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1.
Biochem Biophys Res Commun ; 526(2): 349-354, 2020 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-32222278

RESUMO

Apolipoprotein A-I (ApoA-I) mimetic peptides are potential therapeutic agents for promoting the efflux of excess cellular cholesterol, which is dependent upon the presence of an amphipathic helix. Since α-methylated Ala enhances peptide helicity, we hypothesized that incorporating other types of α-methylated amino acids into ApoA-I mimetic peptides may also increase their helicity and cholesterol efflux potential. The last helix of apoA-I, peptide 'A' (VLESFKVSFLSALEEYTKKLNT), was used to design peptides containing a single type of α-methylated amino acid substitution (Ala/Aα, Glu/Dα, Lys/Kα, Leu/Lα), as well as a peptide containing both α-methylated Lys and Leu (6α). Depending on the specific residue, the α-helical content as measured by CD-spectroscopy and calculated hydrophobic moments were sometimes higher for peptides containing other types of α-methylated amino acids than those with α-methylated Ala. In ABCA1-transfected cells, cholesterol efflux to the peptides showed the following order of potency: 6α>Kα≈Lα≈Aα≫Dα≈A. In general, α-methylated peptides were resistant to proteolysis, but this varied depending on the type of protease and specific amino acid substitution. In summary, increased helicity and amphilicity due to α-methylated amino acid substitutions in ApoA-I mimetic peptides resulted in improved cholesterol efflux capacity and resistance to proteolysis, indicating that this modification may be useful in the future design of therapeutic ApoA-I mimetic peptides.


Assuntos
Aminoácidos/química , Apolipoproteína A-I/química , Colesterol/metabolismo , Peptidomiméticos/química , Peptidomiméticos/farmacologia , Sequência de Aminoácidos , Animais , Linhagem Celular , Desenho de Fármacos , Humanos , Metilação
2.
Pestic Biochem Physiol ; 151: 32-39, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30524149

RESUMO

The widespread emergence of pyrethroid-resistant Anopheles gambiae has intensified the need to find new contact mosquitocides for indoor residual spraying and insecticide treated nets. With the goal of developing new species-selective and resistance-breaking acetylcholinesterase (AChE)-inhibiting mosquitocides, in this report we revisit the effects of carbamate substitution on aryl carbamates, and variation of the 1-alkyl group on pyrazol-4-yl methylcarbamates. Compared to aryl methylcarbamates, aryl dimethylcarbamates were found to have lower selectivity for An. gambiae AChE (AgAChE) over human AChE (hAChE), but improved tarsal contact toxicity to G3 strain An. gambiae. Molecular modeling studies suggest the lower species-selectivity of the aryl dimethylcarbamates can be attributed to a less flexible acyl pocket in AgAChE relative to hAChE. The improved tarsal contact toxicity of the aryl dimethylcarbamates relative to the corresponding methylcarbamates is attributed to a range of complementary phenomena. With respect to the pyrazol-4-yl methylcarbamates, the previously observed low An. gambiae-selectivity of compounds bearing α-branched 1-alkyl groups was improved by employing ß- and γ-branched 1-alkyl groups. Compounds 22a (cyclopentylmethyl), 21a (cyclobutylmethyl), and 26a (3-methylbutyl) offer 250-fold, 120-fold, and 96-fold selectivity, respectively, for inhibition of AgAChE vs. hAChE. Molecular modeling studies suggests the high species-selectivity of these compounds can be attributed to the greater mobility of the W84 side chain in the choline-binding site of AgAChE, compared to that of W86 in hAChE. Compound 26a has reasonable contact toxicity to G3 strain An. gambiae (LC50 = 269 µg/mL) and low cross-resistance to Akron strain (LC50 = 948 µg/mL), which bears the G119S resistance mutation.


Assuntos
Anopheles/efeitos dos fármacos , Carbamatos/toxicidade , Inibidores da Colinesterase/toxicidade , Inseticidas/toxicidade , Acetilcolinesterase/metabolismo , Animais , Anopheles/fisiologia , Carbamatos/química , Inibidores da Colinesterase/química , Feminino , Humanos , Resistência a Inseticidas/genética , Inseticidas/química , Modelos Moleculares , Mutação
3.
Biochim Biophys Acta Biomembr ; 1859(2): 135-145, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27814978

