RESUMO
Drug-target binding kinetics are an important predictor of in vivo drug efficacy, yet the relationship between ligand structures and their binding kinetics is often poorly understood. We show that both rupatadine (1) and desloratadine (2) have a long residence time at the histamine H1 receptor (H1R). Through development of a [3H]levocetirizine radiolabel, we find that the residence time of 1 exceeds that of 2 more than 10-fold. This was further explored with 22 synthesized rupatadine and desloratadine analogues. Methylene-linked cycloaliphatic or ß-branched substitutions of desloratadine increase the residence time at the H1R, conveying a longer duration of receptor antagonism. However, cycloaliphatic substituents directly attached to the piperidine amine (i.e., lacking the spacer) have decreased binding affinity and residence time compared to their methylene-linked structural analogues. Guided by docking studies, steric constraints within the binding pocket are hypothesized to explain the observed differences in affinity and binding kinetics between analogues.
Assuntos
Ciproeptadina/análogos & derivados , Antagonistas dos Receptores Histamínicos H1/farmacologia , Loratadina/análogos & derivados , Receptores Histamínicos H1/metabolismo , Ciproeptadina/química , Ciproeptadina/farmacologia , Antagonistas dos Receptores Histamínicos H1/química , Humanos , Cinética , Loratadina/química , Loratadina/farmacologia , Simulação de Acoplamento Molecular , Ligação Proteica , Fatores de TempoRESUMO
Drug-target binding kinetics are suggested to be important parameters for the prediction of in vivo drug-efficacy. For G protein-coupled receptors (GPCRs), the binding kinetics of ligands are typically determined using association binding experiments in competition with radiolabelled probes, followed by analysis with the widely used competitive binding kinetics theory developed by Motulsky and Mahan. Despite this, the influence of the radioligand binding kinetics on the kinetic parameters derived for the ligands tested is often overlooked. To address this, binding rate constants for a series of histamine H1 receptor (H1R) antagonists were determined using radioligands with either slow (low koff) or fast (high koff) dissociation characteristics. A correlation was observed between the probe-specific datasets for the kinetic binding affinities, association rate constants and dissociation rate constants. However, the magnitude and accuracy of the binding rate constant-values was highly dependent on the used radioligand probe. Further analysis using recently developed fluorescent binding methods corroborates the finding that the Motulsky-Mahan methodology is limited by the employed assay conditions. The presented data suggest that kinetic parameters of GPCR ligands depend largely on the characteristics of the probe used and results should therefore be viewed within the experimental context and limitations of the applied methodology.
Assuntos
Ligação Competitiva , Antagonistas dos Receptores Histamínicos H1/farmacocinética , Sondas Moleculares/química , Ensaio Radioligante/métodos , Receptores Histamínicos H1/metabolismo , Cetirizina/química , Cetirizina/farmacocinética , Conjuntos de Dados como Assunto , Transferência Ressonante de Energia de Fluorescência/métodos , Corantes Fluorescentes/química , Corantes Fluorescentes/farmacocinética , Células HEK293 , Antagonistas dos Receptores Histamínicos H1/química , Humanos , Ligantes , Sondas Moleculares/farmacocinética , Cloridrato de Olopatadina/química , Cloridrato de Olopatadina/farmacocinética , Ligação Proteica , Pirilamina/química , Pirilamina/farmacocinética , TrítioRESUMO
The aryl methyl group is found in many drug-like compounds, but there are limited ways of preparing compounds with an isotope label in this methyl position. The process of cyanation of an aryl halide followed by complete reduction of the nitrile to a methyl group was investigated as a route for preparing stable and radiolabelled isotopologues of drug-like compounds. Using this methodology, carbon-13, deuterium, carbon-14, and tritium labelled isotopologues of the nonsteroidal anti-inflammatory drug tolmetin were produced, as well as carbon-13, deuterium, and carbon-14 labelled isotopologues of another nonsteroidal anti-inflammatory drug, celecoxib. The radiolabelled compounds were produced at high specific activity and the stable isotope labelled compounds with high incorporation making them suitable for use as internal standards in mass spectrometry assays. This approach provides a common synthetic route to multiple isotopologues of compounds using inexpensive and readily available labelled starting materials.
