RESUMO
Gargantulide A (1), an extremely complex 52-membered macrolactone, was isolated from Streptomyces sp. A42983 and displayed moderate activity against MRSA. The planar structure of 1 was determined using 2D NMR, and its stereochemistry was partially established on the basis of NOESY correlations, J-based configuration analysis, and Kishi's universal NMR database.
Assuntos
Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Macrolídeos/isolamento & purificação , Macrolídeos/farmacologia , Streptomyces/química , Antibacterianos/química , Candida albicans/efeitos dos fármacos , Clostridium/efeitos dos fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Macrolídeos/química , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Saccharomyces cerevisiae/efeitos dos fármacos , Streptococcus pneumoniae/efeitos dos fármacos , Vancomicina/farmacologiaRESUMO
A 384-well microtitre plate fluorescence cleavage assay was developed to identify inhibitors of the cysteine protease falcipain-2, an important antimalarial drug target. Bioassay-guided isolation of a MeOH extract from a myxobacterium Chitinophaga sp. Y23 isolated from soil collected in Singapore, led to the identification of a new acyltetrapeptide, falcitidin (1), which displayed an IC50 value of 6 µM against falcipain-2. The planar structure of 1 was secured by NMR and MS/MS analysis. Attempts to isolate further material for biological testing were hampered by inconsistent production and by a low yield (<100 µg l(-1)). The absolute configuration of 1 was determined by Marfey's analysis and the structure was confirmed through total synthesis as isovaleric acid-D-His-L-Ile-L-Val-L-Pro-NH2. Falcitidin (1) is the first member of a new class of falcipain-2 inhibitors and, unlike other peptide-based inhibitors, does not contain reactive groups that irreversibly bind to active cysteine sites.
Assuntos
Antimaláricos/isolamento & purificação , Antimaláricos/farmacologia , Cisteína Endopeptidases/metabolismo , Oligopeptídeos/isolamento & purificação , Oligopeptídeos/farmacologia , Inibidores de Proteases/isolamento & purificação , Inibidores de Proteases/farmacologia , Antimaláricos/síntese química , Antimaláricos/química , Bacteroidetes/química , Bacteroidetes/isolamento & purificação , Bioensaio , Avaliação Pré-Clínica de Medicamentos , Humanos , Concentração Inibidora 50 , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Oligopeptídeos/síntese química , Oligopeptídeos/química , Inibidores de Proteases/síntese química , Inibidores de Proteases/química , Singapura , Microbiologia do Solo , Espectrometria de Massas em TandemRESUMO
A prefractionated Streptomyces-derived extract was initially identified as being active using a luciferase-based AMP-activated protein kinase (AMPK) assay. Bioassay-guided fractionation led to the isolation of the new compound quinazolin-4(3H)-one (1) as the active component. However, 1 was shown to have potent firefly luciferase inhibitory activity with no effect on AMPK. This is the first report of a natural luciferase inhibitor.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Produtos Biológicos/isolamento & purificação , Produtos Biológicos/farmacologia , Luciferases de Vaga-Lume/antagonistas & inibidores , Quinazolinonas/isolamento & purificação , Quinazolinonas/farmacologia , Streptomyces/química , Animais , Produtos Biológicos/química , Luciferases de Vaga-Lume/metabolismo , Estrutura Molecular , Quinazolinonas/químicaRESUMO
The cytotoxic macrolide kendomycin was identified as a ligand of Bcl-xl, an anti-apoptotic member of the Bcl-2 protein family. Hydrolysis-stable and protonable semi-synthetic analogues have been obtained that retain cytotoxicity and Bcl-xl binding.
Assuntos
Apoptose/efeitos dos fármacos , Rifabutina/análogos & derivados , Proteína bcl-X/química , Linhagem Celular Tumoral , Humanos , Rifabutina/química , Rifabutina/farmacologiaRESUMO
Bioassay-directed fractionation using a glucocorticoid receptor assay led to the isolation of two new, weakly active polyprenylated acylphloroglucinol derivatives, sundaicumones A (1) and B (2), from the leaves of Calophyllum sundaicum collected in Singapore. The structures of 1 and 2, which were established by spectroscopic methods, contain a 3-substituted hexanoic acid unit not previously reported in other polyprenylated acylphloroglucinols.
