RESUMEN
We have synthesized a novel and highly selective severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease peptide mimetic inhibitor mimicking the replicase 1ab recognition sequence -Val-Leu-Gln- and utilizing a cysteine selective acyloxymethyl ketone as the electrophilic warhead to target the active site Cys145. Utilizing a constrained cyclic peptide that locks the conformation between the P3 (Val) and P2 (Leu) residues, we identified a highly selective inhibitor that fills the P2 pocket occupied by the leucine residue sidechain of PF-00835231 and the dimethyl-3-azabicyclo-hexane motif in nirmatrelvir (PF-07321332). This strategy resulted in potent and highly selective Mpro inhibitors without inhibiting essential host cathepsin cysteine or serine proteases. The lead prototype compound 1 (MPro IC50 = 230 ± 18 nM) also inhibits the replication of multiple SARS-CoV-2 variants in vitro, including SARS-CoV-2 variants of concern, and can synergize at lower concentrations with the viral RNA polymerase inhibitor, remdesivir, to inhibit replication. It also reduces SARS-CoV-2 replication in SARS-CoV-2 Omicron-infected Syrian golden hamsters without obvious toxicities, demonstrating in vivo efficacy. This novel lead structure provides the basis for optimization of improved agents targeting evolving SARS-CoV-2 drug resistance that can selectively act on Mpro versus host proteases and are less likely to have off-target effects due to non-specific targeting. Developing inhibitors against the active site of the main protease (Mpro), which is highly conserved across coronaviruses, is expected to impart a higher genetic barrier to evolving SARS-CoV-2 drug resistance. Drugs that selectively inhibit the viral Mpro are less likely to have off-target effects warranting efforts to improve this therapy.
RESUMEN
Postinfluenza bacterial pneumonia is a significant cause of hospitalization and death in humans. The mechanisms underlying this viral and bacterial synergy remain incompletely understood. Recent evidence indicates that influenza-induced IFNs, particularly type I IFN (IFN-I) and IFN-γ, suppress antibacterial defenses. In this study, we have investigated the relative importance and interplay of IFN-I and IFN-γ pathways in influenza-induced susceptibility to Streptococcus pneumoniae infection. Using gene-deficient mouse models, as well as in vivo blocking Abs, we show that both IFN-I and IFN-γ signaling pathways contribute to the initial suppression of antibacterial immunity; however, IFN-γ plays a dominant role in the disease deterioration, in association with increased TNF-α production and alveolar macrophage (AM) depletion. We have previously shown that IFN-γ impairs AM antibacterial function and thereby acute bacterial clearance. The findings in this study indicate that IFN-γ signaling also impairs AM viability and αß T cell recruitment during the progression of influenza/S. pneumoniae coinfection. Macrophages insensitive to IFN-γ mice express a dominant-negative mutant IFN-γR in mononuclear phagocytes. Interestingly, macrophages insensitive to IFN-γ mice exhibited significantly improved recovery and survival from coinfection, despite delayed bacterial clearance. Importantly, we demonstrate that IFN-I receptor signaling is essential for preventing IFN-γ hyperproduction and animal death during the progression of postinfluenza pneumococcal pneumonia.
Asunto(s)
Coinfección , Gripe Humana , Interferón Tipo I/metabolismo , Infecciones por Orthomyxoviridae , Infecciones Neumocócicas , Neumonía Neumocócica , Animales , Antibacterianos , Humanos , Interferón gamma , Ratones , Ratones Endogámicos C57BL , Ratones NoqueadosRESUMEN
Inflammatory cytokine storm is a known cause for acute respiratory distress syndrome. In this study, we have investigated the role of IFN-γ in lethal lung inflammation using a mouse model of postinfluenza methicillin-resistant Staphylococcus aureus (MRSA) pneumonia. To mimic the clinical scenario, animals were treated with antibiotics for effective bacterial control following MRSA superinfection. However, antibiotic therapy alone is not sufficient to improve survival of wild-type animals in this lethal acute respiratory distress syndrome model. In contrast, antibiotics induce effective protection in mice deficient in IFN-γ response. Mechanistically, we show that rather than inhibiting bacterial clearance, IFN-γ promotes proinflammatory cytokine response to cause lethal lung damage. Neutralization of IFN-γ after influenza prevents hyperproduction of TNF-α, and thereby protects against inflammatory lung damage and animal mortality. Taken together, the current study demonstrates that influenza-induced IFN-γ drives a stepwise propagation of inflammatory cytokine response, which ultimately results in fatal lung damage during secondary MRSA pneumonia, despite of antibiotic therapy.
