RESUMO
The total synthesis of the naturally occurring antibiotic GE81112A, a densely functionalized tetrapeptide, is reported. Comparison of spectral data with those of the natural product and the lack of biological activity of the synthesized compound led us to revise the published configuration of the 3-hydroxypipecolic acid moiety. This hypothesis was fully validated by the synthesis of the corresponding epimer.
Assuntos
Antibacterianos/síntese química , Oligopeptídeos/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Produtos Biológicos/síntese química , Produtos Biológicos/química , Produtos Biológicos/farmacologia , Escherichia coli/efeitos dos fármacos , Histidina/síntese química , Histidina/química , Testes de Sensibilidade Microbiana , Oligopeptídeos/química , Oligopeptídeos/farmacologia , EstereoisomerismoRESUMO
Imidazopyrazinones (IPYs) are a new class of compounds that target bacterial topoisomerases as a basis for their antibacterial activity. We have characterized the mechanism of these compounds through structural/mechanistic studies showing they bind and stabilize a cleavage complex between DNA gyrase and DNA ('poisoning') in an analogous fashion to fluoroquinolones, but without the requirement for the water-metal-ion bridge. Biochemical experiments and structural studies of cleavage complexes of IPYs compared with an uncleaved gyrase-DNA complex, reveal conformational transitions coupled to DNA cleavage at the DNA gate. These involve movement at the GyrA interface and tilting of the TOPRIM domains toward the scissile phosphate coupled to capture of the catalytic metal ion. Our experiments show that these structural transitions are involved generally in poisoning of gyrase by therapeutic compounds and resemble those undergone by the enzyme during its adenosine triphosphate-coupled strand-passage cycle. In addition to resistance mutations affecting residues that directly interact with the compounds, we characterized a mutant (D82N) that inhibits formation of the cleavage complex by the unpoisoned enzyme. The D82N mutant appears to act by stabilizing the binary conformation of DNA gyrase with uncleaved DNA without direct interaction with the compounds. This provides general insight into the resistance mechanisms to antibiotics targeting bacterial type II topoisomerases.
Assuntos
Antibacterianos/química , DNA Girase/química , Pirazinas/química , Inibidores da Topoisomerase II/química , Trifosfato de Adenosina/metabolismo , Antibacterianos/classificação , Ciprofloxacina/química , DNA/química , Clivagem do DNA , DNA Girase/metabolismo , Farmacorresistência Bacteriana , Fluoroquinolonas/química , Magnésio/química , Modelos Moleculares , MutaçãoRESUMO
In our quest for new antibiotics able to address the growing threat of multidrug resistant infections caused by Gram-negative bacteria, we have investigated an unprecedented series of non-quinolone bacterial topoisomerase inhibitors from the Sanofi patrimony, named IPYs for imidazopyrazinones, as part of the Innovative Medicines Initiative (IMI) European Gram Negative Antibacterial Engine (ENABLE) organization. Hybridization of these historical compounds with the quinazolinediones, a known series of topoisomerase inhibitors, led us to a novel series of tricyclic IPYs that demonstrated potential for broad spectrum activity, in vivo efficacy, and a good developability profile, although later profiling revealed a genotoxicity risk. Resistance studies revealed partial cross-resistance with fluoroquinolones (FQs) suggesting that IPYs bind to the same region of bacterial topoisomerases as FQs and interact with at least some of the keys residues involved in FQ binding.
Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Imidazóis/farmacologia , Pirazinas/farmacologia , Quinazolinonas/farmacologia , Inibidores da Topoisomerase/farmacologia , Animais , Antibacterianos/síntese química , Antibacterianos/farmacocinética , Antibacterianos/toxicidade , Farmacorresistência Bacteriana/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Células Hep G2 , Humanos , Imidazóis/síntese química , Imidazóis/farmacocinética , Imidazóis/toxicidade , Masculino , Camundongos , Testes de Sensibilidade Microbiana , Pirazinas/síntese química , Pirazinas/farmacocinética , Pirazinas/toxicidade , Quinazolinonas/síntese química , Quinazolinonas/farmacocinética , Quinazolinonas/toxicidade , Inibidores da Topoisomerase/síntese química , Inibidores da Topoisomerase/farmacocinética , Inibidores da Topoisomerase/toxicidadeRESUMO
Hitherto unknown 2'-deoxy-2'-C-trifluoromethyl-beta-D-ribonucleoside derivatives bearing the five naturally occurring nucleic acid bases have been synthesized. The compounds were tested for their activity against HIV, HBV and several RNA viruses, but they did not show significant antiviral effect.
