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1.
Int J Mol Sci ; 25(4)2024 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-38396919

RESUMO

High dose (S)-efavirenz (EFV) inhibits the HIV reverse transcriptase enzyme and is used to lower HIV load. Low-dose EFV allosterically activates CYP46A1, the key enzyme for cholesterol elimination from the brain, and is investigated as a potential treatment for Alzheimer's disease. Simultaneously, we evaluate EFV dihydroxymetabolites for in vivo brain effects to compare with those of (S)-EFV. We have already tested (rac)-8,14dihydroxy EFV on 5XFAD mice, a model of Alzheimer's disease. Herein, we treated 5XFAD mice with (rac)-7,8dihydroxy EFV. In both sexes, the treatment modestly activated CYP46A1 in the brain and increased brain content of acetyl-CoA and acetylcholine. Male mice also showed a decrease in the brain levels of insoluble amyloid ß40 peptides. However, the treatment had no effect on animal performance in different memory tasks. Thus, the overall brain effects of (rac)-7,8dihydroxy EFV were weaker than those of EFV and (rac)-8,14dihydroxy EFV and did not lead to cognitive improvements as were seen in treatments with EFV and (rac)-8,14dihydroxy EFV. An in vitro study assessing CYP46A1 activation in co-incubations with EFV and (rac)-7,8dihydroxy EFV or (rac)-8,14dihydroxy EFV was carried out and provided insight into the compound doses and ratios that could be used for in vivo co-treatments with EFV and its dihydroxymetabolite.


Assuntos
Doença de Alzheimer , Fármacos Anti-HIV , Infecções por HIV , Feminino , Masculino , Camundongos , Animais , Colesterol 24-Hidroxilase/metabolismo , Doença de Alzheimer/tratamento farmacológico , Peptídeos beta-Amiloides , Benzoxazinas/química , Alcinos/uso terapêutico , Ciclopropanos/uso terapêutico , Infecções por HIV/tratamento farmacológico , Inibidores da Transcriptase Reversa/farmacologia , Fármacos Anti-HIV/uso terapêutico
2.
Macromol Rapid Commun ; 45(2): e2300470, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37716013

RESUMO

Herein, an evaluation of the initial step of benzoxazine polymerization is presented by mass spectrometry, with a focus on differentiating the phenoxy and phenolic products formed by distinct pathways of the cationic ring opening polymerization (ROP) mechanism of polybenzoxazine formation. The use of infrared multiple photon dissociation (IRMPD) and ion mobility spectrometry (IMS) techniques allows for differentiation of the two pathways and provides valuable insights into the ROP mechanism. The results suggest that type I pathway is favored in the initial stages of the reaction yielding the phenoxy product, while type II product should be observed at later stages when the phenoxy product would interconvert to the most stable type II phenolic product. Overall, the findings presented here provide important information on the initial step of the benzoxazine polymerization, allowing the development of optimal polymerization conditions and represents a way to evaluate other multifunctional polymerization processes.


Assuntos
Benzoxazinas , Fenóis , Polimerização , Benzoxazinas/química , Fenóis/química , Cátions
3.
J Agric Food Chem ; 71(39): 14221-14231, 2023 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-37729497

RESUMO

Protoporphyrinogen IX oxidase (PPO/Protox, E.C. 1.3.3.4) is recognized as one of the most important targets for herbicide discovery. In this study, we report our ongoing research efforts toward the discovery of novel PPO inhibitors. Specifically, we identified a highly potent new compound series containing a pyrimidinedione moiety and bearing a versatile building block-benzoxazinone scaffold. Systematic bioassays resulted in the discovery of compound 7af, ethyl 4-(7-fluoro-6-(3-methyl-2,6-dioxo-4-(trifluoromethyl)-3,6-dihydropyrimidin-1(2H)-yl)-3-oxo-2,3-dihydro-4H-benzo[b][1,4]oxazin-4-yl)butanoate, which exhibited broad-spectrum and excellent herbicidal activity at the dosage of 37.5 g a.i./ha through postemergence application. The inhibition constant (Ki) value of 7af to Nicotiana tabacum PPO (NtPPO) was 14 nM, while to human PPO (hPPO), it was 44.8 µM, indicating a selective factor of 3200, making it the most selective PPO inhibitor to date. Moreover, molecular simulations further demonstrated the selectivity and the binding mechanism of 7af to NtPPO and hPPO. This study not only identifies a candidate that showed excellent in vivo bioactivity and high safety toward humans but also provides a paradigm for discovering PPO inhibitors with improved performance through molecular simulation and structure-guided optimization.


