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1.
Nat Commun ; 11(1): 5371, 2020 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-33097715

RESUMO

Autoinducer-2 (AI-2) is a quorum sensing signal that mediates communication within and between many bacterial species. However, its known receptors (LuxP and LsrB families) are not found in all the bacteria capable of responding to this signaling molecule. Here, we identify a third type of AI-2 receptor, consisting of a dCACHE domain. AI-2 binds to the dCACHE domain of chemoreceptors PctA and TlpQ of Pseudomonas aeruginosa, thus inducing chemotaxis and biofilm formation. Boron-free AI-2 is the preferred ligand for PctA and TlpQ. AI-2 also binds to the dCACHE domains of histidine kinase KinD from Bacillus subtilis and diguanylate cyclase rpHK1S-Z16 from Rhodopseudomonas palustris, enhancing their enzymatic activities. dCACHE domains (especially those belonging to a subfamily that includes the AI-2 receptors identified in the present work) are present in a large number of bacterial and archaeal proteins. Our results support the idea that AI-2 serves as a widely used signaling molecule in the coordination of cell behavior among prokaryotic species.


Assuntos
Quimiotaxia/fisiologia , Homosserina/análogos & derivados , Homosserina/metabolismo , Lactonas/metabolismo , Células Procarióticas/metabolismo , Proteínas Arqueais , Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biofilmes/crescimento & desenvolvimento , Liases de Carbono-Enxofre/genética , Liases de Carbono-Enxofre/metabolismo , Proteínas de Transporte/metabolismo , Escherichia coli/metabolismo , Proteínas de Escherichia coli , Homosserina/química , Homosserina/genética , Lactonas/química , Ligantes , Fósforo-Oxigênio Liases , Pseudomonas aeruginosa/metabolismo , Percepção de Quorum , Rodopseudomonas/metabolismo , Transdução de Sinais/fisiologia
2.
J Chromatogr A ; 1626: 461361, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797840

RESUMO

The alkaloid enantiomers are well-known to have different physiological and pharmacological effects, and to play an important role in enantioselectivity metabolism with enzymes catalysis in tobacco plants. Here, we developed an improved method for simultaneous and high-precision determination of the individual enantiomers of nornicotine, anatabine and anabasine in four tobacco matrices, based on an achiral gas chromatography-nitrogen phosphorus detector (GCNPD) with commonly available Rtx-200 column using (1S)-(-)-camphanic chloride derivatization. The method development consists of the optimization of extraction and derivatization, screening of achiral column, analysis of the fragmentation mechanisms and evaluation of matrix effect (ME). Under the optimized experimental conditions, the current method exhibited excellent detection capability for the alkaloid enantiomers, with coefficients of determination (R2) > 0.9989 and normality test of residuals P > 0.05 in linear regression parameters. The ME can be neglected for the camphanic derivatives. The limit of detection (LOD) and limit of quantitation (LOQ) ranged from 0.087 to 0.24 µg g - 1 and 0.29 to 0.81 µg g - 1, respectively. The recoveries and within-laboratory relative standard deviations (RSDR) were 94.3%~104.2% and 0.51%~3.89%, respectively. The developed method was successfully applied to determine the enantiomeric profiling of cultivars and curing processes. Tobacco cultivars had a significant impact on the nornicotine, anatabine, anabasine concentration and enantiomeric fraction (EF) of (R)-nornicotine, whereas the only significant change induced by the curing processes was an increase in the EF of (R)-anabasine.


Assuntos
Alcaloides/análise , Anabasina/análise , Cromatografia Gasosa/métodos , Nicotina/análogos & derivados , Piridinas/análise , Tabaco/química , Alcaloides/química , Anabasina/química , Hidrocarbonetos Aromáticos com Pontes/química , Cloretos/química , Lactonas/química , Nicotina/análise , Nicotina/química , Piridinas/química , Estereoisomerismo
3.
Proc Natl Acad Sci U S A ; 117(33): 19720-19730, 2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32732435