Assuntos
Celecoxib/química , Celecoxib/síntese química , Marcação por Isótopo/métodos , Nitrilas/química , Tolmetino/química , Tolmetino/síntese química , Técnicas de Química Sintética , OxirreduçãoRESUMO
As part of a Medicinal Chemistry program aimed at developing an orally bioavailable selective estrogen receptor degrader, a number of tritium, carbon-14, and stable isotope labelled (E)-3-[4-(2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indol-1-yl)phenyl]prop-2-enoic acids were required. This paper discusses 5 synthetic approaches to this compound class.
Assuntos
Radioisótopos de Carbono/química , Indóis/química , Indóis/síntese química , Receptores de Estrogênio/metabolismo , Trítio/química , Disponibilidade Biológica , Técnicas de Química Sintética , Indóis/farmacocinética , Indóis/farmacologia , Marcação por IsótopoRESUMO
[(14) C]-AZD1152 (barasertib) drug substance was prepared in order to support a hADME study that was to be dosed as an intravenous infusion to patients with acute myeloid leukaemia. A long patient recruitment time (1-2 years) was expected, and because of its limited stability several batches of [(14) C]-AZD1152 drug substance needed to be prepared in order to maintain a supply of [(14) C]-AZD1152 in the clinic over this period. A method was developed to purify the [(14) C]-AZD1152 to a GMP-like standard at high specific activity to provide material for each of these batches. This approach to the delivery of the drug substance was successful in supplying the study with radiolabelled drug for over 1 year until all patients had been recruited.
Assuntos
Radioisótopos de Carbono/química , Organofosfatos/administração & dosagem , Organofosfatos/química , Quinazolinas/administração & dosagem , Quinazolinas/química , Desenho de Fármacos , Humanos , Infusões Intravenosas , Organofosfatos/farmacocinética , Quinazolinas/farmacocinéticaRESUMO
Ceftazidime is a third generation cephalosporin antibiotic that has activity against a wide range of Gram-negative and Gram-positive bacterial pathogens, including Escherichia coli and Pseudomonas aeruginosa. Stable isotope-labeled ceftazidime was required for use as an internal standard in LC-MS/MS assays, and a route was developed to make [(2)H6]ceftazidime in eight steps from the commercially available labeled starting material [(2)H7]isobutyric acid.
Assuntos
Anti-Infecciosos/química , Ceftazidima/química , Deutério/química , Marcação por IsótopoRESUMO
An updated approach to the 1960s synthesis of [(14)C] fenclozic acid from labelled potassium cyanide is presented. By employing modern synthetic methodology and purification techniques, many of the inherent hazards in the original synthesis are avoided or significantly reduced. The concomitant labelled stereoselective synthesis of the key acyl glucuronide metabolite (the 1-ß-O-acyl glucuronide) is also described.
Assuntos
Compostos Radiofarmacêuticos/síntese química , Tiazóis/síntese química , Radioisótopos de Carbono/química , Técnicas de Química Sintética/métodos , Glucuronídeos/síntese química , Glucuronídeos/química , Marcação por Isótopo/métodos , Cianeto de Potássio/químicaRESUMO
The in vitro metabolism of cediranib (4-[(4-fluoro-2-methyl-1H-indol-5-yl)oxy]-6-methoxy-7-[3-(1-pyrrolidinyl)propoxy]quinazoline), a vascular endothelial growth factor (VEGF) tyrosine kinase inhibitor (TKI) of all three VEGF receptors in late-stage development for the treatment of colorectal cancer and recurrent glioblastoma was investigated in hepatic proteins from preclinical species and humans using radiolabeled material. In human hepatocyte cultures, oxidative and conjugative metabolic pathways were identified, with pyrrolidine N(+)-glucuronidation being the major route. The primary oxidative pathways were di-and trioxidations and pyrrolidine N-oxidation. All metabolites with the exception of the N(+)-glucuronide metabolite were observed in rat and cynomolgus monkey hepatocyte preparations. Additional metabolism studies in liver microsomes from these or other preclinical species (CD-1 mouse, Han Wistar rat, Dunkin Hartley guinea pig, Göttingen mini-pig, New Zealand White rabbit, beagle dog, and cynomolgus and rhesus monkey) indicated that the N(+)-glucuronide metabolite was not formed in these additional species. Incubations with recombinant flavin-containing monooxygenase (FMO) and UDP-glucuronosyltransferase (UGT) enzymes and inhibition studies using the nonselective cytochrome P450 (P450) chemical inhibitor 1-aminobenzotriazole in human hepatocytes indicated that FMO1 and FMO3 contributed to cediranib N-oxidation, whereas UGT1A4 had a major role in cediranib N(+)-glucuronidation. P450 enzymes had only a minor role in the metabolism of cediranib. In conclusion, species differences in the formation of the N(+)-glucuronide metabolite of cediranib were observed. All other metabolites of cediranib found in humans were also detected in rat and cynomolgus monkey. Non-P450 enzymes are predominantly involved in the metabolism of cediranib, and this suggests that clinical drug interactions involving other coadministered drugs are unlikely.