Assuntos
Benzoxazinas , Herbicidas , Humanos , Benzoxazinas/farmacologia , Benzoxazinas/química , Protoporfirinogênio Oxidase , Inibidores Enzimáticos/química , Herbicidas/química , /metabolismo
4.
Molecules ; 28(13)2023 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-37446739

RESUMO

In this work, a novel bio-based high-performance bisbenzoxazine resin was synthesized from daidzein, 2-thiophenemethylamine and paraformaldehyde. The chemical structure was confirmed using nuclear magnetic resonance spectroscopy (NMR) and Fourier-transform infrared spectroscopy (FT-IR). The polymerization process was systematically studied using differential scanning calorimetry (DSC) and in situ FT-IR spectra. It can be polymerized through multiple polymerization behaviors under the synergistic reaction of thiophene rings with benzopyrone rather than a single polymerization mechanism of traditional benzoxazines, as reported. In addition, thermogravimetric analysis (TGA) and a microscale combustion calorimeter (MCC) were used to study the thermal stability and flame retardancy of the resulting polybenzoxazine. The thermosetting material showed a high carbon residue rate of 62.8% and a low heat release capacity (HRC) value of 33 J/gK without adding any flame retardants. Based on its outstanding capability of carbon formation, this newly obtained benzoxazine resin was carbonized and activated to obtain a porous carbon material doped with both sulfur and nitrogen. The CO2 absorption of the carbon material at 0 °C and 25 °C at 1 bar was 3.64 mmol/g and 3.26 mmol/g, respectively. The above excellent comprehensive properties prove its potential applications in many advanced fields.


Assuntos
Benzoxazinas , Carbono , Benzoxazinas/química , Espectroscopia de Infravermelho com Transformada de Fourier , Polimerização
5.
Org Lett ; 25(23): 4276-4280, 2023 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-37272614

RESUMO

2-(1,1-Difluoroethyl)-2H-1,3-benzoxazines were synthesized by (i) the regioselective ring opening of 1,1-difluorocyclopropanes bearing an aryloxy group and (ii) the Ritter reaction followed by a Friedel-Crafts-type ring closure. When 2-aryloxy-1,1-difluorocyclopropanes were treated with triflic acid, the C-C bond distal to the CF2 moiety was cleaved regioselectively via protonation to generate the corresponding oxocarbenium ions. These intermediates readily underwent nucleophilic attack by nitriles, followed by a carbocationic cyclization to afford the 2-difluoroethylated benzoxazines.


Assuntos
Benzoxazinas , Prótons , Benzoxazinas/química , Ciclização
6.
Macromol Rapid Commun ; 44(10): e2200910, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37017474

RESUMO

This work synthesizes a new bifunctional furan derivative (PDMS-FBZ) through a sequence of hydrosilylation of nadic anhydride (ND) with polydimethylsiloxane (PDMS), reaction of the product with p-aminophenol to form PDMS-ND-OH, and its subsequent Mannich reaction with furfurylamine and CH2 O. Then, the main chain-type copolymer PDMS-DABZ-DDSQ is prepared through a Diels-Alder (DA) cycloaddition of PDMS-FBZ with the bismaleimide-functionalized double-decker silsesquioxane derivative DDSQ-BMI. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy confirm the structure of this PDMS-DABZ-DDSQ copolymer; differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA) reveal it to have high flexibility and high thermal stability (Tg = 177 °C; Td10 = 441 °C; char yield = 60.1 wt%); contact angle measurements reveal a low surface free energy (18.18 mJ m-2 ) after thermal ring-opening polymerization, because the inorganic PDMS and DDSQ units are dispersed well, as revealed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). This PDMS-DABZ-DDSQ copolymer possesses reversible properties arising from the DA and retro-DA reactions, suggesting its possible application as a functional high-performance material.