RESUMO

Apolipoprotein B (apoB) is a large amphipathic protein that is the structural scaffold for the formation of several classes of lipoproteins involved in lipid transport throughout the body. The goal of the present study was to identify specific domains in the apoB sequence that contribute to its lipid binding properties. A sequence analysis algorithm was developed to identify stretches of hydrophobic amino acids devoid of charged amino acids, which are referred to as hydrophobic cluster domains (HCDs). This analysis identified 78 HCDs in apoB with hydrophobic stretches ranging from 6 to 26 residues. Each HCD was analyzed in silico for secondary structure and lipid binding properties, and a subset was synthesized for experimental evaluation. One HCD peptide, B38, showed high affinity binding to both isolated HDL and LDL, and could exchange between lipoproteins. All-atom molecular dynamics simulations indicate that B38 inserts 3.7Å below the phosphate plane of the bilayer. B38 forms an unusual α-helix with a broad hydrophobic face and polar serine and threonine residues on the opposite face. Based on this structure, we hypothesized that B38 could efflux cholesterol from cells. B38 showed a 12-fold greater activity than the 5A peptide, a bihelical Class A amphipathic helix (EC50 of 0.2658 vs. 3.188µM; p<0.0001), in promoting cholesterol efflux from ABCA1 expressing BHK-1 cells. In conclusion, we have identified novel domains within apoB that contribute to its lipid biding properties. Additionally, we have discovered a unique amphipathic helix design for efficient ABCA1-specific cholesterol efflux.


Assuntos
Apolipoproteínas B/química , Apolipoproteínas B/metabolismo , Lipídeos/química , Estrutura Secundária de Proteína/fisiologia , Transportador 1 de Cassete de Ligação de ATP/química , Transportador 1 de Cassete de Ligação de ATP/metabolismo , Aminoácidos/química , Aminoácidos/metabolismo , Sítios de Ligação/fisiologia , Células Cultivadas , HDL-Colesterol/química , HDL-Colesterol/metabolismo , LDL-Colesterol/química , LDL-Colesterol/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Peptídeos/química , Peptídeos/metabolismo , Ligação Proteica/fisiologia
4.
Pestic Biochem Physiol ; 143: 33-38, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29183608

RESUMO

New public health insecticides are urgently required to prevent the spread of vector-borne disease. With the goal of identifying new K+-channel-directed mosquitocides, analogs of the RH-5849 family of diacyl t-butylhydrazines were synthesized and tested for topical toxicity against adult Anopheles gambiae, the African vector of malaria. In total, 80N'-monoacyl and N, N'-diacyl derivatives of benzyl- and arylhydrazines were prepared. Three compounds (2bo, 2kb, 3ab) were identified that were more toxic than RH-5849 and RH-1266. The potencies of these compounds to block K+ currents in An. gambiae and human Kv2.1 channels were assessed to address their possible mechanism of mosquitocidal action. Selectivity for inhibition of An. gambiae Kv2.1 vs human Kv2.1 did not exceed 3-fold. Furthermore, no correlation was seen between the potency of insecticidal action and K+ channel blocking potency. These observations, combined with the minimal knockdown seen with 2bo near its LD50 value, suggests a mode of action outside of the nervous system.


Assuntos
Anopheles/efeitos dos fármacos , Hidrazinas/toxicidade , Inseticidas/toxicidade , Bloqueadores dos Canais de Potássio/toxicidade , Animais , Linhagem Celular Tumoral , Células HEK293 , Humanos , Controle de Mosquitos/métodos , Canais de Potássio Shab/genética , Canais de Potássio Shab/fisiologia
5.
Bioorg Med Chem Lett ; 25(20): 4405-11, 2015 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-26386602

RESUMO

Malaria is a devastating disease in sub-Saharan Africa, and current vector control measures are threatened by emerging resistance mechanisms. With the goal of developing new, selective, resistance-breaking insecticides we explored α-fluorinated methyl ketones as reversible covalent inhibitors of Anopheles gambiae acetylcholinesterase (AgAChE). Trifluoromethyl ketones 5 demonstrated remarkable volatility in microtiter plate assays, but 5c,e-h exhibited potent (1-100 nM) inhibition of wild type (WT) AgAChE and weak inhibition of resistant mutant G119S mutant AgAChE. Fluoromethyl ketones 10c-i exhibited submicromolar to micromolar inhibition of WT AgAChE, but again only weakly inhibited G119S AgAChE. Interestingly, difluoromethyl ketone inhibitors 9c and 9g had single digit nanomolar inhibition of WT AgAChE, and 9g had excellent potency against G119S AgAChE. Approach to steady-state inhibition was quite slow, but after 23 h incubation an IC50 value of 25.1 ± 1.2 nM was measured. We attribute the slow, tight-binding G119S AgAChE inhibition of 9g to a balance of steric size and electrophilicity. However, toxicities of 5g, 9g, and 10g to adult A. gambiae in tarsal contact, fumigation, and injection assays were lower than expected based on WT AgAChE inhibition potency and volatility. Potential toxicity-limiting factors are discussed.