Asunto(s)
Antibacterianos/uso terapéutico , Inflamación/inmunología , Virus de la Influenza A/fisiología , Gripe Humana/inmunología , Interferón gamma/metabolismo , Pulmón/inmunología , Infecciones por Orthomyxoviridae/inmunología , Neumonía Estafilocócica/inmunología , Infecciones Estafilocócicas/inmunología , Staphylococcus aureus/fisiología , Animales , Células Cultivadas , Humanos , Gripe Humana/complicaciones , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Infecciones por Orthomyxoviridae/complicaciones , Neumonía Estafilocócica/complicaciones , Infecciones Estafilocócicas/complicaciones , Sobreinfección , Factor de Necrosis Tumoral alfaRESUMEN
Secondary Streptococcus pneumoniae infection is a significant cause of morbidity and mortality during influenza epidemics and pandemics. Multiple pathogenic mechanisms, such as lung epithelial damage and dysregulation of neutrophils and alveolar macrophages (AMs), have been suggested to contribute to the severity of disease. However, the fundamental reasons for influenza-induced susceptibility to secondary bacterial pneumonia remain unclear. In this study, we revisited these controversies over key pathogenic mechanisms in a lethal model of secondary bacterial pneumonia with an S. pneumoniae strain that is innocuous to mice in the absence of influenza infection. Using a series of in vivo models, we demonstrate that rather than a systemic suppression of immune responses or neutrophil function, influenza infection activates IFN-γR signaling and abrogates AM-dependent bacteria clearance and thereby causes extreme susceptibility to pneumococcal infection. Importantly, using mice carrying conditional knockout of Ifngr1 gene in different myeloid cell subsets, we demonstrate that influenza-induced IFN-γR signaling in AMs impairs their antibacterial function, thereby enabling otherwise noninvasive S. pneumoniae to cause deadly pneumonia.
Asunto(s)
Virus de la Influenza A/fisiología , Gripe Humana/inmunología , Macrófagos Alveolares/fisiología , Infecciones por Orthomyxoviridae/inmunología , Neumonía Neumocócica/inmunología , Receptores de Interferón/metabolismo , Streptococcus pneumoniae/fisiología , Animales , Coinfección , Modelos Animales de Enfermedad , Susceptibilidad a Enfermedades , Humanos , Tolerancia Inmunológica , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores de Interferón/genética , Transducción de Señal , Receptor de Interferón gammaRESUMEN
Postinfluenza methicillin-resistant Staphylococcus aureus (MRSA) infection can quickly develop into severe, necrotizing pneumonia, causing over 50% mortality despite antibiotic treatments. In this study, we investigated the efficacy of antibiotic therapies and the impact of S. aureus alpha-toxin in a model of lethal influenza virus and MRSA coinfection. We demonstrate that antibiotics primarily attenuate alpha-toxin-induced acute lethality, even though both alpha-toxin-dependent and -independent mechanisms significantly contribute to animal mortality after coinfection. Furthermore, we found that the protein synthesis-suppressing antibiotic linezolid has an advantageous therapeutic effect on alpha-toxin-induced lung damage, as measured by protein leak and lactate dehydrogenase (LDH) activity. Importantly, using a Panton-Valentine leucocidin (PVL)-negative MRSA isolate from patient sputum, we show that linezolid therapy significantly improves animal survival from postinfluenza MRSA pneumonia compared with vancomycin treatment. Rather than improved viral or bacterial control, this advantageous therapeutic effect is associated with a significantly attenuated proinflammatory cytokine response and acute lung damage in linezolid-treated mice. Together, our findings not only establish a critical role of alpha-toxin in the extreme mortality of secondary MRSA pneumonia after influenza but also provide support for the possibility that linezolid could be a more effective treatment than vancomycin to improve disease outcomes.
