Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.920
Filtrar
1.
J Chem Phys ; 151(12): 125103, 2019 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-31575200

RESUMO

This article reports on a frequency domain analysis of quasielastic neutron scattering spectra from free and Huperzine-A-inhibited human acetylcholinesterase, extending a recent time domain analysis of the same experimental data [M. Saouessi et al., J. Chem. Phys. 150, 161104 (2019)]. An important technical point here is the construction of a semianalytical model for the resolution-broadened dynamic structure factor that can be fitted to the experimental spectra. We find comparable parameters as in our previous study and demonstrate that our model is sensitive to subpercent changes in the experimental data, which are caused by reversible binding of the inhibitor Huperzine A.


Assuntos
Acetilcolinesterase/química , Alcaloides/química , Inibidores da Colinesterase/química , Sesquiterpenos/química , Alcaloides/farmacologia , Inibidores da Colinesterase/farmacologia , Humanos , Difração de Nêutrons , Domínios Proteicos , Sesquiterpenos/farmacologia
2.
J Agric Food Chem ; 67(40): 11244-11255, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31532667

RESUMO

Evaluation of acetylcholinesterase (AChE) activity and determination of organophosphorus pesticides (OPs) are of great importance for the clinical diagnosis of several serious diseases correlated with their variations in human blood serum. In this study, a highly selective and sensitive ratiometric fluorescent probe was innovatively fabricated for the evaluation of AChE activity and the determination of OPs in tap water and food on the basis of the inner filter effect (IFE) between nitrogen-doped carbon dots (N-CDs) and 2,3-diaminophenazine (DAP). N-CDs were synthesized via a one-pot hydrothermal method by using pancreatin and 1,2-ethanediamine as precursors. N-CDs showed excellent fluorescence properties and negligible cytotoxicity on human cervical carcinoma HeLa cells and human embryonic kidney 293T cells, suggesting their further biological applications. Upon the addition of AChE and choline oxidase, acetylcholine was catalyzed to produce choline that was further oxidized to produce H2O2. In the presence of horseradish peroxidase, o-phenylenediamine reacted with H2O2 to produce fluorescent DAP. Therefore, a ratiometric fluorescent probing platform existed via IFE between N-CDs with a fluorescence signal at 450 nm and DAP with a fluorescence signal at 574 nm. OPs irreversibly impeded the catalytic activity of AChE, finally leading to the decrease of DAP amount and the variation of ratiometric fluorescent signal. Under optimal conditions, such a fluorescent probe showed relatively low detection limits of 0.38 U/L for AChE, 3.2 ppb for dichlorvos, and 13 ppb for methyl-parathion. Practical application of this ratiometric fluorescent probe to detect OPs was further verified in tap water and food samples with satisfying results that were highly consisted with the results obtained by GC-MS.


Assuntos
Acetilcolinesterase/química , Técnicas Biossensoriais/métodos , Carbono/química , Corantes Fluorescentes/química , Contaminação de Alimentos/análise , Compostos Organofosforados/análise , Praguicidas/análise , Poluentes Químicos da Água/análise , Fluorescência , Água Doce/análise , Células HeLa , Humanos , Limite de Detecção , Pontos Quânticos/química
3.
J Agric Food Chem ; 67(33): 9210-9219, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31390203

RESUMO

The insecticidal and antifeedant activities of five 7-chloro-4-(1H-1,2,3-triazol-1-yl)quinoline derivatives were evaluated against the maize armyworm, Spodoptera frugiperda (J.E. Smith). These hybrids were prepared through a copper-catalyzed azide alkyne cycloaddition (CuAAC, known as a click reaction) and displayed larvicidal properties with LD50 values below 3 mg/g insect, and triazolyl-quinoline hybrid 6 showed an LD50 of 0.65 mg/g insect, making it 2-fold less potent than methomyl, which was used as a reference insecticide (LD50 = 0.34 mg/g insect). Compound 4 was the most active antifeedant derivative (CE50 = 162.1 µg/mL) with a good antifeedant index (56-79%) at concentrations of 250-1000 µg/mL. Additionally, triazolyl-quinoline hybrids 4-8 exhibited weak inhibitory activity against commercial acetylcholinesterase from Electrophorus electricus (electric-eel AChE) (IC50 = 27.7 µg/mL) as well as low anti-ChE activity on S. frugiperda larvae homogenate (IC50 = 68.4 µg/mL). Finally, molecular docking simulations suggested that hybrid 7 binds to the catalytic active site (CAS) of this enzyme and around the rim of the enzyme cavity, acting as a mixed (competitive and noncompetitive) inhibitor like methomyl. Triazolyl-quinolines 4-6 and 8 inhibit AChE by binding over the perimeter of the enzyme cavity, functioning as noncompetitive inhibitors. The results described in this work can help to identify lead triazole structures from click chemistry for the development of insecticide and deterrent products against S. frugiperda and related insect pests.