Assuntos
Benzoxazinas , Polímeros , Reação de Cicloadição , Benzoxazinas/química , Polímeros/química , Microscopia Eletrônica de Varredura , Dimetilpolisiloxanos
7.
Macromol Rapid Commun ; 44(7): e2200895, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36594347

RESUMO

Exploring the ring-opening polymerization (ROP) mechanism of benzoxazines is a fundamental issue in benzoxazine chemistry. Though some research papers on the topic have been reported, the ROP mechanism of mono-benzoxazines is still elusive. The key point for mechanistic studies is to determine and characterize the structure and formation pathways of the products generated in ROP. In this paper, the ROP of a vanillin-furfurylamine-based benzoxazine and a mono-azomethine derivative is studied with differential scanning calorimetry, fourier transform infrared spectroscopy, nuclear magnetic resonance, and electrospray ionization mass spectrometry, respectively. The results show that the products consist of a range of cationic species, zwitterions, fragments, and series of cyclic and linear oligomers of varying molecular sizes. It is proposed that both mono-benzoxazines undergo thermally activated cationic ring-opening oligomerization via zwitterion intermediates. Upon thermal induction, multi-bond-cleavage takes place to form various zwitterionic intermediates, which react with a monomer, a fragment, or a second zwitterion by several pathways to generate cyclic and linear oligomers.


Assuntos
Benzoxazinas , Furanos , Benzoxazinas/química , Polimerização
8.
ChemMedChem ; 18(5): e202200617, 2023 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-36598081

RESUMO

Benzoxazines and benzoxazepines are nitrogen and oxygen-containing six and seven-membered benzo-fused heterocyclic scaffolds, respectively. Benzoxazepines and benzoxazines are well-known pharmacophores in pharmaceutical chemistry, which are of significant interest and have been extensively studied because of their promising activity against various diseases including their wide range of anticancer activity. Several reports are known for synthesizing benzoxazine and benzoxazepine-based compounds in the literature. Herein this review provides a critical analysis of synthetic strategies towards benzoxazines and benzoxazepines along with various ranges of anticancer activities based on these molecules that have been reported from 2010 onwards. This review also focuses on the structure-activity relationship of the benzoxazine and benzoxazepine scaffolds containing bioactive compounds and describes how the structural modification affects their anticancer activity.


Assuntos
Antineoplásicos , Benzoxazinas , Benzoxazinas/química , Antineoplásicos/farmacologia , Relação Estrutura-Atividade , Farmacóforo
9.
Int J Pharm ; 632: 122564, 2023 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-36586638

RESUMO

In this study, the stability and intrinsic dissolution of vacuum compression molded (VCM) amorphous solid dispersions (ASDs) of efavirenz (EFV) were investigated in relation to its solubility limits in seven polymers determined by the melting point depression (MPD) method. The extrapolated solubility limits of EFV at 22 °C ranged from 3 to 68% (w/w) with PVOH being the only polymer suggesting immiscibility with EFV according to both MPD and Hansen solubility parameters (HSPs). All ASDs with EFV loadings below or close to their calculated solubility limit did not show any signs of crystallization upon conditioning for 7 months at either 22 or 37 °C and 23 or 75% relative humidity. However, all ASDs with EFV loading above the solubility limit crystallized at high humidity, while the ASDs with cellulose derived carrier polymers proved kinetically stable at low humidity over 7 months. While the EFV intrinsic dissolution rates from the VCM ASDs were partly depending on the polymer dissolution rate, no correlation was observed between EFV matrix crystallization and its miscibility in the polymer. Altogether, the observations of the study underline the importance of combining preformulation miscibility determination and dissolution studies to rationally decide on both stability and viability of ASD formulations.