Assuntos
Calophyllum/química , Floroglucinol , Plantas Medicinais/química , Receptores de Glucocorticoides/antagonistas & inibidores , Humanos , Estrutura Molecular , Floroglucinol/análogos & derivados , Floroglucinol/química , Floroglucinol/isolamento & purificação , Floroglucinol/farmacologia , Folhas de Planta/química , Singapura , Células Tumorais CultivadasRESUMO
Natural products have played a pivotal role in antibiotic drug discovery with most antibacterial drugs being derived from a natural product or natural product lead. However, the rapid onset of resistance to most antibacterial drugs diminishes their effectiveness considerably and necessitates a constant supply of new antibiotics for effective treatment of infections. The natural product templates of actinonin, pleuromutilin, ramoplanin and tiacumicin B, which are compounds undergoing clinical evaluation, represent templates not found in currently marketed antibacterial drugs. In addition, the new templates present in the recently discovered lead antibacterials arylomycin, GE23077, mannopeptimycin, muraymycin/caprazamycin, nocathiacin and ECO-0501, are discussed. Despite extensive efforts to identify antibiotic leads from molecular targets, only the peptide deformylase inhibitor LBM-415 is currently in clinical trials. It is proposed that new antibacterial assays which combine cell-based screening with molecular targets could offer better prospects for lead discovery.
Assuntos
Antibacterianos/química , Produtos Biológicos/química , Desenho de Fármacos , Indústria Farmacêutica/tendências , Antibacterianos/farmacologia , Produtos Biológicos/farmacologia , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Humanos , Estrutura MolecularRESUMO
The root and stem bark extracts of a Nigerian sample of Leptonychia pubescens Keay (Sterculiaceae) were found to inhibit the serine protease tryptase, a potential therapeutic target for the treatment of asthma and chronic obstructive pulmonary disease (COPD). Bioassay-guided isolation led to the identification of 1-beta-ribofuranosylbrunfelsamidine as the active component with a tryptase IC (50) of 3 microM. Brunfelsamidine was also isolated, but was only weakly active.
Assuntos
Malvaceae/química , Monossacarídeos/farmacologia , Serina Endopeptidases/metabolismo , Inibidores de Serina Proteinase/farmacologia , Humanos , Pulmão/enzimologia , Estrutura Molecular , Monossacarídeos/química , Monossacarídeos/isolamento & purificação , Casca de Planta/química , Extratos Vegetais/química , Raízes de Plantas/química , Inibidores de Serina Proteinase/química , Inibidores de Serina Proteinase/isolamento & purificação , TriptasesRESUMO
An extract from the fungus Emericella aurantiobrunnea was found to compete with macrophage inflammatory protein (MIP)-1alpha for binding to human CCR5 in a scintillation proximity assay (SPA). Bioassay-guided fractionation led to the isolation of variecolin (1) and variecolol (2), which had IC50 values of 9 and 32 microM, respectively. An X-ray crystal structure of variecolin (1) was obtained for the first time. Also isolated were four new inactive analogues, emericolin A (3), B (4), C (5), and D (6), and the relative stereochemistry of these compounds was determined by NMR methods using ROESY spectra and 1H/1H coupling constants.
Assuntos
Ascomicetos/química , Antagonistas dos Receptores CCR5 , Proteínas Inflamatórias de Macrófagos/metabolismo , Terpenos/isolamento & purificação , Terpenos/farmacologia , Quimiocina CCL3 , Quimiocina CCL4 , Cristalografia por Raios X , Humanos , Concentração Inibidora 50 , Conformação Molecular , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Terpenos/químicaAssuntos
Ascomicetos/química , Benzoquinonas/isolamento & purificação , Benzoquinonas/farmacologia , Antagonistas dos Receptores CCR5 , Stachybotrys/química , Animais , Ascomicetos/metabolismo , Benzoquinonas/química , Benzoquinonas/metabolismo , Ligação Competitiva , Células CHO , Quimiocina CCL4 , Cricetinae , Fermentação , Humanos , Concentração Inibidora 50 , Proteínas Inflamatórias de Macrófagos/metabolismo , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Receptores CCR5/metabolismo , Espectrometria de Massas por Ionização por Electrospray , Stachybotrys/metabolismoRESUMO
Three compounds, 2,3-dihydroxy-4-methoxy-6,6,9-trimethyl-6H-dibenzo[b,d]pyran (1), 8-methoxy-2-methyl-2-(4-methyl-3-pentenyl)-2H-1-benzopyran-6-ol (2) and 4-methoxy-3-(3-methyl-2-butenyl)-benzoic acid (3), have been isolated from Wigandia urens. The structures of compounds 1, 2 and 3 were determined from spectroscopic data and showed activity in a CCR5 assay with IC(50) values of 33, 46 and 26 muM respectively.
