Maria Kristina Parr

• Prof. Dr.
• Professor at Freie Universität Berlin

Rationale Gas chromatography/electron ionization mass spectrometry (GC/EI‐MS) is a well‐established tool for the identification of unknown compounds such as new metabolites of xenobiotics. But it reaches the limits of confident structural assignment if it comes to stereoisomers. This work helps to overcome this difficulty by getting a deeper compre...

Within the last two decades, the European Medicines Agency and the US Food and Drug Administration have approved several gene therapies. One category is oligonucleotide therapeutics, which allow for the regulation of the expression of target genes. Besides already approved therapeutics, there are several preclinical and clinical trials ongoing. The...

Inhaled beta-2 adrenoceptor agonists (iβ2A) are routinely used as bronchodilators in the treatment of asthma. However, their cardiac effects in athletes are scarcely examined. Thus, the aim of this study was to evaluate the effects of iβ2A on left ventricular (LV) systolic function (SF) by echocardiography in healthy, non-asthmatic female and male...

Non‐targeted screenings (NTS) are essential tools in different fields, such as forensics, health and environmental sciences. NTSs often employ mass spectrometry (MS) methods due to their high throughput and sensitivity in comparison to, for example, nuclear magnetic resonance–based methods. As the identification of mass spectral signals, called ann...

This work aims to characterize the serum profile of athletes after the administration of ecdysteroids, natural steroid hormones recently reported to enhance athletic performance. The combination of mass spectrometry and chemometric tools may allow to differentiate physiological effects from post‐training and intake‐driven effects. Serum samples wer...

A sustainable reversed-phase chromatographic method has been developed and validated for the simultaneous determination of three active pharmaceutical ingredients, dorzolamide, brinzolamide, and timolol, used to treat glaucoma. The eco-friendly solvent isopropanol has been used as an organic mobile phase constituent. According to the Hansen space g...

The phytosteroid ecdysterone is classified as an anabolic agent and has been included on the monitoring list of the World Anti‐Doping Agency since 2020. Therefore, the consumption of food rich in ecdysterone, such as quinoa and spinach, is the focus of a lively debate. Thus, the urinary excretion of ecdysterone and its metabolites in humans was inv...

Supercritical fluid chromatography-mass spectrometry (SFC-MS) has proved to be a beneficial tool for sample analysis for a wide variety of compounds and, as such, has recently gained the attention of the anti-doping community. We have tested the applicability of SFC-MS for routine doping control analysing approximately 3 × 1000 identical anti-dopin...

Chromatographic modeling software packages are valuable tools during method optimization steps. These are well established for reversed‐phase applications utilizing retention time (RT) prediction to optimize separations and receive robust methods, which is of high interest for the analysis of pharmaceuticals. In contrast to liquid chromatography, t...

Going green, rendering HPLC methods green or better white for sustainable analytical chemistry. In our previous work Cyrene, a bio-based and biodegradable green solvent, was used for the first time as a mobile phase component in Chromatography. Here, we are delighted to share our early preprint manuscript in Separations entitled “Whiter and Greener...

The proposed ICH Q14 guideline “Analytical procedure development” describes science and risk‐based approaches for development and maintenance of analytical procedures suitable for the assessment of the quality of drug substances and drug products. As a case study, the systematic development and validation of a supercritical fluid chromatography (SF...

The misuse of growth-promoting drugs such as beta-2 agonists and steroids is a known problem in farming and sports competitions. Prior to the analysis of biological samples via liquid chromatography (LC)–mass spectrometry (MS) or gas chromatography (GC)–MS, sufficient sample preparation is required to reliably identify or determine the residues of...

Because of their performance‐enhancing effect, anabolic androgenic steroids (AAS) are often misused in sports. Nearly half of the adverse analytical findings (AAF) in 2022 doping controls are correlated to AAS misuse. Metabolites play a crucial role in the bioanalysis of endogenous and exogenous steroids. Therefore, one important field in antidopin...

