RESUMEN
We previously reported medicinal chemistry efforts that identified MK-5204, an orally efficacious ß-1,3-glucan synthesis inhibitor derived from the natural product enfumafungin. Further extensive optimization of the C2 triazole substituent identified 4-pyridyl as the preferred replacement for the carboxamide of MK-5204, leading to improvements in antifungal activity in the presence of serum, and increased oral exposure. Reoptimizing the aminoether at C3 in the presence of this newly discovered C2 substituent, confirmed that the (R) t-butyl, methyl aminoether of MK-5204 provided the best balance of these two key parameters, culminating in the discovery of ibrexafungerp, which is currently in phase III clinical trials. Ibrexafungerp displayed significantly improved oral efficacy in murine infection models, making it a superior candidate for clinical development as an oral treatment for Candida and Aspergillus infections.
Asunto(s)
Antifúngicos/farmacología , Aspergillus/efectos de los fármacos , Candida albicans/efectos de los fármacos , Glicósidos/química , Triterpenos/química , beta-Glucanos/metabolismo , Administración Oral , Animales , Antifúngicos/síntesis química , Antifúngicos/farmacocinética , Antifúngicos/uso terapéutico , Aspergilosis/tratamiento farmacológico , Candidiasis/tratamiento farmacológico , Modelos Animales de Enfermedad , Glicósidos/farmacocinética , Glicósidos/farmacología , Glicósidos/uso terapéutico , Semivida , Ratones , Relación Estructura-Actividad , Triterpenos/farmacocinética , Triterpenos/farmacología , Triterpenos/uso terapéuticoRESUMEN
Our previously reported efforts to produce an orally active ß-1,3-glucan synthesis inhibitor through the semi-synthetic modification of enfumafungin focused on replacing the C2 acetoxy moiety with an aminotetrazole and the C3 glycoside with a N,N-dimethylaminoether moiety. This work details further optimization of the C2 heterocyclic substituent, which identified 3-carboxamide-1,2,4-triazole as a replacement for the aminotetrazole with comparable antifungal activity. Alkylation of either the carboxamidetriazole at C2 or the aminoether at C3 failed to significantly improve oral efficacy. However, replacement of the isopropyl alpha amino substituent with a t-butyl, improved oral exposure while maintaining antifungal activity. These two structural modifications produced MK-5204, which demonstrated broad spectrum activity against Candida species and robust oral efficacy in a murine model of disseminated Candidiasis without the N-dealkylation liability observed for the previous lead.
Asunto(s)
Antifúngicos/química , Triazoles/química , beta-Glucanos/metabolismo , Administración Oral , Animales , Antifúngicos/metabolismo , Antifúngicos/farmacología , Antifúngicos/uso terapéutico , Candida/efectos de los fármacos , Candidiasis/tratamiento farmacológico , Modelos Animales de Enfermedad , Glucosiltransferasas/antagonistas & inhibidores , Glucosiltransferasas/metabolismo , Glicósidos/química , Semivida , Ratones , Pruebas de Sensibilidad Microbiana , Estereoisomerismo , Relación Estructura-Actividad , Triazoles/metabolismo , Triazoles/farmacología , Triazoles/uso terapéutico , Triterpenos/química , beta-Glucanos/químicaRESUMEN
The clinical success of the echinocandins, which can only be administered parentally, has validated ß-1,3-glucan synthase (GS) as an antifungal target. Semi-synthetic modification of enfumafungin, a triterpene glycoside natural product, was performed with the aim of producing a new class of orally active GS inhibitors. Replacement of the C2 acetoxy moiety with various heterocycles did not improve GS or antifungal potency. However, replacement of the C3 glycoside with an aminoether moiety dramatically improved oral pharmacokinetic (PK) properties while maintaining GS and antifungal potency. Installing an aminotetrazole at C2 in conjunction with an N-alkylated aminoether at C3 produced derivatives with significantly improved GS and antifungal potency that exhibited robust oral efficacy in a murine model of disseminated candidiasis.
