RESUMEN
CONTEXT: Mitotic kinase enzymes regulate critical stages of mitosis and are amenable to pharmacological inhibition. Since natural products have been a rich source of antimitotic inhibitors, we postulated that natural products would also provide effective inhibitors of mitotic kinases. OBJECTIVE: To explore unique marine and terrestrial natural product sources for new anticancer drug leads, we screened our natural product extract library for polo-like kinase-1 (Plk1) kinase inhibitors. MATERIALS AND METHODS: Extracts of the lichen Parmotrema sp. (Parmeliaceae) exhibited in vitro inhibitory activity. Bioassay-guided fractionation of the Parmotrema sp. extract led to the isolation of depside inhibitors. RESULTS: A new depside 1 has been isolated from the Sri Lankan lichen Parmotrema sp. along with the known metabolites 2 (ß-collatolic acid) and 3 (ß-alectoronic acid). The structure of depside 1 was elucidated by spectroscopic analysis. The three depsides 1-3 exhibited moderate inhibition of purified recombinant Plk1 kinase with IC50 of 2.8, 0.7, and 1.7 µM, respectively, at 1 µM ATP. Inhibitory activity was also observed at high concentrations of ATP, suggesting the potential for activity in a cellular environment. The depsides were also tested against a panel of 23 other recombinant kinases and were found to possess up to 30-fold selectivity toward Plk1. DISCUSSION AND CONCLUSION: These data suggest that the depsides 1-3 may serve as core structures that can be further explored as potential inhibitors of Plk1 and other kinases.
Asunto(s)
Ascomicetos , Proteínas de Ciclo Celular/antagonistas & inhibidores , Depsidos/farmacología , Líquenes , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , Secuencia de Aminoácidos , Proteínas de Ciclo Celular/metabolismo , Depsidos/química , Depsidos/aislamiento & purificación , Humanos , Datos de Secuencia Molecular , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/aislamiento & purificación , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Sri Lanka , Quinasa Tipo Polo 1RESUMEN
The synthesis and stereochemical determination of 1-(4-(4-((1R,5R,6R)-6-hydroxy-3-oxa-8-azabicyclo[3.2.1]octan-8-yl)-6-morpholino-1,3,5-triazin-2-yl)phenyl)-3-(pyridin-4-yl)urea (2), an active metabolite of the potent PI3 kinase inhibitor PKI-179 (1), is described. Stereospecific hydroboration of the double bond of 2,5-dihydro-1H-pyrrole 8 gave the 2,3-trans alcohol 9 exclusively. The configuration of the 3-hydroxyl group in 9 was inverted by an oxidation and stereoselective reduction sequence to give the corresponding 2,3-cis isomer 23. Both exo (21) and endo (27) isomers of the metabolite 2 were prepared via a practical synthetic route from 9 and 23, respectively, and the stereochemistry of 2 was determined to be endo. The endo isomer (27) was separated into two enantiomers 28 and 29 by chiral HPLC. Compound 2 was found to be enantiomerically pure and identical to the enantiomer 28. The absolute stereochemistry of the enantiomer 28 was determined by Mosher's method, thus establishing the stereochemistry of the active metabolite 2.
