RESUMEN
(S)-CPW399 (2b) is a novel, potent, and subtype-selective AMPA receptor full agonist that, unlike (S)-willardiine and related compounds, in mouse cerebellar granule cells, stimulated an increase in [Ca(2+)](i), and induced neuronal cell death in a time- and concentration-dependent manner. Compound 2b appears to be a weakly desensitizing, full agonist at AMPA receptors and therefore represents a new pharmacological tool to investigate the role of AMPA receptors in excitotoxicity and their molecular mechanisms of desensitization.
Asunto(s)
Alanina/síntesis química , Agonistas de Aminoácidos Excitadores/síntesis química , Pirimidinas/síntesis química , Pirimidinonas/síntesis química , Receptores AMPA/agonistas , Alanina/análogos & derivados , Alanina/farmacología , Animales , Encéfalo/citología , Encéfalo/metabolismo , Muerte Celular/efectos de los fármacos , Línea Celular , Electrofisiología , Agonistas de Aminoácidos Excitadores/farmacología , Técnicas In Vitro , Ligandos , Ratones , Modelos Moleculares , Neuronas/citología , Neuronas/efectos de los fármacos , Oocitos/metabolismo , Pirimidinas/farmacología , Pirimidinonas/farmacología , Ensayo de Unión Radioligante , Ratas , Receptores AMPA/metabolismo , Receptores AMPA/fisiología , Proteínas Recombinantes/metabolismo , Estereoisomerismo , Xenopus laevisRESUMEN
Some members of a series of novel pyrrolo-1,5-benzoxazepines (PBOXs) potently induce apoptosis in a number of human cancerous cell lines including HL-60 cells and the drug-resistant chronic myelogenous leukaemia cell line, K562. The apoptotic induction seems to be independent of the mitochondrial peripheral-type benzodiazepine receptor (PBR), which binds these PBOXs with high affinity, due to a lack of correlation between their affinities for the receptor and their apoptotic potencies and their high apoptotic activity in PBR-deficient cells. PBOX-6, a potent member of the series, induces a transient activation of c-Jun N-terminal kinase (JNK) in a dose-dependent manner, which correlates with induction of apoptosis. Expression of a cytoplasmic inhibitor of the JNK signal transduction pathway, Jip-1, prevents JNK activity and significantly reduces the extent of apoptosis induced by PBOX-6. This demonstrates the requirement for JNK in the cellular response to this apoptotic agent. In addition, PBOX-6 activates caspase-3-like proteases in K562 and HL-60 cells. The caspase-3 inhibitor, Z-Asp-Glu-Val-Asp-fluoromethylketone (z-DEVD-fmk), blocks caspase-3-like protease activity in both cell types but only prevents PBOX-6-induced apoptosis in HL-60 cells, suggesting that the requirement for caspase-3-like proteases in the apoptotic pathway is dependent on the cell type.
Asunto(s)
Apoptosis , Benzazepinas/farmacología , Oxazepinas/farmacología , Pirroles/farmacología , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Células HL-60 , Humanos , Células K562 , FosforilaciónRESUMEN
The human immunodeficiency virus type 1 (HIV-1) nonnucleoside reverse transcriptase (RT) inhibitor pyrrolopyridooxazepinone (PPO) derivative, (+/-)-PPO294, was shown to be active toward wild type and mutated HIV-1 RT and to act synergistically in combination with 3'-azido-3'-deoxythymidine (Campiani, G., Morelli, E., Fabbrini, M., Nacci, V., Greco, G., Novellino, E., Ramunno, A., Maga, G., Spadari, S., Caliendo, G., Bergamini, A., Faggioli, E., Uccella, I., Bolacchi, F., Marini, S., (1999) J. Med. Chem. 42, 4462-4470). The (+/-)-PPO294 racemate was resolved into its pure enantiomers, and the absolute configuration was determined by x-ray analysis. Only one enantiomer, (R)-(-)-PPO464, displayed antiviral activity against both the wild type and the K103N mutant HIV-1 RT and was found to interact exclusively with the reaction intermediate formed by RT complexed with both the DNA and the nucleotide substrates. Being the first compound of its class to display this behavior, (R)-(-)-PPO464 is the representative of a novel generation of nonnucleoside inhibitors. (R)-(-)-PPO464 showed significant synergism when tested in combination with other RT inhibitors and efficiently inhibited viral replication when tested against the laboratory strain HIV-1 IIIB or against either wild type or multidrug-resistant clinical isolates. Pharmacokinetic studies in mice and rats showed a more favorable profile for (R)-(-)-PPO464 than for the corresponding racemate. (R)-(-)-PPO464 was also found to easily cross the blood-brain barrier. The coadministration of the HIV-1 protease inhibitor ritonavir increased the bioavailability of (R)-(-)-PPO464, having little effect on its plasma and brain elimination rates.
