ABSTRACT
Dopamine is one of the crucial neurotransmitters in the human brain. Its out-of-range concentration can lead to various neurological diseases with special interest for dopamine D2 and D3 receptor subtypes. Although BODIPY is a highly versatile structural moiety for fluorescence labeling, we have looked out for structurally related pyridine-based moieties. We used BOPPY labelling of well-described D2R/D3R pharmacophores to obtain ligands with moderate to low nanomolar binding affinities as well as low to excellent quantum yields for bright fluorescence ligands. To best of our knowledge, this is the first report on the application of BOPPY fluorophores to GPCR ligands. This approach offers a general applicable way for fluorescence labelling via primary aliphatic amine elements.
Subject(s)
Amines/chemistry , Fluorescent Dyes/chemistry , Receptors, Dopamine D2/chemistry , Receptors, Dopamine D3/chemistry , Humans , Ligands , Molecular StructureABSTRACT
Ligands with different properties and different selectivity are highly needed for in vitro and in vivo studies on the (patho)physiological influence of the chemical mediator histamine and its receptor subtypes. A selection of well-described ligands for the different receptor subtypes and different studies is shown with a particular focus on affinity and selectivity. In addition, compounds with radioactive or fluorescence elements will be presented with their beneficial use for other species or different investigations.
Subject(s)
Histamine Antagonists , Histamine , Histamine/pharmacology , Histamine Antagonists/chemistry , Ligands , Receptors, HistamineABSTRACT
Dopamine is an important neurotransmitter in the human brain and its altered concentrations can lead to various neurological diseases. We studied the binding of novel compounds at the dopamine D2 (D2 R) and D3 (D3 R) receptor subtypes, which belong to the D2 -like receptor family. The synthesis, in silico, and in vitro characterization of 10 dopamine receptor ligands were performed. Novel ligands were docked into the D2 R and D3 R crystal structures to examine the precise binding mode. A quantum mechanics/molecular mechanics study was performed to gain insights into the nature of the intermolecular interactions between the newly introduced pentafluorosulfanyl (SF5 ) moiety and D2 R and D3 R. A radioligand displacement assay determined that all of the ligands showed moderate-to-low nanomolar affinities at D2 R and D3 R, with a slight preference for D3 R, which was confirmed in the in silico studies. N-{4-[4-(2-Methoxyphenyl)piperazin-1-yl]butyl}-4-(pentafluoro-λ6-sulfanyl)benzamide (7i) showed the highest D3 R affinity and selectivity (pKi values of 7.14 [D2 R] and 8.42 [D3 R]).
Subject(s)
Benzamides , Dopamine Antagonists , Dopamine/metabolism , Ligands , Receptors, Dopamine D2/metabolism , Receptors, Dopamine D3/metabolism , Benzamides/chemical synthesis , Benzamides/chemistry , Benzamides/pharmacology , Binding, Competitive , Dopamine Antagonists/chemical synthesis , Dopamine Antagonists/chemistry , Dopamine Antagonists/pharmacology , Humans , Nervous System Diseases/drug therapy , Nervous System Diseases/metabolism , Protein Binding , Radioligand Assay , Structure-Activity RelationshipABSTRACT
Fast and simple hydrophilic interaction liquid chromatography (HILIC) method was developed and validated for the analysis of moxonidine and its four impurities (A, B, C, and D) in pharmaceutical dosage form. All experiments were performed on the Agilent Technologies 1200 high-performance liquid chromatography (HPLC) system using Zorbax RX-SIL, 250 mm × 4.6 mm, 5 µm column as stationary phase (T = 25°C, F = 1 mL/min, and λ = 255 nm), and mixture of acetonitrile and 40 mM ammonium formate buffer (pH 2.8) 80 : 20 (v/v) as mobile phase. Under the optimal chromatographic conditions, selected by central composite design, separation and analysis of moxonidine and its four impurities are enabled within 12 minutes. Validation of the method was conducted in accordance with ICH guidelines. Based on the obtained results selectivity, linearity (r ≥ 0.9976), accuracy (recovery: 93.66%-114.08%), precision (RSD: 0.56%-2.55%), and robustness of the method were confirmed. The obtained values of the limit of detection and quantification revealed that the method can be used for determination of impurities levels below 0.1%. Validated method was applied for determination of moxonidine and its impurities in commercially available tablet formulation. Obtained results confirmed that validated method is fast, simple, and reliable for analysis of moxonidine and its impurities in tablets.