RESUMO

The synthesis of quinolinic acid from tryptophan is a critical step in the de novo biosynthesis of nicotinamide adenine dinucleotide (NAD+) in mammals. Herein, the nonheme iron-based 3-hydroxyanthranilate-3,4-dioxygenase responsible for quinolinic acid production was studied by performing time-resolved in crystallo reactions monitored by UV-vis microspectroscopy, electron paramagnetic resonance (EPR) spectroscopy, and X-ray crystallography. Seven catalytic intermediates were kinetically and structurally resolved in the crystalline state, and each accompanies protein conformational changes at the active site. Among them, a monooxygenated, seven-membered lactone intermediate as a monodentate ligand of the iron center at 1.59-Å resolution was captured, which presumably corresponds to a substrate-based radical species observed by EPR using a slurry of small-sized single crystals. Other structural snapshots determined at around 2.0-Å resolution include monodentate and subsequently bidentate coordinated substrate, superoxo, alkylperoxo, and two metal-bound enol tautomers of the unstable dioxygenase product. These results reveal a detailed stepwise O-atom transfer dioxygenase mechanism along with potential isomerization activity that fine-tunes product profiling and affects the production of quinolinic acid at a junction of the metabolic pathway.


Assuntos
3-Hidroxiantranilato 3,4-Dioxigenase/química , Proteínas de Bactérias/química , Cupriavidus/enzimologia , 3-Hidroxiantranilato 3,4-Dioxigenase/genética , 3-Hidroxiantranilato 3,4-Dioxigenase/metabolismo , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Domínio Catalítico , Cristalização , Cristalografia por Raios X , Cupriavidus/química , Cupriavidus/genética , Cinética , Lactonas/química , Lactonas/metabolismo , Modelos Moleculares , Especificidade por Substrato
4.
J Chromatogr A ; 1624: 461155, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32540056

RESUMO

The topic in the present paper is to prepare molecularly imprinted polymer (MIP) using the template molecule with low purity. For the first time, a surrounding of macromolecular crowding was established to promote the formation of the complex of the template with functional monomer efficiently thus highly pure template molecule was unnecessary. In this study, the MIP monolith was synthesized using low purity lactucopicrin as template in place of highly pure one, and polystyrene was used as macromolecular crowding agent. 4-Vinylpyridine and ethyleneglycol dimethacrylate were used as functional monomer and crosslinker, respectively. Polymerization parameters, including the ratio of functional monomer/template, various template concentrations, and PS concentration on the affinity of the resulting MIP were systematically investigated. For the lactucopicrin MIP made with the purity of lactucopicrin of 92%, the imprinting factor can be up to 2.2. The resulting MIP was filled in solid phase extraction (SPE) cartridge to purify lactucopicrin from the crude extract of Cichorium glandulosum Boiss. et Huet. After two cycles of MIP SPE for the crude extract, the highest recovery and purity of lactucopicrin was 64.8% and 97.8%, respectively. The results indicated that the use of macromolecular crowding agent is an effective method for improving the performance of the MIP prepared with the template of low purity, particularly valuable to the cases in which the highly pure target molecule is hard to be obtained.


Assuntos
Impressão Molecular , Polímeros/química , Asteraceae/química , Reagentes para Ligações Cruzadas/química , Lactonas/química , Lactonas/isolamento & purificação , Metacrilatos/química , Polimerização , Poliestirenos/química , Piridinas/química , Sesquiterpenos/química , Sesquiterpenos/isolamento & purificação , Extração em Fase Sólida
5.
Mol Pharmacol ; 98(2): 156-167, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32591477

RESUMO

The natural product (+)-discodermolide (DDM) is a microtubule stabilizing agent and potent inducer of senescence. We refined the structure of DDM and evaluated the activity of novel congeners in triple negative breast and ovarian cancers, malignancies that typically succumb to taxane resistance. Previous structure-activity analyses identified the lactone and diene as moieties conferring anticancer activity, thus identifying priorities for the structural refinement studies described herein. Congeners possessing the monodiene with a simplified lactone had superior anticancer efficacy relative to taxol, particularly in resistant models. Specifically, one of these congeners, B2, demonstrated 1) improved pharmacologic properties, specifically increased maximum response achievable and area under the curve, and decreased EC50; 2) a uniform dose-response profile across genetically heterogeneous cancer cell lines relative to taxol or DDM; 3) reduced propensity for senescence induction relative to DDM; 4) superior long-term activity in cancer cells versus taxol or DDM; and 5) attenuation of metastatic characteristics in treated cancer cells. To contrast the binding of B2 versus DDM in tubulin, X-ray crystallography studies revealed a shift in the position of the lactone ring associated with removal of the C2-methyl and C3-hydroxyl. Thus, B2 may be more adaptable to changes in the taxane site relative to DDM that could account for its favorable properties. In conclusion, we have identified a DDM congener with broad range anticancer efficacy that also has decreased risk of inducing chemotherapy-mediated senescence. SIGNIFICANCE STATEMENT: Here, we describe the anticancer activity of novel congeners of the tubulin-polymerizing molecule (+)-discodermolide. A lead molecule is identified that exhibits an improved dose-response profile in taxane-sensitive and taxane-resistant cancer cell models, diminished risk of chemotherapy-mediated senescence, and suppression of tumor cell invasion endpoints. X-ray crystallography studies identify subtle changes in the pose of binding to ß-tubulin that could account for the improved anticancer activity. These findings support continued preclinical development of discodermolide, particularly in the chemorefractory setting.


