Optimization of enantioselective high-performance liquid chromatography-tandem mass spectrometry method for the quantitative determination of 3,4-methylenedioxy-methamphetamine (MDMA) and its phase-1 metabolites in human biological fluids

Recently we published in this journal an enantioselective high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantitative determination of 3,4-methylenedioxymethamphetamine (MDMA) and its major phase-1 metabolites, 4-hydroxy-3-methoxyamphetamine (HMA), 4-hydroxy-3-methoxymethamphetamine (HMMA) and 3,4-methylenedioxyamphetamine (MDA) in human plasma, sweat, oral fluid and urine. Since we did not achieve simultaneous enantioseparation of all 4 compounds with a single chiral column, two amylose-based chiral columns were used alternatively. Further optimization of the mobile phase in the present study enabled baseline separation of all four pairs of enantiomers on a single Lux AMP column. In addition, by optimization of the column dimension and applied flow-rate it became possible to complete the separation within 6 minutes. These new methods were applied to the analysis of human plasma, oral fluid and urine. While results on the concentration of MDMA and its metabolites in various biological fluids were reported in our recent publication, in the present study an attempt was made to hydrolyze glucuronides in urine samples by using alternatively, hydrochloric acid or glucuronidase and to evaluate the effect of hydrolysis on the concentration and enantiomeric distribution of hydroxy metabolites of MDMA such as HMA and HMMA.

Development of enantioselective high-performance liquid chromatography-tandem mass spectrometry method for the quantitative determination of 3,4-methylenedioxy-methamphetamine (MDMA) and its phase-1 metabolites in human biological fluids

In the present study enantioselective high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods were developed for the quantitative determination of 3,4-methylenedioxy-methamphetamine (MDMA) and its major phase-1 metabolites 4-hydroxy-3-methoxyamphetamine (HMA), 4-hydroxy-3-methoxymethamphetamine (HMMA) and 3,4-methylenedioxyamphetamine (MDA) in human plasma, sweat, oral fluid (OF) and urine. The simultaneous separation of all these compounds and their respective enantioseparation was accomplished on two polysaccharide-based chiral columns. The Lux AMP column with a proprietary chiral selector enabled baseline separation of the enantiomers of MDMA, HMA and HMMA while MDA enantiomers could not be separated with this column under the experimental conditions used in this study. The Lux i-Amylose-3 column based on amylose tris(5-chloro-3-methylphenylcarbamate) as chiral selector baseline-separated the enantiomers of MDMA, HMMA and MDA while the enantiomers of HMA could not be separated. Thus, the various samples were analyzed by using both columns alternatively in combinations with acetonitrile containing 25% (v/v) 5 mM ammonium bicarbonate buffer at pH 11.0 as mobile phase. Analysis time was less than 4 min with the Lux AMP column and less than 6 min with the Lux i-Amylose-3 column. Both methods were validated and applied to the enantioselective determination of MDMA and its phase-I metabolites in human biological fluids, and enantioselective metabolism of MDMA was confirmed.

Metabolic Profiling and In Vitro Assessment of the Biological Activities of the Ethyl Acetate Extract of Penicillium chrysogenum “Endozoic of Cliona sp. Marine Sponge” from the Red Sea (Egypt)

Marine sponge-derived endozoic fungi have been gaining increasing importance as promising sources of numerous and unique bioactive compounds. This study investigates the phytochemical profile and biological activities of the ethyl acetate extract of Penicillium chrysogenum derived from Cliona sp. sponge. Thirty-six compounds were tentatively identified from P. chrysogenum ethyl acetate extract along with the kojic acid (KA) isolation. The UPLC-ESI-MS/MS positive ionization mode was used to analyze and identify the extract constituents while 1D and 2D NMR spectroscopy were used for kojic acid (KA) structure confirmation. The antimicrobial, antioxidant, and cytotoxic activities were assessed in vitro. Both the extract and kojic acid showed potent antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa with MIC 250 ± 0.82 µg/mL. Interestingly, the extract showed strong antifungal activity against Candida albicans and Cryptococcus neoformans with MIC 93.75 ± 0.55 and 19.53 ± 0.48 µg/mL, respectively. Furthermore, KA showed the same potency against Fusarium oxysporum and Cryptococcus neoformans with MIC 39.06 ± 0.85 and 39.06 ± 0.98 µg/mL, respectively. Ultimately, KA showed strong antioxidant activity with IC₅₀ 33.7 ± 0.8 µg/mL. Moreover, the extract and KA showed strong cytotoxic activity against colon carcinoma (with IC₅₀ 22.6 ± 0.8 and 23.4 ± 1.4 µg/mL, respectively) and human larynx carcinoma (with equal IC₅₀ 30.8 ± 1.3 and ± 2.1 µg/mL, respectively), respectively. The current study represents the first insights into the phytochemical profile and biological properties of P. chrysoenum ethyl acetate extract, which could be a promising source of valuable secondary metabolites with potent biological potentials.

