RESUMO
This paper describes the synthesis and the physico-chemical characterization of cationic peptides (CPs) for possible application as non-viral gene delivery systems. Particularly, the production of cationic liposomes and micelle solutions was considered. Liposomes were prepared by REV-phase and extrusion presenting an average diameter reflecting the pore size of the membrane used for the extrusion. After DNA complexation the mean diameter of complexes decreased by increasing the number of positive charges. The non-complexed liposome preparations showed a net positive zeta potential comprised between 17.8-30 mV. After adding Defibrotide (DFT) to liposomes (at a 1:4 +/- molar ratio) the zeta potential fell down to a net negative value indicating the formation of the ionic complex. Concerning micelles, before complexation it was not possible to measure their size by PCS. However, after DFT complexation the size of complexes highly increased. In addition, as previously seen for liposomes, before complexation, the five CPs solutions showed a positive zeta potential ranging from 10-17.8 mV, while after addition of DFT the zeta potential fell to negative values. Concerning toxicity studies, in general CP-liposomes displayed a lower toxicity towards K562 cells as compared to the corresponding CP-solution. Taking into account these results, the studied CPs could be efficiently used to obtain both cationic liposomes and micelles. Moreover they are able to complex DNA with different interaction strength, depending on the type of peptide-based cationic molecule used.
Assuntos
DNA/administração & dosagem , Técnicas de Transferência de Genes , Peptídeos/administração & dosagem , DNA/química , Sistemas de Liberação de Medicamentos , Terapia Genética , Humanos , Células K562 , Lipossomos , Micelas , Peptídeos/síntese química , Polidesoxirribonucleotídeos/administração & dosagem , Polidesoxirribonucleotídeos/químicaRESUMO
Here we report the synthesis and biological activities of new tripeptidic-based vinyl ester derivative proteasome inhibitors. Starting from Hmb-Val-Ser-Leu-VE prototype, we investigated P2 position and N-terminal substitution. The more effective inhibitors of the series showed remarkable inhibition and selectivity for the trypsin-like (beta2) subunit and were revealed to be specific for the proteasome. In vitro metabolic stability studies of the new vinyl ester analogues are also reported here.
Assuntos
Oligopeptídeos/síntese química , Oligopeptídeos/farmacologia , Inibidores de Proteases/síntese química , Inibidores de Proteases/farmacologia , Inibidores de Proteassoma , Avaliação Pré-Clínica de Medicamentos , Espectroscopia de Ressonância Magnética , Sensibilidade e EspecificidadeRESUMO
We describe the synthesis and activities of a series of pseudopeptides containing an N-aryl-N'-hydroxyalkyl hydrazide core structure to inhibit human immunodeficiency virus protease and viral replication. Of the series, compound Hmb-Leu-N(Bzl)-N(CH2-CH-OH)-rPro-Boc (24) displayed the greatest inhibitory potency (IC50 < 1 microM) and exhibited enzymatic resistance and stability in vitro.
Assuntos
Inibidores da Protease de HIV/síntese química , Inibidores da Protease de HIV/farmacologia , HIV-1/efeitos dos fármacos , Hidrazinas/síntese química , Peptídeos/síntese química , Peptídeos/farmacologia , Infecções por HIV/tratamento farmacológico , Inibidores da Protease de HIV/química , HIV-1/enzimologia , HIV-1/fisiologia , Humanos , Hidrazinas/química , Hidrazinas/farmacologia , Concentração Inibidora 50 , Espectroscopia de Ressonância Magnética , Peptídeos/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Relação Estrutura-Atividade , Replicação Viral/efeitos dos fármacosRESUMO
H-Cys-Leu-Gly-Gly-Leu-Leu-Thr-Met-Val-OH (CLG) peptide is an EBV subdominant epitope that represents the target of HLA-A2 restricted CTL responses. The CLG peptide has low affinity for HLA-A2 and does not produce stable complexes, both factors that determine weak CTL responses. In contrast, the [Tyr(1), Ala(3)]CLG (YLA) analogue showed high affinity for HLA-A2 molecules and efficiently stimulated CLG-specific CTL precursors. Nevertheless, this modified epitope showed low enzymatic stability. To further improve the immunotherapeutical potential of this "improved epitope", we have synthesized and tested YLA analogues containing different modifications next to the scissile peptide bond. Among the analogues we found three peptides, with higher enzymatic resistance, that efficiently stimulate CTL responses. These peptides may be used for EBV-specific immunotherapies.
