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1.
J Chem Inf Model ; 63(23): 7588-7602, 2023 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-37994801

RESUMO

The estrogen-receptor alfa (ERα) is considered pivotal for breast cancer treatment. Although selective estrogen-receptor degraders (SERDs) have been developed to induce ERα degradation and antagonism, their agonistic effect on the uterine tissue and poor pharmacokinetic properties limit further application of ERα; thus, discovering novel SERDs is necessary. The ligand preferentially interacts with several key residues of the protein (defined as hot-spot residues). Improving the interaction with hot-spot residues of ERα offers a promising avenue for obtaining novel SERDs. In this study, pharmacophore modeling, molecular mechanics/generalized Born surface area (MM/GBSA), and amino-acid mutation were combined to determine several hot-spot residues. Focusing on the interaction with these hot-spot residues, hit fragments A1-A3 and A9 were virtually screened from two fragment libraries. Finally, these hit fragments were linked to generate compounds B1-B3, and their biological activities were evaluated. Remarkably, compound B1 exhibited potent antitumor activity against MCF-7 cells (IC50 = 4.21 nM), favorable ERα binding affinity (Ki = 14.6 nM), and excellent ERα degradative ability (DC50 = 9.7 nM), which indicated its potential to evolve as a promising SERD for breast cancer treatment.


Assuntos
Neoplasias da Mama , Feminino , Humanos , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Detecção Precoce de Câncer , Antagonistas de Estrogênios/farmacologia , Receptor alfa de Estrogênio/metabolismo , Estrogênios , Células MCF-7
2.
J Org Chem ; 87(17): 11722-11734, 2022 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-35968716

RESUMO

In this study, we report a novel and efficient synthetic method to construct isoquinolone scaffold via the Rh(III)-catalyzed (4 + 2) annulation of benzamide with an unreported coupling reagent methyl 2-chloroacrylate. Accordingly, other valuable 1,2-benzothiazine and naphtho[1',2':4,5]imidazo[1,2-a]pyridine derivatives are also obtained through a similar synthetic protocol. Thus, our developed method is highlighted by high yield and reaction versatility.


Assuntos
Ródio , Catálise , Piridinas , Tiazinas
3.
Bioorg Chem ; 115: 105268, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34426149

RESUMO

Inhibition of the interactions of the tumor suppressor protein p53 with its negative regulators MDM2 in vitro and in vivo, representing a valuable therapeutic strategy for cancer treatment. The natural product chalcone exhibited moderate inhibitory activity against MDM2, thus based on the binding mode between chalcone and MDM2, a hit unsaturated pyrrolidone scaffold was obtained through virtual screening. Several unsaturated pyrrolidone derivatives were synthesized and biological evaluated. As a result, because the three critical hydrophobic pockets of MDM2 were occupied by the substituted-phenyl linked at the pyrrolidone fragment, compound 4 h demonstrated good binding affinity with the MDM2. Additionally, compound 4 h also showed excellent antitumor activity and selectivity, and no cytotoxicity against normal cells in vitro. The further antitumor mechanism studies were indicated that compound 4 h could successfully induce the activation of p53 and corresponding downstream p21 proteins, thus successfully causing HCT116 cell cycle arrest in the G1/M phase and apoptosis. Thus, the novel unsaturated pyrrolidone p53-MDM2 inhibitors could be developed as novel antitumor agents.


Assuntos
Antineoplásicos/farmacologia , Desenho de Fármacos , Proteínas Proto-Oncogênicas c-mdm2/antagonistas & inibidores , Pirrolidinonas/farmacologia , Proteína Supressora de Tumor p53/antagonistas & inibidores , Antineoplásicos/síntese química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Estrutura Molecular , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Pirrolidinonas/síntese química , Pirrolidinonas/química , Relação Estrutura-Atividade , Proteína Supressora de Tumor p53/metabolismo
4.
Bioorg Med Chem ; 40: 116183, 2021 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-33965839