Assuntos
Benzoxazinas , Polímeros , Solubilidade , Vácuo , Polímeros/química , Benzoxazinas/química , Estabilidade de Medicamentos
10.
N Biotechnol ; 72: 48-57, 2022 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-36155894

RESUMO

Herbicides play a vital role in agriculture, contributing to increased crop productivity by minimizing weed growth, but their low degradability presents a threat to the environment and human health. Allelochemicals, such as DIBOA (2,4-dihydroxy-(2H)-1,4-benzoxazin-3(4 H)-one), are secondary metabolites released by certain plants that affect the survival or growth of other organisms. Although these metabolites have an attractive potential for use as herbicides, their low natural production is a critical hurdle. Previously, the synthesis of the biologically active analog D-DIBOA (4-hydroxy-(2H)-1,4-benzoxazin-3(4H)-one) was achieved, using an engineered E. coli strain as a whole-cell biocatalyst, capable of transforming a precursor compound into D-DIBOA and exporting it into the culture medium, although it cannot be directly applied to crops. Here a chromatographic method to purify D-DIBOA from this cell culture medium without producing organic solvent wastes is described. The purification of D-DIBOA from a filtered culture medium to the pure compound could also be automated. Biological tests with the purified compound on weed models showed that it has virtually the same activity than the chemically synthesized D-DIBOA.


Assuntos
Escherichia coli , Herbicidas , Humanos , Escherichia coli/metabolismo , Benzoxazinas/química , Ácidos Hidroxâmicos/metabolismo , Herbicidas/farmacologia , Herbicidas/química , Herbicidas/metabolismo
11.
Molecules ; 27(13)2022 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-35807481

RESUMO

A series of pyrimidine conjugates containing a fragment of racemic 7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine and its (S)-enantiomer attached via a 6-aminohexanoyl fragment were synthesized by the reaction of nucleophilic substitution of chlorine in various chloropyrimidines. The structures of the synthesized compounds were confirmed by 1H, 19F, and 13C NMR spectral data. Enantiomeric purity of optically active derivatives was confirmed by chiral HPLC. Antiviral evaluation of the synthesized compounds has shown that the replacement of purine with a pyrimidine fragment leads to a decrease in the anti-herpesvirus activity compared to the lead compound, purine conjugate. The studied compounds did not exhibit significant activity against influenza A (H1N1) virus.


Assuntos
Vírus da Influenza A Subtipo H1N1 , Vírus da Influenza A , Antivirais/química , Benzoxazinas/química , Purinas , Pirimidinas/farmacologia
12.
Drug Metab Dispos ; 50(7): 923-930, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35489779

RESUMO

(S)-Efavirenz (EFV) is a reverse transcriptase inhibitor and an antiviral drug. In addition, (S)-EFV can interact off target with CYP46A1, the major cholesterol hydroxylating enzyme in the mammalian brain, and allosterically activate CYP46A1 at a small dose in mice and humans. Studies with purified CYP46A1 identified two allosteric sites on the enzyme surface, one for (S)-EFV and the second site for L-glutamate (Glu), a neurotransmitter that also activates CYP46A1 either alone or in the presence of (S)-EFV. Previously, we found that racemic (rac)-7-hydroxyefavirenz, (rac)-8-hydroxyefavirenz, (S)-8-hydroxyefavirenz, and (rac)-8,14-dihydroxyefavirenz, compounds with the hydroxylation positions corresponding to the metabolism of (S)-EFV in the liver, activated CYP46A1 in vitro. Yet, these compounds differed from (S)-EFV in how they allosterically interacted with CYP46A1. Herein, we further characterized (rac)-7-hydroxyefavirenz, (rac)-8-hydroxyefavirenz, (S)-8-hydroxyefavirenz, and (rac)-8,14-dihydroxyefavirenz, and, in addition, (R)-EFV, (S)-7-hydroxyefavirenz, (rac)-7,8-dihydroxyefavirenz, (S)-7,8-dihydroxyefavirenz, and (S)-8,14-dihydroxyefavirenz for activation and binding to CYP46A1 in vitro. We found that the spatial configuration of all tested compounds neither affected the CYP46A1 activation nor the sites of binding to CYP46A1. Yet, the hydroxylation position determined whether the hydroxylated metabolite interacted with the allosteric site for (S)-EFV [(R)-EFV, (rac)-7,8-dihydroxyefavirenz, and (S)-7,8-dihydroxyefavirenz], L-Glu [(rac)- and (S)-8,14-dihydroxyefavirenz], or both [(rac)-7-hydroxyefavirenz, (S)-7-hydroxyefavirenz, (rac)-8-hydroxyefavirenz, and (S)-8-hydroxyefavirenz]. This difference in binding to the allosteric sites determined, in turn, how CYP46A1 activity was changed in the coincubations with (S)-EFV and either its metabolite or L-Glu. The results suggest EFV metabolites that could be more potent for CYP46A1 activation in vivo than (S)-EFV. SIGNIFICANCE STATEMENT: This study found that not only efavirenz but also all its hydroxylated metabolites allosterically activate CYP46A1 in vitro. The enzyme activation depended on the hydroxylation position but not the metabolite spatial configuration and involved either one or two allosteric sites-for efavirenz, L-glutamate, or both. The results suggest that the hydroxylated efavirenz metabolites may differ from efavirenz in how they interact with the CYP46A1 allosteric and active sites.