Asunto(s)
Azepinas/farmacología , Azepinas/farmacocinética , Transcriptasa Inversa del VIH/metabolismo , Piridinas/farmacología , Piridinas/farmacocinética , Inhibidores de la Transcriptasa Inversa/farmacología , Animales , Antivirales/farmacología , Barrera Hematoencefálica/efectos de los fármacos , Cristalografía por Rayos X , Relación Dosis-Respuesta a Droga , Cinética , Masculino , Ratones , Modelos Químicos , Mutación , Unión Proteica , Ratas , Proteínas Recombinantes/metabolismo , Ritonavir/farmacología , Especificidad por Sustrato , Temperatura , Termodinámica , Factores de Tiempo , Rayos XAsunto(s)
Sistema de Transporte de Aminoácidos X-AG , Ácido Aspártico/síntesis química , Proteínas Portadoras/química , Glutamatos/síntesis química , Sodio/metabolismo , Simportadores , Animales , Ácido Aspártico/química , Ácido Aspártico/metabolismo , Transporte Biológico , Proteínas Portadoras/metabolismo , Corteza Cerebral/metabolismo , Diseño de Fármacos , Transportador 3 de Aminoácidos Excitadores , Proteínas de Transporte de Glutamato en la Membrana Plasmática , Glutamatos/química , Glutamatos/metabolismo , Técnicas In Vitro , Modelos Moleculares , Conformación Molecular , Fármacos Neuroprotectores/síntesis química , Fármacos Neuroprotectores/química , Fármacos Neuroprotectores/metabolismo , Técnicas de Placa-Clamp , Ensayo de Unión Radioligante , Ratas , Relación Estructura-ActividadRESUMEN
Quinoxalinylethylpyridylthioureas (QXPTs) represent a new class of human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse transcriptase (RT) inhibitors (NNRTIs) whose prototype is 6-FQXPT (6). Docking studies based on the three-dimensional structure of RT prompted the synthesis of novel heteroarylethylpyridylthioureas which were tested as anti-HIV agents. Several compounds proved to be potent broad-spectrum enzyme inhibitors and significantly inhibited HIV-1 replication in vitro. Their potency depends on the substituents and the nature of the heterocyclic skeleton linked to the ethyl spacer, and structure-activity relationships are discussed in terms of the possible interaction with the RT binding site. Although the new QXPTs analogues show potent antiviral activity, none of the compounds tested overcome the pharmacokinetic disadvantages inherent to ethylpyridylthioureidic antiviral agents, which in general have very low oral bioavailability. Through an integrated effort involving synthesis, docking studies, and biological and pharmacokinetic evaluation, we investigated the structural dependence of the poor bioavailability and rapid clearance within the thioureidic series of antivirals. Replacing the ethylthioureidic moiety with a hydrazine linker led to a new antiviral lead, offering promising pharmacological and pharmacokinetic properties in terms of antiviral activity and oral bioavailability.
Asunto(s)
Fármacos Anti-VIH/síntesis química , Transcriptasa Inversa del VIH/antagonistas & inhibidores , Piridinas/síntesis química , Quinoxalinas/síntesis química , Inhibidores de la Transcriptasa Inversa/síntesis química , Tiourea/análogos & derivados , Tiourea/síntesis química , Animales , Fármacos Anti-VIH/química , Fármacos Anti-VIH/farmacología , Disponibilidad Biológica , Línea Celular , Didanosina/farmacología , Sinergismo Farmacológico , VIH-1/efectos de los fármacos , Humanos , Ratones , Modelos Moleculares , Piridinas/química , Piridinas/farmacología , Quinoxalinas/química , Quinoxalinas/farmacología , Inhibidores de la Transcriptasa Inversa/química , Inhibidores de la Transcriptasa Inversa/farmacología , Estereoisomerismo , Relación Estructura-Actividad , Tiourea/química , Tiourea/farmacología , Zidovudina/farmacologíaRESUMEN
Expression of the transforming oncogene bcr-abl in chronic myelogenous leukemia (CML) cells is reported to confer resistance against apoptosis induced by many chemotherapeutic agents such as etoposide, ara-C, and staurosporine. In the present study some members of a series of novel pyrrolo-1,5-benzoxazepines potently induce apoptosis, as shown by cell shrinkage, chromatin condensation, DNA fragmentation, and poly(ADP-ribose) polymerase (PARP) cleavage, in three CML cell lines, K562, KYO.1, and LAMA 84. Induction of apoptosis by a representative member of this series, PBOX-6, was not accompanied by either the down-regulation of Bcr-Abl or by the attenuation of its protein tyrosine kinase activity up to 24 h after treatment, when approximately 50% of the cells had undergone apoptosis. These results suggest that down-regulation of Bcr-Abl is not part of the upstream apoptotic death program activated by PBOX-6. By characterizing the mechanism in which this novel agent executes apoptosis, this study has revealed that PBOX-6 caused activation of caspase 3-like proteases in only two of the three CML cell lines. In addition, inhibition of caspase 3-like protease activity using the inhibitor z-DEVD-fmk blocked caspase 3-like protease activity but did not prevent the induction of apoptosis, suggesting that caspase 3-like proteases are not essential in the mechanism by which PBOX-6 induces apoptosis in CML cells. In conclusion, this study demonstrates that PBOX-6 can bypass Bcr-Abl-mediated suppression of apoptosis, suggesting an important potential use of these compounds in the treatment of CML.