RESUMO

In an effort to probe the biophysical mechanisms of inhibition for ten previously-reported inhibitors of metallo-ß-lactamases (MBL) with MBL IMP-1, equilibrium dialysis, metal analyses coupled with atomic absorption spectroscopy (AAS), native state mass spectrometry (native MS), and ultraviolet-visible spectrophotometry (UV-VIS) were used. 6-(1H-tetrazol-5-yl) picolinic acid (1T5PA), ANT431, D/l-captopril, thiorphan, and tiopronin were shown to form IMP-1/Zn(II)/inhibitor ternary complexes, while dipicolinic acid (DPA) and 4-(3-aminophenyl)pyridine-2,6-dicarboxylic acid (3AP-DPA) stripped some metal from the active site of IMP but also formed ternary complexes. DPA and 3AP-DPA stripped less metal from IMP-1 than from VIM-2 but stripped more metal from IMP-1 than from NDM-1. In contrast to a previous report, pterostilbene does not appear to bind to IMP-1 under our conditions. These results, along with previous studies, demonstrate similar mechanisms of inhibition toward different MBLs for different MBL inhibitors.


Assuntos
Ácidos Dicarboxílicos/farmacologia , Inibidores Enzimáticos/farmacologia , Compostos de Sulfidrila/farmacologia , Sulfetos/farmacologia , beta-Lactamases/metabolismo , Ácidos Dicarboxílicos/química , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/química , Espectrometria de Massas , Estrutura Molecular , Pseudomonas aeruginosa/enzimologia , Serratia marcescens/enzimologia , Espectrofotometria Atômica , Espectrofotometria Ultravioleta , Relação Estrutura-Atividade , Compostos de Sulfidrila/química , Sulfetos/química
5.
Sci Rep ; 11(1): 6906, 2021 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-33767227

RESUMO

Emerging evidence has highlighted the connection between exposure to air pollution and the increased risk of obesity, metabolic syndrome, and comorbidities. Given the recent interest in studying the effects of ultrafine particle (UFP) on the health of obese individuals, this study examined the effects of gastrointestinal UFP exposure on gut microbial composition and metabolic function using an in vivo murine model of obesity in both sexes. UFPs generated from light-duty diesel engine combustion of petrodiesel (B0) and a petrodiesel/biodiesel fuel blend (80:20 v/v, B20) were administered orally. Multi-omics approaches, including liquid chromatography-mass spectrometry (LC-MS) based targeted metabolomics and 16S rRNA gene sequence analysis, semi-quantitatively compared the effects of 10-day UFP exposures on obese C57B6 mouse gut microbial population, changes in diversity and community function compared to a phosphate buffer solution (PBS) control group. Our results show that sex-specific differences in the gut microbial population in response to UFP exposure can be observed, as UFPs appear to have a differential impact on several bacterial families in males and females. Meanwhile, the alteration of seventy-five metabolites from the gut microbial metabolome varied significantly (ANOVA p < 0.05) across the PBS control, B0, and B20 groups. Multivariate analyses revealed that the fuel-type specific disruption to the microbial metabolome was observed in both sexes, with stronger disruptive effects found in females in comparison to male obese mice. Metabolic signatures of bacterial cellular oxidative stress, such as the decreased concentration of nucleotides and lipids and increased concentrations of carbohydrate, energy, and vitamin metabolites were detected. Furthermore, blood metabolites from the obese mice were differentially affected by the fuel types used to generate the UFPs (B0 vs. B20).


Assuntos
Microbioma Gastrointestinal/efeitos dos fármacos , Obesidade/microbiologia , Material Particulado/toxicidade , Emissões de Veículos/toxicidade , Animais , Feminino , Masculino , Redes e Vias Metabólicas/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Obesidade/sangue , Caracteres Sexuais
6.
Cells ; 10(2)2021 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-33672651

RESUMO

Hepatocellular carcinoma (HCC) that is triggered by metabolic defects is one of the most malignant liver cancers. A much higher incidence of HCC among men than women suggests the protective roles of estrogen in HCC development and progression. To begin to understand the mechanisms involving estrogenic metabolic effects, we compared cell number, viability, cytotoxicity, and apoptosis among HCC-derived HepG2 cells that were treated with different concentrations of 2-deoxy-d-glucose (2-DG) that blocks glucose metabolism, oxamate that inhibits lactate dehydrogenase and glycolysis, or oligomycin that blocks ATP synthesis and mitochondrial oxidative phosphorylation. We confirmed that HepG2 cells primarily utilized glycolysis followed by lactate fermentation, instead of mitochondrial oxidative phosphorylation, for cell growth. We hypothesized that estrogen altered energy metabolism via its receptors to carry out its anticancer effects in HepG2 cells. We treated cells with 17ß-estradiol (E2), 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT) an estrogen receptor (ER) α (ERα) agonist, or 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN), an ERß agonist. We then used transcriptomic and metabolomic analyses and identified differentially expressed genes and unique metabolite fingerprints that are produced by each treatment. We further performed integrated multi-omics analysis, and identified key genes and metabolites in the gene-metabolite interaction contributed by E2 and ER agonists. This integrated transcriptomic and metabolomic study suggested that estrogen acts on estrogen receptors to suppress liver cancer cell growth via altering metabolism. This is the first exploratory study that comprehensively investigated estrogen and its receptors, and their roles in regulating gene expression, metabolites, metabolic pathways, and gene-metabolite interaction in HCC cells using bioinformatic tools. Overall, this study provides potential therapeutic targets for future HCC treatment.