Assuntos
Inseticidas/síntese química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Quinolinas/química , Quinolinas/farmacologia , Spodoptera/efeitos dos fármacos , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Animais , Inibidores da Colinesterase/síntese química , Inibidores da Colinesterase/química , Inibidores da Colinesterase/farmacologia , Química Click , Simulação por Computador , Proteínas de Insetos/antagonistas & inibidores , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Inseticidas/química , Larva/enzimologia , Larva/crescimento & desenvolvimento , Simulação de Acoplamento Molecular , Doenças das Plantas/parasitologia , Spodoptera/enzimologia , Spodoptera/crescimento & desenvolvimento , Zea mays/parasitologia
4.
Chem Biodivers ; 16(8): e1900318, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31364803

RESUMO

Sponges from freshwater environments, unlike marine's, are poorly known producers of natural compounds with medicinal purposes. Amazonian sponges produce massive large specimens and are widely spread, taxonomically diverse and their metabolites could represent a new frontier on unusual natural products to treat diseases such as Alzheimer's and Malaria. Species of Metania and Drulia (Metaniidae) genera are major contributors to the fauna of Amazonian freshwater sponges. Methanolic extracts from several species from these genera had their inhibitory activities evaluated in vitro, for parasite Plasmodium falciparum and acetyl and butyrylcholinesterase enzymes (AChE and BChE). All extracts were able to inhibit AChE, although no activity was observed towards BChE. Drulia uruguayensis extract was the most potent, inhibiting AChE with IC50 =1.04 mg/mL. For antiplasmodial activity, all species showed inhibition to P. falciparum, but Metania reticulata being the most efficient with IC50 =2.7 µg/mL. Mass spectrometry analyses evidenced the presence of fatty acids and sterols in active extracts.


Assuntos
Antiprotozoários/química , Inibidores da Colinesterase/química , Poríferos/química , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Animais , Antiprotozoários/isolamento & purificação , Antiprotozoários/farmacologia , Butirilcolinesterase/química , Butirilcolinesterase/metabolismo , Inibidores da Colinesterase/metabolismo , Ácidos Graxos/análise , Ácidos Graxos/química , Plasmodium falciparum/efeitos dos fármacos , Poríferos/metabolismo , Espectrometria de Massas por Ionização por Electrospray , Esteróis/química
5.
Chem Biol Interact ; 310: 108735, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31276662

RESUMO

Organophosphates (OPs) irreversibly inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. The reactivation of these inhibited enzymes is paramount for their normal function. Present study evaluates reactivation potency of two newly developed oximes, K456 and K733, against paraoxon (POX)-inhibited human-RBC-AChE and human-plasma-BChE in comparison to reported reactivator, pralidoxime (2-PAM). In vitro studies showed higher intrinsic toxicities of both oximes than 2-PAM for AChE. No substantial reactivation of hBChE was noted by tested concentration. Contrary to 2-PAM, the in silico study predicted lower binding free energies for both oximes. However, the detailed interaction study revealed inability of oximes to interact with catalytic anionic site of AChE and hBChE in contrast to 2-PAM. Both in vitro and in silico studies conclude that K456 and K733 are unlikely to be used as reactivators of paraoxon-inhibited AChE or BChE.


Assuntos
Inibidores da Colinesterase/farmacologia , Reativadores da Colinesterase/farmacologia , Oximas/farmacologia , Paraoxon/antagonistas & inibidores , Compostos de Piridínio/farmacologia , Acetilcolinesterase/química , Butirilcolinesterase/química , Eritrócitos/enzimologia , Humanos , Paraoxon/farmacologia
6.
Chem Biol Interact ; 310: 108737, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31279792

RESUMO

AIMS: K117 and K127 are bis-pyridinium aldoximes but K117 is a bis-pyridinium bis-aldoxime while K127 has only one single aldoxime in addition to its amide substituent. Is there any difference in pharmacokinetics in these compounds that otherwise have the same chemical structure? Both K117 and K127 are developed as antidotes in acetylcholinesterase and butyrylcholinesterase poisoning in terrorist attacks or intoxication with other organophosphorous compounds. Their distributions have been scouted in the bodies of rats. MAIN METHODS: White male Wistar rats were intramuscularly injected. The animals were sacrificed, tissue samples were homogenized, and either K117 or K127 concentrations were determined using reversed-phase high-performance liquid chromatography. KEY FINDINGS: Both K117 and K127 were present in all tissues that were analyzed including blood (serum), the brains, cerebrospinal fluid, the eyes, livers, kidneys, lungs and testes. Their pharmacokinetics and body distributions are similar. SIGNIFICANCE: Either K117 or K127 meets the essential requirements for antidotes. Dose dependence and kinetics of their distribution were compared to that of other pyridinium aldoximes.