Asunto(s)
Antineoplásicos/farmacología , Apoptosis , Proteínas de Fusión bcr-abl , Leucemia Mielógena Crónica BCR-ABL Positiva/patología , Proteínas de Fusión Oncogénica/fisiología , Oxazepinas/farmacología , Pirroles/farmacología , Western Blotting , Caspasa 3 , Caspasas/metabolismo , Regulación hacia Abajo , Resistencia a Antineoplásicos , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Proteínas de Fusión Oncogénica/genética , Fosforilación , Poli(ADP-Ribosa) Polimerasas/metabolismo , Proteínas Tirosina Quinasas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Células Tumorales CultivadasRESUMEN
New heterocyclic derivatives of ethylpyridylthiourea, quinoxalinylethylpyridylthiourea (QXPT) and analogues, inhibited human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) activity and prevented HIV-1 cytopathogenicity in T4 lymphocytes. Several of these novel non-nucleoside RT inhibitors, with a substituted pyrroloquinoxalinone heteroaromatic skeleton, showed inhibitory activity against wild-type RT as well as against mutant RTs containing the single amino acid substitutions L1001, K103N, V106A, Y1811 and Y188L that was much greater than other non-nucleoside inhibitors such as nevirapine. Maximum potency in enzymatic assays was achieved with a fluoropyrroloquinoxaline skeleton linked to the ethylpyridylthiourea moiety (FQXPT). In cell-based assays on different cell lines and on human monocyte-macrophages, 6-FQXPT exhibited EC50 values in the nanomolar range, with a promising selectivity index. Moreover, 6-FQXPT showed synergistic antiviral activity with zidovudine.
Asunto(s)
VIH-1/efectos de los fármacos , Quinoxalinas/síntesis química , Quinoxalinas/farmacología , Inhibidores de la Transcriptasa Inversa/síntesis química , Inhibidores de la Transcriptasa Inversa/farmacología , Tiourea/análogos & derivados , Sustitución de Aminoácidos , Animales , Transcriptasa Inversa del VIH/antagonistas & inhibidores , Transcriptasa Inversa del VIH/genética , VIH-1/enzimología , Humanos , Masculino , Ratones , Ratones Endogámicos , Mutación , Nucleósidos/química , Tiourea/síntesis química , Tiourea/farmacologíaRESUMEN
Some, but not all, of a series of novel pyrrolo-1,5-benzoxazepines (PBOXs) induce apoptosis as shown by cell shrinkage, chromatin condensation, and DNA fragmentation in three human cell lines, HL-60 promyelocytic, Jurkat T lymphoma, and Hut-78 s.c. lymphoma cells. This chemical selectivity, together with the lack of apoptotic activity against rat Leydig cells, argues against a general cell poisoning effect. PBOX-6, a potent member of the series, caused activation of a member of the caspase-3 family of proteases. In addition, the caspase-3-like inhibitor z-DEVD-fmk, but not the caspase-1-like inhibitor z-YVAD-fmk prevented PBOX-6-induced apoptosis, suggesting that caspase 3-like proteases are involved in the mechanism by which PBOX compounds induce apoptosis. The release of cytochrome c into the cytosol in HL-60 cells in response to PBOX-6 suggests that this cellular response may be important in the mechanism by which PBOX-6 induces apoptosis. However, reactive oxygen intermediates do not play a key role in PBOX-6-induced apoptosis because neither the free radical scavenger TEMPO nor the antioxidant N-acetylcysteine had any effect on PBOX-6-induced apoptosis. The apoptotic induction seems independent of the mitochondrial peripheral-type benzodiazepine receptor (PBR) that binds these pyrrolobenzoxazepines with high affinity, due to the lack of correlation between their affinities for the receptor and their apoptotic potencies, their high apoptotic activity in PBR-deficient cells such as Jurkats, and their lack of apoptotic induction in PBR-rich rat Leydig cells. These PBOXs also can overcome nuclear factor-kappaB-mediated resistance to apoptosis. This suggests an important potential use of these compounds in drug-resistant cancers.