Asunto(s)
Antibacterianos/farmacología , Toxinas Bacterianas/antagonistas & inhibidores , Proteínas Hemolisinas/antagonistas & inhibidores , Linezolid/farmacología , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Infecciones por Orthomyxoviridae/complicaciones , Neumonía Estafilocócica/tratamiento farmacológico , Animales , Toxinas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Femenino , Expresión Génica , Gentamicinas/farmacología , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , L-Lactato Deshidrogenasa/metabolismo , Pulmón/microbiología , Pulmón/patología , Masculino , Staphylococcus aureus Resistente a Meticilina/crecimiento & desarrollo , Staphylococcus aureus Resistente a Meticilina/patogenicidad , Ratones , Ratones Endogámicos C57BL , Infecciones por Orthomyxoviridae/mortalidad , Infecciones por Orthomyxoviridae/patología , Infecciones por Orthomyxoviridae/virología , Plásmidos/química , Plásmidos/metabolismo , Neumonía Estafilocócica/complicaciones , Neumonía Estafilocócica/microbiología , Neumonía Estafilocócica/mortalidad , Análisis de Supervivencia , Vancomicina/farmacologíaRESUMEN
A series of novel tetracycline derivatives were synthesized with the goal of creating new antibiotics that would be unaffected by the known tetracycline resistance mechanisms. New C-9-position derivatives of minocycline (the aminomethylcyclines [AMCs]) were tested for in vitro activity against Gram-positive strains containing known tetracycline resistance mechanisms of ribosomal protection (Tet M in Staphylococcus aureus, Enterococcus faecalis, and Streptococcus pneumoniae) and efflux (Tet K in S. aureus and Tet L in E. faecalis). A number of aminomethylcyclines with potent in vitro activity (MIC range of ≤0.06 to 2.0 µg/ml) were identified. These novel tetracyclines were more active against one or more of the resistant strains than the reference antibiotics tested (MIC range, 16 to 64 µg/ml). The AMC derivatives were active against bacteria resistant to tetracycline by both efflux and ribosomal protection mechanisms. This study identified the AMCs as a novel class of antibiotics evolved from tetracycline that exhibit potent activity in vitro against tetracycline-resistant Gram-positive bacteria, including pathogenic strains of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant enterococci (VRE). One derivative, 9-neopentylaminomethylminocycline (generic name omadacycline), was identified and is currently in human trials for acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP).
Asunto(s)
Antibacterianos/farmacología , Minociclina/farmacología , Tetraciclinas/farmacología , Enterococcus faecalis/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Staphylococcus aureus/efectos de los fármacos , Streptococcus pneumoniae/efectos de los fármacos , Relación Estructura-Actividad , Enterococos Resistentes a la Vancomicina/efectos de los fármacosRESUMEN
With increasing resistance to existing antimalarials, there is an urgent need to discover new drugs at affordable prices for countries in which malaria is endemic. One approach to the development of new antimalarial drugs is to improve upon existing antimalarial agents, such as the tetracyclines. Tetracyclines exhibit potent, albeit relatively slow, action against malaria parasites, and doxycycline is used for both treatment (with other agents) and prevention of malaria. We synthesized 18 novel 7-position modified tetracycline derivatives and screened them for activity against cultured malaria parasites. Compounds with potent in vitro activity and other favorable drug properties were further tested in a rodent malaria model. Ten compounds inhibited the development of cultured Plasmodium falciparum with a 50% inhibitory concentration (IC50) after 96 h of incubation of <30 nM, demonstrating activity markedly superior to that of doxycycline (IC50 at 96 h of 320 nM). Most compounds showed little mammalian cell cytotoxicity and no evidence of in vitro phototoxicity. In a murine Plasmodium berghei model, 13 compounds demonstrated improved activity relative to that of doxycycline. In summary, 7-position modified tetracyclines offer improved activity against malaria parasites compared to doxycycline. Optimized compounds may allow lower doses for treatment and chemoprophylaxis. If safety margins are adequate, dosing in children, the group at greatest risk for malaria in countries in which it is endemic, may be feasible.