Assuntos
Antídotos/farmacocinética , Organofosfatos/antagonistas & inibidores , Oximas/farmacocinética , Compostos de Piridínio/farmacocinética , Acetilcolinesterase/química , Animais , Butirilcolinesterase/química , Substâncias para a Guerra Química/farmacocinética , Inibidores da Colinesterase/farmacocinética , Reativadores da Colinesterase/farmacocinética , Oximas/análise , Compostos de Piridínio/análise , Ratos , Ratos Wistar , Distribuição Tecidual
7.
Chem Biol Interact ; 310: 108753, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31319075

RESUMO

Multitarget ligands (MTL) based on sterically hindered phenol and containing a quaternary ammonium moiety (SHP-n-Q) were synthesized. These compounds are inhibitors of cholinesterases with antioxidant properties. The inhibitory selectivity is 10-fold potent for BChE than for AChE. IC50 of SHP-n-Q for BChE is 20 µM. SHP-n-Q and their nanosystems exhibit more pronounced antioxidant properties than the synthetic antioxidant (hindered phenol, butylated hydroxytoluene). These compounds display a low hemolytic activity against human red blood cells. The nanotechnological approach was used to increase the bioavailability of SHP-n-Q derivatives. For water soluble SHP-n-Q derivative, the self-assembled structures have a size close to 100 nm at critical association concentration (0.01 M). Mixed cationic liposomes based on l-α-phosphatidylcholine and SHP-n-Q of 100 nm diameter were prepared. The stability, encapsulation efficacy and release from liposomes of a model drug, Rhodamine B, depend on the structure of SHP-n-Q. Cationic liposomes based on l-α-phosphatidylcholine and SHP-3-Q show a good stability in time (1year) and a sustained release (>65 h). They are promising templates for the development of anti-Alzheimer MT-drug delivery systems.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Fenóis/química , Acetilcolinesterase/química , Compostos de Amônio , Antioxidantes/farmacologia , Butirilcolinesterase/química , Inibidores da Colinesterase/farmacologia , Humanos , Lipossomos/química , Nanoestruturas , Fenóis/síntese química , Relação Estrutura-Atividade
8.
Toxicol Lett ; 314: 124-132, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31362050

RESUMO

Organophosphates are chemical pollutants that are existed widely in the environment, but the reactions of these agents with blood proteins are still not fully clarified. The current story was to analyze the static and dynamic interactions between human serum albumin (HSA) and phenthoate and then uncover the impact of the conjugations on the acetylcholinesterase (AChE) activity at the microscopic scale. Experimental results revealed clearly that the bioconjugate of the HSA-phenthoate was yielded and the conformation of HSA can produce autoregulation during the reaction. Dynamic reaction processes suggested that the conformational flexibility of the specific protein domain was changed significantly in equilibrium, and the electrostatic interaction energy played a major role in total energy of the biosystems, which matches the results of wet experiment and molecular docking. We also found that the modes of homologous proteins-phenthoate have obvious distinctions, and this point is related closely to the local dynamic flexibility of biomolecular structures. Additionally, the degree of bioconjugation of the HSA-phenthoate is positively associated with the enzymatic activity of target AChE, which may be attributed to the competitive reactions between HSA and AChE. Evidently, this scenario could provide useful molecular information for the systematic exploration of the toxicokinetics of organophosphorus compounds.