Propranolol, a non-selective beta-blocker medication, has been utilized in the treatment of cardiovascular diseases for several decades. Its hydroxynaphthyl metabolites have been recognized to possess varying degrees of beta-blocker activity due to the unaltered side-chain. This study achieved the successful separation and identification of diaster...

Background Antibody-drug conjugates are cancer therapeutics that combine specificity and toxicity. A highly cytotoxic drug is covalently attached to an antibody that directs it to cancer cells. The conjugation of the drug-linker to the antibody is a key point in research and development as well as in industrial production. The consensus is to conju...

The aim of this study was to develop and optimize a chiral HPLC-MS/MS method for quantitative analysis of (R)-/(S)-salbutamol and (R)-/(S)-salbutamol-4′-O-sulfate in human urine to allow for bioanalytical quantitation of the targeted analytes and investigations of stereoselectivity in the sulfonation pathway of human phase Ⅱ metabolism. For analyti...

Cyrene (dihydrolevoglucosenone) was evaluated for the first time as a potential sustainable mobile phase solvent in reversed-phase chromatography. As a benign biodegradable solvent, Cyrene is an attractive replacement to classical non-green organic chromatographic solvents such as acetonitrile and a modifier, co-eluent to known green solvents such...

The phytosteroid ecdysterone is included on the monitoring list of the World Anti-Doping Agency. Therefore, the consumption of food rich in ecdysterone is the focus of a lively debate. Thus, urinary excretion of ecdysterone and its metabolites in humans was investigated following quinoa consumption alone and in combination with spinach. After intak...

- Cyrene is an attractive replacement to classical nongreen organic chromatographic solvents such as acetonitrile and a modifier, co-eluent to known green solvents such as ethanol. - Compared to ethanol, Cyrene is less toxic, non-flammable, biobased, biodegradable, and cheaper solvent.

The purity analysis of therapeutic peptides can often be challenging, demanding the application of more than a single analytical technique. Supercritical fluid chromatography nowadays is a promising alternative to reversed‐phase liquid chromatography, providing orthogonal and complementary information. This study investigated its applicability for...

Cyrene was evaluated for the first time as a potential sustainable mobile phase solvent in re-versed-phase chromatography. As a benign biodegradable solvent, Cyrene is an attractive re-placement to classical non-green organic chromatographic solvents such as acetonitrile and a modifier, co-eluent to known green solvents such as ethanol. Compared to...

Background High prevalence rates of β2-agonist use among athletes in competitive sports makes it tempting to speculate that illegitimate use of β2-agonists boosts performance. However, data regarding the potential performance-enhancing effects of inhaled β2-agonists and its underlying molecular basis are scarce. Methods In total, 24 competitive en...

Cytochromes P450 (CYP) and UDP-glucuronosyltransferases (UGT) are two enzyme families that play an important role in drug metabolism, catalyzing either the functionalization or glucuronidation of xenobiotics. However, their mutual interactions are poorly understood. In this study, the functional interactions of human CYP2D6 with four human UGTs (UG...

Higenamine (Hige), a plant derived alkaloid is classified as β2 agonist by the World Anti-Doping Agency (WADA). However, pharmacologic mechanisms of its performance-enhancing activity have not been investigated so far. Therefore, we investigate the anabolic activity and associated molecular mechanisms of Hige in C2C12 myotubes. In differentiated C2...

The aim of the study was a comprehensive and quantitative determination of salbutamol and its sulfoconjugated major metabolite in urine samples using achiral ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Therefore, salbutamol-4′-O-sulfate was biosynthesized as a reference using genetically modified fission yeas...

Monoclonal antibodies (mAbs) used as therapeutics need comprehensive characterization for appropriate quality assurance. For analysis, cost-effective methods are of high importance, especially when it comes to biosimilar development which is based on extended physicochemical characterization. The use of forced degradation to study the occurrence of...