Asunto(s)
Antifúngicos/química , Glicósidos/química , Triterpenos/química , beta-Glucanos/química , Administración Oral , Animales , Antifúngicos/farmacocinética , Antifúngicos/uso terapéutico , Aspergillus fumigatus/efectos de los fármacos , Candida albicans/efectos de los fármacos , Candidiasis/tratamiento farmacológico , Candidiasis/veterinaria , Glucosiltransferasas/antagonistas & inhibidores , Glucosiltransferasas/metabolismo , Semivida , Ratones , Pruebas de Sensibilidad Microbiana , Relación Estructura-Actividad , Terpenos/química , beta-Glucanos/farmacocinética , beta-Glucanos/uso terapéuticoRESUMEN
Orally bioavailable inhibitors of ß-(1,3)-D-glucan synthase have been pursued as new, broad-spectrum fungicidal therapies suitable for treatment in immunocompromised patients. Toward this end, a collaborative medicinal chemistry program was established based on semisynthetic derivatization of the triterpenoid glycoside natural product enfumafungin in order to optimize in vivo antifungal activity and oral absorption properties. In the course of these studies, it was hypothesized that the pharmacokinetic properties of the semisynthetic enfumafungin analog 3 could be improved by tethering the alkyl groups proximal to the basic nitrogen of the C3-aminoether side chain into an azacyclic system, so as to preclude oxidative N-demethylation. The results of this research effort are disclosed herein.
Asunto(s)
Antifúngicos/síntesis química , Inhibidores Enzimáticos/síntesis química , Glucosiltransferasas/antagonistas & inhibidores , Glicósidos/química , Triterpenos/química , Administración Oral , Animales , Antifúngicos/química , Antifúngicos/farmacocinética , Candida albicans/efectos de los fármacos , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacocinética , Glucosiltransferasas/metabolismo , Glicósidos/síntesis química , Glicósidos/farmacocinética , Semivida , Ratones , Relación Estructura-Actividad , Triterpenos/síntesis química , Triterpenos/farmacocinéticaRESUMEN
Parnafungins, natural products containing an isoxazolidinone ring, have been isolated from Fusarium larvarum and have been shown to be potent inhibitors of the fungal polyadenosine polymerase. The extraction and analysis of fermentation broths of taxonomically related organisms identified as closely related Fusarium spp. produce not only parnafungin A and B, but also significant quantities of two related components. These members of the paranfungin family of natural products have been isolated and the structure of each has been elucidated. While structurally analogous to parnafungin A, parnafungin C is further elaborated by methylation of a phenolic hydroxyl group, and parnafungin D has both the methyl phenol ether as well as an epoxide in the xanthone ring system. Parnafungin C and D have potent, broad spectrum antifungal activity and also have been shown to target fungal mRNA cleavage and polyadenylation.
Asunto(s)
Antifúngicos/aislamiento & purificación , Antifúngicos/farmacología , Productos Biológicos/aislamiento & purificación , Productos Biológicos/farmacología , Fusarium/química , Oxazolidinonas/aislamiento & purificación , Oxazolidinonas/farmacología , Antifúngicos/química , Productos Biológicos/química , Candida albicans/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Oxazolidinonas/químicaRESUMEN
Natural products provide an unparalleled source of chemical scaffolds with diverse biological activities and have profoundly impacted antimicrobial drug discovery. To further explore the full potential of their chemical diversity, we survey natural products for antifungal, target-specific inhibitors by using a chemical-genetic approach adapted to the human fungal pathogen Candida albicans and demonstrate that natural-product fermentation extracts can be mechanistically annotated according to heterozygote strain responses. Applying this approach, we report the discovery and characterization of a natural product, parnafungin, which we demonstrate, by both biochemical and genetic means, to inhibit poly(A) polymerase. Parnafungin displays potent and broad spectrum activity against diverse, clinically relevant fungal pathogens and reduces fungal burden in a murine model of disseminated candidiasis. Thus, mechanism-of-action determination of crude fermentation extracts by chemical-genetic profiling brings a powerful strategy to natural-product-based drug discovery.