Assuntos
Estrogênios/metabolismo , Neoplasias Hepáticas/metabolismo , Metabolômica , Contagem de Células , Proliferação de Células/efeitos dos fármacos , Desoxiglucose/farmacologia , Estradiol/farmacologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Células Hep G2 , Humanos , Redes e Vias Metabólicas/efeitos dos fármacos , Metaboloma/efeitos dos fármacos , Nitrilas/farmacologia , Oligomicinas/farmacologia , Pirazóis/farmacologia , Receptores de Estrogênio/metabolismo , Transcriptoma/genética
7.
Artigo em Inglês | MEDLINE | ID: mdl-33468463

RESUMO

Metallo-ß-lactamases (MBLs) are a growing clinical threat because they inactivate nearly all ß-lactam-containing antibiotics, and there are no clinically available inhibitors. A significant number of variants have already emerged for each MBL subfamily. To understand the evolution of imipenemase (IMP) genes (blaIMP) and their clinical impact, 20 clinically derived IMP-1 like variants were obtained using site-directed mutagenesis and expressed in a uniform genetic background in Escherichia coli strain DH10B. Strains of IMP-1-like variants harboring S262G or V67F substitutions exhibited increased resistance toward carbapenems and decreased resistance toward ampicillin. Strains expressing IMP-78 (S262G/V67F) exhibited the largest changes in MIC values compared to IMP-1. In order to understand the molecular mechanisms of increased resistance, biochemical, biophysical, and molecular modeling studies were conducted to compare IMP-1, IMP-6 (S262G), IMP-10 (V67F), and IMP-78 (S262G/V67F). Finally, unlike most New Delhi metallo-ß-lactamase (NDM) and Verona integron-encoded metallo-ß-lactamase (VIM) variants, the IMP-1-like variants do not confer any additional survival advantage if zinc availability is limited. Therefore, the evolution of MBL subfamilies (i.e., IMP-6, -10, and -78) appears to be driven by different selective pressures.


Assuntos
Carbapenêmicos , beta-Lactamases , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Carbapenêmicos/farmacologia , Escherichia coli/genética , Testes de Sensibilidade Microbiana , beta-Lactamases/genética
8.
Molecules ; 25(21)2020 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-33153091

RESUMO

The human gut microbiome plays an important role in human health, and many factors such as environment, host genetics, age, and diet have been found to influence the microbial composition. Tea, as one of the widely consumed beverages, has been known for centuries to have antioxidant, anti-inflammatory, and anticancer effects. To investigate the impact of green tea polyphenol on the diversity and metabolic functions of human gut microbes, we applied an in vitro human colonic model (HCM) in this study to mimic a short-term green tea ingestion event and investigate its related changes to gut microbial composition and their metabolic functions. The pH, temperature, anaerobic environment, feeding nutrient, and time point in each compartment of the HCM were tightly controlled to simulate the intestinal system, and pooled human fecal samples of two healthy volunteers were used for the colon microbiota inoculation within the colonic model. By adding green tea extract (GTE) to the growth medium, the detailed impacts of GTE polyphenol on gut microbial population/diversity, gut microbial metabolites, metabolic pathways, and their associations were investigated via 16 S ribosomal DNA sequencing and liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) analyses. Our data indicated that the treatment of green tea extract applied to gut microbiota can induce a significant decrease in the abundance of Firmicutes and a slight decrease in the abundance of Bacteroidetes, and these changes result in a decreased Firmicutes/Bacteroidetes ratio, which can be an effective indicator for successful GTE intervention, which may generate beneficial health effect to human. Meanwhile, the relative abundances of many detected bacteria genera among three HCM vessels changed through the GTE intervention. The overall effects of GTE on gut microbial beta-diversity were observed by multivariate statistical analyses, and the differences in metabolic profiles from different GTE treatment stages were detected. Moreover, we identified several associations between microbial population and microbial metabolites, which may assist us in establishing new hypotheses for future related studies. In summary, our study suggested that the microbial compositional changes induced by GTE also changed their metabolic functions, and consequentially, may change the host metabolism and impact human health.