The adrenergic beta-2 agonists formoterol and salbutamol are used for the treatment of asthma and COPD but are also misused in sports competitions. Therefore, they are included in WADA regulations. Both drugs are mainly excreted in urine after administration via inhalation. A four-armed, double-blind cross-over clinical trial was conducted involvin...

Scope: The phytosteroid ecdysterone is present in spinach. In this study, the urinary elimination of ecdysterone and its metabolites in humans was investigated following spinach consumption of two different culinary preparations. Methods and results: Eight participants (4 male, 4 female) ingested 950 (27.1) g sautéed spinach (average (±SD)) and...

Rationale: The proposed metabolomic workflow, based on coupling high-resolution mass spectrometry with computational tools, can be an alternative strategy for metabolite detection and identification. This approach allows the extension of the investigation field to chemically different compounds, maximizing the information obtainable from the data...

It was the aim of this study to compare the ratio of salbutamol and its major metabolite salbutamol-4’-O-sulfate as well as the quantity excreted renally after oral and inhalative administration. Additionally, the excretion pattern after application of racemic salbutamol opposed to the pure enantiomer levosalbutamol was evaluated. For quantitation...

Supercritical fluid chromatography is proving to be a good separation and sample preparation tool for various analytical applications and, as such, has gained the attention of the anti-doping community. Here, the applicability of supercritical fluid chromatography hyphenated to MS/MS for routine doping control analysis was tested. A multi-analyte m...

β2-agonists are used for the treatment of bronchoconstriction, but also abused in doping. Beside an ergogenic activity β2-agonists may have also anabolic activity. Therefore, we investigated the anabolic activity and associated molecular mechanisms of Salbutamol (SAL) and Formoterol (FOR) alone, as well as in combination in C2C12 myotubes. In diffe...

Neuroinflammation is one of the common features in most neurological diseases including multiple sclerosis (MScl) and neurodegenerative diseases such as Alzheimer’s disease (AD). It is associated with local brain inflammation, microglial activation, and infiltration of peripheral immune cells into cerebrospinal fluid (CSF) and the central nervous s...

Currently, little information has been published on the application of ternary eluent compositions in supercritical fluid chromatography for separating peptides. This work investigates the benefits of adding acetonitrile to methanol as the modifier. Three cyclic antibiotic peptides (bacitracin, colistin and daptomycin) ranging between 1000 and 2000...

Various drug samples (N = 249; drug substances, tablets, capsules, solutions, crèmes, and more) from the European pharmaceutical market were collected since 2019 and analyzed for 16 nitrosamines (NAs). In 2.0% of the cases, NAs were detected. These findings included four active pharmaceutical ingredients already known for potential NA contamination...

Myeloid cells are suggested as an important player in Alzheimer´s disease (AD). However, its continuum of phenotypic and functional changes across different body compartments and their use as a biomarker in AD remains elusive. Here, we perform multiple state-of-the-art analyses to phenotypically and metabolically characterize immune cells between p...

Alprazolam is a triazolobenzodiazepine which is most commonly used in the short-term management of anxiety disorders, often in combination with antipsychotics. The four human members of the CYP3A subfamily are mainly responsible for its metabolism, which yields the main metabolites 4-hydroxyalprazolam and α-hydroxyalprazolam. We performed a compari...

Differences in metabolic profiles can link to functional changes of immune cells in disease conditions. Here, we detail a protocol for the detection and quantitation of 19 metabolites in one analytical run. We provide the parameters for chromatographic separation and mass spectrometric analysis of isotopically labeled and unlabeled metabolites. We...

The application area of supercritical fluid chromatography expanded tremendously over the last years and more polar analytes such as biomolecules have become accessible. The growing interest in biopharmaceuticals and associated regulatory requirements demand alternative analytical tools. The orthogonal nature of supercritical fluid chromatography c...