Assuntos
Antígenos Virais/química , Herpesvirus Humano 4/química , Neoplasias/imunologia , Oligopeptídeos/síntese química , Fragmentos de Peptídeos/síntese química , Linhagem Celular , Epitopos , Técnica Indireta de Fluorescência para Anticorpo , Antígeno HLA-A2/metabolismo , Humanos , Hidrólise , Neoplasias/virologia , Oligopeptídeos/química , Oligopeptídeos/metabolismo , Oligopeptídeos/farmacologia , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/metabolismo , Fragmentos de Peptídeos/farmacologia , Ligação Proteica , Linfócitos T Citotóxicos/citologiaRESUMO
Two series of peptidomimetics containing an N-hydroxyamino acid core structure were prepared by mixed solution solid-phase synthesis and tested for inhibitory activity against the human immunodeficiency virus (HIV-1) protease (Pr) and the virus in cell culture. In general, N-hydroxy Gly containing pseudopeptides displayed modest HIV Pr inhibition (IC50 > or = 930 nM). In the N-hydroxy Phe derivatives, Fmoc-Phe-psi[CO-N(OH)]-Phe-Pro-NHtBu was the best inhibitor of the series (IC50 = 144nM) showing satisfactory inhibition of HIV replication in cell culture (ED50 = 98 nM) and remarkable stability against cell culture and plasma enzymes.
Assuntos
Inibidores da Protease de HIV/síntese química , Inibidores da Protease de HIV/farmacologia , HIV-1/efeitos dos fármacos , HIV-1/enzimologia , Células Cultivadas , Cromatografia Líquida de Alta Pressão , Humanos , Ácidos Hidroxâmicos/síntese química , Ácidos Hidroxâmicos/farmacologia , CinéticaRESUMO
Single amino acid substitutions at TCR contacts may transform a natural peptide Ag in CTL ligands with partial agonist, antagonist, or null activity. We obtained peptide variants by changing nonanchor amino acid residues involved in MHC class I binding. These peptides were derived from a subdominant HLA-A2-presented, latent membrane protein 2-derived epitope expressed in EBV-infected cells and in EBV-associated tumors. We found that small structural changes produced ligands with vastly different activities. In particular, the variants that associated more stably to HLA-A2/molecules did not activate any CTL function, behaving as null ligands. Interestingly, T cell stimulations performed with the combination of null ligands and the natural epitope produced significantly higher specific CTL reactivation than reactivation of CTLs induced by the wild-type epitope alone. In addition, these particular variants activated memory CTL responses in the presence of concentrations of natural epitope that per se did not induce T cell responses. We show here that null ligands increased ZAP-70 tyrosine kinase activation induced by the natural epitope. Our results demonstrate for the first time that particular peptide variants, apparently behaving as null ligands, interact with the TCR, showing a supra-agonist activity. These variant peptides did not affect the effector T cell functions activated by the natural epitope. Supra-agonist peptides represent the counterpart of antagonists and may have important applications in the development of therapeutic peptides.
Assuntos
Adjuvantes Imunológicos/agonistas , Adjuvantes Imunológicos/fisiologia , Citotoxicidade Imunológica/imunologia , Memória Imunológica/imunologia , Ativação Linfocitária/imunologia , Oligopeptídeos/agonistas , Oligopeptídeos/fisiologia , Linfócitos T Citotóxicos/imunologia , Adjuvantes Imunológicos/metabolismo , Células Cultivadas , Relação Dose-Resposta Imunológica , Epitopos de Linfócito T/fisiologia , Antígeno HLA-A2/metabolismo , Herpesvirus Humano 4/imunologia , Humanos , Oligopeptídeos/imunologia , Oligopeptídeos/metabolismo , Proteínas Tirosina Quinases/metabolismo , Transdução de Sinais/imunologia , Células Tumorais Cultivadas , Regulação para Cima/imunologia , Proteínas da Matriz Viral/agonistas , Proteínas da Matriz Viral/imunologia , Proteínas da Matriz Viral/metabolismo , Proteína-Tirosina Quinase ZAP-70RESUMO
A series of secondary and tertiary pyridyl amides as potential central nicotinic acetylcholine receptors (nAChRs) ligands were prepared. Amides displayed negligible or very low affinity, whereas two amines achieved by reduction of corresponding secondary amides, showed affinity in the nanomolar range for nAChRs.