Recent advances in chiral analysis for biosamples in clinical research and forensic toxicology

This article covers current methods and applications in chiral analysis from 2010 to 2020 for biosamples in clinical research and forensic toxicology. Sample preparation for aqueous and solid biological samples prior to instrumental analysis were discussed in the article. GC, HPLC, capillary electrophoresis and sub/supercritical fluid chromatography provide the efficient tools for chiral drug analysis coupled to fluorescence, UV and MS detectors. The application of chiral analysis is discussed in the article, which involves differentiation between clinical use and drug abuse, pharmacokinetic studies, pharmacology/toxicology evaluations and chiral inversion. Typical chiral analytes, including amphetamines and their analogs, anesthetics, psychotropic drugs, β-blockers and some other chiral compounds, are also reviewed.

[Research progress on chiral separation of amphetamines, ketamine, cathinones]

Enantiomers are ubiquitous in nature, and they are especially important in the field of pharmaceutical chemistry. Although the enantiomers of chiral drugs have identical chemical structures, they differ notably in their pharmacological, toxicological, pharmacokinetic, metabolic, and other biological activities. The same is true for amphetamines, ketamine, and cathinones, as the chiral separation of these three drugs is representative of drugs. Gas chromatography (GC), high performance liquid chromatography (HPLC), and capillary electrophoresis (CE) are widely used for the chiral separation of these three kinds of drugs. There are some similarities among the three methods for the chiral separation of amphetamines, ketamine, and cathinones: n-trifluoroacetyl-L-prolinyl chloride and (+)R-α-methoxy-α-trifluoromethylphenylacetic acid are the two typical chiral derivatization reagents used in GC. In HPLC, three kinds of chiral stationary phases are used: proteins, polysaccharides, and macrocyclic antibiotics. Cyclodextrin and its derivatives are most commonly used in CE. However, these three methods have inherent shortcomings. In the case of GC, impurities produced during chiral derivatization may interfere with the analysis, and high reaction temperatures affect the efficiency of chiral separation. HPLC has limited application scope and is expensive. In CE, there has no established process to determine the appropriate chiral selector. In recent years, research into application of the chiral separation of the above-mentioned three kinds of drugs has its own characteristics in forensic toxicology. The chiral separation of amphetamine drugs is mostly used to infer the prototype and synthesis route of drugs on the market. The chiral separation of ketamine involves a variety of biological samples. For cathinones, chiral separation methods emphasize their wide applicability. In this review, 66 reports published in professional local and overseas magazines during the past decade are collated. The characteristics of the enantiomers of amphetamines, ketamine, and cathinones as well as the mechanism of chiral recognition are briefly introduced. The commonness of the research and the application of chiral separation in forensic toxicology are reviewed. This paper proposes that the chiral separation of drugs can be further investigated from the following three aspects: 1) the use of computer technology to establish a molecular model for exploring the mechanism of chiral recognition; 2) developing new technologies for chiral separation and carrying out commercial research on the supercritical fluid method; 3) applying chiral separation to judicial practice, pharmaceutical research and development, and other practical fields.

Interpol review of controlled substances 2016-2019

This review paper covers the forensic-relevant literature in controlled substances from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Analytical Considerations When Developing an LC-MS/MS Method for More than 30 Analytes

BACKGROUND

While validation of analytical (LC-MS/MS) methods has been documented in any number of articles and reference texts, the optimal design and subsequent validation of a method for over 30 analytes presents special challenges. Conventional approaches to calibration curves, controls, and run time are not tenable in such methods. This report details the practical aspects of designing and implementing such a method in accordance with College of American Pathologists validation criteria.

METHODS

Conventional criteria were followed in the design and validation of a method for 34 analytes and 15 internal standards by LC-MS/MS. These criteria are laid out in a standard operating procedure, which is followed without exception and is consistent with College of American Pathologists criteria.