Propranolol is a competitive non-selective beta-receptor antagonist that is available on the market as a racemic mixture. In the present study, glucuronidation of propranolol and its equipotent phase I metabolite 4-hydroxypropranolol by all 19 members of the human UGT1 and UGT2 families was monitored. UGT1A7, UGT1A9, UGT1A10 and UGT2A1 were found t...

In anti-doping science, the knowledge of drug metabolism is a prerequisite to identify analytical targets for the detection of misused prohibited substances. As the most obvious way to study xenobiotic metabolism, the administration to human volunteers, faces ethical concerns, there is a need for model systems. In the present study, we investigated...

Terbutaline is mainly metabolized by sulfoconjugation stereoselectively, favoring its (S)-(+) enantiomer. Reported chiral separations of Terbutaline enantiomers were achieved by various chromatographic methods. However, the simultaneous enantioseparation of Terbutaline and the monosulfate conjugate metabolites was never reported. This study aims at...

1. Olanzapine is an atypical antipsychotic primarily used to treat schizophrenia and bipolar disorder. An intronic single nucleotide polymorphism (SNP) that highly significantly predicts increased olanzapine clearance (rs472660) was previously identified in the CYP3A43 gene, which encodes a cytochrome P450 enzyme. But until now there was no experim...

For in vitro investigations on human sulfotransferase (SULT) catalyzed phase II metabolism, the costly cofactor 3′-phosphoadenosine-5′-phosphosulfate (PAPS) is generally needed. In the present study, we developed and optimized a new approach that combines SULT-dependent biotransformation using recombinant and permeabilized fission yeast cells (enzy...

Since June 2018, thousands of drug products from around the world had to be recalled due to the unexpected presence of nitrosamines (NAs). Starting with the pharmaceutical group of sartans, antidiabetic drugs, antihistamines, and antibiotics also became the subject of investigation. The occurrence of NAs has shown that pharmaceutical companies and...

Doping is considered as cheating in sports and contradicts the ethics of sports. Anti-doping laboratories accredited by the World Anti-Doping Agency target the administration of prohibited compounds or application of prohibited methods by means of instrumental analysis. The majority of methods is based on mass spectrometry with prior chromatographi...

Background Asthma and/or airway hyper-responsiveness (AHR) are common in elite endurance athletes with a high prevalence rate of beta-2 adrenoreceptor (beta-2) agonists use. Nevertheless, there are data on dose-dependent ergogenic effects of beta-2 agonists suggesting increased muscle strength, endurance and neuromuscular performance. Therefore, mo...

Rationale: This work demonstrated the high potential of combining high-resolution mass spectrometry with chemometric tools, using metabolomics as a guided tool for anti-doping analysis. The administration of 7-keto-DHEA was studied as a proof-of-concept of the effectiveness of the combination of knowledge-based and machine-learning approaches to d...

Rationale: Systematic electron ionization fragmentation studies of steroids have been performed to elucidate and trace their characteristic fragmentation pattern. However, the electron ionization source setting at 70 eV electron energy is much higher than the ionization potential (7-15 eV) of most organic compounds, leading to extensive fragmentat...

Dehydrochloromethyltestosterone (DHCMT) is an anabolic-androgenic steroid that was developed by Jenapharm in the 1960s and was marketed as Oral Turinabol ® . It is prohibited in sports at all times; nevertheless, there are several findings by anti-doping laboratories every year. New long-term metabolites have been proposed in 2011/12, which resulte...

The α-Gal epitope is an immunogen trisaccharide structure consisting of N-acetylglucosamine (GlcNAc)β1,4-galactose (Gal)α1,3-Gal. It is presented as part of complex-type glycans on glycoproteins or glycolipids on cell surfaces of non-primate mammalians. About 1% of all antibodies in human sera are specific toward α1,3-Gal and are therefore named as...

Dehydrochloromethyltestosterone (DHCMT) is an anabolic-androgenic steroid that was developed by Jenapharm in the 1960s and was marketed as Oral Turinabol®. It is prohibited in sports at all times; nevertheless, there are several findings by anti-doping laboratories every year. New long-term metabolites have been proposed in 2011/12, which resulted...