Assuntos
Aminopiridinas/síntese química , Aminopiridinas/metabolismo , Sistema Nervoso Central/metabolismo , Receptores Nicotínicos/metabolismo , Animais , Sistema Nervoso Central/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Fenômenos Químicos , Físico-Química , Técnicas In Vitro , Masculino , Nicotina/metabolismo , Agonistas Nicotínicos/metabolismo , Ratos , Ratos Wistar , Receptores Nicotínicos/efeitos dos fármacos , Relação Estrutura-AtividadeRESUMO
A series of HIV-1 protease inhibitors based on the lead compound Pc (IC50 = 165 nmol/l) with structural modifications at P1/P1' substituents or with a lengthening at its core unit were synthesized from amino acid starting materials. All analogues were less active than Pc against the protease.
Assuntos
Alcanos/síntese química , Inibidores da Protease de HIV/síntese química , Alcanos/farmacologia , Células Cultivadas , Fenômenos Químicos , Físico-Química , Cromatografia Líquida de Alta Pressão , Inibidores da Protease de HIV/farmacologia , HIV-1/efeitos dos fármacos , Humanos , Espectrometria de Massas , Rotação Ocular , Relação Estrutura-AtividadeRESUMO
The latent membrane protein 2 (LMP2) is expressed in EBV-associated tumours. LMP2 is a target of HLA-A2 restricted EBV-specific CTL responses and consequently it may represent a good target for specific CTL-based immunotherapies. However, the efficacy of such therapy is limited by the poor immunogenicity of the protein that induces weak cytotoxic T lymphocyte (CTL) responses directed against the CLGGLLTMV (CLG) epitope. Indeed, the CLG peptide presents low affinity for HLA-A2 and does not produce stable complexes. Therefore we synthesized and tested CLG-dimeric analogues with the purpose of characterizing new compounds with the capacity to bind HLA-A2 molecules. By these studies we have identified a few peptides which, compared to the natural epitope, showed higher affinity for HLA-A2 molecules and superior capacity to form a complex. These dimeric peptides may have the potential to induce efficient CTL responses directed to the natural epitope.
Assuntos
Epitopos/química , Antígeno HLA-A2/metabolismo , Peptídeos/química , Peptídeos/imunologia , Proteínas da Matriz Viral/imunologia , Sequência de Aminoácidos , Aminoácidos/química , Bioquímica/métodos , Linhagem Celular , Desenho de Fármacos , Humanos , Dados de Sequência Molecular , Relação Estrutura-Atividade , Proteínas da Matriz Viral/químicaRESUMO
A series of thirty 2-(3-pyridylaminomethyl)azetidine, pyrrolidine and piperidine analogues as nicotinic acetylcholine receptor (nAChR) ligands was explored. In general, pyrrolidinyl and many azetidinyl compounds were found to bind with enhanced affinity relative to the piperidines. In the three series, the parallel structural changes (stereochemistry, N-methylation and/or chloro substitution) do not consistently lead to parallel shifts in affinity. The more active compounds (K(i) affinity values ranging from 8.9 to 90 nM) were about as analgesic as nicotine in a tail-flick assay in mice after subcutaneous injections.