Assuntos
Inibidores da Colinesterase/sangue , Inseticidas/sangue , Modelos Biológicos , Simulação de Acoplamento Molecular , Compostos Organotiofosforados/sangue , Albumina Sérica Humana/metabolismo , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Sítios de Ligação , Ligação Competitiva , Inibidores da Colinesterase/química , Inibidores da Colinesterase/toxicidade , Humanos , Inseticidas/química , Inseticidas/toxicidade , Compostos Organotiofosforados/química , Compostos Organotiofosforados/toxicidade , Ligação Proteica , Conformação Proteica , Domínios Proteicos , Albumina Sérica Humana/química
9.
Anal Chim Acta ; 1074: 131-141, 2019 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-31159933

RESUMO

Semiconducting single-walled carbon nanotubes (s-SWCNTs) have been demonstrated as an excellent material for transistors, miniaturized devices and sensors due to their high carrier mobility, stability, scattering-free ballistic transport of carriers etc. Herein, we have designed a biosensor to selectively detect methyl parathion (MP, organophosphorus pesticide) using glutaraldehyde (Glu) cross-linked with acetylcholinesterase (AChE) immobilized on s-SWCNTs wrapped with bovine serum albumin (BSA). The fabricated biosensor was characterized and confirmed by Fourier-transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). In the presence of MP, the effective interaction between AChE and MP favours the accumulation of MP-AChE complex on the glassy carbon electrode (GCE) surface which reduces the electron transfer property. Based on this interaction, detection of various concentration of MP was demonstrated by SWV using BSA/AChE-Glu-s-SWCNTs composite modified electrode. The proposed biosensor exhibited a wide linear range (WLR) for MP target in 100 mM phosphate buffered saline solution (PBS) (pH 7.4) from 1 × 10-10 M to 5 × 10-6 M with a limit of detection (LOD) of 3.75 × 10-11 M. In addition, the BSA/AChE-Glu-s-SWCNTs/GCE biosensor showed good repeatability and reproducibility for MP detection. Moreover, the proposed biosensor showed better electrode stability when stored at 4 °C. This new electrochemical biosensor is also exhibited high selectivity and sensitivity for MP, which made it possible to test MP in real strawberry and apple juices. Furthermore, the BSA/AChE-Glu-s-SWCNTs/GCE offered a favourable electron transfer between the acetylthiocholine chloride (ATCl) and electrode interface than BSA/AChE-s-SWCNTs/GCE, s-SWCNTs/GCE and bare GCE.


Assuntos
Acetilcolinesterase/química , Inseticidas/análise , Metil Paration/análise , Nanocompostos/química , Nanotubos de Carbono/química , Soroalbumina Bovina/química , Animais , Técnicas Biossensoriais/métodos , Carbono , Bovinos , Reagentes para Ligações Cruzadas/química , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Electrophorus , Enzimas Imobilizadas/química , Contaminação de Alimentos/análise , Fragaria/química , Glutaral/química , Inseticidas/química , Limite de Detecção , Malus/química , Metil Paration/química , Reprodutibilidade dos Testes
10.
Chem Biol Interact ; 309: 108698, 2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31176713

RESUMO

Structure-guided design of novel pharmacologically active molecules relies at least in part on functionally relevant accuracy of macromolecular structures for template based drug design. Currently, about 95% of all macromolecular X-ray structures available in the PDB (Protein Data Bank) were obtained from diffraction experiments at low, cryogenic temperatures. However, it is known that functionally relevant conformations of both macromolecules and pharmacological ligands can differ at higher, physiological temperatures. We describe in this article development and properties of new human acetylcholinesterase (AChE) crystals of space group P31 and a new unit cell, amenable for room-temperature X-ray diffraction studies. We co-crystallized hAChE in P31 unit cell with the reversible inhibitor 9-aminoacridine that binds at the base of the active center gorge in addition to inhibitors that span the full length of the gorge, donepezil (Aricept, E2020) and AChE specific inhibitor BW284c51. Their new low temperature P31 space group structures appear similar to those previously obtained in the different P3121 unit cell. Successful solution of the new room temperature 3.2 Å resolution structure of BW284c51*hAChE complex from large P31 crystals enables us to proceed with studying room temperature structures of lower affinity complexes, such as oxime reactivators bound to hAChE, where temperature-related conformational diversity could be expected in both oxime and hAChE, which could lead to better informed structure-based design under conditions approaching physiological temperature.