Asunto(s)
Antimaláricos/farmacología , Malaria/tratamiento farmacológico , Malaria/prevención & control , Plasmodium berghei/efectos de los fármacos , Tetraciclinas/farmacología , Animales , Resistencia a Medicamentos , Ratones , Pruebas de Sensibilidad ParasitariaRESUMEN
Acute Respiratory Distress Syndrome (ARDS) is an inflammatory disease that is associated with high mortality but no specific treatment. Our understanding of initial events that trigger ARDS pathogenesis is limited. We have developed a mouse model of inflammatory lung injury by influenza and methicillin-resistant Staphylococcus aureus (MRSA) coinfection plus daily antibiotic therapy. Using this pneumonic ARDS model, here we show that IFN-γ receptor signaling drives inflammatory cytokine storm and lung tissue damage. By single-cell RNA sequencing (scRNA-seq) analysis, we demonstrate that IFN-γ signaling induces a transcriptional shift in airway immune cells, particularly by upregulating macrophage and monocyte expression of genes associated with inflammatory diseases. Further evidence from conditional knockout mouse models reveals that IFN-γ receptor signaling in myeloid cells, particularly CD11c+ mononuclear phagocytes, directly promotes TNF-α hyperproduction and inflammatory lung damage. Collectively, the findings from this study, ranging from cell-intrinsic gene expression to overall disease outcome, demonstrate that influenza-induced IFN-γ triggers myeloid cell hyperresponsiveness to MRSA, thereby leading to excessive inflammatory response and lethal lung damage during coinfection.
Asunto(s)
Coinfección , Gripe Humana , Lesión Pulmonar , Staphylococcus aureus Resistente a Meticilina , Síndrome de Dificultad Respiratoria , Animales , Antibacterianos/farmacología , Humanos , Interferón gamma/genética , Lesión Pulmonar/etiología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Células Mieloides , Transcriptoma , Factor de Necrosis Tumoral alfa/genéticaRESUMEN
The reaction of Fe(N{SiMe(3)}(2))(2) (1) with 1 equiv of arylthiol (ArSH) results in material of notional composition Fe(SAr)(N{SiMe(3)}(2)) (2), from which crystalline Fe(2)(µ-SAr)(2)(N{SiMe(3)}(2))(2)(THF)(2) (Ar = Mes) can be isolated from tetrahydrofuran (THF) solvent. Treatment of 2 with 0.5 equiv of 1,2-diarylhydrazine (Ar'NH-NHAr', Ar' = Ph, p-Tol) yields ferric-imide-thiolate cubanes Fe(4)(µ(3)-NAr')(4)(SAr)(4) (3). The site-differentiated, 1-electron reduced iron-imide cubane derivative [Fe(THF)(6)][Fe(4)(µ(3)-N-p-Tol)(4)(SDMP)(3)(N{SiMe(3)}(2))](2) ([Fe(THF)(6)][4](2); DMP = 2,6-dimethylphenyl) can be isolated by adjusting the reaction stoichiometry of 1/ArSH/Ar'NHNHAr' to 9:6:5. The isolated compounds were characterized by a combination of structural (X-ray diffraction), spectroscopic (NMR, UV-vis, Mössbauer, EPR), and magnetochemical methods. Reactions with a range of hydrazines reveal complex chemical behavior that includes not only N-N bond reduction for 1,2-di- and trisubstituted arylhydrazines, but also catalytic disproportionation for 1,2-diarylhydrazines, N-C bond cleavage for 1,2-diisopropylhydrazine, and no reaction for hindered and tetrasubstituted hydrazines.
