide and protein drugs highly susceptible to abuse by either athletes or farmers who seek for products to illicitly enhance muscle growth. Mass spectrometry (MS) for qualitative analysis of peptides and proteins is well-established, particularly due to tremendous efforts in the proteomics community. Similarly, due to advancements in targeted proteomic strategies and the rapid growth of protein-based biopharmaceuticals, MS for quantitative analysis of peptides and proteins is becoming more widely accepted. These continuous advances in MS instrumentation and MS-based methodologies offer enormous opportunities for detection and confirmation of peptides and proteins. Therefore, MS seems to be the method of choice to improve the qualitative and quantitative analysis of peptide and proteins with growth-promoting properties. This review aims to address the opportunities of MS for peptide and protein analysis in veterinary control and sports-doping control with a particular focus on detection of illicit growth promotion. An overview of potential peptide and protein targets, including their amino acid sequence characteristics and current MS-based detection strategies is, therefore, provided. Furthermore, improvements of current and new detection strategies with state-of-the-art MS instrumentation are discussed for qualitative and quantitative approaches.

Detection and quantification of dermorphin and selected analogs in equine urine

Background: Dermorphin, a hepta-peptide with potent analgesic properties, is classified as a doping agent in equine racing. Since its discovery, a number of biologically active structural analogs have been synthesized and made commercially available so there is a need for reliable methods of detection. Methodology/Results: A sensitive detection method was developed for dermorphin and six analogs in equine urine. Peptide enrichment was achieved using weak cation exchange with subsequent separation and detection by nano-UHPLC–MS/MS. Method validation parameters included: specificity, linearity (5–10000 pg/ml), recovery (58–93%), intra and inter-assay repeatability, LOD (5–50 pg/ml) and matrix effects. Conclusion: The presented method will facilitate the control of the abuse of dermorphin and selected analogs in equine sports.