Assuntos
Antivirais/síntese química , Ribonucleosídeos/química , Ribonucleosídeos/síntese química , Antivirais/química , Antivirais/farmacologia , HIV/efeitos dos fármacos , Vírus da Hepatite B/efeitos dos fármacos , Vírus de RNA/efeitos dos fármacos , Ribonucleosídeos/farmacologiaRESUMO
2'-Deoxy-2'-C-trifluoromethyl-beta-D-ribonucleoside derivatives bearing the five naturally occurring acid bases have been synthesized. All these derivatives were prepared by glycosylation reactions of purine and pyrimidine bases with a suitable peracylated 2-deoxy-2-C-trifluoromethyl sugar precursor to afford anomeric mixtures of protected nucleosides. After separation and deprotection, the resulting beta-nucleoside analogues were tested for their activity against HIV, HBV and several RNA viruses. However, none of these compounds showed significant antiviral activity nor cytotoxicity.
Assuntos
Antivirais/síntese química , Desoxirribonucleosídeos/síntese química , Hidrocarbonetos Fluorados/síntese química , Antivirais/farmacologia , Desoxirribonucleosídeos/farmacologia , Glicosilação , HIV/efeitos dos fármacos , Vírus da Hepatite B/efeitos dos fármacos , Hidrocarbonetos Fluorados/química , Hidrocarbonetos Fluorados/farmacologia , Purinas/química , Pirimidinas/química , Vírus de RNA/efeitos dos fármacosRESUMO
3'-C-Trifloromethyl-beta-D-ribonucleoside derivatives bearing the five naturally occurring nucleic acid bases have been synthesized. All these derivatives were prepared by glycosylation reactions of purine and pyrimidine bases with a suitable peracylated 3-C-trifluoromethyl ribofuranose precursor. After deprotection, the resulting title nucleoside analogues were tested for their inhibitory properties against the replication of HIV, HBV and several RNA viruses. However, none of these compounds showed significant antiviral activity.
Assuntos
Flúor/química , Ribonucleosídeos/síntese química , Antivirais/síntese química , Antivirais/química , Antivirais/farmacologia , Glicosilação , HIV/efeitos dos fármacos , Vírus da Hepatite B/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Purinas/química , Pirimidinas/química , Vírus de RNA/efeitos dos fármacos , Ribonucleosídeos/química , Ribonucleosídeos/farmacologiaRESUMO
3'-Deoxy-3'-C-CF3, 2',3'-dideoxy-3'-C-CF3 and 2',3'-unsaturated-3'-C-CF3 nucleoside derivatives of adenosine and cytidine have been synthesized. All these derivatives were prepared by glycosylation of adenine and uracil with a suitable peracylated 3-trifluoromethyl sugar precursor. The resulting protected nucleosides were subject to appropriate chemical modifications to afford the target nucleoside derivatives. Additionally, the chemical stability in acidic and neutral media of the 2',3'-dideoxy-3'-C-CF3 and 2',3'-unsaturated-3'-C-CF3 nucleoside derivatives of adenosine was compared to that of their parent nucleosides 2',3'-dideoxyadenosine (ddA) and 2',3'-dideoxy-2',3'-didehydroadenosine (d(4)A). Our results confirm that addition of a trifluoromethyl group at C-3' on such nucleoside derivatives appears to confer increased chemical stability toward acid-catalyzed cleavage of the glycosidic bond comparatively to their parent counterparts. When evaluated for their antiviral activity in cell culture experiments, two compounds, namely, 2',3'-dideoxy-3'-C-CF3-adenosine and 2',3'-dideoxy-2',3'-didehydro-3'-C-CF3-cytidine exhibited moderate anti-HBV activity with EC50 values of 10 and 5 microM, respectively.