Asunto(s)
Hidrazinas/química , Hidrocarburos Cíclicos/síntesis química , Imidas/síntesis química , Hierro/química , Compuestos Organometálicos/síntesis química , Carbono/química , Furanos/química , Hidrocarburos Cíclicos/química , Imidas/química , Modelos Químicos , Nitrógeno/química , Compuestos Organometálicos/química , Solventes/química , Análisis Espectral , Compuestos de Sulfhidrilo/química , Difracción de Rayos XRESUMEN
LcrF (VirF), a transcription factor in the multiple adaptational response (MAR) family, regulates expression of the Yersinia type III secretion system (T3SS). Yersinia pseudotuberculosis lcrF-null mutants showed attenuated virulence in tissue culture and animal models of infection. Targeting of LcrF offers a novel, antivirulence strategy for preventing Yersinia infection. A small molecule library was screened for inhibition of LcrF-DNA binding in an in vitro assay. All of the compounds lacked intrinsic antibacterial activity and did not demonstrate toxicity against mammalian cells. A subset of these compounds inhibited T3SS-dependent cytotoxicity of Y. pseudotuberculosis toward macrophages in vitro. In a murine model of Y. pseudotuberculosis pneumonia, two compounds significantly reduced the bacterial burden in the lungs and afforded a dramatic survival advantage. The MAR family of transcription factors is well conserved, with members playing central roles in pathogenesis across bacterial genera; thus, the inhibitors could have broad applicability.
Asunto(s)
Proteínas Bacterianas/antagonistas & inhibidores , Bencimidazoles/farmacología , Neumonía Bacteriana/patología , Factores de Transcripción/antagonistas & inhibidores , Infecciones por Yersinia pseudotuberculosis/patología , Yersinia pseudotuberculosis/efectos de los fármacos , Yersinia pseudotuberculosis/patogenicidad , Animales , Antibacterianos/administración & dosificación , Antibacterianos/síntesis química , Antibacterianos/química , Antibacterianos/farmacología , Proteínas Bacterianas/metabolismo , Bencimidazoles/administración & dosificación , Bencimidazoles/síntesis química , Bencimidazoles/química , Línea Celular , Modelos Animales de Enfermedad , Femenino , Humanos , Pulmón/microbiología , Macrófagos/microbiología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Neumonía Bacteriana/tratamiento farmacológico , Neumonía Bacteriana/microbiología , Neumonía Bacteriana/mortalidad , Factores de Transcripción/metabolismo , Resultado del Tratamiento , Virulencia , Yersinia pseudotuberculosis/metabolismo , Infecciones por Yersinia pseudotuberculosis/tratamiento farmacológico , Infecciones por Yersinia pseudotuberculosis/microbiología , Infecciones por Yersinia pseudotuberculosis/mortalidadRESUMEN
The dinuclear precursors Fe(2)(N(t)Bu)(2)Cl(2)(NH(2)(t)Bu)(2), [Fe(2)(N(t)Bu)(S)Cl(4)](2-), and Fe(2)(NH(t)Bu)(2)(S)(N{SiMe(3)}(2))(2) allowed the selective syntheses of the cubane clusters [Fe(4)(N(t)Bu)(n)(S)(4-n)Cl(4)](z) with [n, z] = [3, 1-], [2, 2-], [1, 2-]. Weak-field iron-sulfur clusters with heteroleptic, nitrogen-containing cores are of interest with respect to observed or conjectured environments in the iron-molybdenum cofactor of nitrogenase. In this context, the present iron-imide-sulfide clusters constitute a new class of compounds for study, with the Fe(4)NS(3) core of the [1, 2-] cluster affording the first synthetic representation of the corresponding heteroligated Fe(4)S(3)X subunit in the cofactor.