Assuntos
Aminas/síntese química , Aminas/farmacologia , Receptores Nicotínicos/efeitos dos fármacos , Aminas/química , Aminas/metabolismo , Analgésicos/síntese química , Analgésicos/química , Analgésicos/metabolismo , Analgésicos/farmacologia , Animais , Córtex Cerebral/metabolismo , Ligantes , Masculino , Camundongos , Estrutura Molecular , Piridinas/química , Ratos , Ratos Wistar , Receptores Nicotínicos/metabolismoRESUMO
The octapeptide D-Ala-Ser-Thr-Thr-Thr-Asn-Tyr-Thr-NH(2) ([D-Ala(1)]TNH(2)), an analog of peptide T (H-Ala-Ser-Thr-Thr-Thr-Asn-Tyr-Thr-OH) associated with CD(4)/T(4) receptors involved in human immunodeficiency virus infection, was combined with the chelating polyazamacrocycle 1,4,8,11-tetraazacyclotetradecane (cyclam) to afford the bifunctional ligand cyc-[D-Ala(1)]TNH(2). This was then reacted with [(99m)TcO(4)](-) and Sn(2+) to yield the monocationic complex [(99m)Tc(O)(2)(cyc-[D-Ala(1)]TNH(2))](+). Biological activity of both the cyclam-peptide conjugate and the resulting Tc-99m complex were evaluated by measuring their chemotactic indexes. Results showed that N-cyclam acylation and subsequent labeling with Tc-99m of [D-Ala(1)]TNH(2) were tolerated, and both cyc-[D-Ala(1)]TNH(2) and [(99m)Tc(O)(2)(cyc-[D-Ala(1)]TNH(2))](+) retained the high chemotactic capacity of the original octapeptide. Biodistribution of the Tc-99m complex was carried out in rats. Fast blood clearance and no accumulation in organs of interest were observed.
Assuntos
Antígenos CD4/metabolismo , Oligopeptídeos/síntese química , Oligopeptídeos/metabolismo , Compostos de Organotecnécio/síntese química , Compostos de Organotecnécio/metabolismo , Compostos Radiofarmacêuticos/síntese química , Compostos Radiofarmacêuticos/metabolismo , Animais , Quimiotaxia de Leucócito , Cromatografia Líquida de Alta Pressão , Cromatografia em Papel , Feminino , Humanos , Técnicas In Vitro , Ligantes , Monócitos/metabolismo , Oligopeptídeos/farmacocinética , Compostos de Organotecnécio/farmacocinética , Compostos Radiofarmacêuticos/farmacocinética , Ratos , Ratos Sprague-Dawley , Distribuição TecidualRESUMO
The latent membrane protein 2 is an immunogenic antigen expressed in Epstein-Barr virus (EBV)-associated tumors and consequently it may represent a target for specific cytotoxic T lymphocyte (CTL)-based immunotherapies. However, the efficacy of such a therapy is limited by the poor immunogenicity of the protein that induces weak CTL responses directed to the CLGGLLTMV (CLG) epitope only in the minority of EBV-seropositive donors. We have now demonstrated that selective peptide stimulation of peripheral blood lymphocytes induced CLG-specific CTL in all donors, suggesting that this epitope can be a suitable target for specific immunotherapies. We found that the CLG peptide has a low affinity for HLA-A*0201 and does not produce stable complexes, both factors that are likely to determine the strength of CTL responses to this epitope. Therefore, we synthesized and tested CLG analogues carrying single or combined amino acid substitutions to increase HLA/peptide stability. Among the analogues tested we identified two peptides which, compared to the natural epitope, showed higher affinity for HLA-A*0201 molecules, and produced stable complexes. These peptides demonstrated a potent, specific stimulatory capacity and could be used for selective CTL-based therapies.