Assuntos
Alcanos/química , Carbamatos/química , Lactonas/síntese química , Neoplasias Ovarianas/metabolismo , Pironas/química , Neoplasias de Mama Triplo Negativas/metabolismo , Moduladores de Tubulina/síntese química , Células A549 , Área Sob a Curva , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Feminino , Humanos , Lactonas/química , Lactonas/farmacologia , Estrutura Molecular , Neoplasias Ovarianas/tratamento farmacológico , Taxoides/farmacologia , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Moduladores de Tubulina/química , Moduladores de Tubulina/farmacologia
6.
Food Chem ; 331: 127277, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32544653

RESUMO

A novel nanocomposite poly(ethylene-co-vinyl acetate) (EVA) film with controlled in vitro release of iprodione (ID) was prepared. Chitosan (CS) was used as the reinforcement which enhances the water and oxygen permeability of films. ID loaded poly(ethylene glycol)-poly(ε-caprolactone) (PEG-PCL) (IPP) micelles were used as the drug carrier which endows the films with antifungal and controlled release ability. IPP micelles with spherical shape and uniform size were obtained, and the maximum encapsulation efficacy (EE) was 91.17 ± 5.03% by well controlling the feeding amount of ID. Incorporation CS could improve the oxygen and moisture permeability of films, and the maximum oxygen permeability (OP) and water vapor transmission rate (WVTR) were 477.84 ± 13.03 cc/(m2·d·0.1 MPa) and 8.60 ± 0.25 g m-2 d-1, respectively. After loading IPP micelles, the films showed an improved antifungal ability and temperature-sensitive drug release behavior, and were found to enhance the quality of grapes by pre-harvest spraying.


Assuntos
Aminoimidazol Carboxamida/análogos & derivados , Hidantoínas/farmacocinética , Nanocompostos/química , Vitis/efeitos dos fármacos , Aminoimidazol Carboxamida/administração & dosagem , Aminoimidazol Carboxamida/farmacocinética , Quitosana/química , Preparações de Ação Retardada , Portadores de Fármacos , Microbiologia de Alimentos , Fungicidas Industriais/administração & dosagem , Fungicidas Industriais/farmacocinética , Hidantoínas/administração & dosagem , Lactonas/química , Micelas , Oxigênio , Permeabilidade , Polietilenoglicóis/química , Polivinil/química , Vapor
7.
Chemosphere ; 255: 126945, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32388260

RESUMO

This study investigated the effects of exogenous N-acyl-homoserine lactone (AHL) signal molecules, N-hexanoyl-l-homoserine lactone (C6-HSL) and N-octanoyl-l-homoserine lactone (C8-HSL), on treatment performance, sludge properties and microbial community structures in activated sludge systems. Results showed that the nitrification and denitrification efficiencies were enhanced with the addition of signal molecules. The particle size, irregularity, and internal mass transfer resistance of activated sludge flocs (ASFs) increased, primarily because dosing AHLs led to a content increase and chemical composition variation of extracellular polymeric substances (EPS) in sludge. Microbial analysis indicated an increase in both the bacterial richness and diversity of the systems. The relative abundances of the key functional groups, including bacteria related to C and N removal and EPS production, varied correspondingly. This study presents an insight into the comprehensive understanding of the effects of AHL-based quorum sensing on activated sludge treatment process.