Asunto(s)
Imidas/síntesis química , Hierro/química , Molibdoferredoxina/química , Sulfuros/síntesis química , Cristalografía por Rayos XRESUMEN
The sterically hindered Fe(II) thiolate dimer Fe(2)(mu-STriph)(2)(STriph)(2) (1; [STriph](-) = 2,4,6-triphenylbenzenethiolate) reacts with primary amines ((t)BuNH(2), aniline) and N(2)H(4) to form the structurally characterized addition complexes Fe(STriph)(2)(NH(2)(t)Bu)(2), Fe(2)(mu-STriph)(2)(STriph)(2)(NH(2)Ph)(2), and Fe(2)(mu-eta(1):eta(1)-N(2)H(4))(2)(N(2)H(4))(4)(STriph)(4) in high yield. Chemical and NMR spectroscopic evidence indicate that the binding of these nitrogen donors is labile in solution and multispecies equilibria are likely. With arylhydrazines, 1 catalytically disproportionates 1,2-diphenylhydrazine to aniline and azobenzene, and it rearranges 1-methyl-1,2-diarylhydrazines to give, after treatment with alumina, mononuclear, trigonal bipyramidal Fe(III) complexes of composition Fe(ISQ)(2)(STriph), where [ISQ](-) denotes an appropriately substituted bidentate o-diiminobenzosemiquinonate ligand. Complex 1 shows no reaction with hindered 1,2-dialkylhydrazines (isopropyl or tert-butyl) or tetrasubstituted 1,2-dimethyl-1,2-diphenylhydrazine.
Asunto(s)
Aminas/química , Dimerización , Compuestos Ferrosos/química , Hidrazinas/química , Espectroscopía de Resonancia Magnética , Polímeros/química , Sulfuros/químicaRESUMEN
The reaction of [(C(5)Me(5))M(MeCN)(3)](PF(6))(2) with (C(5)Me(5))(2)Ru(2)S(4) gives the cluster compounds [(C(5)Me(5))(3)MRu(2)S(4)(MeCN)](PF(6))(2), 1(PF(6))(2) (M = Rh) and 3(PF(6))(2) (M = Ir). Crystallographic studies of 1(PF(6))(2) show that the dication consists of an asymmetric RhRu(2)S(4) core containing an isosceles triangle of metal atoms with a Ru-Ru bond of 2.88 Å. The three metal atoms are joined by two &mgr;(3)-eta(1):eta(2):eta(1-)S(2) units, each persulfide being monodentate toward Rh. NMR studies show that 1(2+) is stereochemically nonrigid such that the two Ru(C(5)Me(5)) resonances coalesce at higher temperatures. The dynamic processes involving 1(2+) are unaffected by added (C(5)Me(5))Rh(MeCN)(3)(2+), ruling out dissociation of the (C(5)Me(5))Rh center. Exchange of the (C(5)Me(5))Ru sites in [(C(5)Me(5))(2)(C(5)Me(4)Et)RhRu(2)S(4)(MeCN)](PF(6))(2), 2(PF(6))(2), is associated with coalescence of the pairs of C(5)Me(4)Et resonances, suggesting that the dynamics in 1(2+) involve racemization. It is proposed that these dynamics proceed via the "base-free" intermediate [(C(5)Me(5))(3)RhRu(2)S(4)](2+), wherein one S-S bond has been cleaved. Solutions of 1(2+) react with acetone to give the S-acetonyl derivative [(C(5)Me(5))(3)RhRu(2)S(3)(SCH(2)COCH(3))]PF(6), 4(PF(6)). This species, which is not fluxional on the NMR time scale, is a rare example of a metal sulfido cluster with a trigonal prismatic M(3)S(3) core. There is one metal-metal bond of 2.75 Å between the two Ru atoms, spanned by the acetonylthio ligand. The M-S distances are nearly equivalent at 2.33 Å while the S-S bonding distance is 2.12 Å. This reaction is reversed by acid to give 1(2+) and acetone.