Asunto(s)
Apoptosis/efectos de los fármacos , Oxazepinas/farmacología , Pirroles/farmacología , Animales , Western Blotting , Caspasa 3 , Caspasas/análisis , Caspasas/metabolismo , Línea Celular , Cicloheximida/farmacología , Grupo Citocromo c/metabolismo , Citosol/efectos de los fármacos , Citosol/enzimología , Fragmentación del ADN/efectos de los fármacos , Electroforesis , Precursores Enzimáticos/análisis , Precursores Enzimáticos/metabolismo , Células HL-60 , Humanos , Células Jurkat , Hígado/citología , Hígado/efectos de los fármacos , FN-kappa B/genética , FN-kappa B/metabolismo , Estrés Oxidativo/fisiología , Inhibidores de la Síntesis de la Proteína/farmacología , Ensayo de Unión Radioligante , Ratas , Linfocitos T/efectos de los fármacos , Linfocitos T/fisiología , Regulación hacia Arriba/efectos de los fármacosRESUMEN
The synthesis, pharmacological evaluation, and structure-activity relationships (SARs) of a series of novel pyrroloquinoxalines and heteroaromatic-related derivatives are described. The new pyrroloquinoxaline-related ligands were tested in rat cortex, a tissue expressing high density of 5-HT(3) receptors, and on NG108-15 cells and exhibited IC(50) values in the low nanomolar or subnanomolar range, as measured by the inhibition of [(3)H]zacopride binding. The SAR studies detailed herein delineated a number of structural features required for improving affinity. Some of the ligands were employed as "molecular yardsticks" to probe the spatial dimensions of the lipophilic pockets L1, L2, and L3 in the 5-HT(3) receptor cleft, while the 7-OH pyrroloquinoxaline analogue was designed to investigate hydrogen bonding with a putative receptor site H1 possibly interacting with the serotonin hydroxy group. The most active pyrroloquinoxaline derivatives showed subnanomolar affinity for the 5-HT(3) receptor. In functional studies ([(14)C]guanidinium accumulation test in NG108-15 hybrid cells, in vitro) most of the tested compounds showed clear-cut 5-HT(3) agonist properties, while some others were found to be partial agonists. Several heteroaromatic systems, bearing N-substituted piperazine moieties, have been explored with respect to 5-HT(3) affinity, and novel structural leads for the development of potent and selective central 5-HT(3) receptor agonists have been identified. Preliminary pharmacokinetic studies indicate that these compounds easily cross the blood-brain barrier (BBB) after systemic administration with a brain/plasma ratio between 2 and 20, unless they bear a highly hydrophilic group on the piperazine ring. None of the tested compounds showed in vivo anxiolytic-like activity, but potential analgesic-like properties have been possibly disclosed for this new class of 5-HT(3) receptor agonists.
Asunto(s)
Pirroles/síntesis química , Quinoxalinas/síntesis química , Receptores de Serotonina/efectos de los fármacos , Agonistas de Receptores de Serotonina/síntesis química , Animales , Ansiolíticos/síntesis química , Ansiolíticos/química , Ansiolíticos/farmacocinética , Ansiolíticos/farmacología , Antiinflamatorios no Esteroideos/síntesis química , Antiinflamatorios no Esteroideos/química , Antiinflamatorios no Esteroideos/farmacocinética , Antiinflamatorios no Esteroideos/farmacología , Barrera Hematoencefálica , Encéfalo/metabolismo , Guanidina/metabolismo , Cobayas , Células Híbridas , Técnicas In Vitro , Ligandos , Masculino , Pirroles/química , Pirroles/farmacocinética , Pirroles/farmacología , Quinoxalinas/química , Quinoxalinas/farmacocinética , Quinoxalinas/farmacología , Ratas , Ratas Sprague-Dawley , Receptores de Serotonina 5-HT3 , Antagonistas de la Serotonina/síntesis química , Antagonistas de la Serotonina/química , Antagonistas de la Serotonina/farmacocinética , Antagonistas de la Serotonina/farmacología , Agonistas de Receptores de Serotonina/química , Agonistas de Receptores de Serotonina/farmacocinética , Agonistas de Receptores de Serotonina/farmacología , Relación Estructura-ActividadRESUMEN
Pyrrolobenzoxazepinone (PBO) derivatives represent a new class of human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse transcriptase (RT) inhibitors (NNRTs) whose prototype is (+/-)-6-ethyl-6-phenylpyrrolo[2,1-d][1,5]benzoxazepin-7(6H)- one (6). Docking studies based on the three-dimensional structure of RT prompted the synthesis and biological evaluation of novel derivatives and analogues of 6 featuring a meta-substituted phenyl or a 2-thienyl ring at C-6 and a pyridine system in place of the fused-benzene ring to yield pyrrolopyridooxazepinones (PPOs). Compared with the lead 6 and nevirapine, several of the synthesized compounds (PBOs 13a-d and PPOs 13i-k) displayed higher inhibitory activity against wild-type RT and clinically relevant mutant RTs containing the single amino acid substitutions L100I, K103N, V106A, Y181I, and Y188L. The most potent inhibitors were further evaluated for in vitro antiviral activity on lymphocytes and monocyte-macrophages, for cytotoxicity on a panel of cell lines, and for potential synergistic antiviral activity with AZT. Pharmacokinetic studies performed on 13b, 13c, and 13i showed that these compounds achieve high concentrations in the brain. The results of the biological and pharmacokinetic experiments suggest a potential clinical utility of analogues such as 13b-d, 13i, and 13j, in combination with nucleoside RT inhibitors, against strains of HIV-1 bearing those mutations that confer resistance to known NNRTI.
