RESUMEN
Cyclohelminthols Y1-Y4 (1-4) were isolated from the culture broth of Helminthosporium velutinum yone96. These compounds are diastereomers to each other featuring 3-azabicyclo[3.1.0]hexane-6-spirocyclopentane linked with a cyclopentanespirocyclopropane framework. Their planar structures were established via the comparison of their spectra with the simpler analogue cyclohelminthol X as well as analysis of their HMBC spectra. Although the proton-deficient core frameworks of 1-4 prevented us from obtaining configurational information via conventional NMR analysis, their total structures involving the relative and absolute configurations were established using density functional theory (DFT)-based molecular modeling calculations. The present study demonstrates the effectiveness of the comparison between the theoretical and experimental δ13C values for stereochemical analysis by focusing on the carbons that show relatively large δ13C deviations among the isomers. The G-ring of these molecules most likely originates from the cyclopropanation of the C6C7 double bond with the carbene equivalent 6 derived from cyclohelminthol IV (7), which was isolated from the same producer fungus. Preliminary biological experiments revealed the potent cytotoxicity of the (6 S)-isomers against COLO201 cells, whereas the (6 R)-isomers exhibited weak activity. The antifungal assay with Cochiobolus miyabeanus showed a slightly different profile.
Asunto(s)
Antifúngicos/farmacología , Antineoplásicos/farmacología , Ascomicetos/efectos de los fármacos , Ciclopropanos/farmacología , Helminthosporium/química , Compuestos de Espiro/farmacología , Antifúngicos/química , Antifúngicos/metabolismo , Antineoplásicos/química , Antineoplásicos/metabolismo , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Ciclopropanos/química , Ciclopropanos/metabolismo , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Helminthosporium/metabolismo , Humanos , Pruebas de Sensibilidad Microbiana , Conformación Molecular , Teoría Cuántica , Compuestos de Espiro/química , Compuestos de Espiro/metabolismo , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
Helminthosporium velutinum yone96 produces cyclohelminthol X (1), a unique hexa-substituted spirocyclopropane. Although its molecular formula and NMR spectral data resemble those of AD0157, being isolated from marine fungus Paraconiothyrium sp. HL-78-gCHSP3-B005, our detailed analyses disclosed a totally different structure. Chemical shift calculations and electronic circular dichroism spectral calculations were quite helpful to establish the structure, when those were performed based on density functional theory. The carbon framework of cyclohelminthols I-IV is found at the C1-C8 propenylcyclopentene substructure of 1. Thus, 1 is assumed to be biosynthesized by cyclopropanation between an oxidized form of cyclohelminthol IV and a succinic anhydride derivative 4. Cytotoxicity for two cancer cell lines and proteasome inhibition efficiency are measured.
Asunto(s)
Antineoplásicos/química , Antineoplásicos/farmacología , Ciclopropanos/química , Ciclopropanos/farmacología , Helminthosporium/química , Compuestos de Espiro/química , Compuestos de Espiro/farmacología , Antineoplásicos/aislamiento & purificación , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Dicroismo Circular , Ciclopropanos/aislamiento & purificación , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Electrones , Células HL-60 , Humanos , Conformación Molecular , Complejo de la Endopetidasa Proteasomal/efectos de los fármacos , Compuestos de Espiro/aislamiento & purificación , Relación Estructura-ActividadRESUMEN
Treatment of high-risk neuroblastoma (NB) is difficult. Novel therapeutics improving survival rates are urgently required. We have previously shown that the histone deacetylase inhibitor (HDACI) Helminthosporium carbonum (HC)-toxin induces differentiation of neuroblastoma (NB) cells. Here, we show that HC-toxin inhibits the growth of both established NB cell lines and primary cultures with and without amplified MYCN stronger than retinoids (RAs) and other HDACIs (MS-275, n-butyric acid, suberoylanilide hydroxamic acid, trichostatin A, valproic acid). Nanomolar dosages suppress E2F-1, N-myc, Skp2, Mad2 and survivin proteins, found at high levels in high-risk NBs, more efficiently than both RAs and other HDACIs. The level of hypophosphorylated active retinoblastoma (RB) tumor suppressor protein is increased most effectively. HC-toxin's epoxy group is essential for inhibiting HDACs and promoting anti-NB activity. Without this functional group, those cellular effects are not observed. In conclusion, the anti-NB activity of HC-toxin is superior to that of RAs and that of all other HDACIs tested.