Assuntos
Acetilcolinesterase/química , Cristalografia por Raios X , Acetilcolinesterase/genética , Acetilcolinesterase/metabolismo , Aminacrina/química , Aminacrina/metabolismo , Sítios de Ligação , Inibidores da Colinesterase/química , Inibidores da Colinesterase/metabolismo , Dimerização , Humanos , Simulação de Dinâmica Molecular , Estrutura Quaternária de Proteína , Estrutura Terciária de Proteína , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Temperatura Ambiente
11.
Chem Biol Interact ; 308: 216-223, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31150627

RESUMO

In this study, 68 crystal structures of complexes between acetylcholinesterase (AChE, EC 3.1.1.7) and its ligands, deposited in the PDB, were analyzed by scoring the functions: LigScore1, LigScore2, PLP1, PLP2, Jain, PMF and PMF04. The scores derived from scoring functions were correlated with an inhibition constant for each ligand (Ki or IC50) in a broad range 10-3 - 10-12 M. The linear correlation model resulted in the highest coefficient of determination (r2) for the PLP2 function, 0.591. The LigScore1 function resulted in the lowest r2 value of 0.226. The PubChem database was the source of in silico computed ligand properties which were then correlated with an inhibition constant for each ligand. For the purposes of this study, two additional non-PubChem parameters were evaluated: total and relative number of sp2 hybridized atoms in the ligand. A high coefficient of determination (r2 > 0.5) was calculated for the following parameters: the number of heavy atoms, molecular mass, and number of atoms with sp2 hybridization. The PLP2 scoring function is a good candidate for drug discovery related to AChE, although a better scoring function could be developed with a higher number of crystal structures of AChE complexes and more reliable kinetic data.


Assuntos
Acetilcolinesterase/metabolismo , Ligantes , Acetilcolinesterase/química , Sítios de Ligação , Domínio Catalítico , Inibidores da Colinesterase/química , Inibidores da Colinesterase/metabolismo , Bases de Dados de Proteínas , Humanos , Cinética , Modelos Moleculares , Ligação Proteica
12.
Chem Biol Interact ; 308: 312-316, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31153983

RESUMO

K-oximes were developed as modern drug candidates acting as AChE reactivators. In this study, it has been investigated which interspecies and intergender differences changes could be observed in Wistar rats and Swiss mice, both genders, after the treatment with increasing doses of selected acetylcholinesterase reactivators - asoxime, obidoxime, K027, K048, and K075. After the 24 h, a number of died animals was counted and the median lethal dose (LD50) for each oxime was calculated. By using the intramuscular route of administration, asoxime and K027 had the least toxicity in female rats (640.21 mg/kg and 686.08 mg/kg), and in female mice (565.75 mg/kg and 565.74 mg/kg), respectively. Moreover, asoxime and K027 showed 3, 4 or 8 times less acute toxicity in comparison to K048, obidoxime and K075, respectively. Beyond, K075 had the greatest toxicity in male rats (81.53 mg/kg), and in male mice (57.34 mg/kg), respectively. Our results can help to predict likely adverse toxic effects, target organ systems and possible outcome in the event of massive human overexposure, and in establishing risk categories or in dose selection for the initial repeated dose toxicity tests to be conducted for each oxime.


Assuntos
Oximas/toxicidade , Testes de Toxicidade Aguda/métodos , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Animais , Reativadores da Colinesterase/química , Reativadores da Colinesterase/metabolismo , Reativadores da Colinesterase/toxicidade , Feminino , Dose Letal Mediana , Masculino , Camundongos , Cloreto de Obidoxima/toxicidade , Pró-Fármacos/toxicidade , Ratos , Ratos Wistar
13.
Chem Biol Interact ; 308: 317-322, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31170385

RESUMO

Acetylcholinesterase (AChE) hydrolyzes acetylcholine at cholinergic synapses, and which has various isoforms of AChE, i.e. AChER, AChEH and AChET, deriving from single gene. AChEH exists as a glycophosphatidylinositol (GPI)-linked dimer (G2), presents mainly in plasma membrane of mammalian erythrocyte. Transgenic mice with ACHE gene depletion were employed here to investigate the possible role of AChE in blood cell formation. ACHE knock-out mice were found to suffer normocytic anemia. In erythrocyte of ACHE-/- mice, the amount of hemoglobin, especially α-globin, was found to be markedly reduced. In addition, the number of erythrocyte and hematocrit of ACHE-/- mice were significantly lowered. To probe the role of AChE isoforms in erythroid differentiation, erythroblast-like cells (TF-1) over-expressed with different AChE isoforms were induced to differentiate by erythropoietin (EPO): this differentiation induced the expression of each AChE isoform. Only in the TF-1 cells over-expressed with AChEH, the EPO-induced transcriptions and protein expressions of α- and ß-globins could be significantly enhanced, which therefore suggested that AChEH might regulate the responsiveness of TF-1 cells to EPO. The alternation of EPO-induced downstream signaling might be accounted by association of AChE with EPO receptor in cell surface. The findings indicated the significance of AChE in erythroblast maturation, which provided an insight in elucidating possible mechanisms in regulating erythropoiesis.