Asunto(s)
Fármacos Anti-VIH/síntesis química , Azepinas/síntesis química , Transcriptasa Inversa del VIH/antagonistas & inhibidores , VIH-1/efectos de los fármacos , Inhibidores de la Transcriptasa Inversa/síntesis química , Animales , Fármacos Anti-VIH/química , Fármacos Anti-VIH/farmacología , Fármacos Anti-VIH/toxicidad , Azepinas/química , Azepinas/farmacología , Azepinas/toxicidad , Línea Celular , Diseño de Fármacos , Sinergismo Farmacológico , Técnica del Anticuerpo Fluorescente , Humanos , Ratones , Modelos Moleculares , Inhibidores de la Transcriptasa Inversa/química , Inhibidores de la Transcriptasa Inversa/farmacología , Inhibidores de la Transcriptasa Inversa/toxicidad , Relación Estructura-Actividad , Zidovudina/farmacologíaRESUMEN
A series of thiazolothiazepines were prepared and tested against purified human immunodeficiency virus type-1 integrase (HIV-1 IN) and viral replication. Structure-activity studies reveal that the compounds possessing the pentatomic moiety SC(O)CNC(O) with two carbonyl groups are in general more potent against purified IN than those containing only one carbonyl group. Substitution with electron-donating or -withdrawing groups did not enhance nor abolish potency against purified IN. By contrast, compounds with a naphthalene ring system showed enhanced potency, suggesting that a hydrophobic pocket in the IN active site might accommodate an aromatic system rather than a halogen. The position of sulfur in the thiazole ring appears important for potency against IN, as its replacement with an oxygen or carbon abolished activity. Further extension of the thiazole ring diminished potency. Compounds 1, 19, and 20 showed antiviral activity and inhibited IN within similar concentrations. These compounds inhibited IN when Mn(2+) or Mg(2+) was used as cofactor. None of these compounds showed detectable activities against HIV-1 reverse transcriptase, protease, virus attachment, or nucleocapsid protein zinc fingers. Therefore, thiazolothiazepines are potentially important lead compounds for development as inhibitors of IN and HIV replication.
Asunto(s)
Inhibidores de Integrasa VIH/síntesis química , VIH-1 , Tiazepinas/síntesis química , Tiazoles/síntesis química , Tiazolidinedionas , Adhesión Celular/efectos de los fármacos , Línea Celular , Inhibidores de Integrasa VIH/química , Inhibidores de Integrasa VIH/farmacología , Inhibidores de la Proteasa del VIH/síntesis química , Inhibidores de la Proteasa del VIH/química , Inhibidores de la Proteasa del VIH/farmacología , Magnesio/química , Manganeso/química , Proteínas de la Nucleocápside/química , Inhibidores de la Transcriptasa Inversa/síntesis química , Inhibidores de la Transcriptasa Inversa/química , Inhibidores de la Transcriptasa Inversa/farmacología , Relación Estructura-Actividad , Tiazepinas/química , Tiazepinas/farmacología , Tiazoles/química , Tiazoles/farmacología , Replicación Viral/efectos de los fármacos , Dedos de Zinc/efectos de los fármacosRESUMEN
The development of a synthetic approach to the novel pyrrolo[2, 1-b][1,3]benzothiazepine and its derivatives and their biological evaluation as potential antipsychotic drugs are described. In binding studies these compounds proved to be potent 5-HT2, D2, and D3 receptor ligands. The more potent benzothiazepine (+/-)-3b was resolved into its enantiomers by using HPLC techniques. In vitro testing confirmed that (-)-3b is a more potent D2 receptor ligand, maintaining high affinity for 5-HT2 receptors. In contrast, the (+)-3b enantiomer presents a 35 times higher affinity for 5-HT2 than for dopamine D2 receptors with a similar dopamine D1 receptor affinity to that of (-)-3b. Overall, (+)-3b shows an "atypical" neuroleptic binding profile, while (-)-3b has a more "classical" profile. Furthermore pharmacological and biochemical testing displayed that the novel benzothiazepine (+/-)-3b is able to increase the extracellular levels of dopamine in the rat striatum and causes a dose-related suppression of apomorphine-induced locomotor activity. At low doses (+/-)-3b does not induce catalepsy, showing atypical antipsychotic properties similar to those of olanzapine. These heterocyclic compouds represent new leads for the development of novel antipsychotic drugs with atypical properties.