Asunto(s)
Hidrocarburos Aromáticos con Puentes/síntesis química , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/síntesis química , Morfolinas/síntesis química , Inhibidores de las Quinasa Fosfoinosítidos-3 , Urea/análogos & derivados , Sitios de Unión , Hidrocarburos Aromáticos con Puentes/química , Inhibidores Enzimáticos/farmacología , Estructura Molecular , Morfolinas/química , Morfolinas/farmacología , Oxidación-Reducción , Fosfatidilinositol 3-Quinasas/química , Estereoisomerismo , Urea/síntesis química , Urea/química , Urea/farmacologíaRESUMEN
Fungi are well known for their vast diversity of secondary metabolites that include many life-saving drugs and highly toxic mycotoxins. In general, fungal cultures producing such metabolites are immune to their toxic effects. However, some are known to produce self-toxic compounds that can pose production optimization challenges if the metabolites are needed in large amounts for chemical modification. One such culture, LV-2841, was identified as the lead for one of our exploratory projects. This culture was found to be a slow grower that produced trace amounts of a known metabolite, cercosporamide, under the standard flask fermentation conditions, and extensive medium optimization studies failed to yield higher titers. Poor growth of the culture in liquid media was attributed to the self-toxicity of cercosporamide to the producing organism, and the minimum inhibitory concentration (MIC) of cercosporamide was estimated to be in the range of 8-16 microg/ml. Fermentations carried out in media containing Diaion HP20 resin afforded significantly higher titers of the desired compound. While several examples of resin-based fermentations of soil streptomyces have been published, this approach has rarely been used for fungal fermentations. Over a 100-fold increase in the production titer of cercosporamide, a self-toxic secondary metabolite, was achieved by supplementing the production medium with a commercially available neutral adsorbent resin.
Asunto(s)
Antifúngicos/metabolismo , Antifúngicos/toxicidad , Benzofuranos/metabolismo , Benzofuranos/toxicidad , Hongos/efectos de los fármacos , Hongos/metabolismo , Medios de Cultivo/química , Fermentación , Resinas de Intercambio Iónico/metabolismo , Pruebas de Sensibilidad Microbiana , Poliestirenos/metabolismoRESUMEN
Four new indolosesquiterpenes, lecanindoles A-D (1-4), were isolated from fermentations of the terrestrial fungus Verticillium lecanii 6144. The structures of compounds 1-4 were elucidated from analysis of spectroscopic data. Compound 2 was reduced to give 4 and its isomer 5. Compound 4 was found to be a potent and selective progesterone receptor agonist with an EC50 of 1.1 +/- 0.4 nM in a cell-based luciferase reporter assay.
Asunto(s)
Hypocreales/química , Indoles/aislamiento & purificación , Progestinas/aislamiento & purificación , Receptores de Progesterona/agonistas , Sesquiterpenos/aislamiento & purificación , Animales , Chlorocebus aethiops , Femenino , Humanos , Indoles/química , Indoles/farmacología , Luciferasas/metabolismo , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Progestinas/química , Progestinas/farmacología , Sesquiterpenos/química , Sesquiterpenos/farmacologíaRESUMEN
The naturally occurring pyranonaphthoquinone (PNQ) antibiotic lactoquinomycin and related aglycones were found to be selective inhibitors of the serine-threonine kinase AKT. A set of synthetic PNQs were prepared and a minimum active feature set and preliminary SAR were determined. PNQ lactones inhibit the proliferation of human tumor cell lines containing constitutively activated AKT and show expected effects on cellular biomarkers. Biochemical data are presented supporting a proposed bioreductive alkylation mechanism of action.
Asunto(s)
Antineoplásicos/síntesis química , Cisteína/metabolismo , Lactonas/síntesis química , Proteína Oncogénica v-akt/antagonistas & inhibidores , Piranos/síntesis química , Alquilación , Antineoplásicos/química , Antineoplásicos/farmacología , Biomarcadores/metabolismo , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Humanos , Lactonas/química , Lactonas/farmacología , Naftoquinonas/síntesis química , Naftoquinonas/química , Naftoquinonas/farmacología , Piranos/química , Piranos/farmacología , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
Three new sulfated sterol dimers, fibrosterol sulfates A-C (1-3), have been isolated from the sponge Lissodendoryx (Acanthodoryx) fibrosa, collected in the Philippines. The structures were assigned on the basis of extensive 1D and 2D NMR studies as well as analysis by HRESIMS. Compounds 1 and 2 inhibited PKCzeta with IC(50) values of 16.4 and 5.6 microM, respectively.