Assuntos
Bacteroidetes , Colo/microbiologia , Firmicutes , Microbioma Gastrointestinal , Modelos Biológicos , Chá , Bacteroidetes/classificação , Bacteroidetes/crescimento & desenvolvimento , Firmicutes/classificação , Firmicutes/crescimento & desenvolvimento , Humanos
9.
J Inorg Biochem ; 210: 111123, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32622213

RESUMO

To probe the mechanism of inhibition of several previously-published metallo-ß-lactamase (MBL) inhibitors for the clinically-important MBL Verona integron-encoded metallo-ß-lactamase 2 (VIM-2), equilibrium dialyses with metal analyses, native state electrospray ionization mass spectrometry (ESI-MS), and UV-Vis spectrophotometry were utilized. The mechanisms of inhibition were analyzed for ethylenediaminetetraacetic acid (EDTA); dipicolinic acid (DPA) and DPA analogs 6-(1H-tetrazol-5-yl)picolinic acid (1T5PA) and 4-(3-aminophenyl)pyridine-2,6-dicarboxylic acid (3AP-DPA); thiol-containing compounds, 2,3-dimercaprol, thiorphan, captopril, and tiopronin; and 5-(pyridine-3-sulfonamido)-1,3-thiazole-4-carboxylic acid (ANT-431). UV-Vis spectroscopy and native-state ESI-MS results showed the formation of ternary complexes between VIM-2 and 1T5PA, ANT-431, thiorphan, captopril, and tiopronin, while a metal stripping mechanism was shown with VIM-2 and EDTA and DPA. The same approaches were used to show the formation of a ternary complex between New Delhi Metallo-ß-lactamase (NDM-1) and ANT-431. The studies presented herein show that most of the inhibitors utilize a similar mechanism of inhibition as previously reported for NDM-1. These studies also demonstrate that native mass spectrometry can be used to probe the mechanism of inhibition at lower enzyme/inhibitor concentrations than has previously been achieved.


Assuntos
Inibidores de beta-Lactamases/metabolismo , beta-Lactamases/metabolismo , Ligação Proteica , Espectrometria de Massas por Ionização por Electrospray , Espectrofotometria Ultravioleta , Zinco/química , Inibidores de beta-Lactamases/química , beta-Lactamases/química
10.
Angew Chem Int Ed Engl ; 59(38): 16398-16403, 2020 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-32495485

RESUMO

The difluoromethyl group (CF2 H) is considered to be a lipophilic and metabolically stable bioisostere of an amino (NH2 ) group. Therefore, methods that can rapidly convert an NH2 group into a CF2 H group would be of great value to medicinal chemistry. We report herein an efficient Cu-catalyzed approach for the conversion of alkyl pyridinium salts, which can be readily synthesized from the corresponding alkyl amines, to their alkyl difluoromethane analogues. This method tolerates a broad range of functional groups and can be applied to the late-stage modification of complex amino-containing pharmaceuticals.

11.
J Biol Inorg Chem ; 25(5): 717-727, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32500360

RESUMO

Due to the rapid proliferation of antibiotic-resistant pathogenic bacteria, known as carbapenem-resistant enterobacteriaceae, the efficacy of ß-lactam antibiotics is threatened. ß-lactam antibiotics constitute over 50% of the available antibiotic arsenal. Recent efforts have been focused on developing inhibitors to these enzymes. In an effort to understand the mechanism of inhibition(s) of four FDA-approved thiol-containing drugs that were previously reported to be inhibitors of New Delhi metallo-ß-lactamase (NDM-1), various biochemical and spectroscopic techniques were used. Isothermal titration calorimetry demonstrated the binding affinity to NDM-1 corresponds to the reported IC50 values of the inhibitors. Equilibrium dialyses and metal analyses demonstrated that all of these inhibitors formed ternary complexes with ZnZn-NDM-1. Spectroscopic studies on CoCo-NDM-1 revealed two distinct binding modes for the thiol-containing compounds. These findings validate the need to further investigate the mechanism of inhibition of MBL inhibitors. Further research to identify inhibition capabilities beyond reported IC50 values is necessary for understanding the binding modes of these identified compounds and to provide the necessary foundation for developing clinically relevant MBL inhibitors.