Asunto(s)
Antipsicóticos/síntesis química , Antagonistas de Dopamina/síntesis química , Pirroles/síntesis química , Antagonistas de la Serotonina/síntesis química , Tiazepinas/síntesis química , Ácido 3,4-Dihidroxifenilacético/metabolismo , Animales , Antipsicóticos/química , Antipsicóticos/metabolismo , Antipsicóticos/farmacología , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Catalepsia/inducido químicamente , Dopamina/metabolismo , Antagonistas de Dopamina/química , Antagonistas de Dopamina/metabolismo , Antagonistas de Dopamina/farmacología , Relación Dosis-Respuesta a Droga , Masculino , Actividad Motora/efectos de los fármacos , Pirroles/química , Pirroles/metabolismo , Pirroles/farmacología , Ratas , Receptores de Dopamina D1/metabolismo , Receptores de Dopamina D2/metabolismo , Receptores de Dopamina D3 , Receptores de Serotonina/metabolismo , Antagonistas de la Serotonina/química , Antagonistas de la Serotonina/metabolismo , Antagonistas de la Serotonina/farmacología , Estereoisomerismo , Relación Estructura-Actividad , Tiazepinas/química , Tiazepinas/metabolismo , Tiazepinas/farmacologíaRESUMEN
Three novel peripheral-type benzodiazepine binding site (PBBS) ligands, NF 182, 213 and 262, along with the classically used PBBS ligands, PK 11195 and Ro5-4864, were found to inhibit, at micromolar concentrations and in dose-dependent manner, the proliferation of rat C6 glioma and human 1321N1 astrocytoma, without being cytotoxic. This antiproliferative effect is mediated by arrest in the G1 phase of the cell cycle and does not appear to be mediated by a specific interaction of these ligands with the peripheral-type benzodiazepine binding site.
Asunto(s)
Benzodiazepinas/metabolismo , División Celular/efectos de los fármacos , Oxazepinas/metabolismo , Oxazepinas/farmacología , Animales , Benzodiazepinonas/metabolismo , Benzodiazepinonas/farmacología , Sitios de Unión , Línea Celular , Humanos , Isoquinolinas/metabolismo , Isoquinolinas/farmacología , Cinética , Ligandos , RatasRESUMEN
Based upon modeling results obtained using the crystal structure of huperzine A in complex with acetylcholinesterase (AChE), two novel analogues of this potent AChE inhibitor were designed with phenol or catechol rings replacing the pyridone ring. From the modeling studies, the catechol analogue appeared capable of replacing one of the crystallographic waters bridging huperzine with Tyr 130 and Glu 199 of AChE. The synthesis of these materials by use of a palladium catalyzed bicycloannulation strategy is detailed together with the results of AChE inhibition assays.
Asunto(s)
Inhibidores de la Colinesterasa/síntesis química , Sesquiterpenos/síntesis química , Alcaloides , Animales , Catálisis , Catecoles/síntesis química , Catecoles/farmacología , Bovinos , Inhibidores de la Colinesterasa/farmacología , Cristalografía por Rayos X , Enlace de Hidrógeno , Modelos Moleculares , Paladio , Fenoles/síntesis química , Fenoles/farmacología , Piridonas/química , Sesquiterpenos/farmacología , Relación Estructura-ActividadRESUMEN
The synthesis and the biological evaluation of a series of novel pyrroloquinoxaline derivatives are described. In binding studies several compounds proved to be potent and selective 5-HT3 receptor ligands. The most active pyrroloquinoxalines, 11d and 11e, showed a subnanomolar affinity for 5-HT3 receptor and were able to functionally discriminate the central and peripheral 5-HT3 receptor, being agonists and antagonists, respectively. In functional studies ([14C]-guanidinium accumulation test in NG 108-15 cells, in vitro) most of the synthesized compounds showed clear-cut 5-HT3 agonist properties. In in vivo studies on the von Bezold-Jarisch reflex test (a peripheral interaction model) the behavior of the tested compounds ranged from agonist to antagonist, while clear agonist properties were obtained with 12a on cortical acetylcholine release in freely moving rats. Pharmacokinetic studies with 11e and 12c indicate that the compounds easily cross the blood-brain barrier (BBB) after systemic administration with a brain/plasma ratio of 17.5 and 37.5, respectively. Thus compounds 11e and 12c represent the most potent central 5-HT3 agonists identified to date that are able to cross the blood-brain barrier.
Asunto(s)
Quinoxalinas/farmacología , Receptores de Serotonina/efectos de los fármacos , Agonistas de Receptores de Serotonina/farmacología , Animales , Barrera Hematoencefálica , Línea Celular , Corteza Cerebral/efectos de los fármacos , Corteza Cerebral/metabolismo , Células Híbridas , Espectroscopía de Resonancia Magnética , Masculino , Ratones , Quinoxalinas/química , Quinoxalinas/farmacocinética , Ratas , Ratas Sprague-Dawley , Receptores de Serotonina 5-HT3 , Reflejo/efectos de los fármacos , Agonistas de Receptores de Serotonina/química , Agonistas de Receptores de Serotonina/farmacocinética , Espectrofotometría Infrarroja , Relación Estructura-ActividadRESUMEN
A series of 26 pyrrolo[2,1-c][1,4]benzothiazines, which have been already synthesized and reported to show calcium antagonist activity in both radioligand-binding assays and functional studies, were investigated using the comparative molecular field analysis (CoMFA) paradigm. Due to the lack of experimental structural data on these derivatives, the minimum energy conformers obtained by molecular mechanics calculations were used in the subsequent study. Structures were aligned following an alignment criterion based on the pharmacophoric groups of the studied compounds. The predictive ability of the CoMFA model was evaluated using a test set consisting of three representative compounds. The best 3D-quantitative structure-activity relationship model found yields significant cross-validated, conventional, and predictive r2 values equal to 0.703, 0.970, and 0.865, respectively, the average absolute error of predictions being 0.26 log unit. The predictive capability of this model was also tested on a further test set of molecules consisting of diltiazem and nine pyrrolo[2,1-d][1,5]benzothiazepines endowed with calcium antagonist activity. The accurate results obtained also in this case revealed the robustness of the model. On the basis of the same alignment, the structural moieties of the studied calcium entry blockers which are thought to contribute to the biological activity were identified, and a possible receptor-binding site for all these compounds is presented taking into account the information derived from the analysis of the steric and electrostatic CoMFA contour maps.