Hair samples are frequently analyzed in order to characterize consumption patterns of drugs. However, the interpretation of new psychoactive substance (NPS) findings in hair remains difficult because of lacking data for comparison. In this study, selected postmortem hair samples (n = 1203) from 2008 to 2020 were reanalyzed for synthetic cathinones,...

Ecdysterone is a phytosteroid widely discussed for its various pharmacological, growth-promoting, and anabolic effects, mediated by the activation of estrogen receptor beta (ERbeta). Performance-enhancement in sports was demonstrated recently, and ecdysterone was consequently included in the Monitoring Program, to detect potential patterns of misus...

The emergence of e-cigarettes on the consumer market led to a tremendous rise in e-cigarette consumption among adolescents in the United States. The success of JUUL and other pod systems was linked to its high nicotine delivery capacity. In compliance with the European Tobacco Product directive, liquid nicotine contents in the European JUUL variant...

Cytochrome P450s (CYPs) are an essential family of enzymes in the human body. They play a crucial role in metabolism, especially in human steroid biosynthesis. Reactions catalyzed by these enzymes are highly stereo- and regio-specific. Lack or severe malfunctions of CYPs can cause severe diseases and even shorten life. Hence, investigations on meta...

Modern supercritical fluid chromatography (SFC) is now a well-established technique, especially in the field of pharmaceutical analysis. We recently demonstrated the transferability and the reproducibility of a SFC-UV method for pharmaceutical impurities by means of an inter-laboratory study. However, as this study involved only one brand of SFC in...

Ecdysterone is a phytosteroid widely discussed for its various pharmacological, growth-promoting and anabolic effects mediated by activation of estrogen receptor beta (ERbeta). Performance-enhancement in sports was demonstrated recently, and ecdysterone was consequently included in the Monitoring Program to detect potential patterns of misuse in sp...

New nicotine delivery products are gaining market share. For evaluation of their characteristics toxicokinetic investigations are in current research focus. For reliable determination of blood plasma levels of nicotine and its main metabolites cotinine and trans-3’-hydroxycotinine, a quantitation method based on LC-ESI-MS/MS was developed and valid...

Metandienone and methyltestosterone are orally active anabolic-androgenic steroids with a 17α-methyl structure that are prohibited in sports but are frequently detected in anti-doping analysis. Following the previously reported detection of long-term metabolites with a 17ξ-hydroxymethyl-17ξ-methyl-18-nor-5ξ-androst-13-en-3ξ-ol structure in the chlo...

Metandienone and methyltestosterone are orally available anabolic-androgenic steroids with a 17α-methyl structure that are prohibited in sports but are frequently detected in anti-doping analysis. After the previously reported detection of long-term metabolites with a 17ξ-hydroxymethyl-17ξ-methyl-18-nor-5ξ-androst-13-en-3ξ-ol structure in the chlor...

Predictive models have been developed for the early identification of novel anabolic androgenic steroids and to obtain information on their molecular structure. To this purpose, gas-chromatographic and mass spectrometric characteristic parameters of 133 anabolic androgenic steroids have been specifically considered. Starting from Principal Componen...

Since the detection of nitrosamines (NA) in valsartan pharmaceuticals, over two years have passed. At present, the occurrence of NAs can be limited to a few drug substances and drug products, but it is already becoming apparent that the issue appears to be much bigger than initially thought. The impact on the global pharmaceutical market has been t...

The objective of this work was to develop a high-performance liquid chromatographic method coupled with a mass spectrometer (LC-MS) for the simultaneous analysis of artemisinin-based drugs (e.g. artemisinin, dihydroartemisinin, artesunate, artemether) and piperaquine in formulations. Simultaneous separation of the investigated drugs was achieved in...

