RESUMO
The critical roles played by GABAA receptors as inhibitory regulators of excitation in the central nervous system has been known for many years. Aberrant GABAA receptor function and trafficking deficits have also been associated with several diseases including anxiety, depression, epilepsy, and insomnia. As a consequence, important drug groups such as the benzodiazepines, barbiturates, and many general anesthetics have become established as modulators of GABAA receptor activity. Nevertheless, there is much we do not understand about the roles and mechanisms of GABAA receptors at neural network and systems levels. It is therefore crucial to develop novel technologies and especially chemical entities that can interrogate GABAA receptor function in the nervous system. Here, we describe the chemistry and characterization of a novel set of 4-PIOL and 4-PHP analogues synthesized with the aim of developing a toolkit of drugs that can photoinactivate GABAA receptors. Most of these new analogues show higher affinities/potencies compared with the respective lead compounds. This is indicative of cavernous areas being present near their binding sites that can be potentially associated with novel receptor interactions. The 4-PHP azide-analogue, 2d, possesses particularly impressive nanomolar affinity/potency and is an effective UV-inducible photoinhibitor of GABAA receptors with considerable potential for photocontrol of GABAA receptor function in situ.
Assuntos
Isoxazóis/metabolismo , Marcadores de Fotoafinidade/metabolismo , Piperidinas/metabolismo , Receptores de GABA-A/metabolismo , Células HEK293 , Humanos , Isoxazóis/análise , Marcadores de Fotoafinidade/análise , Piperidinas/análise , Estrutura Secundária de Proteína , Receptores de GABA-A/análise , Receptores de GABA-A/químicaRESUMO
Based on our 3-hydroxy-7-chloroquinazoline-2,4-dione derivatives, previously reported as antagonists at ionotropic glutamate receptors, we synthesized new 3-hydroxyquinazoline-2,4-diones bearing a trifluoromethyl group at the 7-position and different groups at position 6. Glycine/NMDA, AMPA and kainate receptor binding data showed that the 7-trifluoromethyl residue increased AMPA and kainate receptor affinity and selectivity, with respect to the 7-chlorine atom. Among the probed 6-substituents, the 6-(1,2,4-triazol-4-yl) group (compound 8) was the most advantageous for AMPA receptor affinity and selectivity. Derivative 8 demonstrated to be effective in decreasing neuronal damage produced by oxygen and glucose deprivation in organotypic rat hippocampal slices and also showed anticonvulsant effects in pentylenetetrazole-induced convulsions. The previously reported kainate receptor antagonist 6-(2-carboxybenzoyl)-amino-7-chloro-3-hydroxyquinazoline-2,4-dione 3 prevented the failure of neurotransmission induced by oxygen and glucose deprivation in the CA1 region of rat hippocampal slices.
Assuntos
Anticonvulsivantes/química , Anticonvulsivantes/farmacologia , Simulação de Acoplamento Molecular , Quinazolinonas/química , Quinazolinonas/farmacologia , Receptores de AMPA/antagonistas & inibidores , Receptores de Ácido Caínico/antagonistas & inibidores , Animais , Anticonvulsivantes/síntese química , Anticonvulsivantes/metabolismo , Fenômenos Eletrofisiológicos/efeitos dos fármacos , Glucose/deficiência , Hipocampo/citologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Hipocampo/fisiologia , Humanos , Técnicas In Vitro , Masculino , Camundongos , Oxigênio/metabolismo , Quinazolinonas/síntese química , Quinazolinonas/metabolismo , Ratos , Ratos Wistar , Receptores de AMPA/química , Receptores de AMPA/metabolismo , Receptores de Ácido Caínico/química , Receptores de Ácido Caínico/metabolismo , Relação Estrutura-Atividade , Especificidade por SubstratoRESUMO
This paper reports the study of new 2-phenyl- and 2-methylpyrazolo[3,4-c]quinolin-4-ones (series A) and 4-amines (series B), designed as adenosine receptor (AR) antagonists. The synthesized compounds bear at the 6-position various groups, with different lipophilicity and steric hindrance, that were thought to increase human A(1) and A(2A) AR affinities and selectivities, with respect to those of the parent 6-unsubstituted compounds. In series A, this modification was not tolerated since it reduced AR affinity, while in series B it shifted the binding towards the hA(1) subtype. To rationalize the observed structure-affinity relationships, molecular docking studies at A(2A)AR-based homology models of the A(1) and A(3) ARs and at the A(2A)AR crystal structure were carried out.