Assuntos
Fígado/enzimologia , Fígado/metabolismo , Quinazolinas/farmacocinética , Receptores Proteína Tirosina Quinases/antagonistas & inibidores , Fator A de Crescimento do Endotélio Vascular/antagonistas & inibidores , Adulto , Animais , Células Cultivadas , Sistema Enzimático do Citocromo P-450/metabolismo , Cães , Feminino , Glucuronosiltransferase/metabolismo , Cobaias , Hepatócitos/enzimologia , Hepatócitos/metabolismo , Humanos , Macaca fascicularis , Macaca mulatta , Masculino , Desintoxicação Metabólica Fase I , Desintoxicação Metabólica Fase II , Camundongos , Microssomos Hepáticos/enzimologia , Microssomos Hepáticos/metabolismo , Pessoa de Meia-Idade , Oxigenases/metabolismo , Quinazolinas/metabolismo , Quinazolinas/farmacologia , Coelhos , Ratos , Ratos Wistar , Especificidade da Espécie , Suínos , Porco MiniaturaRESUMO
[Structure: see text] The total synthesis of the marine metabolite clavosolide A is reported which confirms the structure and absolute configuration of the natural product as the symmetrical diolide glycosylated by permethylated D-xylose moieties, 2.
Assuntos
Produtos Biológicos/síntese química , Macrolídeos/síntese química , Produtos Biológicos/química , Catálise , Macrolídeos/química , Biologia Marinha , Estrutura Molecular , EstereoisomerismoRESUMO
The first total synthesis of the reported structure of the sponge metabolite clavosolide A is described using a Prins cyclisation to assemble the tetrahydropyran core followed by manipulation of the side-chain, dimerisation and finally glycosidation.
Assuntos
Produtos Biológicos/síntese química , Macrolídeos/síntese química , Animais , Produtos Biológicos/química , Cristalografia por Raios X , Dimerização , Macrolídeos/química , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estrutura Molecular , Oceanos e Mares , Poríferos/química , EstereoisomerismoRESUMO
Trapping intermediates on the Prins cyclisation pathway with carbon-based nucleophiles has given further insight into factors affecting the acid-mediated reactions of homoallylic alcohols with aldehydes, enabling the design of efficient syntheses of 4-hydroxy-2,6-disubstituted tetrahydropyrans.
Assuntos
Compostos Heterocíclicos/síntese química , Hidrogênio/química , Acetais/química , Álcoois/química , Catecóis/química , Cianetos/química , Ciclização , Compostos Heterocíclicos/química , Hidroxilação , Estrutura MolecularRESUMO
[reaction: see text] A concise and stereoselective synthesis of the tetrasubstituted tetrahydropyran core of polycavernoside A was achieved in 55% overall yield from 3-benzyloxypropanal. A stereoselective allyl transfer reaction was used in the synthesis of enol ether 18 followed by a TFA-mediated cyclization to create the three new asymmetric centers in the tetrahydropyran with complete stereocontrol in a single-pot process.