Assuntos
Acil-Butirolactonas/química , Lactonas/química , 4-Butirolactona/análogos & derivados , Bactérias , Microbiota , Nitrificação , Nutrientes , Percepção de Quorum , Esgotos/química
8.
Phytomedicine ; 71: 153239, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32447245

RESUMO

BACKGROUND AND PURPOSE: Multidrug resistance (MDR) remains the main obstacle in cancer treatment and overexpression of P-glycoprotein (P-gp) is one of the most common causes of chemoresistance. The development of novel P-gp inhibitors from natural products is a prospective strategy to combat MDR cancers. Among the natural sesquiterpene compounds, sesquiterpene pyridine alkaloids exhibit various biological properties. Therefore, in the present study, we evaluated the modulatory effects of wilforine on P-gp expression and function. The molecular mechanisms and kinetic models of wilforine-mediated P-gp inhibition were further investigated. METHODS: The human P-gp stable expression cells (ABCB1/Flp-InTM-293) and human cervical cancer cells (sensitive: HeLaS3; MDR: KBvin) were used. The cell viability was assessed by SRB assay. The inhibitory effect of wilforine on P-gp efflux and the underlying mechanism were evaluated by assays for calcein-AM uptake, rhodamine123 and doxorubicin efflux, ATPase activity, real-time quantitative RT-PCR, apoptosis, and cell cycle analysis. Molecular docking was performed by the docking software CDOCKER with BIOVIA Discovery Studio 4.5 (D.S. 4.5). RESULTS: We found that wilforine significantly inhibited the efflux activity of P-gp in a concentration-dependent manner. Further kinetic analysis demonstrated that wilforine significantly inhibited P-gp efflux function by competitive inhibition and stimulated the basal P-gp ATPase activity. In addition, wilforine re-sensitized MDR cancer cells to chemotherapeutic drugs. The docking model indicated that wilforine was bound to residues of P-gp such as LEU884, LYS887, THR176 and ASN172. CONCLUSION: These results suggest a novel future therapeutic strategy for MDR cancer using wilforine as an adjuvant treatment with chemotherapy.


Assuntos
Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Lactonas/farmacologia , Piridinas/farmacologia , Subfamília B de Transportador de Cassetes de Ligação de ATP/antagonistas & inibidores , Subfamília B de Transportador de Cassetes de Ligação de ATP/química , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Resistencia a Medicamentos Antineoplásicos/fisiologia , Células HeLa , Humanos , Cinética , Lactonas/química , Simulação de Acoplamento Molecular , Estudos Prospectivos , Piridinas/química
9.
Mar Drugs ; 18(4)2020 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-32294900

RESUMO

Dysregulation of the Wnt/ß-catenin signaling pathway is involved in the development of human hepatocellular carcinoma and has thus emerged as a therapeutic target for this malignant tumor. In this study, we employed sensitive cell-based assays to identify aplykurodin A isolated from Aplysia kurodai as an antagonist of Wnt/ß-catenin signaling. Aplykurodin A inhibited ß-catenin responsive transcription, which was stimulated by a Wnt3a-conditioned medium or a glycogen synthase kinase 3ß inhibitor by accelerating intracellular ß-catenin degradation. Aplykurodin A downregulated the level of oncogenic ß-catenin and decreased the expression of ß-catenin-dependent gene, leading to inhibition of human hepatoma Hep3B and SNU475 cell proliferation. Moreover, apoptosis and autophagy were elicited by aplykurodin A, as indicated by an increase the number of Annexin V-FITC-stained cells and the formation of microtubule-associated protein 1 light chain 3 puncta, respectively, in Hep3B and SNU475 cells. Our findings suggest that aplykurodin A provides a novel therapeutic strategy for human hepatocellular carcinoma via stimulation of oncogenic ß-catenin degradation.


Assuntos
Antineoplásicos/química , Aplysia , Indanos/química , Lactonas/química , Animais , Antineoplásicos/farmacologia , Linhagem Celular Tumoral/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica , Humanos , Indanos/farmacologia , Lactonas/farmacologia , Via de Sinalização Wnt/efeitos dos fármacos , beta Catenina/genética
10.
J Chromatogr A ; 1621: 461054, 2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32204880

RESUMO

The enantioselective separation of newly prepared, pharmacologically significant isopulegol-based ß-amino lactones and ß-amino amides has been studied by carrying out high-performance liquid chromatography on diverse amylose and cellulose tris-(phenylcarbamate)-based chiral stationary phases (CSPs) in n-hexane/alcohol/diethylamine or n-heptane/alcohol/ diethylamine mobile phase systems. For the elucidation of mechanistic details of the chiral recognition, seven polysaccharide-based CSPs were employed under normal-phase conditions. The effect of the nature of selector backbone (amylose or cellulose) and the position of substituents of the tris-(phenylcarbamate) moiety was evaluated. Due to the complex structure and solvation state of polysaccharide-based selectors and the resulting enantioselective interaction sites, the chromatographic conditions (e.g., the nature and content of alcohol modifier) were found to exert a strong influence on the chiral recognition process, resulting in a particular elution order of the resolved enantiomers. Since no prediction can be made for the observed enantiomeric resolution, special attention has been paid to the identification of the elution sequences. The comparison between the effectiveness of covalently immobilized and coated polysaccharide phases allows the conclusion that, in several cases, the application of coated phases can be more advantageous. However, in general, the immobilized phases may be preferred due to their increased robustness. Thermodynamic parameters derived from the temperature-dependence of the selectivity revealed enthalpically-driven separations in most cases, but unusual temperature behavior was also observed.