Asunto(s)
Antineoplásicos/farmacología , Diferenciación Celular/efectos de los fármacos , Helminthosporium , Micotoxinas/farmacología , Neuroblastoma/tratamiento farmacológico , Péptidos Cíclicos/farmacología , Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Helminthosporium/química , Inhibidores de Histona Desacetilasas , Humanos , Concentración 50 Inhibidora , Neuroblastoma/metabolismo , Fosforilación/efectos de los fármacos , Proteína de Retinoblastoma/efectos de los fármacos , Proteína de Retinoblastoma/metabolismo , Relación Estructura-ActividadRESUMEN
(-)-Siccanin (1), a natural product possessing significant antifungal properties, was synthesized enantioselectively via a biomimetic route. This synthetic route features two sequential radical cyclizations: a Ti(III)-mediated radical cyclization of epoxyolefin 48 to construct the B-ring, and a Suarez reaction to establish the tetrahyrofuran ring. Chiral chroman moiety of siccanin was prepared based on our recent development of the Pd-catalyzed asymmetric allylic alkylation (AAA) of phenol trisubstituted allyl carbonates. Several other members of the siccanin family were also synthesized including siccanochromenes A (2), B (3), E (6), F (7), and the methyl ether of siccanochromene C (55). These studies may shed light on the biosynthesis of this novel family of compounds.
Asunto(s)
Compuestos Alílicos/química , Xantenos/síntesis química , Alquilación , Antifúngicos/síntesis química , Materiales Biomiméticos/química , Catálisis , Ciclización , Helminthosporium/química , Helminthosporium/metabolismo , Modelos Moleculares , Paladio/química , EstereoisomerismoRESUMEN
It has been shown that sodium butyrate (NaBu) does not elicit neurite outgrowth of PC12, one of the most widely used cell lines as a model of neuronal differentiation. In this study, the effects of NaBu on nerve growth factor (NGF)- and cholera toxin-induced neurite outgrowth in PC12 cells were examined. NaBu dose-dependently enhanced neurite formation induced by both agents. The maximum responses obtained at 0.5 mM NaBu were nearly twice those of the inducers alone. Propionate and valerate were also effective, but acetate and caproate were ineffective. Among the butyrate analogs with a moiety of three to five carbon atoms tested, isobutyrate, isovalerate, vinylacetate and 3-chloropropionate enhanced neurite outgrowth promoted by both inducers. However, neither alpha-, beta-, and gamma-aminobutyrates nor alpha-, beta-, and gamma-hydroxybutyrates were effective. All of the effective short-chain fatty acids and their analogs increased the level of histone acetylation, while ineffective ones did not. Furthermore, Helminthosporium carbonum toxin (HC toxin), a structurally dissimilar inhibitor of histone deacetylase, mimicked the effect of butyrate. These results suggest that NaBu enhances neurite outgrowth induced by NGF and cholera toxin in PC12 cells through a mechanism involving an increase in the level of histone acetylation.
Asunto(s)
Butiratos/farmacología , Toxina del Cólera/farmacología , Factores de Crecimiento Nervioso/farmacología , Neuritas/efectos de los fármacos , Acetilación , Animales , Diferenciación Celular/efectos de los fármacos , Densitometría , Sinergismo Farmacológico , Inhibidores Enzimáticos/farmacología , Helminthosporium/química , Inhibidores de Histona Desacetilasas , Histona Desacetilasas/metabolismo , Histonas/metabolismo , Ácidos Hidroxámicos/farmacología , Indicadores y Reactivos , Micotoxinas/química , Células PC12 , RatasRESUMEN
From the inner tissue of the marine red alga Liagora viscida the fungus Drechslera dematioidea was isolated. After mass cultivation, the fungus was investigated for its secondary metabolite content, and 10 new sesquiterpenoids [isosativenetriol (1), drechslerines A (2) and B (3), 9-hydroxyhelminthosporol (5), drechslerines C-G (6-10), and sativene epoxide (12)] were isolated. Compounds 8 and 10 exhibited antiplasmodial activity against Plasmodium falciparum strains K1 and NF54. The known compounds helminthosporol (4), cis-sativenediol (11), isocochlioquinone A (14), isocochlioquinone C (15), and cochlioquinone B (16) were also isolated. All structures were elucidated using spectroscopic methods, mainly 1D and 2D NMR and MS.