Assuntos
Benzoxazinas , Colesterol 24-Hidroxilase , Ácido Glutâmico , Alcinos , Animais , Benzoxazinas/química , Colesterol 24-Hidroxilase/química , Colesterol 24-Hidroxilase/metabolismo , Ciclopropanos , Ácido Glutâmico/metabolismo , Hidroxilação , Camundongos
13.
Carbohydr Res ; 510: 108458, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34634551

RESUMO

A convenient protocol for the two component preparation of 1,3-benzoxazines by using several protected and unprotected carbohydrate molecules as organocatalysts have been developed which is broadly applicable to condensation reaction between variety of Mannich bases and paraformaldehyde. This study revealed that fructose have much higher catalytic activity than the other carbohydrates and can be an alternative to metal-containing catalysts as a green renewable organocatalyst for efficient and rapid construction of 1,3-benzoxazine skeleton. In this context, 21 benzoxazine compounds were successfully synthesized and spectral characterizations of these compounds were carried out by spectroscopic methods and elemental analysis. Furthermore, density functional theory (DFT) calculations have been performed to study the detailed mechanism of organocatalyst assisted synthesis of the benzoxazine monomers. The results obtained from these calculations showed that the more realistic reaction pathway involves formation of a phenolate based intermediate which loses a water molecule to form benzenaminium ion. Subsequently, this ion provides the formation of the corresponding benzoxazines with good yields through the intramolecular ring closure step.


Assuntos
Benzoxazinas/síntese química , Carboidratos/química , Benzoxazinas/química , Catálise , Teoria da Densidade Funcional , Avaliação Pré-Clínica de Medicamentos , Estrutura Molecular
14.
Int J Mol Sci ; 22(20)2021 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-34681877

RESUMO

The activation of the human cannabinoid receptor type II (CB2R) is known to mediate analgesic and anti-inflammatory processes without the central adverse effects related to cannabinoid receptor type I (CB1R). In this work we describe the synthesis and evaluation of a novel series of N-aryl-2-pyridone-3-carboxamide derivatives tested as human cannabinoid receptor type II (CB2R) agonists. Different cycloalkanes linked to the N-aryl pyridone by an amide group displayed CB2R agonist activity as determined by intracellular [cAMP] levels. The most promising compound 8d exhibited a non-toxic profile and similar potency (EC50 = 112 nM) to endogenous agonists Anandamide (AEA) and 2-Arachidonoylglycerol (2-AG) providing new information for the development of small molecules activating CB2R. Molecular docking studies showed a binding pose consistent with two structurally different agonists WIN-55212-2 and AM12033 and suggested structural requirements on the pyridone substituents that can satisfy the orthosteric pocket and induce an agonist response. Our results provide additional evidence to support the 2-pyridone ring as a suitable scaffold for the design of CB2R agonists and represent a starting point for further optimization and development of novel compounds for the treatment of pain and inflammation.