Asunto(s)
Antifúngicos/farmacología , Antifúngicos/uso terapéutico , Productos Biológicos/farmacología , Productos Biológicos/uso terapéutico , Candida albicans/efectos de los fármacos , Candida albicans/genética , Evaluación Preclínica de Medicamentos/métodos , Polinucleotido Adenililtransferasa/antagonistas & inhibidores , Alelos , Secuencia de Aminoácidos , Animales , Antifúngicos/química , Antifúngicos/aislamiento & purificación , Aspergillus fumigatus/efectos de los fármacos , Aspergillus fumigatus/crecimiento & desarrollo , Aspergillus fumigatus/metabolismo , Productos Biológicos/química , Productos Biológicos/aislamiento & purificación , Candida albicans/metabolismo , Candidiasis/tratamiento farmacológico , Candidiasis/metabolismo , Mezclas Complejas/farmacología , Desoxiadenosinas/metabolismo , Desoxiadenosinas/farmacología , Farmacorresistencia Fúngica , Fermentación , Heterocigoto , Ratones , Pruebas de Sensibilidad Microbiana , Datos de Secuencia Molecular , Mutación , Poliadenilación/efectos de los fármacos , Polinucleotido Adenililtransferasa/genética , Polinucleotido Adenililtransferasa/metabolismo , ARN Mensajero/metabolismo , Saccharomyces cerevisiae/efectos de los fármacos , Saccharomyces cerevisiae/metabolismo , Resultado del TratamientoRESUMEN
A Candida krusei strain from a patient with acute myelogenous leukemia that displayed reduced susceptibility to echinocandin drugs contained a heterozygous mutation, T2080K, in FKS1. The resulting Phe655-->Cys substitution altered the sensitivity of glucan synthase to echinocandin drugs, consistent with a common mechanism for echinocandin resistance in Candida spp.
Asunto(s)
Antifúngicos/farmacología , Candida/efectos de los fármacos , Glucosiltransferasas/genética , Lipoproteínas/farmacología , Péptidos Cíclicos/farmacología , Secuencia de Aminoácidos , Anidulafungina , Candida/enzimología , Candida/genética , Caspofungina , Farmacorresistencia Fúngica , Equinocandinas , Glucosiltransferasas/química , Lipopéptidos , Micafungina , Pruebas de Sensibilidad Microbiana , Datos de Secuencia Molecular , Subunidades de ProteínaRESUMEN
Caspofungin inhibits synthesis of beta-D-1,3 glucan, essential to cell walls in Candida and Aspergillus spp., but activity against less common molds is largely uncharacterized. We demonstrate that caspofungin inhibits beta-D-1,3 glucan synthesis and reduces in vitro growth of clinical isolates from the genera Alternaria, Curvularia, Scedosporium, Acremonium, Bipolaris, and Trichoderma.
Asunto(s)
Antifúngicos/farmacología , Aspergillus fumigatus/efectos de los fármacos , Hongos/efectos de los fármacos , Glucosiltransferasas/antagonistas & inhibidores , Péptidos Cíclicos/farmacología , beta-Glucanos/metabolismo , Aspergillus fumigatus/genética , Aspergillus fumigatus/crecimiento & desarrollo , Aspergillus fumigatus/aislamiento & purificación , Caspofungina , Equinocandinas , Colorantes Fluorescentes , Hongos/genética , Hongos/crecimiento & desarrollo , Hongos/aislamiento & purificación , Técnicas In Vitro , Lipopéptidos , Pruebas de Sensibilidad MicrobianaRESUMEN
The sordarin class of natural products selectively inhibits fungal protein synthesis by impairing the function of eukaryotic elongation factor 2 (eEF2). Mutations in Saccharomyces cerevisiae eEF2 or the ribosomal stalk protein rpP0 can confer resistance to sordarin, although eEF2 is the major determinant of sordarin specificity. It has been shown previously that sordarin specifically binds S. cerevisiae eEF2 while there is no detectable binding to eEF2 from plants or mammals, despite the high level of amino acid sequence conservation among these proteins. In both whole-cell assays and in vitro translation assays, the efficacy of sordarin varies among different species of pathogenic fungi. To investigate the basis of sordarin's fungal selectivity, eEF2 has been cloned and characterized from several sordarin-sensitive and -insensitive fungal species. Results from in vivo expression of Candida species eEF2s in S. cerevisiae and in vitro translation and growth inhibition assays using hybrid S. cerevisiae eEF2 proteins demonstrate that three amino acid residues within eEF2 account for the selectivity of this class of compounds. It is also shown that the corresponding residues at these positions in human eEF2 are sufficient to confer sordarin insensitivity to S. cerevisiae identical to that observed with mammalian eEF2.