Maria Kristina Parr

Maria Kristina Parr
Freie Universität Berlin | FUB · Institute of Pharmacy

Prof. Dr.

About

177
Publications
129,612
Reads
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3,043
Citations
Citations since 2017
93 Research Items
1737 Citations
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
Additional affiliations
April 2012 - present
Freie Universität Berlin
Position
  • Univ-Prof

Publications

Publications (177)
Article
Full-text available
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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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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...
Article
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...
Article
Full-text available
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...
Article
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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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
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...
Article
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...
Preprint
Full-text available
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...
Article
Full-text available
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...
Article
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...
Article
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,...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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 metab...
Article
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...
Preprint
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...
Article
Full-text available
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...
Article
Full-text available
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...
Preprint
Full-text available
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...
Article
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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Chapter
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...
Article
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...
Article
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...
Article
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...
Poster
Full-text available
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...
Presentation
Full-text available
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...
Article
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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
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...
Preprint
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...
Article
Full-text available
The role of psychoactive substances in the treatment of mental disorders and the risk of suicide are major public health issues. This cross-sectional study examined the prevalence of antidepressants and antipsychotics detected in toxicological screenings in suicides. Cases from the Institute of Legal Medicine of the Charité-University Medicine Berl...
Article
Formestane (4-hydroxyandrost-4-ene-3,17-dione, 4OH-AED) is an aromatase inhibitor prohibited in sports. In recent years, it has been demonstrated that it can also originate endogenously by the hydroxylation in C4 position of androstenedione. Thus, the use of isotope ratio mass spectrometry (IRMS) is mandatory according to the World Antidoping Agenc...
Poster
Full-text available
Systematic investigation of different ion sources for steroid analysis using SFC MS/MS
Article
Batch recalls for valsartan containing pharmaceutical products in July 2018 initiated a discussion on possible contaminations with N-nitrosodimethylamine (NDMA). It appeared that NDMA was generated during synthesis of the active pharmaceutical ingredient (API) from the solvent dimethylformamide (DMF) and the reagent nitrite. Discussion on NDMA as A...
Article
The human cytochrome P450 enzyme CYP8B1 is a crucial regulator of the balance of cholic acid (CA) and chenodeoxycholic acid (CDCA) in the liver. It was previously shown to catalyze the conversion of 7α-hydroxycholest-4-en-3-one, a CDCA precursor, to 7α,12α- dihydroxycholest-4-en-3-one, which is an intermediate of CA biosynthesis. In this study we d...
Article
Rationale In various fields of chemical analyses, structurally unknown analytes are considered. Proper structure confirmation may be challenged by the low amounts of analytes that are available e.g. in early stage drug development, in metabolism studies, in toxicology or in environmental analyses. In these cases, mass spectrometric techniques are o...
Article
This review covers literature investigating methods for enantioselective chromatography using supercritical fluids as mobile phase constituents (SFC) in the field of bioanalysis. It provides an overview on method development and screening approaches published in scientific literature 2014-2018. Chiral stationary phases are used to create a chiral e...
Article
The use of trial-and-error principles is a frequently used technique in method development. This may lead to the fact that analytical methods are used routinely without developers and users having gained extensive and well-founded knowledge about the robustness of their analytical methods and the influence of critical key parameters. This very ofte...
Article
A systematic evaluation of splitless hyphenation of supercritical fluid chromatography (SFC) with mass spectrometry (MS) was performed using different techniques for ambient pressure ionization. Interfaces commonly known from HPLC-MS/MS, i.e. electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure ph...