Assuntos
Agonistas de Receptores de Canabinoides/química , Agonistas de Receptores de Canabinoides/farmacologia , Piridonas/química , Receptor CB2 de Canabinoide/agonistas , Animais , Ácidos Araquidônicos/química , Ácidos Araquidônicos/farmacologia , Benzoxazinas/química , Benzoxazinas/farmacologia , Sítios de Ligação , Células CHO , Agonistas de Receptores de Canabinoides/síntese química , Sobrevivência Celular/efeitos dos fármacos , Cricetulus , AMP Cíclico/metabolismo , Avaliação Pré-Clínica de Medicamentos , Endocanabinoides/química , Endocanabinoides/farmacologia , Glicerídeos/química , Glicerídeos/farmacologia , Células HL-60 , Células Hep G2 , Humanos , Simulação de Acoplamento Molecular , Morfolinas/química , Morfolinas/farmacologia , Naftalenos/química , Naftalenos/farmacologia , Alcamidas Poli-Insaturadas/química , Alcamidas Poli-Insaturadas/farmacologia , Piridonas/farmacologia , Receptor CB2 de Canabinoide/química , Receptor CB2 de Canabinoide/genética , Receptor CB2 de Canabinoide/metabolismo , Relação Estrutura-Atividade
15.
Anal Bioanal Chem ; 413(25): 6401-6412, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34557941

RESUMO

We demonstrate the suitability of a fast, green, easy-to-perform, and modified sample extraction procedure, i.e., dispersive liquid-liquid microextraction (DLLME) for the determination of efavirenz (EFV) in human plasma. Data acquisition was done by gas chromatography-mass spectrometry (GC-MS) in the selected ion monitoring (SIM) mode. The simplicity of the method lies in, among others, the avoidance of the use of large organic solvent volumes as mobile phases and non-volatile buffers that tend to block the plumbing in high-performance liquid chromatography (HPLC). Chromatographic and mass spectral parameters were optimized using bovine whole blood for matrix matching due to insufficient human plasma. Method validation was accomplished using the United States Food and Drug Administration (USFDA) 2018 guidelines. The calibration curve was linear with a dynamic range of 0.10-2.0 µg/mL and an R2 value of 0.9998. The within-run accuracy and precision were both less than 20% at the lower limit of quantification (LLOQ) spike level. The LLOQ was 0.027 µg/mL which compared well with some values but was also orders of magnitude better than others reported in the literature. The percent recovery was 91.5% at the LLOQ spike level. The DLLME technique was applied in human plasma samples from patients who were on treatment with EFV. The human plasma samples gave concentrations of EFV ranging between 0.14-1.00 µg/mL with three samples out of seven showing concentrations that fell within or close to the recommended therapeutic range.


Assuntos
Alcinos/sangue , Benzoxazinas/sangue , Ciclopropanos/sangue , Cromatografia Gasosa-Espectrometria de Massas/métodos , Microextração em Fase Líquida/métodos , Inibidores da Transcriptase Reversa/sangue , Alcinos/química , Antibacterianos/sangue , Antibacterianos/química , Benzoxazinas/química , Ciclopropanos/química , Humanos , Limite de Detecção , Metronidazol/sangue , Metronidazol/química , Estrutura Molecular
16.
Nat Commun ; 12(1): 2500, 2021 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-33947853

RESUMO

Reverse transcription of the HIV-1 viral RNA genome (vRNA) is an integral step in virus replication. Upon viral entry, HIV-1 reverse transcriptase (RT) initiates from a host tRNALys3 primer bound to the vRNA genome and is the target of key antivirals, such as non-nucleoside reverse transcriptase inhibitors (NNRTIs). Initiation proceeds slowly with discrete pausing events along the vRNA template. Despite prior medium-resolution structural characterization of reverse transcriptase initiation complexes (RTICs), higher-resolution structures of the RTIC are needed to understand the molecular mechanisms that underlie initiation. Here we report cryo-EM structures of the core RTIC, RTIC-nevirapine, and RTIC-efavirenz complexes at 2.8, 3.1, and 2.9 Å, respectively. In combination with biochemical studies, these data suggest a basis for rapid dissociation kinetics of RT from the vRNA-tRNALys3 initiation complex and reveal a specific structural mechanism of nucleic acid conformational stabilization during initiation. Finally, our results show that NNRTIs inhibit the RTIC and exacerbate discrete pausing during early reverse transcription.