RESUMEN
Toluene solutions of C(60) react upon UV irradiation with Fe(2)S(2)(CO)(6) to give C(60)[S(2)Fe(2)(CO)(6)](n)() where n = 1-6. C(60)[S(2)Fe(2)(CO)(6)](n)() where n = 1-3 have been isolated and characterized. Crystallographic studies of C(60)S(2)Fe(2)(CO)(6) show that the S-S bond of the Fe(2) reagent is cleaved to give a dithiolate with idealized C(2)(v)() symmetry. The addition occurred at a 6,6 fusion, and the metrical details show that the Fe(2) portion of the molecule resembles C(2)H(4)S(2)Fe(2)(CO)(6). IR spectroscopic measurements indicate that the Fe(2)(CO)(6) subunits in the multiple-addition species (n > 1) interact only weakly. UV-vis spectra of the adducts show a shift to shorter wavelength with addition of each S(2)Fe(2)(CO)(6) unit. Photoaddition of the phosphine complex Fe(2)S(2)(CO)(5)(PPh(3)) to C(60) gave C(60)[S(2)Fe(2)(CO)(5)(PPh(3))](n)(), where n = 1-3. (31)P{(1)H} NMR studies show that the double adduct consists of multiple isomers. Photoaddition of Fe(2)S(2)(CO)(6) to C(70) gave a series of adducts C(70)[S(2)Fe(2)(CO)(6)](n)() where n = 1-4. HPLC analyses show one, four, and three isomers for the adducts, respectively.
RESUMEN
LcrF, a multiple adaptational response (MAR) transcription factor, regulates virulence in Yersinia pestis and Yersinia pseudotuberculosis. In a search for small molecule inhibitors of LcrF, an acrylic amide series of N-hydroxybenzimidazoles was synthesized and the SAR (structure-activity relationship) was examined. Selected test compounds demonstrated inhibitory activity in a primary cell-free LcrF-DNA binding assay as well as in a secondary whole cell assay (type III secretion system dependent Y. pseudotuberculosis cytotoxicity assay). The inhibitors exhibited no measurable antibacterial activity in vitro, confirming that they do not target bacterial growth. These results demonstrate that N-hydroxybenzimidazole inhibitors, exemplified by 14, 22, and 36, are effective antivirulence agents and have the potential to prevent infections caused by Yersinia spp.
Asunto(s)
Antibacterianos/química , Antibacterianos/farmacología , Proteínas Bacterianas/antagonistas & inhibidores , Bencimidazoles/química , Bencimidazoles/farmacología , Transactivadores/antagonistas & inhibidores , Yersinia pestis/efectos de los fármacos , Yersinia pseudotuberculosis/efectos de los fármacos , Animales , Antibacterianos/síntesis química , Antibacterianos/uso terapéutico , Proteínas Bacterianas/metabolismo , Bencimidazoles/síntesis química , Bencimidazoles/uso terapéutico , Línea Celular , Sistema Libre de Células/metabolismo , ADN/metabolismo , Descubrimiento de Drogas , Concentración 50 Inhibidora , Ratones , Peste/tratamiento farmacológico , Relación Estructura-Actividad , Transactivadores/metabolismo , Virulencia/efectos de los fármacos , Yersinia pestis/patogenicidad , Yersinia pseudotuberculosis/patogenicidadRESUMEN
Structure-based drug design was utilized to identify potent small-molecule inhibitors of proteins within the AraC family of bacterial transcription factors, which control virulence in medically important microbes. These agents represent a novel approach to fight infectious disease and may be less likely to promote resistance development. These compounds lack intrinsic antibacterial activity in vitro and were able to limit a bacterial infection in a mouse model of urinary tract infection.