Assuntos
Infecções por Vírus Epstein-Barr/terapia , Antígenos HLA-A/metabolismo , Herpesvirus Humano 4/imunologia , Imunoterapia , Proteínas da Matriz Viral/imunologia , Sequência de Aminoácidos , Substituição de Aminoácidos , Antígenos Virais/genética , Linhagem Celular , Epitopos/genética , Infecções por Vírus Epstein-Barr/imunologia , Herpesvirus Humano 4/genética , Humanos , Memória Imunológica , Linfócitos T Citotóxicos/imunologia , Proteínas da Matriz Viral/genéticaRESUMO
Major histocompatibility complex (MHC)/peptide association and stability are determined by specific amino acid interactions between peptide antigens and the MHC groove, and are regarded as a critical feature in ensuring efficient monitoring by T cells. In this investigation we examined the relationship between MHC/peptide stability and the immunostimulatory capacity of MHC/peptide complexes. For this purpose we compared synthetic peptide analogues derived from the immunodominant HLA-A11-presented IVTDFSVIK (IVT) epitope, for their capacity to reactivate IVT-specific memory cytotoxic T-lymphocyte (CTL) responses. The analogues differentiated from the wild-type epitope by single amino acid substitution at position 2. All peptides showed similar affinity for HLA-A11 molecules and were recognized by IVT-specific CTL clones, but induced HLA-A11 complexes at the cell surface with different lifespan. This model offered the possibility of comparing the capacity of an immunogenic epitope to stimulate a unique population of T-cell precursors depending on the lifespan of its presentation at the cell surface. We demonstrated that stable HLA-A11/peptide complexes efficiently stimulate IVT-specific CTL responses, while HLA-A11/peptide complexes with short lifespan do not. The precise identification of the role of amino acid residues in the formation of stable MHC/peptide complexes may be relevant for the design of wild-type-derived epitopes with high immunogenicity. These analogues may have important applications in the immunotherapy of infectious diseases and immunogenic tumours.
Assuntos
Antígenos de Histocompatibilidade Classe I/imunologia , Fragmentos de Peptídeos/imunologia , Linfócitos T Citotóxicos/imunologia , Técnicas de Cultura de Células , Linhagem Celular , Citotoxicidade Imunológica , Epitopos/imunologia , Antígenos Nucleares do Vírus Epstein-Barr/imunologia , Antígenos HLA-A/imunologia , Antígeno HLA-A11 , Meia-Vida , Herpesvirus Humano 4/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Humanos , Memória Imunológica , Fragmentos de Peptídeos/metabolismoRESUMO
The solid phase synthesis, based on the Fmoc chemical protocol, was used to prepare ten deltorphin C (Del-C; H-Tyr-D-Ala-Phe-Asp-Val-Val-Gly-NH2) analogues containing cis- and trans- 2 or 3- or 4- aminocyclohexanecarboxylic acid (ACCA) residues at position 2. ACCA-peptides showed high resistance to degradation by plasma or brain enzymes, negligible affinity for the kappa-binding site and modest delta- and/or mu-receptor affinities. Both [cis-3-ACCA2]Del-C analogues and one trans isomer are the only deltorphin analogues of this series exhibiting an appreciable delta-affinity and selectivity. These data suggest that the presence of a conformationally constrained ACCA residue in position 2 of the "message" sequence of deltorphin C is slightly tolerated.
Assuntos
Aminoácidos Cíclicos , Aminoácidos/química , Analgésicos Opioides/síntese química , Ácidos Cicloexanocarboxílicos/química , Cicloexilaminas/química , Oligopeptídeos/síntese química , Receptores Opioides/efeitos dos fármacos , Analgésicos Opioides/química , Analgésicos Opioides/farmacologia , Animais , Encéfalo/enzimologia , Encéfalo/metabolismo , Cobaias , Íleo/efeitos dos fármacos , Técnicas In Vitro , Masculino , Camundongos , Conformação Molecular , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores Opioides delta/efeitos dos fármacos , Receptores Opioides kappa/efeitos dos fármacos , Receptores Opioides mu/efeitos dos fármacos , Espectrofotometria Ultravioleta , Estereoisomerismo , Ducto Deferente/efeitos dos fármacosRESUMO
In the present study, we examined the structural requirements of peptide Ags for productive interactions with the TCR of CTL. For this purpose, we used as a model a previously identified immunodominant epitope that represents the target of EBV-specific HLA-A11-restricted CTL responses. By the use of peptides having minimal sequence homology with the wild-type epitope, we demonstrated that it is possible to selectively expand and reactivate memory CTL precursors without triggering the lytic mechanisms of wild-type specific effectors. In fact, stimulation of PBL from EBV-seropositive donors by polyalanine analogues, sharing only the putative TCR contact residue with the natural epitope, exclusively induced clonal expansion and reactivation of EBV-specific memory CTL precursors. Interestingly, these polyalanine peptides failed to trigger the cytotoxic function of CTLs specific for the wild-type viral epitope. This clearly indicates that reactivation of memory CTL precursors and triggering of the cytotoxic function have different requirements. The same phenomenon was observed using as stimulators naturally occurring peptides carrying the appropriate TCR contact residue. These data strongly suggest that cross-reactive peptides may play an important role in the expansion and reactivation of CTL clones from the memory T cell pool, and may be involved in long-term maintenance of T cell memory.