Assuntos
Compostos de Sulfidrila/farmacologia , Inibidores de beta-Lactamases/farmacologia , beta-Lactamases/metabolismo , Humanos , Simulação de Acoplamento Molecular , Estrutura Molecular , Compostos de Sulfidrila/química , Inibidores de beta-Lactamases/química , beta-Lactamases/genética
12.
ChemMedChem ; 15(14): 1272-1282, 2020 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-32315115

RESUMO

The fungal natural product aspergillomarasmine A (AMA) has been identified as a noncompetitive inhibitor of New Delhi metallo-ß-lactamase-1 (NDM-1) that inhibits by removing ZnII from the active-site. The nonselective metal-chelating properties and difficult synthesis and derivatization of AMA have hindered the development of this scaffold into a potent and selective inhibitor of NDM-1. Iminodiacetic acid (IDA) has been identified as the metal-binding pharmacophore (MBP) core of AMA that can be leveraged for inhibitor development. Herein, we report the use of IDA for fragment-based drug discovery (FBDD) of NDM-1 inhibitors. IDA (IC50 =120 µM) was developed into inhibitor 23 f (IC50 =8.6 µM, Ki =2.6 µM), which formed a ternary complex with NDM-1, as evidenced by protein thermal-shift and native-state electrospray ionization mass spectrometry (ESI-MS) experiments. Combining mechanistic analysis with inhibitor derivatization, the use of IDA as an alternative AMA scaffold for NDM-1 inhibitor development is detailed.


Assuntos
Complexos de Coordenação/farmacologia , Iminoácidos/farmacologia , Zinco/farmacologia , Inibidores de beta-Lactamases/farmacologia , beta-Lactamases/metabolismo , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Relação Dose-Resposta a Droga , Humanos , Iminoácidos/síntese química , Iminoácidos/química , Estrutura Molecular , Relação Estrutura-Atividade , Zinco/química , Inibidores de beta-Lactamases/síntese química , Inibidores de beta-Lactamases/química
13.
J Proteome Res ; 19(5): 1991-1998, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32275156

RESUMO

Gut microbiome plays fundamental roles in host physiology, and gut microbial metabolism is important to the host-microbiome homeostasis. As major contributors to gut microbial metabolism, the medium nutritional components are essential to in vitro gut microbiome growths, and four nutrients, namely, inorganic salts, bile salts, short-chain fatty acids (SCFAs), and mucin, have gained particular attention because of their significant variation found in different growth environments and their ability to modulate the gut microbial population and functions. However, a systematic study is lacking to evaluate the effects of these four nutrients on the gut microbiome in terms of their impact on the microbial metabolic profiles. To fill the gap of the knowledge, we applied mass-spectrometry-based targeted metabolomics approach to study the regulation effects of these four medium components on in vitro-cultured gut microbiota. Our results show that inorganic salts and mucin had the greatest impacts on the gut microbiome metabolic profile compared to the other components studied, with gut microbial cultures grown with low-concentration inorganic salts and mucin-supplemented medium demonstrating greater numbers of metabolites detected. We also applied metabolic pathway impact analysis, which revealed several significantly impacted metabolic pathways during the comparison of different medium supplements, which could further assist our understanding of the overall impacts of certain critical nutrients on gut microbial metabolism. In summary, this pilot study can serve as a first attempt to evaluate the individual nutritional component in their contribution to gut microbial metabolic functions.


Assuntos
Microbioma Gastrointestinal , Metaboloma , Metabolômica , Nutrientes , Projetos Piloto
14.
Org Lett ; 22(7): 2657-2662, 2020 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-32186885

RESUMO

The C-H annulation of the five-position of quinolines and acrylates to afford heterocycles is an active field of research in organic synthesis. Herein the annulation of 4-aminoquinolines with acrylates through two consecutive C-H activations catalyzed by Rh(III) is described. The reaction proceeds with high atom efficiency under mild reaction conditions, and this protocol will provide appealing strategies for the synthesis of fused quinoline heterocycles.