Assuntos
Transcriptase Reversa do HIV/química , HIV-1/efeitos dos fármacos , RNA de Transferência de Lisina/química , RNA Viral/química , Inibidores da Transcriptase Reversa/química , Alcinos/química , Alcinos/farmacologia , Benzoxazinas/química , Benzoxazinas/farmacologia , Domínio Catalítico , Microscopia Crioeletrônica , Ciclopropanos/química , Ciclopropanos/farmacologia , Transcriptase Reversa do HIV/genética , Transcriptase Reversa do HIV/metabolismo , HIV-1/enzimologia , HIV-1/genética , HIV-1/metabolismo , Modelos Moleculares , Nevirapina/química , Nevirapina/farmacologia , Conformação de Ácido Nucleico/efeitos dos fármacos , RNA de Transferência de Lisina/genética , RNA Viral/genética , Inibidores da Transcriptase Reversa/farmacologia
17.
Int J Mol Sci ; 22(9)2021 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-33925031

RESUMO

According to current opinion, the first step of benzoxazinoids (BXs) synthesis, that is, the conversion of indole-3-glycerol phosphate to indole, occurs exclusively in the photosynthesising parts of plants. However, the results of our previous work and some other studies suggest that this process may also occur in the roots. In this study, we provide evidence that the first step of BXs synthesis does indeed occur in the roots of rye seedlings. We detected ScBx1 transcripts, BX1 enzyme, and six BXs (2-hydroxy-1,4-benzoxazin-3-one, 2,4-dihydroxy-1,4-benzoxazin-3-one, (2R)-2-O-ß-d-glucopyranosyl-4-hydroxy-(2H)-1,4-benzoxazin-3(4H)-one glucoside, 2,4-dihydroxy- 7-methoxy-1,4-benzoxazin-3-one, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one glucoside, and 6-methoxy-2-benzoxazolinone) in the roots developed from seeds deprived of the coleoptile at 2 days after sowing (i.e., roots without contact with aerial parts). In roots regenerated in vitro, both ScBx1 transcripts and BX1 enzyme were detected at a low but still measurable levels. Thus, BXs are able to be synthesised in both the roots and above-ground parts of rye plants.


Assuntos
Benzoxazinas/metabolismo , Secale/metabolismo , Sequência de Aminoácidos , Benzoxazinas/química , Vias Biossintéticas/genética , Biologia Computacional , Expressão Gênica , Genes de Plantas , Imuno-Histoquímica , Indol-3-Glicerolfosfato Sintase/genética , Indol-3-Glicerolfosfato Sintase/metabolismo , Microscopia Imunoeletrônica , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Plastídeos/genética , Plastídeos/metabolismo , Plastídeos/ultraestrutura , Secale/genética , Plântula/metabolismo , Homologia de Sequência de Aminoácidos
18.
J Med Chem ; 64(9): 5838-5849, 2021 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-33876629

RESUMO

Sirtuins are signaling hubs orchestrating the cellular response to various stressors with roles in all major civilization diseases. Sirtuins remove acyl groups from lysine residues of proteins, thereby controlling their activity, turnover, and localization. The seven human sirtuins, SirT1-7, are closely related in structure, hindering the development of specific inhibitors. Screening 170,000 compounds, we identify and optimize SirT1-specific benzoxazine inhibitors, Sosbo, which rival the efficiency and surpass the selectivity of selisistat (EX527). The compounds inhibit the deacetylation of p53 in cultured cells, demonstrating their ability to permeate biological membranes. Kinetic analysis of inhibition and docking studies reveal that the inhibitors bind to a complex of SirT1 and nicotinamide adenine dinucleotide, similar to selisistat. These new SirT1 inhibitors are valuable alternatives to selisistat in biochemical and cell biological studies. Their greater selectivity may allow the development of better targeted drugs to combat SirT1 activity in diseases such as cancer, Huntington's chorea, or anorexia.