RESULTS

The method presented herein provides quality results and accurate medication monitoring. The method was optimized to negate interferences (both from within the method and from potential concomitant compounds), increase throughput, and provide reproducible quality quantification over relevant analyte concentrations ranges.

CONCLUSIONS

The method was designed primarily with quality and accurate medication monitoring in mind. The method achieves these goals by use of novel approaches to calibration curves and controls that both improve performance and minimize risk (financial and operational). As automation and LC-MS/MS equipment continue to improve, it is expected that more methods like this one will be developed.

Differentiating physicochemical properties between NDRIs and sNRIs clinically important for the treatment of ADHD

BACKGROUND

Drugs available for treating attention-deficit hyperactivity disorder (ADHD) are mainly selective norepinephrine (sNRIs) and dual norepinephrine-dopamine (NDRIs) reuptake inhibitors. The major problem of sNRIs lines in their delayed onset of action and partial- or non-responses, which makes NDRIs distinguished in drug efficacy. Understanding of the differential binding modes of these 2 types of drugs to their corresponding targets can give great insights into the discovery of privileged drug-like scaffolds with improved efficacy. So far, no such study has been carried out.

METHODS

A combinatorial computational strategy, integrating homology modeling, molecular docking, molecular dynamics (MD) and binding free energy calculation, was employed to analyze the binding modes of 8 clinically important ADHD drugs in their targets.

RESULTS

Binding modes of 2 types of ADHD drugs (sNRIs and NDRIs) in their targets was identified for the first time by MD simulation, and 15 hot spot residues were discovered as crucial for NDRIs' binding in hNET and hDAT. Comparing to sNRIs, a clear reduction in the hydrophobic property of NDRIs' one functional group was observed, and the depth of drugs' aromatic ring stretched into the pocket of both targets was further identified as key contributors to drugs' selectivity.

CONCLUSIONS

The hydrophobic property of NDRI ADHD drugs' one functional group contributes to their selectivity when bind hNET and hDAT.

GENERAL SIGNIFICANCE

These results provide insights into NDRI ADHD drugs' binding mechanisms, which could be utilized as structural blueprints for assessing and discovering more efficacious drugs for ADHD therapy.

Differentiating Physicochemical Properties between Addictive and Nonaddictive ADHD Drugs Revealed by Molecular Dynamics Simulation Studies

Attention-deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed mental disorder of children and adolescents. Although psychostimulants are currently the first-line drugs for ADHD, their highly addictive profile raises great abuse concerns. It is known that psychostimulants' addictiveness is largely attributed to their interaction with dopamine transporter (DAT) and their binding modes in DAT can thus facilitate the understanding of the mechanism underlining drugs' addictiveness. However, no DAT residue able to discriminate ADHD drugs' addictiveness is identified, and the way how different drug structures affect their abuse liability is still elusive. In this study, multiple computational methods were integrated to differentiate binding modes between approved psychostimulants and ADHD drugs of little addictiveness. As a result, variation in energy contribution of 8 residues between addictive and nonaddictive drugs was observed, and a reduction in hydrophobicity of drugs' 2 functional groups was identified as the indicator of drugs' addictiveness. This finding agreed well with the physicochemical properties of 8 officially reported controlled substances. The identified variations in binding mode can shed light on the mechanism underlining drugs' addictiveness, which may thus facilitate the discovery of improved ADHD therapeutics with reduced addictive profile.

Chromatographic Separation of Vitamin E Enantiomers

Vitamin E is recognized as an essential vitamin since its discovery in 1922. Most vegetable oils contain a mixture of tocopherols and tocotrienols in the vitamin E composition. Structurally, tocopherols and tocotrienols share a similar chromanol ring and a side chain at the C-2 position. Owing to the three chiral centers in tocopherols, they can appear as eight different stereoisomers. Plant sources of tocopherol are naturally occurring in the form of RRR while synthetic tocopherols are usually in the form of all-racemic mixture. Similarly, with only one chiral center, natural tocotrienols occur as the R-isoform. In this review, we aim to discuss a few chromatographic methods that had been used to separate the stereoisomers of tocopherols and tocotrienols. These methods include high performance liquid chromatography, gas chromatography and combination of both. The review will focus on method development including selection of chiral columns, detection method and choice of elution solvent in the context of separation efficiency, resolution and chiral purity. The applications for separation of enantiomers in vitamin E will also be discussed especially in terms of the distinctive biological potency among the stereoisoforms.