15.
mBio ; 10(6)2019 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-31744917

RESUMO

To understand the evolution of Verona integron-encoded metallo-ß-lactamase (VIM) genes (blaVIM) and their clinical impact, microbiological, biochemical, and structural studies were conducted. Forty-five clinically derived VIM variants engineered in a uniform background and expressed in Escherichia coli afforded increased resistance toward all tested antibiotics; the variants belonging to the VIM-1-like and VIM-4-like families exhibited higher MICs toward five out of six antibiotics than did variants belonging to the widely distributed and clinically important VIM-2-like family. Generally, maximal MIC increases were observed when cephalothin and imipenem were tested. Additionally, MIC determinations under conditions with low zinc availability suggested that some VIM variants are also evolving to overcome zinc deprivation. The most profound increase in resistance was observed in VIM-2-like variants (e.g., VIM-20 H229R) at low zinc availability. Biochemical analyses reveal that VIM-2 and VIM-20 exhibited similar metal binding properties and steady-state kinetic parameters under the conditions tested. Crystal structures of VIM-20 in the reduced and oxidized forms at 1.25 Å and 1.37 Å resolution, respectively, show that Arg229 forms an additional salt bridge with Glu171. Differential scanning fluorimetry of purified proteins and immunoblots of periplasmic extracts revealed that this difference increases thermostability and resistance to proteolytic degradation when zinc availability is low. Therefore, zinc scarcity appears to be a selective pressure driving the evolution of multiple metallo-ß-lactamase families, although compensating mutations use different mechanisms to enhance resistance.IMPORTANCE Antibiotic resistance is a growing clinical threat. One of the most serious areas of concern is the ability of some bacteria to degrade carbapenems, drugs that are often reserved as last-resort antibiotics. Resistance to carbapenems can be conferred by a large group of related enzymes called metallo-ß-lactamases that rely on zinc ions for function and for overall stability. Here, we studied an extensive panel of 45 different metallo-ß-lactamases from a subfamily called VIM to discover what changes are emerging as resistance evolves in clinical settings. Enhanced resistance to some antibiotics was observed. We also found that at least one VIM variant developed a new ability to remain more stable under conditions where zinc availability is limited, and we determined the origin of this stability in atomic detail. These results suggest that zinc scarcity helps drive the evolution of this resistance determinant.


Assuntos
Farmacorresistência Bacteriana , Zinco/metabolismo , beta-Lactamases/química , beta-Lactamases/metabolismo , Carbapenêmicos/farmacologia , Escherichia coli/genética , Escherichia coli/metabolismo , Humanos , Testes de Sensibilidade Microbiana , Modelos Moleculares , Mutação , Conformação Proteica , Estabilidade Proteica , beta-Lactamases/genética
16.
J Am Chem Soc ; 141(50): 19941-19949, 2019 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-31756095

RESUMO

We report herein the first catalytic strategy to harness amidyl radicals derived from N-chloroamides for C-C bond formation, allowing for the discovery of the first catalytic benzylic C-H difluoromethylation. Under copper-catalyzed conditions, a wide variety of N-chlorocarboxamides and N-chlorocarbamates direct selective benzylic C-H difluoromethylation with a nucleophilic difluoromethyl source at room temperature. This scalable protocol exhibits a broad substrate scope and functional group tolerance, enabling late-stage difluoromethylation of bioactive molecules. This copper-catalyzed, chloroamide-directed strategy has also been extended to benzylic C-H pentafluoroethylation and trifluoromethylation. Mechanistic studies on the difluoromethylation reactions support that the reactions involve the formation of benzylic radicals via intramolecular C-H activation, followed by the copper-mediated transfer of difluoromethyl groups to the benzylic radicals.

17.
J Am Chem Soc ; 141(29): 11398-11403, 2019 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-31282666

RESUMO

We report herein a highly efficient Cu-catalyzed protocol for the conversion of aliphatic carboxylic acids to the corresponding difluoromethylated analogues. This robust, operationally simple and scalable protocol tolerates a variety of functional groups and can convert a diverse array of acid-containing complex molecules to the alkyl-CF2H products. Mechanistic studies support the involvement of alkyl radicals.