Asunto(s)
Antibacterianos/aislamiento & purificación , Antiinfecciosos/aislamiento & purificación , Antifúngicos/aislamiento & purificación , Antimaláricos/aislamiento & purificación , Inhibidores Enzimáticos/aislamiento & purificación , Helminthosporium/química , Sesquiterpenos/aislamiento & purificación , Animales , Antibacterianos/química , Antibacterianos/farmacología , Antiinfecciosos/química , Antiinfecciosos/farmacología , Antifúngicos/química , Antifúngicos/farmacología , Antimaláricos/química , Antimaláricos/farmacología , Artemia/efectos de los fármacos , Bacillus megaterium/efectos de los fármacos , Caenorhabditis elegans/efectos de los fármacos , Chlorophyta/efectos de los fármacos , Cromatografía Líquida de Alta Presión , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Escherichia coli/efectos de los fármacos , Fusarium/efectos de los fármacos , Proteína Tirosina Quinasa p56(lck) Específica de Linfocito/metabolismo , Espectrometría de Masas , Mar Mediterráneo , Estructura Molecular , Mycobacterium tuberculosis/efectos de los fármacos , Resonancia Magnética Nuclear Biomolecular , Plasmodium falciparum/efectos de los fármacos , Rhodophyta , Sesquiterpenos/química , Sesquiterpenos/farmacología , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
A cellular protein that co-purifies with mycoviral dsRNA was isolated from the plant pathogenic fungus Helminthosporium victoriae (telomorph: Cochliobolus victoriae) infected with two viruses, the totivirus Helminthosporium victoriae 190S virus and the chrysovirus-like Helminthosporium victoriae 145S virus (Hv145SV). The cellular protein, which was, designated Hv-p68, accumulated to higher levels in virus-infected isolates compared to virus-free ones. The majority of the Hv145S dsRNAs were found in association with Hv-p68 and not packaged in virions. Hv-p68 could also be detected as a minor component of the virus capsid. Evidence is presented that Hv-p68 occurs in vivo as an octamer and that it possesses RNA-binding activities. Based on partial amino acid sequence analysis, Hv-p68 was shown to share significant sequence identity with alcohol oxidases from methylotrophic yeasts. Hv-p68 is proposed to play a role in viral RNA packaging/replication and in regulating viral pathogenesis.
Asunto(s)
Helminthosporium/química , Helminthosporium/virología , ARN Bicatenario/metabolismo , ARN Viral/metabolismo , Proteínas de Unión al ARN/aislamiento & purificación , Proteínas de Unión al ARN/metabolismo , Oxidorreductasas de Alcohol/química , Secuencia de Aminoácidos , Cápside/metabolismo , Cápside/ultraestructura , Centrifugación por Gradiente de Densidad , Helminthosporium/enzimología , Helminthosporium/genética , Microscopía Electrónica , Datos de Secuencia Molecular , Unión Proteica , Estructura Cuaternaria de Proteína , Sondas ARN/genética , Sondas ARN/metabolismo , Virus ARN/genética , Virus ARN/aislamiento & purificación , Virus ARN/metabolismo , Virus ARN/ultraestructura , ARN Bicatenario/genética , ARN Bicatenario/aislamiento & purificación , ARN Viral/genética , ARN Viral/aislamiento & purificación , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/ultraestructura , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Ensamble de VirusRESUMEN
Two new sesquiterpenoid antibiotics, hongoquercins A and B, were isolated from the extracts of an unidentified fungus. The structures of both metabolites were determined by spectroscopic analysis. They are related to a class of compounds commonly found in brown algae and dictyoceratid sponges. Hongoquercin A exhibited moderate activity against gram-positive bacteria.
Asunto(s)
Antibacterianos , Helminthosporium/química , Antibacterianos/química , Antibacterianos/aislamiento & purificación , Antibacterianos/farmacología , Candida albicans/efectos de los fármacos , Recuento de Colonia Microbiana , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Espectroscopía de Resonancia Magnética , Conformación Molecular , Estructura Molecular , Sesquiterpenos/química , Sesquiterpenos/aislamiento & purificación , Sesquiterpenos/farmacologíaRESUMEN
In a previous study with airborne mould extracts we verified that Drechslera (Helminthosporium) monoceras presented stronger reactions than those presented by 42 other moulds isolated in São Paulo city. In the present study, we evaluated the biochemical composition and the antigenicity of crude extracts obtained from vegetative and conidial stage of D. monoceras using Czapeck broth (CB) modified and tris-HCl for extraction. The maximum values of total proteins and lipids were verified in the crude extract obtained in the 28th day of growth, and maximum values of carbohydrates were observed in the extracts of the 16th, 22nd and 26th days. The fractionated proteins by SDS-PAGE presented bands with molecular weights between 14.4 to 67 Kd; the 28th day extract showed a larger number of bands. The carbohydrates and amino acids were characterized by thin-layer chromatography. The antigenicity of the crude extracts was verified by immunodiffusion reaction in agar against rabbit hyperimmune sera. Precipitation lines were observed in all studied extracts and common antigenic molecular populations. Based on the above results, the 28th day extract was selected to verify the induction of IgE antibody responses in immunizations of Balb/c and cAF-1 mice, and titer by passive cutaneous anaphylaxis test using Wistar rats. The maximum titers obtained were 160 in cAF-1 mice and 1.280 in Balb/c mice. The results suggest that the 28th day extract contains allergenic fractions and should be chosen for future studies related to fractionation, characterization and standardization in diagnostic methods and immunotherapy.