Assuntos
Amilose/análogos & derivados , Celulose/análogos & derivados , Cromatografia Líquida de Alta Pressão/métodos , Monoterpenos Cicloexânicos/química , Amidas/química , Amidas/isolamento & purificação , Amilose/química , Celulose/química , Lactonas/química , Lactonas/isolamento & purificação , Fenilcarbamatos , Estereoisomerismo , Temperatura , Termodinâmica
11.
Food Chem ; 320: 126632, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32217431

RESUMO

Precise identification of the compounds characteristic to stored white teas is urgently needed as these products have unique flavors and health benefits that improve with storage duration. Owing to the potential applications in food quality discrimination, specific regularities between the enantiomeric distributions of 23 volatile lactones and terpenoids and storage durations of white teas were expected and investigated by enantioselective gas chromatography-mass spectrometry (Es-GC-MS) combined with multivariate statistical analysis. High correlation coefficients (-0.853 to 0.695) and significant differences (P < 0.001) between the enantiomeric ratios (ERs) of (2S, 5S)-linalool oxide A, (2S, 5R)-linalool oxide B, (2R, 5S)-theaspirane B, S-linalool, and (1R, 2S)-methyl epijasmonate and the storage durations (0-7 years) were obtained, and the contents of S-linalool and S/R-dihydroactinidiolide significantly decreased and increased, respectively, with the increasing of storage duration. Therefore, the aforementioned lactone and terpenoid enantiomers are potential markers for the reliable differentiation of white teas stored for different time periods.


Assuntos
Lactonas/química , Extratos Vegetais/química , Chá/química , Terpenos/química , Cromatografia Gasosa-Espectrometria de Massas , Estereoisomerismo
12.
J Chromatogr A ; 1620: 461004, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32143875

RESUMO

In the present study, a fast multiresidue method determining three novel fungicides fenpicoxamid, isofetamid, and mandestrobin in cereals was developed and validated for the first time using ultrahigh-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Samples were extracted by QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) methodology, and cleaned up using the disposable pipette extraction (DPX) tips containing primary secondary amine (PSA) and silica gel modified with zirconium oxide (Z-Sep) in less than 1 min. Linearity (r > 0.99) of three fungicides in the calibration range of 0.001-0.1 µg mL-1 was satisfactory. Mean recoveries (n = 15) from all matrices were between 84.8% and 100.3% as the corresponding intra-day and inter-day relative standard deviations (RSDs) were less than 10.6%. Limits of quantitation (LOQs) of all analytes in different matrices were defined at 0.01 mg kg-1. The results indicate this method can serve as a sensitive and rapid approach to monitoring contents of fenpicoxamid, isofetamid, and mandestrobin in cereals.


Assuntos
Acetamidas/análise , Cromatografia Líquida de Alta Pressão/métodos , Grão Comestível/química , Fungicidas Industriais/análise , Resíduos de Praguicidas/análise , Espectrometria de Massas em Tandem/métodos , Tiofenos/análise , Fracionamento Químico/instrumentação , Fungicidas Industriais/química , Fungicidas Industriais/isolamento & purificação , Lactonas/análise , Lactonas/química , Lactonas/isolamento & purificação , Resíduos de Praguicidas/química , Resíduos de Praguicidas/isolamento & purificação , Piridinas/análise , Piridinas/química , Piridinas/isolamento & purificação , Zircônio/química
13.
Org Biomol Chem ; 18(12): 2346-2359, 2020 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-32163082

RESUMO

Total synthesis of marine secondary metabolite nafuredin B has been achieved for the first time using a convergent strategy. Sharpless epoxidation followed by acid catalyzed epoxide opening were adopted to install the tetrasubstituted hydroxy center, whereas the iterative Julia-Kocienski olefination, Wittig olefination and HWE olefination afforded the olefin bonds. Ring closing metathesis in the presence of a free tetrasubstituted hydroxy group provided the unsaturated δ-lactone moiety. This synthetic study provided unambiguous structural confirmation of the isolated nafuredin B.