18.
J Am Chem Soc ; 141(7): 3153-3159, 2019 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-30678456

RESUMO

Carbon-carbon bond-forming reductive elimination from elusive organocopper(III) complexes has been considered the key step in many copper-catalyzed and organocuprate reactions. However, organocopper(III) complexes with well-defined structures that can undergo reductive elimination are extremely rare, especially for the formation of Csp3-Csp3 bonds. We report herein a general method for the synthesis of a series of [alkyl-CuIII-(CF3)3]- complexes, the structures of which have been unequivocally characterized by NMR spectroscopy, mass spectrometry, and X-ray crystal diffraction. At elevated temperature, these complexes undergo reductive elimination following first-order kinetics, forming alkyl-CF3 products with good yields (up to 91%). Both kinetic studies and DFT calculations indicate that the reductive elimination to form Csp3-CF3 bonds proceeds through a concerted transition state, with a Δ H⧧ = 20 kcal/mol barrier.

19.
J Microbiol Methods ; 154: 147-155, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30359661

RESUMO

Lactobacillus, the major genus of lactic acid bacteria group, plays functional roles in the human body, for example, convert sugars to lactic acid. They are the significant microbiota which can be found at a number of human body sites, such as the digestive system, urinary system, and genital system. A number of Lactobacillus species are often used as probiotics and can benefit host health when administered in adequate amounts. Due to their diverse functional characteristics, it is essential to have identification and high-resolution typing techniques to support the need in health and nutritional research of Lactobacillus species. In this study, we took advantages of both targeted and untargeted metabolomic technologies by using a triple quadrupole mass spectrometer (MS) in combination with a linear ion trap-Orbitrap hybrid MS, to investigate their capability and performance in deciphering the subtle metabolic difference in four closely related Lactobacillus species/strains. First, we evaluated the selected reaction monitoring (SRM) and high-resolution MS data for metabolite quantitation. Then the acquired data quality was further evaluated via the number of metabolites detected, the coefficient variation (CV) distribution, signal intensity distribution and so on. The established platforms were eventually applied to differentiate four Lactobacillus species in identical growth conditions. The proposed workflow demonstrated the capability of targeted and untargeted metabolomics in differentiating closely related bacterial strains/species.


Assuntos
Técnicas de Tipagem Bacteriana/métodos , Lactobacillus/classificação , Lactobacillus/metabolismo , Metabolômica/métodos , Cromatografia Líquida de Alta Pressão/métodos , Humanos , Lactobacillus/crescimento & desenvolvimento , Especificidade da Espécie , Espectrometria de Massas em Tandem/métodos
20.
J Agric Food Chem ; 66(6): 1386-1393, 2018 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-29345909

RESUMO

This study examined the ability of Lactobacillus acidophilus (LA) to ferment black tea extract (BTE) and the enhancement of Escherichia coli cellular uptake of phenolic compounds when these bacteria were incubated with fermented BTE. The inhibitory effects of BTE to E. coli bacteria with and without fermentation were compared. Several intracellular phenolic compounds as well as metabolic profiles of E. coli with and without treatments were also determined using a high-performance liquid chromatography-tandem mass spectrometry-based approach. Our results showed that of three concentrations from the non-fermented BTE treatment, only the extract from the 25 mg/mL tea leaves solution could inhibit E. coli survival, while LA-fermented BTE extract from 5, 10, and 25 mg/mL tea leaves solutions all inhibited E. coli growth significantly. Intracellular concentrations of (+)-catechin-3-gallate/(-)-epicatechin-3-gallate and (+)-catechin/(-)-epicatechin were significantly higher when E. coli was treated with fermented BTE in comparison to non-fermented BTE. Scanning electron microscopy images indicated that the intracellular phenolic compounds inhibited E. coli growth by increasing endogenous oxidative stress. Metabolic profiles of E. coli were also investigated to understand their metabolic response when treated with BTE, and significant metabolic changes of E. coli were observed. Metabolic profile data were further analyzed using partial least squares discriminant analysis to distinguish the fermented BTE treatment group from the control group and the non-fermented BTE treatment group. The results indicated a large-scale E. coli metabolic dysregulation induced by the fermented BTE. Our findings showed that LA fermentation can be an efficient approach to enhance phenolic inhibition of bacterial cells through increased endogenous oxidative stress and dysregulated metabolic activities.


Assuntos
Camellia sinensis/microbiologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/metabolismo , Lactobacillus acidophilus/metabolismo , Extratos Vegetais/farmacologia , Camellia sinensis/química , Camellia sinensis/metabolismo , Fermentação , Metabolômica , Fenóis/química , Fenóis/metabolismo , Fenóis/farmacologia , Extratos Vegetais/química , Extratos Vegetais/metabolismo , Folhas de Planta/química , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia
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