Assuntos
Aminoácidos/imunologia , Antígenos Nucleares do Vírus Epstein-Barr/imunologia , Memória Imunológica , Ativação Linfocitária , Oligopeptídeos/imunologia , Linfócitos T Citotóxicos/imunologia , Substituição de Aminoácidos , Aminoácidos/isolamento & purificação , Linhagem Celular Transformada , Reações Cruzadas , Citotoxicidade Imunológica/efeitos dos fármacos , Epitopos de Linfócito T/química , Antígenos Nucleares do Vírus Epstein-Barr/química , Produtos do Gene pol/química , HIV/imunologia , Antígenos HLA-A/química , Antígeno HLA-A11 , Humanos , Memória Imunológica/efeitos dos fármacos , Ativação Linfocitária/efeitos dos fármacos , Oligopeptídeos/síntese química , Oligopeptídeos/farmacologia , Peptídeos/química , Peptídeos/imunologia , Peptídeos/farmacologia , Receptores de Antígenos de Linfócitos T/antagonistas & inibidores , Homologia de Sequência de Aminoácidos , Subpopulações de Linfócitos T/imunologia , Células Tumorais Cultivadas , Proteína Supressora de Tumor p53/químicaRESUMO
Two series of peptidomimetics containing a novel C(2) pseudosymmetrical hydroxyalkyldiamino core structure were prepared from amino acid starting materials and tested for inhibitory activity against the HIV-1 protease (HIV-1 Pr) and the virus in cell culture. In the 2,3-diamino-1-hydroxypropane series, compound 6a, containing P1/P1(I) benzyl and P2/P2(I) Fmoc substituents, displayed modest HIV-1 Pr inhibition (IC(50) = 430 nM). The corresponding 2,4-diamino-1-hydroxybutane derivative (6b) was the best inhibitor of the series (IC(50) = 160 nM). Interestingly, 6a and 6b showed satisfactory inhibition of HIV replication in cell culture (ED(50) = 340 and 110 nM, respectively), a result which suggests good cell membrane penetration by this class of compounds.
Assuntos
Butanóis/síntese química , Butanóis/farmacologia , Inibidores da Protease de HIV/síntese química , Inibidores da Protease de HIV/farmacologia , Protease de HIV/química , Propano/análogos & derivados , Propano/síntese química , Propano/farmacologia , Acilação , Células Cultivadas , Cromatografia em Camada Fina , Desenho de Fármacos , Humanos , Relação Estrutura-Atividade , Replicação Viral/efeitos dos fármacosRESUMO
The solid phase procedure was used to prepare two peptide T derivatives in which the 4-[(1,4,8,11-tetraazacyclotetradec-1-yl)methyl]benzoyl unit is linked to their N-terminus. In a human monocyte chemotaxis assay, both chelator-peptide conjugates showed a high binding property to the CD4 receptor, comparable to the parent H-D-Ala-Ser-Thr-Thr-Thr-Asn-Tyr-Thr-NH2 and its pentapeptide fragment T(4-8)-NH2. These encouraging results make the above cyclam-oligopeptides candidates for the development of the CD4 receptor imaging agents.