Assuntos
Pironas/síntese química , Alcenos/química , Compostos de Epóxi/química , Lactonas/química , Estrutura Molecular
14.
Chemistry ; 26(26): 5794-5798, 2020 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-32084294

RESUMO

Combining biological and small-molecule catalysts under a chemoenzymatic manifold presents a series of significant advantages to the synthetic community. We report herein the successful development of a two-step/single flask synthesis of γ-lactones through the merger of Umpolung catalysis with a ketoreductase-catalyzed dynamic kinetic resolution, reduction, and cyclization. This combined approach delivers highly enantio- and diastereoenriched heterocycles and demonstrates the feasibility of integrating NHC catalysis with enzymatic processes.


Assuntos
Lactonas/síntese química , Catálise , Ciclização , Cinética , Lactonas/química , Estrutura Molecular
15.
Org Biomol Chem ; 18(7): 1279-1336, 2020 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-32025682

RESUMO

Enantio- and diastereodivergent routes to marine-origin natural products with different sizes of cyclic ethers and lactones have been used in order to assign stereochemical features. Kainoid amino acids such as isodomoic acids have been synthesized using diastereodivergent routes. The bis(indole) alkaloid dragmacidin F has been prepared by enantiodivergent strategies as well as furanoterpenes and the tetracyclic agelastatin A. Natural products containing five-membered lactones like quercus lactones, muricatacins, goniofufuranones, methylenolactocins and frenolicin B have been synthesized using stereodivergent routes. Macrolides are very abundant lactones and have been mainly prepared from the corresponding seco-acids by lactonization, such as lasiodiplodin, zaeralanes, macrosphelides and haloprins, or by ring-closing metathesis, such as aspercyclides, microcarpalides, macrolides FD-891 and 892, and tetradic-5-en-9-olides. Other natural products including cyclic ethers (such as sesamin, asarinin, acetogenins, centrolobines and nabilones), alcohols (such as sulcatol), esters (such as methyl jasmonates), polycyclic precursors of fredericamycin, amino alcohols (such as ambroxol and sphingosines), isoprostanes, isofurans, polyketide precursors of anachelins, brevicomins, gummiferol, shikimic acid and the related compounds, and the pheromone disparlure have been synthesized stereodivergently. Heterocyclic systems such as epoxides, theobroxides and bromoxones, oxetan-3-ones, 5- to 8-membered cyclic ethers, azetidones, γ-lactams, oxazolidinones, bis(oxazolines), dihydropyridoisoindolines and octahydroisoquinolines have been prepared following stereodivergent routes. Stereodivergent routes to unnatural compounds such as alkenes, dienes, allenes, cyclopropanes, alcohols, aldols, amines, amino alcohols, ß-amino acids, carboxylic acids, lactones, nitriles and α-amino nitriles have been considered as well.


Assuntos
Produtos Biológicos/síntese química , Compostos Heterocíclicos/síntese química , Lactonas/síntese química , Álcoois/síntese química , Álcoois/química , Alcenos/síntese química , Alcenos/química , Aminas/síntese química , Aminas/química , Aminoácidos/síntese química , Aminoácidos/química , Produtos Biológicos/química , Ácidos Carboxílicos/síntese química , Ácidos Carboxílicos/química , Compostos Heterocíclicos/química , Lactonas/química , Estrutura Molecular , Nitrilos/síntese química , Nitrilos/química , Estereoisomerismo
16.
mBio ; 11(1)2020 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-32098820