Assuntos
Benzoxazinas/química , Sirtuína 1/antagonistas & inibidores , Acetilação/efeitos dos fármacos , Amidas/química , Benzoxazinas/metabolismo , Benzoxazinas/farmacologia , Sítios de Ligação , Carbazóis/química , Carbazóis/metabolismo , Linhagem Celular Tumoral , Avaliação Pré-Clínica de Medicamentos , Humanos , Concentração Inibidora 50 , Cinética , Simulação de Acoplamento Molecular , NAD/química , NAD/metabolismo , Isoformas de Proteínas/antagonistas & inibidores , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Sirtuína 1/genética , Sirtuína 1/metabolismo , Relação Estrutura-Atividade , Proteína Supressora de Tumor p53/metabolismo
19.
Int J Biol Macromol ; 180: 194-202, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33737176

RESUMO

In the frame of developing sustainable, eco-friendly and high performance materials, microcrystalline cellulose modified through silane coupling agent (MCC Si) is used as a reinforcing agent of benzoxazine resin to manufacture composites at different loadings of 5, 10, 15, 20 wt%. The structural, morphological and crystallinity characterizations of the modified MCC were initially performed to scrutinize the changes and confirm the modification. Then, an investigation on the crosslinking process of the prepared composites was held through curing kinetic study employing isoconversional methods. The kinetic data revealed a decrease in the average values of activation energy and the pre-exponential factor, particularly for composite supplemented with 10% MCC Si, whereas all samples disclosed a tendency of an autocatalytic curing mechanism. Furthermore, the study of the dynamic mechanical properties and degradation features of the cured specimens, respectively, indicated a superior stiffness attributable to the good interaction between BA-a and MCC Si, and enhanced thermal stability for the composites compared to pristine resin.


Assuntos
Benzoxazinas/química , Benzoxazinas/metabolismo , Celulose/química , Celulose/metabolismo , Resinas Vegetais/química , Resinas Vegetais/metabolismo , Silanos/química , Silanos/metabolismo , Temperatura , Resinas Compostas/síntese química , Reagentes de Ligações Cruzadas/química , Cristalização , Ligação de Hidrogênio , Cinética , Estrutura Molecular
20.
Arch Pharm (Weinheim) ; 354(2): e2000199, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33617016

RESUMO

Seventeen 1,4-benzoxazin-2-ones bearing the enaminone moiety and three of their analogs were tested for the antibacterial activity against Mycobacterium tuberculosis (H37Rv). Minimal bactericidal concentrations (MBCs) were determined after 41 days of incubation by BACTEC. 1,4-Benzoxazin-2-ones bearing the unsubstituted benzo moiety showed the most promising activities (MBC = 5.00 µg/ml). For most active compounds, antibacterial activities were determined daily during the 41 days. The most promising compound showed a bacteriostatic effect at a concentration of 0.31 µg/ml on Day 4 of incubation, 0.62 µg/ml on Day 6, 2.50 µg/ml on Day 9, and 5.00 µg/ml on Day 41. All studied compounds, along with some of their reported analogs, were docked to 35 proteins of M. tuberculosis to find their potent targets in these organisms. As a result of reverse docking, aspartate 1-decarboxylase, panD, was selected as the most appropriate target. Docking of the most active compounds to mutant panD from pyrazinamide-resistant strains of M. tuberculosis implies that they would not be active against these strains. Considering that most of pyrazinamide clinical resistance cases are due to loss-of-function mutations in pyrazinamidase, pncA, compounds from this study could be useful drugs for the treatment of some cases of pyrazinamide-resistant tuberculosis.


Assuntos
Antibacterianos/farmacologia , Benzoxazinas/farmacologia , Simulação de Acoplamento Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Antibacterianos/síntese química , Antibacterianos/química , Benzoxazinas/síntese química , Benzoxazinas/química , Relação Dose-Resposta a Droga , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular
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