Asunto(s)
Dimerización , Poríferos/química , Proteína Quinasa C/antagonistas & inhibidores , Esteroles/química , Esteroles/farmacología , Sulfatos/química , Animales , Mezclas Complejas/química , Evaluación Preclínica de Medicamentos , Concentración 50 Inhibidora , Espectroscopía de Resonancia Magnética , Metanol/química , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/aislamiento & purificación , Inhibidores de Proteínas Quinasas/farmacología , Esteroles/aislamiento & purificaciónRESUMEN
The serine/threonine kinase AKT/PKB plays a critical role in cancer and represents a rational target for therapy. Although efforts in targeting AKT pathway have accelerated in recent years, relatively few small molecule inhibitors of AKT have been reported. The development of selective AKT inhibitors is further challenged by the extensive conservation of the ATP-binding sites of the AGC kinase family. In this report, we have conducted a high-throughput screen for inhibitors of activated AKT1. We have identified lactoquinomycin as a potent inhibitor of AKT kinases (AKT1 IC(50), 0.149 +/- 0.045 micromol/L). Biochemical studies implicated a novel irreversible interaction of the inhibitor and AKT involving a critical cysteine residue(s). To examine the role of conserved cysteines in the activation loop (T-loop), we studied mutant AKT1 harboring C296A, C310A, and C296A/C310A. Whereas the ATP-pocket inhibitor, staurosporine, indiscriminately targeted the wild-type and all three mutant-enzymes, the inhibition by lactoquinomycin was drastically diminished in the single mutants C296A and C310A, and completely abolished in the double mutant C296A/C310A. These data strongly implicate the binding of lactoquinomycin to the T-loop cysteines as critical for abrogation of catalysis, and define an unprecedented mechanism of AKT inhibition by a small molecule. Lactoquinomycin inhibited cellular AKT substrate phosphorylation induced by growth factor, loss of PTEN, and myristoylated AKT. The inhibition was substantially attenuated by coexpression of C296A/C310A. Moreover, lactoquinomycin reduced cellular mammalian target of rapamycin signaling and cap-dependent mRNA translation initiation. Our results highlight T-loop targeting as a new strategy for the generation of selective AKT inhibitors.
Asunto(s)
Cisteína/metabolismo , Inhibidores Enzimáticos/farmacología , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Adenosina Trifosfato/farmacología , Regulación Alostérica/efectos de los fármacos , Animales , Catálisis/efectos de los fármacos , Línea Celular Tumoral , Regulación hacia Abajo/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/química , Humanos , Cinética , Naftoquinonas/química , Naftoquinonas/farmacología , Fosforilación/efectos de los fármacos , Biosíntesis de Proteínas/efectos de los fármacos , Proteínas Quinasas/metabolismo , Caperuzas de ARN/metabolismo , Ratas , Relación Estructura-Actividad , Especificidad por Sustrato/efectos de los fármacos , Serina-Treonina Quinasas TOR , Factores de TiempoRESUMEN
07H239-A (1), a new eremophilane sesquiterpene from a marine-derived xylariaceous fungus, was isolated, characterized, and shown to be cytotoxic toward a variety of cancer cell lines, with some selectivity for a CCRFCEM leukemia line (IC(50) = 0.9 microg/mL).
Asunto(s)
Antineoplásicos/aislamiento & purificación , Ascomicetos/química , Naftalenos/aislamiento & purificación , Sesquiterpenos/aislamiento & purificación , Antineoplásicos/química , Antineoplásicos/farmacología , Ensayos de Selección de Medicamentos Antitumorales , Ácidos Grasos Insaturados/química , Concentración 50 Inhibidora , Estructura Molecular , Naftalenos/química , Naftalenos/farmacología , Sesquiterpenos/química , Sesquiterpenos/farmacología , Células Tumorales CultivadasRESUMEN
The molecular formulas for the structures and substructures of muraymycin antibiotics A1 (C52H90N14O19, MW 1214) and B1 (C49H83N11O18, MW 1113) were determined using electrospray ionization (ESI) Fourier transform mass spectrometry (FTMS). The muraymycin A1 and B1 structures were elucidated by utilizing capillary-skimmer fragmentation with up to five stages of mass spectrometry (MS5). Multi-CHEF, a multiple ion isolation method, was used at each stage of MS(n) to isolate a parent ion and up to four reference ions, for exact-mass calibration. The parent ions were fragmented by SORI-CID and the product ions internally calibrated with average absolute mass errors less than 1 ppm at each stage in the fragmentation processes. Using the top-down/bottom-up approach, the molecular formulas for the antibiotics were determined by summing the elemental formulas of the neutral losses, obtained by measuring the mass differences (<500 Da) between the genetically related sequential parent ion masses in the MS(n) spectra, with the unique elemental formula of the lowest parent ion mass (<500 Da). The structures of 12 additional compounds in the muraymycin complex were elucidated using HPLC ESI capillary-skimmer CID FTMS by correlating their fragmentation patterns with those of muraymycins A1 and B1. Sequential neutral losses of an aminosugar, a valine, a uridine, and an ester fatty acid from the muraymycin parent ions provided diagnostic fragments for characterization.