RESUMO

Low doses of antibiotics can trigger secondary metabolite biosynthesis in bacteria, but the underlying mechanisms are generally unknown. We sought to better understand this phenomenon by studying how the antibiotic trimethoprim activates the synthesis of the virulence factor malleilactone in Burkholderia thailandensis Using transcriptomics, quantitative multiplexed proteomics, and primary metabolomics, we systematically mapped the changes induced by trimethoprim. Surprisingly, even subinhibitory doses of the antibiotic resulted in broad transcriptional and translational alterations, with ∼8.5% of the transcriptome and ∼5% of the proteome up- or downregulated >4-fold. Follow-up studies with genetic-biochemical experiments showed that the induction of malleilactone synthesis can be sufficiently explained by the accumulation of methionine biosynthetic precursors, notably homoserine, as a result of inhibition of the folate pathway. Homoserine activated the malleilactone gene cluster via the transcriptional regulator MalR and gave rise to a secondary metabolome which was very similar to that generated by trimethoprim. Our work highlights the expansive changes that low-dose trimethoprim induces on bacterial physiology and provides insights into its stimulatory effect on secondary metabolism.IMPORTANCE The discovery of antibiotics ranks among the most significant accomplishments of the last century. Although the targets of nearly all clinical antibiotics are known, our understanding regarding their natural functions and the effects of subinhibitory concentrations is in its infancy. Stimulatory rather than inhibitory functions have been attributed to low-dose antibiotics. Among these, we previously found that antibiotics activate silent biosynthetic genes and thereby enhance the metabolic output of bacteria. The regulatory circuits underlying this phenomenon are unknown. We take a first step toward elucidating these circuits and show that low doses of trimethoprim (Tmp) have cell-wide effects on the saprophyte Burkholderia thailandensis Most importantly, inhibition of one-carbon metabolic processes by Tmp leads to an accumulation of homoserine, which induces the production of an otherwise silent cytotoxin via a LuxR-type transcriptional regulator. These results provide a starting point for uncovering the molecular basis of the hormetic effects of antibiotics.


Assuntos
Antibacterianos/farmacologia , Burkholderia/efeitos dos fármacos , Burkholderia/metabolismo , Metabolismo Secundário/efeitos dos fármacos , Proteínas de Bactérias , Produtos Biológicos/metabolismo , Vias Biossintéticas/efeitos dos fármacos , Vias Biossintéticas/genética , Burkholderia/genética , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Homosserina/metabolismo , Lactonas/química , Lactonas/metabolismo , Família Multigênica , Metabolismo Secundário/genética , Trimetoprima/farmacologia , Fatores de Virulência/metabolismo
17.
Int J Mol Sci ; 21(3)2020 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-32046263

RESUMO

Reconstruction of ruptured anterior cruciate ligaments (ACLs) is limited by the availability and donor site morbidity of autografts. Hence, a tissue engineered graft could present an alternative in the future. This study was undertaken to determine the performance of lapine (L) ACL-derived fibroblasts on embroidered poly(l-lactide-co-ε-caprolactone) (P(LA-CL)) and polylactic acid (PLA) scaffolds in regard to a tissue engineering approach for ACL reconstruction. Surface modifications of P(LA-CL)/PLA by gas-phase fluorination and cross-linking of a collagen foam using either ethylcarbodiimide (EDC) or hexamethylene diisocyanate (HMDI) were tested regarding their influence on cell adhesion, growth and gene expression. The experiments were performed using embroidered P(LA-CL)/PLA scaffolds that were seeded dynamically or statically with LACL-derived fibroblasts. Scaffold cytocompatibility, cell survival, numbers, metabolic activity, ultrastructure and sulfated glycosaminoglycan (sGAG) synthesis were evaluated. Quantitative real-time polymerase chain reaction (QPCR) revealed gene expression of collagen type I (COL1A1), decorin (DCN), tenascin C (TNC), Mohawk (MKX) and tenomodulin (TNMD). All tested scaffolds were highly cytocompatible. A significantly higher cellularity and larger scaffold surface areas colonized by cells were detected in HMDI cross-linked and fluorinated scaffolds compared to those cross-linked with EDC or without any functionalization. By contrast, sGAG synthesis was higher in controls. Despite the fact that the significance level was not reached, gene expressions of ligament extracellular matrix components and differentiation markers were generally higher in fluorinated scaffolds with cross-linked collagen foams. LACL-derived fibroblasts maintained their differentiated phenotype on fluorinated scaffolds supplemented with a HMDI cross-linked collagen foam, making them a promising tool for ACL tissue engineering.