Anabolic androgenic steroids (AAS) are prohibited as doping substances in sports by the World Anti-Doping Agency. Concentrations and concentration ratios of endogenous AAS (steroid profile markers) in urine samples collected from athletes are used to detect their administration. Certain (non-prohibited) drugs have been shown to influence the steroi...

Cytosolic sulfotransferases (SULTs) catalyze phase II (conjugation) reactions of drugs and endogenous compounds. A complete set of recombinant fission yeast strains each expressing one of the 14 human SULTs was generated, including SULT4A1 and SULT6B1. Sulfation of test substrates by whole-cell biotransformation was successfully demonstrated for al...

The design of experiments (DoE) is one of the quality-by-design tools valued in analytical method development, not only for cost reduction and time effectiveness, but also for enabling analytical method control and understanding via a systematic workflow, leading to analytical methods with built-in quality. This work aimed at using DoE to enhance m...

Determination of steroid hormones synthesized by the human body plays an important role in various fields of endocrinology. Neurosteroids (NS) are steroids that are synthesized in the central (CNS) or peripheral nervous system (PNS), which is not only a source but also a target for neurosteroids. They are discussed as possible biomarkers in various...

Stress and stress-related diseases are leading to drastic consequences in private and professional life. Therefore, the need for stress prevention strategies is of personal and economic interest. Especially during the recent period related to covid-19 outbreak and lock-down, an ongoing discussion of increasing stress etiology is reported. Biomarker...

Rationale: The aromatase inhibitor formestane (4-hydroxyandrost-4-ene-3,17-dione) is included in the World Anti-Doping Agency's List of Prohibited Substances in Sport. However, it also occurs endogenously as do its 2-, 6- and 11-hydroxy isomers. The aim of this study is to distinguish the different isomers using GC/EI-MS for enhanced confidence in...

NMR-based metabolomics investigations of human biofluids offer great potential to uncover new biomarkers. In contrast to protocols for sample collection and biobanking, procedures for sample preparation prior to NMR measurements are still heterogeneous, thus compromising the comparability of the resulting data. Herein, we present results of an inve...

Rationale Several authors have described the generation of androsta‐3,5‐diene‐7‐one structures from androst‐5‐ene‐3,7‐dione or androst‐5‐ene‐3β‐ol‐7‐one under acidic conditions and/or high temperatures. The goal of this paper was to observe and to describe the results obtained after the chromatographic analysis of the trimethylsilyl derivatives of...

Anabolic androgenic steroids (AAS) are prohibited as performance enhancing drugs in sports. Among them, testosterone and its precursors are often referred to as "pseudo-endogenous" AAS, that is, endogenous steroids that are prohibited when administered exogenously. To detect their misuse, among other methods, the World Antidoping Agency (WADA) accr...

Cancer treatment often lacks individual dose adaptation, contributing to insufficient efficacy and severe side effects. Thus, personalized approaches are highly desired. Although various analytical techniques are established to determine drug levels in preclinical models, they are limited in the automated real-time acquisition of pharmacokinetic pr...

Objective Cytochrome P450 enzymes (CYPs) are capable of catalyzing regio‐ and stereo‐specific oxy functionalization reactions which otherwise are major challenges in organic chemistry. In order to make the best possible use of these biocatalysts it is imperative to understand their specificities. Human CYP21A2 (steroid 21‐hydroxylase) is known as o...

New psychoactive substances (NPS)—such as synthetic cathinones and piperazines—are defined as substances designed to replicate the effects of traditional illegal drugs, including cocaine, ecstasy and amphetamines. These substances are known to potentially be much more potent than their analogs. In the past, there were many poisonings and deaths ass...

Certain postmortem case constellations require intensive investigation of the pattern of drug use over a long period before death. Hair analysis of illicit drugs has been investigated intensively over past decades, but there is a lack of comprehensive data on hair concentrations for antidepressants, antipsychotics, and benzodiazepines. This study a...