Asunto(s)
Peptidoglicano/análogos & derivados , Peptidoglicano/química , Ciclotrones , Análisis de Fourier , Estructura Molecular , Nucleótidos , Péptidos , Espectrometría de Masa por Ionización de Electrospray/métodos , Streptomyces/química , UreaRESUMEN
[structure: see text] Herein we report a significant body of spectroscopic data that supports the originally proposed structure of medermycin/lactoquinomycin A. In addition, we demonstrate that these data are inconsistent with the revised structure reported recently in the literature.
Asunto(s)
Antibacterianos/química , Estructura Molecular , Naftoquinonas/química , Resonancia Magnética Nuclear Biomolecular/métodosRESUMEN
The muraymycins, a family of nucleoside-lipopeptide antibiotics, were purified from the extract of Streptomyces sp. LL-AA896. The antibiotics were purified by chromatographic methods and characterized by NMR spectroscopy, degradation studies, and mass spectrometry. The structures of 19 compounds were established. The muraymycins constitute a new antibiotic family whose core structure contains a glycosylated uronic acid derivative joined by an aminopropane group to a hexahydro-2-imino-4-pyrimidylglycyl residue (epicapreomycidine) containing dipeptide that is further extended by a urea-valine moiety. Members of this family show broad-spectrum in vitro antimicrobial activity against a variety of clinical isolates (MIC 2 to >64 mug/mL). The muraymycins inhibited peptidoglycan biosynthesis. The fatty acid substituent and the presence or absence of the amino sugar play important roles in biological activity. One of the most active compounds, muraymycin A1, demonstrated protection in vivo against Staphylococcus aureus infection in mice (ED50 1.1 mg/kg).
Asunto(s)
Antibacterianos/química , Peptidoglicano/biosíntesis , Uracilo/análogos & derivados , Urea/análogos & derivados , Antibacterianos/aislamiento & purificación , Antibacterianos/farmacología , Cromatografía Líquida de Alta Presión , Streptomyces/química , Relación Estructura-Actividad , Uracilo/química , Uracilo/aislamiento & purificación , Uracilo/farmacología , Urea/química , Urea/aislamiento & purificación , Urea/farmacologíaRESUMEN
Sixteen muraymycin derivatives 2-17 were synthesized based on selective reactions of the primary and secondary amino groups of muraymycin C1 (1) with isocyanates and aldehydes. Disubstituted derivatives 3-9 demonstrated no activity against either MraY or MurG at Asunto(s)
Antibacterianos/síntesis química
, Proteínas Bacterianas/antagonistas & inhibidores
, Peptidoglicano/efectos de los fármacos
, Transferasas/antagonistas & inhibidores
, Antibacterianos/farmacología
, Pared Celular/enzimología
, Interacciones Hidrofóbicas e Hidrofílicas
, Nucleótidos
, Péptidos
, Peptidoglicano/análogos & derivados
, Peptidoglicano/biosíntesis
, Peptidoglicano/farmacología
, Staphylococcus epidermidis/enzimología
, Staphylococcus epidermidis/ultraestructura
, Relación Estructura-Actividad
, Transferasas (Grupos de Otros Fosfatos Sustitutos)
, Urea