Assuntos
Modelos Moleculares , Antagonistas de Receptores Purinérgicos P1/química , Antagonistas de Receptores Purinérgicos P1/síntese química , Quinolinas/síntese química , Animais , Células CHO , Simulação por Computador , Cricetinae , Cricetulus , Cristalografia por Raios X , Humanos , Antagonistas de Receptores Purinérgicos P1/farmacologia , Pirazóis/síntese química , Pirazóis/química , Pirazóis/farmacologia , Quinolinas/química , Quinolinas/farmacologia , Relação Estrutura-AtividadeRESUMO
In the present study, some selected, previously reported 4,5-dihydro-4-oxo-1,2,4-triazolo[1,5-a]quinoxaline-2-carboxylates (TQXs) and 3-hydroxy-quinazoline-2,4-diones (QZs), were evaluated for their affinity at the (S)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)-propionic acid (AMPA) receptor in the [(3)H]-6-cyano-7-nitroquinoxaline-2,3-dione ([(3)H]-CNQX) binding assay. Electrophysiological experiments were performed in oocytes expressing rat homomeric GluR3 subunits in order to assess the pharmacological profile of the tested compounds. The binding data, together with those regarding the functional activity, confirmed that most of the TQXs and QZs reported herein are potent AMPA receptor antagonists. When tested for their ability to prevent sound-induced seizures in DBA/2 mice, some of these derivatives showed anticonvulsant properties.
Assuntos
Anticonvulsivantes/química , Quinazolinas/química , Quinoxalinas/química , Receptores de AMPA/antagonistas & inibidores , Animais , Anticonvulsivantes/síntese química , Anticonvulsivantes/uso terapêutico , Camundongos , Oócitos/metabolismo , Quinazolinas/síntese química , Quinazolinas/uso terapêutico , Quinoxalinas/síntese química , Quinoxalinas/uso terapêutico , Ratos , Receptores de AMPA/metabolismo , Convulsões/induzido quimicamente , Convulsões/tratamento farmacológicoRESUMO
A molecular simplification approach of previously reported 2-arylpyrazolo[3,4-c]quinolin-4-ones was applied to design 2-arylpyrazolo[4,3-d]pyrimidin-7-one derivatives as new human A(3) adenosine receptor antagonists. Substituents with different lipophilicity and steric hindrance were introduced at the 5-position of the bicyclic scaffold (R(5) = H, Me, Et, Ph, CH(2)Ph) and on the 2-phenyl ring (OMe, Me). Most of the synthesized derivatives were highly potent hA(3) adenosine receptor antagonists, the best being the 2-(4-methoxyphenyl)pyrazolo[4,3-d]pyrimidin-7-one (K(i) = 1.2 nM). The new compounds were also highly selective, being completely devoid of affinity toward hA(1), hA(2A), and hA(2B) adenosine receptors. On the basis of the recently published human A(2A) receptor crystallographic information, we propose a novel receptor-driven hypothesis to explain both A(3) AR affinity and A(3) versus A(2A) selectivity profiles of these new antagonists.
Assuntos
Antagonistas do Receptor A3 de Adenosina , Pirazóis/metabolismo , Pirazóis/farmacologia , Pirimidinas/metabolismo , Pirimidinas/farmacologia , Pirimidinonas/metabolismo , Pirimidinonas/farmacologia , Receptor A3 de Adenosina/metabolismo , Antagonistas do Receptor A2 de Adenosina , Sequência de Aminoácidos , Animais , Células CHO , Cricetinae , Cricetulus , Humanos , Modelos Moleculares , Conformação Molecular , Dados de Sequência Molecular , Ligação Proteica , Pirazóis/química , Pirimidinas/química , Pirimidinonas/química , Receptor A2A de Adenosina/química , Receptor A2A de Adenosina/metabolismo , Receptor A3 de Adenosina/química , Especificidade por Substrato , Triazinas/metabolismo , Triazinas/farmacologia , Triazóis/metabolismo , Triazóis/farmacologiaRESUMO
The paper describes a new class of human (h) A(3) adenosine receptor antagonists, the 2-arylpyrido[2,3-e]-1,2,4-triazolo[4,3-a]pyrazin-1-one derivatives (PTP), either 4-oxo (1-6, series A) or 4-amino-substituted (7-20, series B). In both series A and B, substituents able to act as hydrogen bond acceptors (OMe, OH, F, COOEt) were inserted on the 2-phenyl ring. In series B, cycloalkyl and acyl residues were introduced on the 4-amino group. Some of the new derivatives showed high hA(3) AR affinities (K(i) < 50 nM) and selectivities vs both hA(1) and hA(2A) receptors. The selected 4-benzoylamino-2-(4-methoxyphenyl)pyrido[2,3-e]-1,2,4-triazolo[4,3-a]pyrazin-1-one (18), tested in an in vitro rat model of cerebral ischemia, proved to be effective in preventing the failure of synaptic activity induced by oxygen and glucose deprivation in the hippocampus. Molecular docking of this new class of hA(3) AR antagonists was carried out to depict their hypothetical binding mode to our refined model of hA(3) receptor.