Assuntos
Acetilcolinesterase/metabolismo , Receptores da Eritropoetina/metabolismo , Acetilcolinesterase/química , Acetilcolinesterase/imunologia , Animais , Anticorpos/imunologia , Diferenciação Celular , Linhagem Celular , Dimerização , Eritroblastos/citologia , Eritroblastos/metabolismo , Eritropoetina/farmacologia , Expressão Gênica/efeitos dos fármacos , Hemoglobinas/metabolismo , Humanos , Camundongos , Camundongos Knockout , Receptores da Eritropoetina/imunologia
14.
Chem Biol Interact ; 309: 108682, 2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31163137

RESUMO

Casualties caused by nerve agents, potent acetylcholinesterase inhibitors, have attracted attention from media recently. Poisoning with these chemicals may be fatal if not correctly addressed. Therefore, research on novel antidotes is clearly warranted. Pyridinium oximes are the only clinically available compounds, but poor penetration into the blood-brain barrier hampers efficient enzyme reactivation at the central nervous system. In searching for structural factors that may be explored in SAR studies, we synthesized and evaluated neutral aryloximes as reactivators for acetylcholinesterase inhibited by NEMP, a VX surrogate. Although few tested compounds reached comparable reactivation results with clinical standards, they may be considered as leads for further optimization.


Assuntos
Acetilcolinesterase/metabolismo , Reativadores da Colinesterase/síntese química , Oximas/química , Pirrolidinas/química , Acetilcolinesterase/química , Animais , Antídotos/síntese química , Antídotos/metabolismo , Inibidores da Colinesterase/química , Inibidores da Colinesterase/metabolismo , Reativadores da Colinesterase/metabolismo , Enguias , Compostos Organotiofosforados/química , Compostos Organotiofosforados/metabolismo , Oximas/metabolismo , Pirrolidinas/metabolismo , Relação Estrutura-Atividade
15.
Chem Biol Interact ; 309: 108707, 2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31194956

RESUMO

Alzheimer's disease (AD) is a slow but progressive neurodegenerative disease. One of the pathological hallmarks of AD is the progressive accumulation of ß-amyloid (Aß) in the form of senile plaques, and Aß insult to neuronal cells has been identified as one of the major causes of AD onset. In the present study, we investigated the anti-AD potential of four flavonoids, naringenin, didymin, prunin, and poncirin, by evaluating their ability to inhibit acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and ß-site amyloid precursor protein cleaving enzyme 1 (BACE1). All four flavonoids displayed promising inhibitory activity against AChE, BChE, and BACE1. Structure-activity relationships suggested that glycosylation of naringenin at sugar moieties, and at different positions of the glycosidic linkage, might be closely associated with anti-AD potential. Kinetic and docking studies showed the lowest binding energy and highest affinity for the mixed, competitive, and non-competitive type inhibitors didymin, prunin, and poncirin. Hydrophobic interactions and the number of hydrogen bonds determined the strength of the protein-inhibitor interaction. We also examined the neuroprotective mechanisms by which flavonoids act against Aß25-35-induced toxicity in PC12 cells. Exposure of PC12 cells to 10 µM Aß25-35 for 24 h resulted in a significant decrease in cell viability. In addition, pretreatment of PC12 cells with different concentrations of flavonoids for 1 h significantly reversed the effects of Aß. Furthermore, treatment with the most active flavonoid, didymin, significantly reduced BACE1, APPsß, and C99 expression levels in a dose-dependent manner, without affecting amyloid precursor protein (APP) levels in the amyloidogenic pathway. Together, our results indicate that flavonoids, and in particular didymin, exhibit inhibitory activity in vitro, and may be useful in the development of therapeutic modalities for the treatment of AD.


Assuntos
Acetilcolinesterase/metabolismo , Secretases da Proteína Precursora do Amiloide/metabolismo , Peptídeos beta-Amiloides/metabolismo , Ácido Aspártico Endopeptidases/metabolismo , Butirilcolinesterase/metabolismo , Flavanonas/química , Glicosídeos/farmacologia , Agregados Proteicos/efeitos dos fármacos , Acetilcolinesterase/química , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/farmacologia , Animais , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Sítios de Ligação , Butirilcolinesterase/química , Domínio Catalítico , Sobrevivência Celular/efeitos dos fármacos , Glicosídeos/química , Cinética , Simulação de Acoplamento Molecular , Células PC12 , Fragmentos de Peptídeos/farmacologia , Substâncias Protetoras/química , Substâncias Protetoras/farmacologia , Ratos , Relação Estrutura-Atividade
16.
Chem Biol Interact ; 309: 108699, 2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31202688