Rationale: Gas chromatography coupled to electron ionization mass spectrometry (GC/EI-MS) is used for routine screening of anabolic steroids in many laboratories after the conversion of polar groups to trimethylsilyl (TMS) derivatives. The aim of this work is to elucidate the origin and formation of common and subclass specific fragments in the ma...

The polyhydroxylated phytosteroid ecdysterone is present in various plants (e.g. spinach). It is widely marketed as the active component of dietary supplements, due to its reported health and performance promoting effects. For evaluation of its actual bioavailability, a fast and sensitive method was developed, optimized and validated for human seru...

Supercritical fluid chromatography (SFC) represents an aspiring alternative to the current gold standard reversed phase high-performance liquid chromatography (RPLC) for bioanalytical analysis. Orthogonal selectivity, high separation efficiency, and fast analysis time are valued in different bioanalytical fields such as forensics, doping control, d...

In this study a heart-cutting 2D-LC method was successfully developed and optimized in order to discriminate and quantitate (S)-propranolol, (R)-propranolol, and its hydroxy metabolites, namely the isomeric (S)-4′‑hydroxy propranolol, (R)-4′‑hydroxy propranolol, (S)-5′‑hydroxy propranolol, (R)-5′‑hydroxy propranolol, (S)-7′-hydroxy propranolol, and...

Supercritical fluid chromatography (SFC) is an orthogonal technique to UHPLC. In recent years, SFC has demonstrated potential for use in the analysis of a broad variety of analytes of different polarities, if modifiers and additives are utilized as additional mobile phase constituents. However, to date, little research has been carried out on ion-e...

Purpose The phytosteroid ecdysterone was recently reported to enhance performance in sports and may thus be considered as a substance of relevance in anti-doping control. To trace back an administration of ecdysterone from urine samples, analytical properties have been investigated to assess its integration into initial testing procedures (ITP) in...

The α-galactose (Gal) epitope is a highly immunogenic carbohydrate antigen composed of the trisaccharide structure N-acetylglucosamine (GlcNAc)-β-1,4-Galα-1,3-Gal. It is present on complex-type N-glycans of proteins or lipids of non-primate mammalians like new world monkeys, pigs and rabbits and is considered to be the main cause of red meat allerg...

The presentation reports proper structure confirmation for one of the recently detected metabolites of the anabolic androgenic steroid chlorodehydromethyltestosterone (DHCMT), which is one of the most frequently detected compounds in nowadays doping control analysis. As isomeric compounds often yield very similar mass spectra, proper structure assi...

The present study aimed to design, develop, and optimize an analytical procedure to perform the quantitative determination of ecdysterone in commercially available dietary supplements. The newly developed procedure is based on the extraction of ecdysterone from the supplements and the subsequent analysis by an optimized UHPLC-MS/MS method. Chromato...

Cytochrome P450 enzymes (CYPs) are capable of catalyzing regio- and stereo-specific oxy functionalization reactions, which otherwise are major challenges in organic chemistry. In order to make the best possible use of these biocatalysts it is imperative to understand their specificities. Human CYP21A2 (steroid 21-hydroxylase) acts on the side-chain...

Oxidation of monoclonal antibodies (mAbs) can impact their efficacy and may therefore represent critical quality attributes (CQA) that require evaluation. To complement classical CQA, bevacizumab and infliximab were subjected to oxidative stress by H2O2 for 24, 48, or 72 h to probe their oxidation susceptibility. For investigation, a middle-up appr...

Recent studies suggest that the anabolic effect of ecdysterone, a naturally occurring steroid hormone claimed to enhance physical performance, is mediated by estrogen receptor (ER) binding. In comparison with the prohibited anabolic agents (e.g., metandienone and others), ecdysterone revealed to be even more effective in a recent study performed in...

Purpose: The phytosteroid ecdysterone was recently reported to enhance performance in sports and may thus be considered as a substance of relevance in anti-doping control. To trace back an administration of ecdysterone from urine samples analytical properties have been investigated to assess its integration into initial testing procedures (ITP) in...