Assuntos
Antígenos CD4/fisiologia , Quelantes , Peptídeo T , Sequência de Aminoácidos , Antígenos CD4/análise , Quimiotaxia de Leucócito/efeitos dos fármacos , Quimiotaxia de Leucócito/fisiologia , Humanos , Indicadores e Reagentes , Monócitos/efeitos dos fármacos , Monócitos/fisiologiaRESUMO
Two series of peptidomimetics containing 1,1-diamino-2-hydroxyethane (gSer) core structure were prepared, from amino acid starting materials, and evaluated as inhibitors of HIV-1 protease (HIV-1 Pr). Asymmetrical pseudodipeptides, Y-Xaa-gSer-Y (Y = Z, Fmoc; Xaa = Cha, Phe, Tyr, Tic) showed weak inhibitory potency (IC50 > or = 5 mumol/l), whereas the corresponding pseudotripeptides displayed a more significant HIV-1 Pr inhibition: Fmoc-Tic-gSer-Tic-Fmoc (Fmoc = fluorenylmethyloxycarbonyl, Tic = 1,2,3,4-tetradroisoquinoline-3-carboxylic acid) was the most potent compound of the series (IC50 = 385 nmol/l).
Assuntos
Etanolaminas/farmacologia , Inibidores da Protease de HIV/farmacologia , Protease de HIV/metabolismo , Peptídeos/química , Fenômenos Químicos , Físico-Química , Etanolaminas/química , Inibidores da Protease de HIV/química , Humanos , Hidrogenação , Mimetismo Molecular , Relação Estrutura-Atividade , Ácido Trifluoracético/farmacologiaRESUMO
Substitution of 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic) in place of Gly2 in dynorphin A-(1-13)-NH2 and -(1-11)-NH2 (DYN) analogues (1 and 2) decreased the affinity to the kappa, delta, and mu receptors, and kappa selectivity. The analogue [D-Ala2, des-Gly3]DYN (4), a chimera between deltorphin/dermorphin N-terminal tripeptide and DYN, was virtually inactive for kappa-sites while the affinities for delta- and mu-receptors remained essentially unchanged. The doubly substituted analogue [2',6'-dimethyl-L-tyrosine (Dmt1)-Tic2]DYN (3) exhibited high delta-affinity (Ki=0.39 nM) while mu- and kappa-affinities were only an order of magnitude less (4-5 nM). Bioactivity of [Tic2]DYN peptides (1-3) on guinea-pig ileum and rabbit jejunum revealed potent delta- and kappa-antagonism, while the delta agonist potency of 4 was comparable to DYN. Thus, conversion from a kappa-agonist to antagonist occurred with the inclusion of Tic into DYN analogues, similar to the appearance of antagonist properties with delta- and mu-opioid agonists containing a Tic2 residue.
Assuntos
Analgésicos Opioides/farmacologia , Dinorfinas/farmacologia , Músculo Liso/efeitos dos fármacos , Fragmentos de Peptídeos/farmacologia , Receptores Opioides delta/antagonistas & inibidores , Receptores Opioides kappa/antagonistas & inibidores , Receptores Opioides mu/antagonistas & inibidores , Tetra-Hidroisoquinolinas , Analgésicos Opioides/síntese química , Animais , Relação Dose-Resposta a Droga , Desenho de Fármacos , Dinorfinas/síntese química , Eletrofisiologia , Cobaias , Íleo , Isoquinolinas/química , Contração Muscular/efeitos dos fármacos , Oligopeptídeos/química , Fragmentos de Peptídeos/síntese química , Coelhos , Relação Estrutura-AtividadeRESUMO
Peptides binding to HLA-A11 contain a hydrophobic or a small polar amino acid at position 2 and a lysine at the carboxy terminus. Synthetic peptides carrying natural and unnatural amino acids in position 2 were used to determine the requirements for formation of stable HLA-A11/peptide complexes. By kinetic analysis we demonstrate that a stereospecific interaction between the side chain residue in position 2 and a subsite of pocket B is required to obtain stable HLA/peptide complexes. This specific interaction is mediated by a methyl group or by an ethyl group bound to the asymmetric Cbeta atom with the correct configuration. Experiments performed with different peptide sequences suggest that the presence of adequate anchor residues may be sufficient to produce stable HLA/peptide complexes.