Assuntos
Antagonistas dos Receptores CCR5 , Hydrophyllaceae/química , Fenóis/química , Fenóis/farmacologia , Animais , Benzoatos/química , Benzoatos/isolamento & purificação , Benzoatos/farmacologia , Benzopiranos/química , Benzopiranos/isolamento & purificação , Benzopiranos/farmacologia , Células CHO , Quimiocina CCL4 , Cricetinae , Cricetulus , Humanos , Concentração Inibidora 50 , Proteínas Inflamatórias de Macrófagos/química , Proteínas Inflamatórias de Macrófagos/genética , Proteínas Inflamatórias de Macrófagos/metabolismo , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Fenóis/isolamento & purificação , Receptores CCR5/genética , Receptores CCR5/metabolismo , Proteínas Recombinantes/antagonistas & inibidores , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMO
Two new compounds, 10-methoxydihydrofuscin (1) and fuscinarin (2), and one known compound, fuscin (3), have been isolated from the soil fungus Oidiodendron griseum. These compounds were found to compete effectively with macrophage inflammatory protein (MIP)-1 alpha for binding to human CCR5, an important anti HIV-1 target that interferes with HIV entry into cells. The structures of these compounds were elucidated by spectroscopic methods.
Assuntos
Benzopiranos/isolamento & purificação , Antagonistas dos Receptores CCR5 , Fungos/química , HIV-1/imunologia , Compostos Heterocíclicos com 3 Anéis/isolamento & purificação , Proteínas Inflamatórias de Macrófagos/metabolismo , Benzopiranos/química , Benzopiranos/farmacologia , Quimiocina CCL4 , HIV-1/fisiologia , Compostos Heterocíclicos com 3 Anéis/química , Compostos Heterocíclicos com 3 Anéis/farmacologia , Humanos , Estrutura Molecular , Ressonância Magnética Nuclear BiomolecularRESUMO
The identification of small molecule inhibitors of antiapoptotic Bcl-2 family members has opened up new therapeutic opportunities, while the vast diversity of chemical structures and biological activities of natural products are yet to be systematically exploited. Here we report the identification of chelerythrine as an inhibitor of BclXL-Bak Bcl-2 homology 3 (BH3) domain binding through a high throughput screening of 107,423 extracts derived from natural products. Chelerythrine inhibited the BclXL-Bak BH3 peptide binding with IC50 of 1.5 micro m and displaced Bax, a BH3-containing protein, from BclXL. Mammalian cells treated with chelerythrine underwent apoptosis with characteristic features that suggest involvement of the mitochondrial pathway. While staurosporine, H7, etoposide, and chelerythrine released cytochrome c from mitochondria in intact cells, only chelerythrine released cytochrome c from isolated mitochondria. Furthermore BclXL-overexpressing cells that were completely resistant to apoptotic stimuli used in this study remained sensitive to chelerythrine. Although chelerythrine is widely known as a protein kinase C inhibitor, the mechanism by which it mediates apoptosis remain controversial. Our data suggest that chelerythrine triggers apoptosis through a mechanism that involves direct targeting of Bcl-2 family proteins.
Assuntos
Antineoplásicos/farmacologia , Fenantridinas/farmacologia , Proteínas Proto-Oncogênicas c-bcl-2/antagonistas & inibidores , Alcaloides , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Benzofenantridinas , Grupo dos Citocromos c/metabolismo , Inibidores Enzimáticos/farmacologia , Etoposídeo/farmacologia , Expressão Gênica , Humanos , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Mimetismo Molecular , Inibidores da Síntese de Ácido Nucleico/farmacologia , Fenantridinas/química , Ligação Proteica/efeitos dos fármacos , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Estaurosporina/farmacologia , Células Tumorais Cultivadas , Proteína Killer-Antagonista Homóloga a bcl-2 , Proteína X Associada a bcl-2 , Proteína bcl-XRESUMO
One new compound, 14-hydroxyartonin E (1), together with the known compound, artonin E (2), was isolated from Artocarpus lanceifolus. Their structures were elucidated by spectroscopic methods.