Asunto(s)
Bloqueadores de los Canales de Calcio/química , Diltiazem/química , Modelos Moleculares , Tiazinas/química , Animales , Bloqueadores de los Canales de Calcio/metabolismo , Corteza Cerebral/metabolismo , Diltiazem/metabolismo , Nitrendipino/metabolismo , Ratas , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
The "peripheral-type" benzodiazepine receptor (PBR) has been reported to play a role in many biological processes. We have synthesized and tested a novel series of PBR ligands based on a pyrrolobenzoxazepine skeleton, in order to provide new receptor ligands. Several of these new compounds proved to be high affinity and selective ligands for PBR, and benzoxazepines 17f and 17j were found to be the most potent ligands for this receptor to have been identified to date. The SAR and the molecular modeling studies detailed herein delineated a number of structural features required for improving affinity. Some of the ligands were employed as "molecular yardsticks" to probe the spatial dimensions of the lipophilic pockets L1 and L3 in the PBR cleft and to determine the effect of occupation of L1 and L3 with respect to affinity, while other C-7 modified analogues provided information specifically on the hydrogen bonding with a putative receptor site H1. The new pyrrolobenzoxazepines were tested in rat cortex, a tissue expressing high density of mitochondrial PBR, and exhibited IC50 and Ki values in the low nanomolar or subnanomolar range, as measured by the displacement of [3H]PK 11195 binding. A subset of the highest affinity ligands was also found to have high affinities for [3H]PK 11195 and [3H]Ro 5-4864 binding in rat adrenal mitochondria. All the ligands in this subset are stimulators of steroidogenesis having similar potency and extent of stimulation as PK 11195 and Ro 5-4864 of steroidogenesis in the mouse Y-1 adrenocortical cell line.
Asunto(s)
Receptores de GABA-A/metabolismo , Animales , Benzodiazepinonas/metabolismo , Sitios de Unión , Corteza Cerebral/metabolismo , Isoquinolinas/metabolismo , Ligandos , Ratones , Ratas , Ratas Wistar , Relación Estructura-ActividadRESUMEN
The synthesis and cardiovascular characterization of a series of novel pyrrolo[2,1-d][1,5]-benzothiazepine derivatives (54-68) are described. Selective peripheral-type benzodiazepine receptor (PBR) ligands, such as PK 11195 and Ro 5-4864, have recently been found to possess low but significant inhibitory activity of L-type calcium channels, and this property is implicated in the cardiovascular effects observed with these compounds. In functional studies both PK 11195 (1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxa mide) and Ro 5-4864 (4'-chlorodiazepam) did not display selectivity between cardiac and vascular tissue. Therefore, several 7-(acyloxy)-6-arylpyrrolo[2,1-d][1,5]benzothiazepines, potent and selective peripheral-type benzodiazepine receptor ligands recently developed by us (3, 7-20), were subjected to calcium channel receptor binding assay. Some of these compounds showed an unexpected potency in displacing the binding of [3H]nitrendipine from L-type calcium channels, much higher than that reported for PK 11195 and Ro 5-4864 and equal to or higher than that of reference calcium antagonists such as verapamil and (+)-cis-diltiazem. Specifically, in rat cortex homogenate, our prototypic PBR ligand 7-acetoxy-6-(p-methoxyphenyl)pyrrolo[2,1-d][1,5]benzothiazepine (3) showed an IC50 equal to 0.13 nM for inhibition of [3H]nitrendipine binding. Furthermore, in functional studies this compound displayed a clear-cut selectivity for cardiac over vascular tissue. Comparison of calcium antagonist activity on guinea pig aorta strips with the negative inotropic activity, determined by using isolated guinea pig left atria, revealed that 3 displayed higher selectivity than the reference (+)-cis-diltiazem. Thus, the pyrrolobenzothiazepine 3 might represent a new tool for characterizing the relationship between the PBR and cardiac function. Furthermore, we have also investigated the structural dependence of binding to PBR and L-type calcium channels, and this study allowed us to identify a new class of potent calcium channel blockers selective for cardiac over vascular tissue, with no affinity for PBR. A number of structure-activity relationship trends have been identified, and a possible explanation is advanced in order to account for the observed differences in selectivity. Three structural features, namely, (i) the saturation of the C(6)-C(7) double bond, with a consequent higher molecular flexibility, (ii) the presence of a substituent in the benzofused ring, and (iii) a basic side chain at C-10 of the pyrrolobenzothiazepine ring system, were found to be responsible for potent L-type calcium channel antagonism and clear-cut selectivity for cardiac over vascular tissue. Among the synthesized compounds the pyrrolobenzothiazepine 62 was found to be the most promising selective calcium channel blocker. Additionally, the molecular structure determination of the key intermediate 48 by X-ray diffraction, molecular modeling, and NMR analysis is reported.