RESUMO

The crystal structures of truncated forms of cholinesterases provide good models for assessing the role of non-covalent interactions in dimer assembly in the absence of cross-linking disulfide bonds. These structures identify the four-helix bundle that serves as the interface for formation of acetylcholinesterase and butyrylcholinesterase dimers. Here we performed a theoretical comparison of the structural and energetic factors governing dimerization. This included identification of inter-subunit and intra-subunit hydrogen bonds and hydrophobic interactions, evaluation of solvent-accessible surfaces, and estimation of electrostatic contributions to dimerization. To reveal the contribution to dimerization of individual amino acids within the contact area, free energy perturbation alanine screening was performed. Markov state modelling shows that the loop between the α13 and α14 helices in BChE is unstable, and occupies 4 macro-states. The order of magnitude of mean first passage times between these macrostates is ~10-8 s. Replica exchange molecular dynamics umbrella sampling calculations revealed that the free energy of human BChE dimerization is -15.5 kcal/mol, while that for human AChE is -26.4 kcal/mol. Thus, the C-terminally truncated human butyrylcholinesterase dimer is substantially less stable than that of human acetylcholinesterase. An animated Interactive 3D Complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:CHEMBIOINT:1.


Assuntos
Acetilcolinesterase/química , Butirilcolinesterase/química , Acetilcolinesterase/metabolismo , Sequência de Aminoácidos , Butirilcolinesterase/metabolismo , Dimerização , Humanos , Interações Hidrofóbicas e Hidrofílicas , Cadeias de Markov , Simulação de Dinâmica Molecular , Conformação Proteica em alfa-Hélice , Alinhamento de Sequência , Eletricidade Estática , Termodinâmica
17.
Chem Biol Interact ; 309: 108671, 2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31207225

RESUMO

Studies with oximes have been extensively developed to design new reactivators with better efficiency, and greater spectrum of action. In this study, we aimed to analyze the influence of the Carbamoyl group position change in two isomeric oximes, K203 and K206, on the reactivation percentage of Mus musculus Acetylcholinesterase (MmAChE), inhibited by different nerve agents. Theoretical calculations were performed to assess the difference for the oxime activity with inhibited AChE-complexes and the factors that govern this difference. Comparing theoretical and experimental data, it is possible to observe that this change between the oximes results in different reactivation percentage for the same nerve agent, due to the different interaction modes and activation energy for the studied systems.


Assuntos
Acetilcolinesterase/metabolismo , Reativadores da Colinesterase/química , Compostos Organofosforados/química , Oximas/química , Acetilcolinesterase/química , Animais , Sítios de Ligação , Reativadores da Colinesterase/metabolismo , Desenho de Drogas , Camundongos , Simulação de Acoplamento Molecular , Agentes Neurotóxicos/química , Agentes Neurotóxicos/metabolismo , Compostos Organofosforados/metabolismo , Compostos Organotiofosforados/química , Compostos Organotiofosforados/metabolismo , Teoria Quântica , Termodinâmica
18.
Chem Biol Interact ; 309: 108714, 2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31228470

RESUMO

Acetylcholinesterase (AChE) is an enzyme which terminates the cholinergic neurotransmission, by hydrolyzing acetylcholine at the nerve and nerve-muscle junctions. The reversible inhibition of AChE was suggested as the pre-treatment option of the intoxications caused by nerve agents. Based on our derived 3D-QSAR model for the reversible AChE inhibitors, we designed and synthesized three novel compounds 8-10, joining the tacrine and aroylacrylic acid phenylamide moieties, with a longer methylene chain to target two distinct, toplogically separated anionic areas on the AChE. The targeted compounds exerted low nanomolar to subnanomolar potency toward the E. eel and human AChE's as well as the human BChE and showed mixed inhibition type in kinetic studies. All compounds were able to slow down the irreversible inhibition of the human AChE by several nerve agents including tabun, soman and VX, with the estimated protective indices around 5, indicating a valuable level of protection. Putative noncovalent interactions of the selected ligand 10 with AChE active site gorge were finally explored by molecular dynamics simulation suggesting a formation of the salt bridge between the protonated linker amino group and the negatively charged Asp74 carboxylate side chain as a significant player for the successful molecular recognition in line with the design strategy. The designed compounds may represent a new class of promising leads for the development of more effective pre-treatment options.