Assuntos
Lesões do Ligamento Cruzado Anterior/terapia , Ligamento Cruzado Anterior/citologia , Fibroblastos/citologia , Engenharia Tecidual/métodos , Animais , Caproatos/química , Linhagem Celular , Sobrevivência Celular/fisiologia , Colágeno/química , Feminino , Lactonas/química , Ligamentos/citologia , Camundongos , Microscopia Eletrônica de Varredura , Poliésteres/química , Tecidos Suporte/química
18.
Molecules ; 25(3)2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32019209

RESUMO

In our continuous search for new, relatively simple 2-alkylidene-1-oxoheterocycles as promising anticancer drug candidates, herein we report an efficient synthesis of 2,2,6-trisubstituted 5-methylidenetetrahydropyran-4-ones. These compounds were obtained in a four step reaction sequence, in which starting diethyl 2-oxopropylphosphonate was transformed into 2,2-disubstituted 5-diethoxyphosphoryldihydropyran-4-ones, followed by Michael addition of various Grignard reagents and Horner-Wadsworth-Emmons reaction of the obtained adducts with formaldehyde. Stereochemistry of the intermediate Michael adducts is also discussed. Final 5-methylidenetetrahydropyran-4-ones were tested for their possible antiproliferative effect against three cancer cell lines and 6-isopropyl-2,2-dimethyl-5-methylidenetetrahydropyran-4-one (11c), which showed very high cytotoxic activity against HL-60 human leukemia cells and was three times more active than known anticancer drug carboplatin, was selected for further biological evaluation, in order to disclose its mechanism of action. The obtained results indicated that 11c induced apoptosis in HL-60 cells and caused the arrest of the cell cycle in the G2/M phase, which may suggest its cytotoxic and cytostatic activity.


Assuntos
Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Ciclo Celular , Lactonas/química , Neoplasias/tratamento farmacológico , Apoptose , Proliferação de Células , Humanos , Estrutura Molecular , Neoplasias/patologia , Relação Estrutura-Atividade , Células Tumorais Cultivadas
19.
Sci Rep ; 10(1): 2614, 2020 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-32054953

RESUMO

Plants live in close association with microorganisms that can have beneficial or detrimental effects. The activity of bacteria in association with flowering plants has been extensively analysed. Bacteria use quorum-sensing as a way of monitoring their population density and interacting with their environment. A key group of quorum sensing molecules in Gram-negative bacteria are the N-acylhomoserine lactones (AHLs), which are known to affect the growth and development of both flowering plants, including crops, and marine algae. Thus, AHLs have potentially important roles in agriculture and aquaculture. Nothing is known about the effects of AHLs on the earliest-diverging land plants, thus the evolution of AHL-mediated bacterial-plant/algal interactions is unknown. In this paper, we show that AHLs can affect spore germination in a representative of the earliest plants on land, the Bryophyte moss Physcomitrella patens. Furthermore, we demonstrate that sporophytes of some wild isolates of Physcomitrella patens are associated with AHL-producing bacteria.


Assuntos
Briófitas/crescimento & desenvolvimento , Briófitas/microbiologia , Germinação , Percepção de Quorum , Bactérias/isolamento & purificação , Briófitas/metabolismo , Homosserina/análogos & derivados , Homosserina/metabolismo , Lactonas/química , Lactonas/metabolismo , Esporos/crescimento & desenvolvimento , Esporos/metabolismo
20.
Molecules ; 25(4)2020 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-32075004

RESUMO

The total synthesis of (-)-antrocin and its enantiomer are presented. Antrocin (-)-1 is an important natural product which acts as an antiproliferative agent in a metastatic breast cancer cell line (IC50: 0.6 µM). The key features of this synthesis are: (a) selective anti-addition of trimethylsilyl cyanide (TMSCN) to α,ß-unsaturated ketone; (b) resolution of (±)-7 using chiral auxiliary L-dimethyl tartrate through formation of cyclic ketal diastereomers followed by simple column chromatography separation and acid hydrolysis; (c) substrate-controlled stereoselective aldol condensation of (+)-12 with monomeric formaldehyde and pyridinium chlorochromate (PCC) oxidation for synthesis of essential lactone core in (-)-14; and (d) non-basic Lombardo olefination of the carbonyl at the final step to yield (-)-antrocin. In addition, (+)-9 cyclic ketal diastereomer was converted to (+)-antrocin with similar reaction sequences.


Assuntos
Produtos Biológicos/síntese química , Neoplasias da Mama/tratamento farmacológico , Proliferação de Células/efeitos dos fármacos , Lactonas/síntese química , Sesquiterpenos/síntese química , Produtos Biológicos/química , Produtos Biológicos/farmacologia , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Cianetos/síntese química , Cianetos/química , Feminino , Humanos , Lactonas/química , Lactonas/farmacologia , Metástase Neoplásica , Sesquiterpenos/química , Sesquiterpenos/farmacologia , Estereoisomerismo , Tartaratos/síntese química , Tartaratos/química , Compostos de Trimetilsilil/síntese química , Compostos de Trimetilsilil/química
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