Asunto(s)
Antibacterianos/química , Antibacterianos/uso terapéutico , Proteínas Bacterianas/antagonistas & inhibidores , Proteínas Bacterianas/metabolismo , Factores de Transcripción/antagonistas & inhibidores , Factores de Transcripción/metabolismo , Animales , Antibacterianos/síntesis química , ADN/genética , Modelos Animales de Enfermedad , Enterobacteriaceae/efectos de los fármacos , Concentración 50 Inhibidora , Ratones , Estructura Molecular , Unión Proteica , Pseudomonas aeruginosa/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Relación Estructura-Actividad , Infecciones Urinarias/tratamiento farmacológico , Infecciones Urinarias/microbiologíaRESUMEN
Tetrahedral FeCl[N(SiMe(3))(2)](2)(THF) (2), prepared from FeCl(3) and 2 equiv of Na[N(SiMe(3))(2)] in THF, is a useful ferric starting material for the synthesis of weak-field iron-imide (Fe-NR) clusters. Protonolysis of 2 with aniline yields azobenzene and [Fe(2)(mu-Cl)(3)(THF)(6)](2)[Fe(3)(mu-NPh)(4)Cl(4)] (3), a salt composed of two diferrous monocations and a trinuclear dianion with a formal 2 Fe(III)/1 Fe(IV) oxidation state. Treatment of 2 with LiCl, which gives the adduct [FeCl(2)(N(SiMe(3))(2))(2)](-) (isolated as the [Li(TMEDA)(2)](+) salt), suppresses arylamine oxidation/iron reduction chemistry during protonolysis. Thus, under appropriate conditions, the reaction of 1:1 2/LiCl with arylamine provides a practical route to the following Fe-NR clusters: [Li(2)(THF)(7)][Fe(3)(mu-NPh)(4)Cl(4)] (5a), which contains the same Fe-NR cluster found in 3; [Li(THF)(4)](2)[Fe(3)(mu-N-p-Tol)(4)Cl(4)] (5b); [Li(DME)(3)](2)[Fe(2)(mu-NPh)(2)Cl(4)] (6a); [Li(2)(THF)(7)][Fe(2)(mu-NMes)(2)Cl(4)] (6c). [Li(DME)(3)](2)[Fe(4)(mu(3)-NPh)(4)Cl(4)] (7), a trace product in the synthesis of 5a and 6a, forms readily as the sole Fe-NR complex upon reduction of these lower nuclearity clusters. Products were characterized by X-ray crystallographic analysis, by electronic absorption, (1)H NMR, and Mössbauer spectroscopies, and by cyclic voltammetry. The structures of the Fe-NR complexes derive from tetrahedral iron centers, edge-fused by imide bridges into linear arrays (5a,b; 6a,c) or the condensed heterocubane geometry (7), and are homologous to fundamental iron-sulfur (Fe-S) cluster motifs. The analogy to Fe-S chemistry also encompasses parallels between Fe-mediated redox transformations of nitrogen and sulfur ligands and reductive core conversions of linear dinuclear and trinuclear clusters to heterocubane species and is reinforced by other recent examples of iron- and cobalt-imide cluster chemistry. The correspondence of nitrogen and sulfur chemistry at iron is intriguing in the context of speculative Fe-mediated mechanisms for biological nitrogen fixation.
RESUMEN
A diverse collection of tetracycline derivatives has been synthesized utilizing Heck, Suzuki, and other palladium-coupling reactions via tetracycline arenediazonium and iodoarene salts. Large numbers of tetracyclines are now possible via these reactions, including numerous upper periphery derivatives of doxycycline, minocycline, sancycline, and methacycline modified at positions C7, C9, and C6-C13 on the tetracycline naphthacene ring. Application of palladium-coupling reactions to the tetracyclines has yielded new tetracycline classes with differing structural attributes, greatly increasing the structural diversity of this family of antibiotics, one of the last of the early antibiotic families to be expanded by organic and medicinal chemistry.