Assuntos
Substâncias para a Guerra Química/química , Inibidores da Colinesterase/química , Colinesterases/metabolismo , Substâncias Protetoras/química , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Sítios de Ligação , Domínio Catalítico , Substâncias para a Guerra Química/metabolismo , Inibidores da Colinesterase/metabolismo , Colinesterases/química , Humanos , Cinética , Simulação de Dinâmica Molecular , Compostos Organofosforados/química , Compostos Organofosforados/metabolismo , Substâncias Protetoras/metabolismo , Relação Quantitativa Estrutura-Atividade , Soman/química , Soman/metabolismo
19.
Phys Chem Chem Phys ; 21(25): 13578-13589, 2019 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-31173012

RESUMO

Donepezil, an acetylcholinesterase inhibitor, is an approved drug for the symptomatic treatment of Alzheimer's disease (AD). The mechanistic pathway for the inhibition mechanism of acetylcholinesterase (AChE) by donepezil is not well explored. We report for the first time, the inhibition mechanism of AChE by the donepezil drug molecule for the hydrolysis of acetylcholine (ACh) with docking and well-tempered metadynamics (WTMtD) simulations with a human acetylcholinesterase (hAChE) crystal structure (). This study explored the orientation of the donepezil drug molecule inside the gorge of AChE. The 1D free energy surface obtained from WTMtD simulation studies reveals that the orientation of donepezil in the crystal donepezil (-87.25 kJ mol-1) is energetically more favored than the other orientation of donepezil (-74.74 kJ mol-1) for inhibition of AChE. The free energy landscape computation for the two sets of CVs further corroborates the 1D free energy surface. The WTMtD simulation performed with the crystal structure of donepezil bound hAChE gives the conformation of donepezil at Basin-I as similar to the conformation of donepezil observed in the crystal structure (). The WTMtD simulations further reveal that the bridged water molecules are more ordered near the catalytic triad of AChE to deter the nucleophilicity of Ser203 through intermolecular hydrogen bonding when donepezil approaches near to the active site gorge of AChE. The presence of donepezil near the active site of AChE can inhibit its approach for ACh hydrolysis; this is revealed through the docking study, where the drug molecule inside the active gorge of hAChE restricts the approach of ACh to Ser203 for the hydrolysis process.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Inibidores da Colinesterase/farmacologia , Donepezila/farmacologia , Modelos Moleculares , Acetilcolinesterase/química , Catálise , Domínio Catalítico , Inibidores da Colinesterase/química , Cristalização , Donepezila/química , Humanos , Ligações de Hidrogênio , Hidrólise , Ligação Proteica , Termodinâmica
20.
Chem Biodivers ; 16(8): e1900243, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31207061

RESUMO

The new complex compounds [RuLCl(p-cymene)] ⋅ 3H2 O and [NiL2 (H2 O)2 ] ⋅ 3H2 O (L: 1-{4-[(2-hydroxy-3-methoxybenzylidene)amino]phenyl}ethanone) were prepared and characterized using FT-IR, 1 H- and 13 C-NMR, mass spectroscopy, TGA, elemental analysis, X-ray powder diffraction and magnetic moment techniques. Octahedral geometry for new Ni(II) and Ru(II) complexes was proposed. Thermal decomposition confirmed the existence of lattice and coordinated water molecule in the complexes. To determine the antioxidant properties of Schiff base ligand and its Ni(II), Ru(II) metal complexes, FRAP, CUPRAC, ABTS and DPPH methods of antioxidant assays were used. Moreover, enzyme inhibition of complexes was evaluated against carbonic anhydrase I and II isoenzymes (CA I and CA II) and acetylcholinesterase (AChE). For CA I and CA II, the best inhibition enzymes, was the Ni(II) complex with 62.98±18.41, 86.17±23.62 Ki values, whereas this inhibition effect showed ligand with 24.53±2.66 Ki value for the AChE enzyme.


Assuntos
Antioxidantes/química , Complexos de Coordenação/química , Inibidores Enzimáticos/química , Níquel/química , Rutênio/química , Bases de Schiff/química , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Anidrase Carbônica I/antagonistas & inibidores , Anidrase Carbônica I/metabolismo , Anidrase Carbônica II/antagonistas & inibidores , Anidrase Carbônica II/metabolismo , Complexos de Coordenação/farmacologia , Inibidores Enzimáticos/metabolismo , Concentração Inibidora 50 , Espectrofotometria Infravermelho
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA