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Journal of Chromatography. A Nov 2021A sensitive, accurate and precise method was developed for the quantification of a large number of organic acids in human urine by GC-MS/MS. The analytes were selected...
A sensitive, accurate and precise method was developed for the quantification of a large number of organic acids in human urine by GC-MS/MS. The analytes were selected based on their role as key metabolic intermediates; intermediates of Krebs cycle, fatty acid oxidation, glycolysis, down-stream metabolites of neurotransmitter synthesis and degradation, metabolites indicative of nutritional deficiencies, byproducts of microbial activity in the gastrointestinal tract (GI) etc. The most efficient sample preparation protocol was selected based on tests for extraction with different solvents such as MTBE and ethyl acetate under acidic conditions, whereas finally a more general protocol was applied with methanol. Regarding derivatization, methoxyamine with MSTFA, 1% TMCS was applied. The method was extensively validated, including stability study, ensuring accurate determination of the studied organic acids in human urine. Proof of its utility was exhibited in a set of samples from human volunteers. The method can find wide applicability in the context of metabolomics for clinical or nutritional studies.
Topics: Gas Chromatography-Mass Spectrometry; Humans; Metabolomics; Tandem Mass Spectrometry
PubMed: 34666271
DOI: 10.1016/j.chroma.2021.462590 -
Acta Pharmaceutica (Zagreb, Croatia) Jun 2023Methoxamine (Mox) is a well-known α1-adrenoceptor agonist, clinically used as a longer-acting analogue of epinephrine. 1,2-Mox (NRL001) has been also undergoing...
Methoxamine (Mox) is a well-known α1-adrenoceptor agonist, clinically used as a longer-acting analogue of epinephrine. 1,2-Mox (NRL001) has been also undergoing clinical testing to increase the canal resting pressure in patients with bowel incontinence. Here we show, that Mox hydrochloride acts as an inhibitor of base excision repair (BER). The effect is mediated by the inhibition of apurinic/apyrimidinic endonuclease APE1. We link this observation to our previous report showing the biologically relevant effect of Mox on BER - prevention of converting oxidative DNA base damage to double-stranded breaks. We demonstrate that its effect is weaker, but still significant when compared to a known BER inhibitor methoxyamine (MX). We further determined Mox's relative at 19 mmol L, demonstrating a significant effect of Mox on APE1 activity in clinically relevant concentrations.
Topics: Humans; Methoxamine; DNA Repair; Epinephrine; Receptors, Adrenergic; Endonucleases
PubMed: 37307375
DOI: 10.2478/acph-2023-0012 -
Drug Testing and Analysis Aug 2020Hair analysis has attracted great attention in the regulatory analysis of food-producing animals, particularly due to the wider detection window of veterinary drugs in...
Determination of steroids in bovine hair: Validation of a microwave-assisted chemical derivatization method using liquid chromatography-tandem mass spectrometry and in vivo studies.
Hair analysis has attracted great attention in the regulatory analysis of food-producing animals, particularly due to the wider detection window of veterinary drugs in this matrix and also the possibility of confirming parent drugs with minimum metabolization. This work involved the development and validation of a quantitative liquid chromatography-tandem mass spectrometry method to determine 25 steroids and steroid esters in bovine hair. Sensitivity was improved using a fast and effective microwave-assisted chemical derivatization with methoxyamine hydrochloride. The validation was conducted in accordance with the Decision 657/2002/EC guidelines. An animal experimentation procedure was performed on 12 bovine animals in which two commercial formulations containing boldenone undecylenate and testosterone propionate were administrated via intramuscular injections on the neck. The samples were collected for 78 days in which the detection of the administrated analytes was only observed near the application sites. For some of the monitored days, no analyte was detected on the neck area. Since the migration of the analytes was not observed in areas other than the application site, false-negative results should be carefully considered when monitoring animal hair samples.
Topics: Animals; Cattle; Chromatography, Liquid; Esters; Hair; Male; Microwaves; Steroids; Tandem Mass Spectrometry; Testosterone; Testosterone Propionate; Veterinary Drugs
PubMed: 32384229
DOI: 10.1002/dta.2815 -
The Journal of Organic Chemistry Nov 2019Mono- and triethylene glycol aminooxy derivatives were reacted with levulinic acid, protected with dimethoxytrityl, and immobilized on solid support. The resulting solid...
Mono- and triethylene glycol aminooxy derivatives were reacted with levulinic acid, protected with dimethoxytrityl, and immobilized on solid support. The resulting solid supports were used for elongation of oligonucleotides. Then, a mild ammonia treatment was applied to remove the oligonucleotide protecting groups, followed by a treatment with 50 mM methoxyamine at pH 4.2, releasing the 3'-aminooxy oligonucleotides by an oxime exchange reaction. The resulting 3'-aminooxy deoxy- or ribo-oligonucleotides were conjugated to various ketones and aldehydes with high efficiency by oxime ligation.
PubMed: 31615211
DOI: 10.1021/acs.joc.9b00848 -
Clinical Cancer Research : An Official... Jun 2024Patients with glioblastoma (GBM) have a dismal prognosis. While DNA alkylating agent temozolomide (TMZ) is mainstay of chemotherapy, therapeutic resistance develops...
PURPOSE
Patients with glioblastoma (GBM) have a dismal prognosis. While DNA alkylating agent temozolomide (TMZ) is mainstay of chemotherapy, therapeutic resistance develops rapidly in patients. Base excision repair inhibitor TRC102 (methoxyamine) reverses TMZ resistance in preclinical glioma models. We sought to investigate efficacy and safety of oral TRC102+TMZ for recurrent GBM (rGBM).
PATIENTS AND METHODS
A pre-registered (NCT02395692), non-randomized, multicenter, phase 2 clinical trial (BERT) was planned and conducted through the Adult Brain Tumor Consortium (ABTC-1402). Arm 1 included bevacizumab-naïve GBM patients at first recurrence, with primary endpoint of response rates. If sufficient activity was identified, a second arm was planned in bevacizumab-refractory patients. Secondary endpoints were overall survival (OS), progression-free survival (PFS), PFS at six months (PFS-6), and toxicity.
RESULTS
Arm 1 enrolled 19 patients with median of two treatment cycles. Objective responses were not observed, hence, arm 2 did not open. Median OS was 11.1 months (95%CI 8.2-17.9). Median PFS was 1.9 months (95%CI 1.8-3.7). PFS-6 was 10.5% (95%CI 1.3-33.1%). Most toxicities were Grade 1-2, with two Grade 3 lymphopenias and one Grade 4 thrombocytopenia. Two patients with PFS ≥17 months and OS >32 months were deemed 'extended survivors'. RNA sequencing of tumor tissue, obtained at diagnosis, demonstrated significantly enriched signatures of DNA damage response (DDR), chromosomal instability (CIN70, CIN25), and cellular proliferation (PCNA25) in 'extended survivors'.
CONCLUSIONS
These findings confirm safety and feasibility of TRC102+TMZ for rGBM patients. They also warrant further evaluation of combination therapy in biomarker-enriched trials enrolling GBM patients with baseline hyperactivated DDR pathways.
PubMed: 38836759
DOI: 10.1158/1078-0432.CCR-23-4098 -
The Journal of Organic Chemistry Oct 2019A ruthenium (Ru)-catalyzed double annulation of easily accessible -methoxybenzamide derivatives with unactivated alkynes for the synthesis of unusual 6,6-fused...
A ruthenium (Ru)-catalyzed double annulation of easily accessible -methoxybenzamide derivatives with unactivated alkynes for the synthesis of unusual 6,6-fused pyranoisoquinolines is described. Both -C-H bonds of arenes and the N- and O-moieties of -methoxybenzamides are involved in the construction of four [(C-C)-(C-N) and (C-C)-(C-O)] bonds in one step under single catalytic conditions. The unsymmetrical annulation of -methoxybenzamides with two distinct alkynes is also demonstrated. The oxidizable directing group -methoxyamine (NHOMe) assists the unsymmetrical double annulations of arenes [that use both N- and O-heteroatoms] in a single operation. This synthetic method features excellent substrate scope and tolerates a wide range of functional groups. Peripheral modification of pyranoisoquinolines for the construction of complex heterocyclic compounds is also demonstrated.
PubMed: 31411030
DOI: 10.1021/acs.joc.9b01878