RESUMO
Polymer based carriers that aid in endosomal escape have proven to be efficacious siRNA delivery agents in vitro and in vivo; however, most suffer from cytotoxicity due in part to a lack of selectivity for endosomal versus cell membrane lysis. For polymer based carriers to move beyond the laboratory and into the clinic, it is critical to find carriers that are not only efficacious, but also have margins that are clinically relevant. In this paper we report three distinct categories of polymer conjugates that improve the selectivity of endosomal membrane lysis by relying on the change in pH associated with endosomal trafficking, including incorporation of low pKa heterocycles, acid cleavable amino side chains, or carboxylic acid pH sensitive charge switches. Additionally, we determine the therapeutic index of our polymer conjugates in vivo and demonstrate that the incorporation of pH responsive elements dramatically expands the therapeutic index to 10-15, beyond that of the therapeutic index (less than 3), for polymer conjugates previously reported.
Assuntos
Concentração de Íons de Hidrogênio , Polímeros/uso terapêutico , RNA Interferente Pequeno/uso terapêutico , Animais , Polímeros/química , Polímeros/farmacocinética , RNA Interferente Pequeno/química , RNA Interferente Pequeno/farmacocinética , RatosRESUMO
The resistance of methicillin-resistant Staphylococcus aureus (MRSA) to all ß-lactam classes limits treatment options for serious infections involving this organism. Our goal is to discover new agents that restore the activity of ß-lactams against MRSA, an approach that has led to the discovery of two classes of natural product antibiotics, a cyclic depsipeptide (krisynomycin) and a lipoglycopeptide (actinocarbasin), which potentiate the activity of imipenem against MRSA strain COL. We report here that these imipenem synergists are inhibitors of the bacterial type I signal peptidase SpsB, a serine protease that is required for the secretion of proteins that are exported through the Sec and Tat systems. A synthetic derivative of actinocarbasin, M131, synergized with imipenem both in vitro and in vivo with potent efficacy. The in vitro activity of M131 extends to clinical isolates of MRSA but not to a methicillin-sensitive strain. Synergy is restricted to ß-lactam antibiotics and is not observed with other antibiotic classes. We propose that the SpsB inhibitors synergize with ß-lactams by preventing the signal peptidase-mediated secretion of proteins required for ß-lactam resistance. Combinations of SpsB inhibitors and ß-lactams may expand the utility of these widely prescribed antibiotics to treat MRSA infections, analogous to ß-lactamase inhibitors which restored the utility of this antibiotic class for the treatment of resistant Gram-negative infections.
Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Compostos de Bifenilo/farmacologia , Depsipeptídeos/farmacologia , Glicopeptídeos/farmacologia , Glicosídeos/farmacologia , Lipopeptídeos/farmacologia , Proteínas de Membrana/antagonistas & inibidores , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Oligopeptídeos/farmacologia , Infecções Estafilocócicas/tratamento farmacológico , beta-Lactamas/farmacologia , Animais , Antibacterianos/isolamento & purificação , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Transporte Biológico , Compostos de Bifenilo/síntese química , Depsipeptídeos/isolamento & purificação , Sinergismo Farmacológico , Quimioterapia Combinada , Feminino , Glicopeptídeos/síntese química , Glicopeptídeos/isolamento & purificação , Glicosídeos/isolamento & purificação , Humanos , Lipopeptídeos/isolamento & purificação , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Família Multigênica , Oligopeptídeos/síntese química , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Infecções Estafilocócicas/microbiologia , Resistência beta-Lactâmica/efeitos dos fármacos , Resistência beta-Lactâmica/genética , beta-Lactamases/genética , beta-Lactamases/metabolismoRESUMO
A practical approach toward the synthesis of 2-arylazoles via direct arylation is described. The transformation relies on a Pd/Cu cocatalyst system that operates with low catalyst loadings. The reaction conditions were found to be tolerant of a wide range of functional groups and nitrogen-containing heterocycles commonly employed in a drug discovery setting.
RESUMO
Transposition of the pyridyl nitrogen from the P(3) substituent to the P(1)' substituent in HIV-1 protease inhibitors (PI) affords compounds such as 3 with an improved inhibitory profile against multiple P450 isoforms. These compounds also displayed increased potency, with 3 inhibiting viral spread (CIC(95)) at <8 nM for every strain of PI-resistant HIV-1 tested. The poor to modest bioavailability of these compounds may correlate in part to their aqueous solubility.
Assuntos
Inibidores da Protease de HIV/química , Protease de HIV/metabolismo , HIV-1/efeitos dos fármacos , HIV-1/enzimologia , Animais , Cães , Farmacorresistência Viral/efeitos dos fármacos , Farmacorresistência Viral/fisiologia , Inibidores da Protease de HIV/administração & dosagem , HumanosRESUMO
A biaryl pyridylfuran P(3) substituent on the hydroxyethylene isostere scaffold affords HIV protease inhibitors (PI's) with picomolar (IC(50)) potency against the protease enzymes from PI-resistant HIV-1 strains. Inclusion of a gem-dimethyl substituent afforded compound 3 with 100% oral bioavailability (dogs) and more than double the t(1/2) of indinavir. Inhibition of multiple P450 isoforms is dependent on the regiochemistry of the pyridyl nitrogen in these compounds.
Assuntos
Farmacorresistência Viral , Inibidores da Protease de HIV/síntese química , Inibidores da Protease de HIV/farmacologia , HIV-1/efeitos dos fármacos , Animais , Disponibilidade Biológica , Inibidores das Enzimas do Citocromo P-450 , Cães , Inibidores da Protease de HIV/farmacocinética , HIV-1/enzimologia , Meia-Vida , Indinavir/farmacocinética , Isoenzimas/antagonistas & inibidores , Macaca mulatta , Mutação/genética , Relação Estrutura-AtividadeRESUMO
Substitution of the t-butylcarboxamide substituent in analogues of the HIV protease inhibitor (PI) Indinavir with a trifluoroethylamide moiety confers greater potency against both the wild-type (NL4-3) virus and PI-resistant HIV. The trifluoroethyl substituent also affords a slower clearance rate in vivo (dogs); however, this may be due to more potent inhibition of at least two P450 isoforms.
Assuntos
Resistência a Múltiplos Medicamentos , Inibidores da Protease de HIV/síntese química , HIV/efeitos dos fármacos , Indinavir/análogos & derivados , Animais , Cães , Protease de HIV/efeitos dos fármacos , Inibidores da Protease de HIV/administração & dosagem , Inibidores da Protease de HIV/farmacocinética , Inibidores da Protease de HIV/farmacologia , Humanos , Indinavir/administração & dosagem , Indinavir/farmacocinética , Concentração Inibidora 50 , Taxa de Depuração Metabólica , Relação Estrutura-Atividade , Células Tumorais CultivadasRESUMO
HIV-1 protease inhibitors (PI) with an N-arylpyrrole moiety in the P(3) position afforded excellent antiviral potency and substantially improved aqueous solubility over previously reported variants. The rapid in vitro clearance of these compounds in human liver microsomes prompted oral coadministration with indinavir to hinder their metabolism by the cyctochrome P450 3A4 isozyme and allow for in vivo PK assessment.