Assuntos
Antagonistas do Receptor A3 de Adenosina , Compostos Heterocíclicos com 3 Anéis/síntese química , Modelos Moleculares , Pirazinas/síntese química , Piridinas/síntese química , Triazóis/síntese química , Animais , Isquemia Encefálica/fisiopatologia , Isquemia Encefálica/prevenção & controle , Bovinos , Linhagem Celular , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Cricetinae , Cricetulus , AMP Cíclico/metabolismo , Compostos Heterocíclicos com 3 Anéis/química , Compostos Heterocíclicos com 3 Anéis/farmacologia , Hipocampo/efeitos dos fármacos , Hipocampo/fisiopatologia , Humanos , Ligação de Hidrogênio , Técnicas In Vitro , Ligantes , Masculino , Pirazinas/química , Pirazinas/farmacologia , Piridinas/química , Piridinas/farmacologia , Ensaio Radioligante , Ratos , Ratos Wistar , Relação Estrutura-Atividade , Transmissão Sináptica/efeitos dos fármacos , Triazóis/química , Triazóis/farmacologiaRESUMO
The study of novel 2-arylpyrazolo[3,4-c]quinolin-4-(hetero)arylamides, designed as human (h) A(3) adenosine receptor antagonists, is reported. The new derivatives are endowed with nanomolar hA(3) receptor affinity and high selectivity versus hA(1), hA(2A) and hA(2B) receptors. Among the (hetero)aroyl residues introduced on the 4-amino group, the 2-furyl and 4-pyridyl rings turned out to be the most beneficial for hA(3) affinity (K(i)=3.4 and 5.0nM, respectively). An intensive molecular docking study to a rhodopsin-based homology model of the hA(3) receptor was carried out to obtain a 'structure-based pharmacophore model' that proved to be helpful for the interpretation of the observed affinities of the new hA(3) pyrazoloquinoline antagonists.
Assuntos
Antagonistas do Receptor A3 de Adenosina , Quinolinas/síntese química , Quinolinas/farmacologia , Amidas , Simulação por Computador , Humanos , Modelos Moleculares , Ligação Proteica , Rodopsina , Relação Estrutura-AtividadeRESUMO
The study of some 4-substituted-2-aryl-1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives, designed as hA(3) adenosine receptor antagonists, is reported. The new compounds bear on the four-position different acylamino, sulfonylamino, benzylureido and benzyloxy moieties, which have also been combined with a para-methoxy group on the 2-phenyl ring or with a nitro residue at the six-position. Many derivatives show high hA(3) adenosine receptor affinities and selectivities both versus hA(1) and hA(2A) receptors. The observed structure-affinity relationships of this class of antagonists have been exhaustively rationalized using the recently published ligand-based homology modeling (LBHM) approach. The selected 4-bismethanesulfonylamino-2-phenyl-1,2,4-triazolo[4,3-a]quinoxalin-1-one (13), which shows high hA(3) affinity (K(i)=5.5nM) and selectivity versus hA(1), hA(2A) (both selectivity ratios>1800) and hA(2B) (cAMP assay, IC(50)>10,000nM) receptors, was tested in an in vitro rat model of cerebral ischemia, proving to be effective in preventing the failure of synaptic activity, induced by oxygen and glucose deprivation in the hippocampus, and in delaying the occurrence of anoxic depolarization.
Assuntos
Antagonistas do Receptor A3 de Adenosina , Modelos Moleculares , Quinoxalinas/síntese química , Quinoxalinas/farmacologia , Triazóis/síntese química , Triazóis/farmacologia , Animais , Ligação Competitiva , Isquemia Encefálica/metabolismo , Isquemia Encefálica/fisiopatologia , Isquemia Encefálica/prevenção & controle , Bovinos , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Modelos Animais de Doenças , Humanos , Ligação de Hidrogênio , Ligantes , Ligação Proteica , Quinoxalinas/metabolismo , Ratos , Receptor A3 de Adenosina/metabolismo , Receptor A3 de Adenosina/fisiologia , Rodopsina/química , Homologia Estrutural de Proteína , Relação Estrutura-Atividade , Triazóis/metabolismo , Xantinas/metabolismo , Xantinas/farmacologiaRESUMO
This paper reports the synthesis and AMPA, Gly/NMDA, and KA receptor binding affinities of a new set of 1,9-disubstituted-8-chloro-pyrazolo[1,5-c]quinazoline-2-carboxylates 2-34. Binding data show that, in general, compounds 2-34 bind to the AMPA receptor with good affinity and selectivity. In particular, the obtained results indicate that the contemporary presence of a 1,2-dicarboxylic acid moiety and suitable benzo-substituents on the PQZ system is important to gain selective AMPA receptor antagonists. Moreover, this study shows that the presence of a 2-carboxybenzoylamino substituent at position-9 (compounds 33-34) is important for obtaining selective KA receptor antagonists. Some selected compounds were also tested for their functional antagonistic activity at both AMPA and NMDA receptor-ion channels.
Assuntos
Pirazóis/química , Quinazolinas/síntese química , Quinazolinas/farmacologia , Receptores de Ácido Caínico/antagonistas & inibidores , Receptores de Ácido Caínico/metabolismo , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/síntese química , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/farmacologia , Estrutura Molecular , N-Metilaspartato/química , Quinazolinas/química , Relação Estrutura-Atividade , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/químicaRESUMO
The concept of molecular simplification as a drug design strategy to shorten synthetic routes, while keeping or enhancing the biological activity of the lead drug, has been applied to design new classes of human A3 adenosine receptor (AR) antagonists. Over the past decade, we have focused a part of our research on the study of AR antagonists belonging to strictly correlated classes of tricyclic compounds. One of these classes is represented by the 2-aryl-1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives, either 4-amino or 4-oxo-substituted, which were intensively investigated by evaluating the effect of different substituents on the 2-phenyl ring and on the 4-amino group. Using an in silico molecular simplification approach, a new series of easily synthesizable 2-amino/2-oxoquinazoline-4-carboxamido derivatives have been discovered, presenting high affinity and selectivity against human A3 AR.
Assuntos
Antagonistas do Receptor A3 de Adenosina , Modelos Moleculares , Pirimidinas/síntese química , Quinoxalinas/síntese química , Receptor A3 de Adenosina/metabolismo , Triazóis/síntese química , Animais , Sítios de Ligação , Ligação Competitiva , Células CHO , Cricetinae , Cricetulus , AMP Cíclico/metabolismo , Humanos , Pirimidinas/química , Pirimidinas/farmacologia , Quinoxalinas/química , Quinoxalinas/farmacologia , Ensaio Radioligante , Receptor A3 de Adenosina/química , Triazóis/química , Triazóis/farmacologiaRESUMO
This paper reports the study of some 2-arylpyrazolo[3,4-c]quinolin-4-ones, 4-amines, and 4-amino-substituted derivatives designed as human A3 adenosine receptor (AR) antagonists. Most of the herein reported compounds showed a nanomolar affinity toward the hA3 receptor subtype and different degrees of selectivity that resulted to be strictly dependent on the presence and nature of the substituent on the 4-amino group. Bulky and lipophilic acyl groups, as well as the benzylcarbamoyl residue, afforded highly potent and selective hA3 receptor antagonists. The selected 4-diphenylacetylamino-2-phenylpyrazoloquinoline (25) and 4-dibenzoylamino-2-(4-methoxyphenyl)pyrazoloquinoline (36), tested in an in vitro rat model of cerebral ischemia, prevented the irreversible failure of synaptic activity induced by oxygen and glucose deprivation in the hippocampus. The observed structure-affinity relationships of this class of antagonists were also exhaustively rationalized using the recently published ligand-based homology modeling (LBHM) approach.
Assuntos
Antagonistas do Receptor A3 de Adenosina , Benzamidas/síntese química , Modelos Moleculares , Pirazóis/síntese química , Quinolinas/síntese química , Animais , Benzamidas/química , Benzamidas/farmacologia , Isquemia Encefálica/fisiopatologia , Células CHO , Córtex Cerebral/metabolismo , Corpo Estriado/metabolismo , Cricetinae , Cricetulus , AMP Cíclico/biossíntese , Eletrofisiologia , Hipocampo/fisiopatologia , Humanos , Técnicas In Vitro , Ligantes , Masculino , Pirazóis/química , Pirazóis/farmacologia , Quinolinas/química , Quinolinas/farmacologia , Ensaio Radioligante , Ratos , Ratos Wistar , Relação Estrutura-Atividade , Transmissão Sináptica , Testículo/metabolismoRESUMO
In this paper, the study of new 7-chloro-3-hydroxy-1H-quinazoline-2,4-dione derivatives, designed as AMPA and kainate (KA) receptor antagonists, is reported. Some derivatives bear different carboxy-containing alkyl chains on the 3-hydroxy group, while various heterocyclic rings or amide moieties are present at the 6-position of other compounds. Binding data at Gly/NMDA, AMPA, and high-affinity KA receptors showed that the presence of the free 3-hydroxy group is of paramount importance for a good affinity at all three investigated receptors, while introduction of some 6-heterocyclic moieties yielded AMPA-selective antagonists. The most significant result was the finding of the 6-(2-carboxybenzoylamino)-3-hydroxy-1H-quinazolin-2,4-dione 12, which possesses good affinity for high-affinity and low-affinity KA receptors (Ki=0.62 microM and 1.6 microM, respectively), as well as good selectivity. To rationalize the trend of affinities of the reported derivatives, an intensive molecular modeling study was carried out by docking compounds to models of the Gly/NMDA, AMPA, and KA receptors.
Assuntos
Analgésicos/síntese química , Modelos Moleculares , Quinazolinas/síntese química , Receptores de AMPA/antagonistas & inibidores , Receptores de Ácido Caínico/antagonistas & inibidores , Dor Abdominal/induzido quimicamente , Dor Abdominal/tratamento farmacológico , Dor Abdominal/fisiopatologia , Ácido Acético , Analgésicos/química , Analgésicos/farmacologia , Animais , Comportamento Animal/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/fisiologia , Eletrofisiologia , Técnicas In Vitro , Camundongos , Medição da Dor , Limiar da Dor/efeitos dos fármacos , Quinazolinas/química , Quinazolinas/farmacologia , Ensaio Radioligante , Ratos , Receptores de AMPA/química , Receptores de Ácido Caínico/química , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
A structural investigation on some 4-amido-2-phenyl-1,2-dihydro-1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives, designed as human A3 adenosine receptor (hA3 AR) antagonists, is described. In the new derivatives, some acyl residues with different steric bulk were introduced on the 4-amino group, and their combination with the 4-methoxy group on the 2-phenyl moiety, and/or the 6-nitro/6-amino substituent on the fused benzo ring, was also evaluated. Most of the new derivatives were potent and selective hA3 AR antagonists. SAR analysis showed that hindering and lipophilic acyl moieties not only are well tolerated but even ameliorate the hA3 affinity. Interestingly, the 4-methoxy substituent on the appended 2-phenyl moiety, as well as the 6-amino group, always exerted a positive effect, shifting the affinity toward the hA3 receptor subtype. In contrast, the 6-nitro substituent exerted a variable effect. An intensive molecular modeling investigation was performed to rationalize the experimental SAR findings.
Assuntos
Antagonistas do Receptor A3 de Adenosina , Modelos Moleculares , Quinoxalinas/síntese química , Triazóis/síntese química , Animais , Ligação Competitiva , Células CHO , Bovinos , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Cricetinae , Cricetulus , AMP Cíclico/metabolismo , Humanos , Técnicas In Vitro , Ligantes , Membranas , Quinoxalinas/química , Quinoxalinas/farmacologia , Ensaio Radioligante , Relação Estrutura-Atividade , Triazóis/química , Triazóis/farmacologiaRESUMO
A number of 4-oxo-substituted 1,2,4-triazolo[1,5-a]quinoxaline derivatives bearing at position-2 the claimed (hetero)aryl moiety (compounds 1-15) but also a carboxylate group (16-28, 32-36) or a hydrogen atom (29-31) were designed as human A3 (hA3) adenosine receptor (AR) antagonists. This study produced some interesting compounds and among them the 2-(4-methoxyphenyl)-1,2,4-triazolo[1,5-a]quinoxalin-4-one (8), which can be considered one of the most potent and selective hA3 adenosine receptor antagonists reported till now. Moreover, as a new finding, replacement of the classical 2-(hetero)aryl moiety with a 2-carboxylate function (compounds 16-28 and 32-36) maintained good hA3 AR binding activity but, most importantly and interestingly, produced a large increase in hA3 versus hA1 selectivity. A receptor-based SAR analysis provided new interesting insights about the steric and electrostatic requirements that are important for the anchoring of these derivatives at the hA3 receptor recognition site, thus highlighting the versatility of the triazoloquinoxaline scaffold for obtaining potent and selective hA3 AR antagonists.
Assuntos
Antagonistas do Receptor A3 de Adenosina , Modelos Moleculares , Quinoxalinas/síntese química , Receptor A3 de Adenosina/química , Triazóis/síntese química , Motivos de Aminoácidos , Animais , Sítios de Ligação , Bovinos , Córtex Cerebral/metabolismo , Corpo Estriado/metabolismo , Desenho de Fármacos , Humanos , Técnicas In Vitro , Quinoxalinas/química , Quinoxalinas/farmacologia , Ensaio Radioligante , Relação Estrutura-Atividade , Triazóis/química , Triazóis/farmacologiaRESUMO
A new set of 5,6-dihydro-pyrazolo[1,5-c]quinazoline-2-carboxylates (2-18), bearing different substituents (COOEt, Cl, Br, CH(3), and COOH) at position-1, were synthesized in order to investigate the influence of various groups at this specific position on Gly/NMDA receptor affinity and/or selectivity. All the herein reported compounds were evaluated for their binding at the Gly/NMDA, AMPA, and KA receptors. Some selected compounds were also tested for their functional antagonistic activity at both the AMPA and NMDA receptor-ion channels. The results obtained in this study have highlighted that a C-1 lipophilic substituent on the pyrazolo[1,5-c]quinazoline-2-carboxylate core shifts selectivity toward the Gly/NMDA receptor, while a C-1 anionic carboxylate residue is able to increase affinity toward this receptor subtype. In particular, the 2-carboxylic acids 15 and 16, bearing a chlorine atom at position-1, are not only potent (K(i)=0.18 and 0.16muM, respectively), but also highly Gly/NMDA versus AMPA selective (selectivity ratio>500). Furthermore, the 1,2-dicarboxylic acids 13 and 14 are endowed with the highest Gly/NMDA receptor binding activity (K(i)=0.09 and 0.059muM, respectively), among the pyrazoloquinazoline series of derivatives. A molecular modeling study has been carried out to better understand receptor affinity and selectivity of these new pyrazoloquinazoline derivatives.
Assuntos
Modelos Moleculares , Pirazóis , Quinazolinas , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Sítios de Ligação , Ligação Competitiva , Cristalografia por Raios X , Ligação de Hidrogênio , Ligantes , Estrutura Molecular , Pirazóis/síntese química , Pirazóis/farmacologia , Quinazolinas/síntese química , Quinazolinas/farmacologia , Relação Estrutura-AtividadeRESUMO
The synthesis and biological evaluation at the Gly/NMDA, AMPA and Kainate receptors of new oxazolo[4,5-c]quinolin-4-one derivatives are reported. Different substituents were introduced at the 2-position (mercapto, carbonyl and methyl groups) and on the fused benzo ring (chlorine atom(s) and trifluoromethyl group). Among the herein reported compounds, the 2-mercapto-derivatives 1-4 showed the highest Gly/NMDA affinities, comparable to that of 5,7-dichlorokynurenic acid. The most active compound was the 7-chloro-substituted derivative 1 (Ki=0.082 microM) which possesses a Gly/NMDA selectivity of 50- and 500-fold with respect to AMPA and KA receptors, respectively. Functional antagonism studies performed on some selected 2-mercapto compounds, at both AMPA and NMDA receptor-ion channels, assessed the antagonistic properties of these derivatives. SAR studies pointed out the importance of the concurrent presence of electron-rich moieties at both the 2- and 3-positions of the oxazolo[4,5-c]quinolin-4-one framework. In fact, the 3-sp2-nitrogen atom plays a significant role in reinforcing the hydrogen bond that the 4-carbonyl oxygen probably forms with the arginine residue (R523) of the Gly/NMDA receptor site. The presence of 2-substituent able to form a hydrogen bonding interaction was also proved to be important for a good Gly/NMDA receptor affinity.
Assuntos
Antagonistas de Aminoácidos Excitatórios/síntese química , Antagonistas de Aminoácidos Excitatórios/farmacologia , Compostos Heterocíclicos com 3 Anéis/síntese química , Compostos Heterocíclicos com 3 Anéis/farmacologia , Receptores de Glutamato/efeitos dos fármacos , Algoritmos , Animais , Ligação Competitiva/efeitos dos fármacos , Córtex Cerebral/química , Córtex Cerebral/metabolismo , Desenho de Fármacos , Antagonistas de Aminoácidos Excitatórios/química , Compostos Heterocíclicos com 3 Anéis/química , Ligação de Hidrogênio , Concentração Inibidora 50 , Camundongos , Estrutura Molecular , Ratos , Receptores de AMPA/antagonistas & inibidores , Receptores de AMPA/química , Receptores de Glutamato/química , Receptores de Ácido Caínico/antagonistas & inibidores , Receptores de Ácido Caínico/química , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Receptores de N-Metil-D-Aspartato/química , Relação Estrutura-AtividadeRESUMO
Some 2-aryl-8-chloro-1,2,4-triazolo[1,5-a]quinoxaline derivatives 2-18, obtained by introducing different substituents on either the 4-amino moiety (acyl or carbamoyl groups) or the 2-phenyl ring (4-OCH3) of previously reported 8-chloro-2-phenyl-1,2,4-triazolo[1,5-a]quinoxalin-4-amine (1), have been synthesized and tested in radioligand binding assays at bovine A1 and A(2A) and at cloned human A1 and A3 adenosine receptors. The rationally designed 8-chloro-2-(4-methoxy-phenyl)-1,2,4-triazolo[1,5-a]quinoxalin-4-acetylamine (14) can be considered one of the most potent and hA3 versus hA1 selective AR antagonists reported till now. The structure-activity relationships of compounds 2-18 are in agreement with those of previously reported 2-aryl-1,2,4-triazolo[4,3-a]quinoxalines (series A) and 2-arylpyrazolo[3,4-c]quinolines (series B), thus suggesting a similar AR binding mode. In fact, the importance for the A3 receptor-ligand interaction of both a strong acidic NH proton donor and a C=O proton acceptor at position-4, able to engage hydrogen-bonding interactions with specific sites on the A3 AR, has been confirmed. Using our recently published hA3 receptor model, to better elucidate our experimental results, we decided to theoretically depict the putative TM binding motif of the herein reported 1,2,4-triazolo[1,5-a]quinoxaline derivatives on human A3 receptor. Structure-activity relationships have been explained analyzing the three-dimensional structure of the antagonist-receptor models obtained by molecular docking simulation.
Assuntos
Antagonistas de Receptores Purinérgicos P1 , Quinoxalinas/química , Quinoxalinas/farmacologia , Animais , Bovinos , Humanos , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Relação Estrutura-AtividadeRESUMO
In the past few years much effort in our laboratory has been directed toward the study of adenosine receptor antagonists, and recently we focused our attention on 2-aryl-1,2,4-triazolo[4,3-a]quinoxaline-1,4-diones and 2-aryl-1,2,4-triazolo[4,3-a]quinoxalin-4-amino-1-ones, some of which were potent and/or selective A(3) receptor antagonists. In the present paper, a new series of triazoloquinoxaline derivatives is described. Most of the new compounds, biologically evaluated in radioligand binding assays at bovine (b) A(1) and A(2A) and at human (h) A(1) and A(3) adenosine receptors, showed high hA(3) adenosine receptor affinity and selectivity. In particular, 2-(4-nitrophenyl)-1,2,4,5-tetrahydro-1,2,4-triazolo[4,3-a]quinoxaline-1,4-dione (1), also tested at the hA(2A) ARs, shows the best binding profile with a high hA(3) affinity (K(i) = 0.60 nM) and strong selectivity vs hA(1) and vs hA(2A) receptors (both selectivity ratios greater than 16 600). To interpret our experimental results, we decided to theoretically depict the putative transmembrane binding motif of our triazoloquinoxaline analogues on hA(3) receptor. Structure-activity relationships have been explained analyzing the three-dimensional structure of the antagonist-receptor models obtained by molecular docking simulation.