Assuntos
Artocarpus , Flavonoides/química , Fitoterapia , Humanos , Espectroscopia de Ressonância Magnética , Extratos Vegetais/química , Caules de PlantaRESUMO
Despite decades of research, malaria remains the world's most deadly parasitic disease. New treatments with novel mechanisms of action are urgently needed. Plasmepsin II is an aspartyl protease that has been validated as an antimalarial therapeutic target enzyme. Although natural products form the basis of most modern antimalarial drugs, no systematic high-throughput screening has been reported against this target. We have designed an effective strategy for carrying out high-throughput screening of an extensive library of natural products that uses a fluorescence resonance energy transfer primary screening assay in tandem with a fluorescence polarization assay. This strategy allows rapid screening of the library coupled with effective discrimination and elimination of false-positive samples and selection of true hits for chemical isolation of inhibitors of plasmepsin II.
Assuntos
Antimaláricos/farmacologia , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Avaliação Pré-Clínica de Medicamentos/métodos , Animais , Ácido Aspártico Endopeptidases/metabolismo , Transferência de Energia , Malária/tratamento farmacológico , Malária/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/enzimologia , Proteínas de Protozoários , Espectrometria de Fluorescência/métodosRESUMO
Two new compounds, agonodepsides A (1) and B (2), were isolated from a nonsporulating filamentous fungus, F7524. The compounds were purified via reversed-phase chromatography and their structures determined by spectroscopic methods. Agonodepside A (1) was found to inhibit the mycobacterial InhA enzyme with an IC50 value of 75 microM, while 2 was inactive at 100 microM.
Assuntos
Fungos/química , Hidroxibenzoatos/isolamento & purificação , Proteínas de Bactérias , Depsídeos , Derris/química , Hidroxibenzoatos/química , Hidroxibenzoatos/farmacologia , Concentração Inibidora 50 , Testes de Sensibilidade Microbiana , Estrutura Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/enzimologia , NAD/efeitos dos fármacos , Ressonância Magnética Nuclear Biomolecular , Oxirredutases/efeitos dos fármacos , Folhas de Planta/química , Plantas/químicaRESUMO
Crude MeOH extracts from the stem bark and leaves of a Panamanian specimen of Albizia adinocephala (Leguminosae) were found to inhibit the malarial enzyme plasmepsin II. Bioassay guided fractionation led to the isolation of two new bioactive spermine alkaloids, budmunchiamines L4 and L5.
Assuntos
Alcaloides/farmacologia , Ácido Aspártico Endopeptidases/efeitos dos fármacos , Fabaceae/química , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/enzimologia , Espermina/análogos & derivados , Espermina/farmacologia , Alcaloides/química , Animais , Antimaláricos/química , Antimaláricos/farmacologia , Cromatografia Líquida de Alta Pressão , Estrutura Molecular , Estruturas Vegetais/química , Proteínas de Protozoários , Espectrofotometria Infravermelho , Espermina/química , Relação Estrutura-AtividadeRESUMO
In addition to the sesquiterpene-phenol aureols (1), 6'-chloroaureol (2), and aureol acetate (3), eight indole alkaloids including the new N-3'-ethylaplysinopsin (9) have been isolated from the Jamaican sponge Smenospongia aurea. Makaluvamine O (10), a new member of the pyrroloiminoquinone class, was also isolated. The structures were characterized by spectroscopic methods, and two new derivatives of aureol were prepared to optimize the biological activity. Aureol N,N-dimethyl thiocarbamate (1a) and 6-bromoaplysinopsin (7) exhibit significant antimalarial and antimycobacterial activity in vitro. Compound 6 showed activity against the Plasmodium enzyme plasmepsin II. The 6-bromo-2'-de-N-methylaplysinopsin (6), 6-bromoaplysinopsin (7), and N-3'-ethylaplysinopsin (9) displaced high-affinity [(3)H]antagonist ligands from cloned human serotonin 5-HT(2) receptor subtypes, whereas the other compounds tested did not. Remarkably, the 6-bromo-2'-de-N-methylaplysinopsin (6) showed a > 40-fold selectivity for the 5-HT(2C) subtype over the 5-HT(2A) subtype.