Asunto(s)
Bloqueadores de los Canales de Calcio/síntesis química , Canales de Calcio/metabolismo , Sistema Cardiovascular/efectos de los fármacos , Pirroles/síntesis química , Receptores de GABA-A/metabolismo , Tiazepinas/síntesis química , Animales , Función Atrial , Unión Competitiva , Bloqueadores de los Canales de Calcio/metabolismo , Bloqueadores de los Canales de Calcio/farmacología , Corteza Cerebral/metabolismo , Depresión Química , Femenino , Cobayas , Frecuencia Cardíaca/efectos de los fármacos , Masculino , Modelos Moleculares , Contracción Miocárdica/efectos de los fármacos , Miocardio/metabolismo , Pirroles/metabolismo , Pirroles/farmacología , Ratas , Ratas Sprague-Dawley , Relación Estructura-Actividad , Tiazepinas/metabolismo , Tiazepinas/farmacologíaRESUMEN
Two novel classes of pyrrolobenzothiazepinones and pyrrolobenzoxazepinones were investigated as potential anti-AIDS drugs. These compounds were found to inhibit HIV-1 reverse transcriptase (RT) enzyme in vitro and to prevent HIV-1 cytopathogenicity in T4 lymphocytes, without appreciable activity on HIV-2 cytopathic effects, and against HBV as well as calfthymus DNA alpha-polymerase. Their potency is influenced by substituents at position 6 and on the fused aromatic ring. Specifically, small lipophilic substituents at C-6 were preferred, whereas substitutions on the benzo-fused ring were found to be detrimental to activity, with respect to the unsubstituted compounds. Modification of the pie-system at C-6 is well tolerated, although the replacement of the benzo-fused with a [2,3]naphtho-fused ring leads to a less active compound. Maximum potency and specificity is achieved with a phenyl and an ethyl group at position 6 of the pyrrolobenzoxazepinone system. In the enzymatic assay the oxazepinone derivative (+/-)-6-ethyl-6-phenylpyrrolo[2,1-d][1,5] benzoxazepin-7(6H)-one 16e (IC50 = 0.25 microM) was found to be more potent than nevirapine (IC50 = 0.5 microM), tested in the same experimental conditions using rC.dG as a template-primer. In cell culture assay benzoxazepine 16e was active against HIV-1, both wild type and AZT-sensitive, and HIV-1 (IIIB) strains, but not against HIV-2. In enzyme assay although 16e inhibited HIV-1 RT, it was inactive against the nevirapine-resistant recombinant RT Y181C at 50 microM. Molecular modeling studies suggest that these derivatives present a 3D pharmacophoric arrangement similar to that of other non-nucleoside inhibitors such as nevirapine.
Asunto(s)
Antivirales/farmacología , VIH-1/efectos de los fármacos , Oxazepinas/farmacología , ADN Polimerasa Dirigida por ARN/efectos de los fármacos , Inhibidores de la Transcriptasa Inversa/farmacología , Antivirales/síntesis química , Línea Celular , Transcriptasa Inversa del VIH , Humanos , Modelos Moleculares , Estructura Molecular , Oxazepinas/síntesis química , ADN Polimerasa Dirigida por ARN/metabolismo , Inhibidores de la Transcriptasa Inversa/síntesis química , Relación Estructura-Actividad , Tiazepinas/síntesis química , Tiazepinas/farmacologíaRESUMEN
The 7-(acyloxy)-6-arylpyrrolo[2,1-d][1,5]benzothiazepine derivatives have been recently proposed as a new class of ligands specific for the mitochondrial benzodiazepine receptor (Fiorini et al. J. Med. Chem. 1994, 37, 1427-1438) (Greco et al. J. Med. Chem. 1994, 37, 4100-4108). In this paper we report the X-ray crystallographic structures of three potent (1-3) and two inactive (4 and 5) previously described benzothiazepines, as well as binding affinity constants for two newly assayed analogs in which the acyloxy side chain was replaced by a methoxy group (6) or removed (7). Structure-affinity relationships and molecular mechanics calculations performed using crystal structures as references have led to a revised 3D pharmacophore model accounting for all the data available up until now. Interestingly, the hypothetical receptor-bound conformations of 1-3 display a considerable degree of similarity with their crystal geometries. Additional calculations have confirmed that the poor affinities of benzothiazepines bearing an aroyloxy group (4 and 5) should be ascribed to the steric and/or electronic features of the side chain aryl moieties rather than to unfavorable conformational properties.