Assuntos
Acetilcolinesterase/metabolismo , Anopheles/enzimologia , Inibidores Enzimáticos/farmacologia , Cetonas/farmacologia , Acetilcolinesterase/genética , Animais , Carbamatos/farmacologia , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Humanos , Cetonas/síntese química , Cetonas/química , Estrutura Molecular , Mutação , Relação Estrutura-Atividade
6.
Bioorg Med Chem ; 23(6): 1321-40, 2015 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-25684426

RESUMO

To identify potential selective and resistance-breaking mosquitocides against the African malaria vector Anopheles gambiae, we investigated the acetylcholinesterase (AChE) inhibitory and mosquitocidal properties of isoxazol-3-yl dimethylcarbamates (15), and the corresponding 3-oxoisoxazole-2(3H)-dimethylcarboxamide isomers (14). In both series, compounds were found with excellent contact toxicity to wild-type susceptible (G3) strain and multiply resistant (Akron) strain mosquitoes that carry the G119S resistance mutation of AChE. Compounds possessing good to excellent toxicity to Akron strain mosquitoes inhibit the G119S mutant of An. gambiae AChE (AgAChE) with ki values at least 10- to 600-fold higher than that of propoxur, a compound that does not kill Akron mosquitoes at the highest concentration tested. On average, inactivation of WT AgAChE by dimethylcarboxamides 14 was 10-20 fold faster than that of the corresponding isoxazol-3-yl dimethylcarbamates 15. X-ray crystallography of dimethylcarboxamide 14d provided insight into that reactivity, a finding that may explain the inhibitory power of structurally-related inhibitors of hormone-sensitive lipase. Finally, human/An. gambiae AChE inhibition selectivities of these compounds were low, suggesting the need for additional structural modification.


Assuntos
Acetilcolinesterase/metabolismo , Anopheles/efeitos dos fármacos , Anopheles/enzimologia , Carbamatos/farmacologia , Inibidores da Colinesterase/farmacologia , Isoxazóis/farmacologia , Malária , Acetilcolinesterase/genética , Animais , Carbamatos/síntese química , Carbamatos/química , Inibidores da Colinesterase/síntese química , Inibidores da Colinesterase/química , Relação Dose-Resposta a Droga , Humanos , Isoxazóis/síntese química , Isoxazóis/química , Malária/transmissão , Estrutura Molecular , Relação Estrutura-Atividade
7.
Biotechnol Lett ; 37(3): 567-75, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25432417

RESUMO

Mono-antennary galacto derivatives of cholesterol are being actively developed to direct lipoplexes to the asialoglycoprotein receptor (ASGP-R) on hepatocytes. Here we report on a novel ASGP-R ligand cholest-5-en-3-yl [1-(ß-D-galactopyranosyl)-1H-1,2,3-triazol-4-yl]methylcarbamate (4), assembled by a copper(I)-catalyzed azide-alkyne cycloaddition (click chemistry), and compare it with cholest-5-en-3-yl-ß-D-galactopyranoside (2) and cholest-5-en-3-yl [1-(ß-D-galactopyranosyl-1'-oxy)phen-4-yl]carbamate (3), in liposome formulations with or without 5 mol% distearoylphosphatidylethanolamine poly(ethylene glycol)2000, intended for DNA delivery to ASGP-R-positive hepatocyte-derived HepG2 cells and the ASGP-R-negative embryo kidney cell line HEK293. Transfection levels attained with lipoplex 4 were 100 and 300% greater than those for lipoplexes 2 and 3 respectively in HepG2 cells, while competition assays reduced transfection levels by up to 98%. Transfection activities achieved in HEK293 cells were up to three orders of magnitude lower. Therefore, 4 is representative of a new class of promising hepatotropic ligands for gene delivery.


Assuntos
Receptor de Asialoglicoproteína/agonistas , DNA/metabolismo , Técnicas de Transferência de Genes , Hepatócitos/metabolismo , Lipossomos/metabolismo , Linhagem Celular , Células Epiteliais/metabolismo , Humanos
8.
J Neurosci ; 33(30): 12306-15, 2013 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-23884937

RESUMO

While sialylation plays important functions in the nervous system, the complexity of glycosylation pathways and limitations of genetic approaches preclude the efficient analysis of these functions in mammalian organisms. Drosophila has recently emerged as a promising model for studying neural sialylation. Drosophila sialyltransferase, DSiaT, was shown to be involved in the regulation of neural transmission. However, the sialylation pathway was not investigated in Drosophila beyond the DSiaT-mediated step. Here we focused on the function of Drosophila cytidine monophosphate-sialic acid synthetase (CSAS), the enzyme providing a sugar donor for DSiaT. Our results revealed that the expression of CSAS is tightly regulated and restricted to the CNS throughout development and in adult flies. We generated CSAS mutants and analyzed their phenotypes using behavioral and physiological approaches. Our experiments demonstrated that mutant phenotypes of CSAS are similar to those of DSiaT, including decreased longevity, temperature-induced paralysis, locomotor abnormalities, and defects of neural transmission at neuromuscular junctions. Genetic interactions between CSAS, DSiaT, and voltage-gated channel genes paralytic and seizure were consistent with the hypothesis that CSAS and DSiaT function within the same pathway regulating neural excitability. Intriguingly, these interactions also suggested that CSAS and DSiaT have some additional, independent functions. Moreover, unlike its mammalian counterparts that work in the nucleus, Drosophila CSAS was found to be a glycoprotein-bearing N-glycans and predominantly localized in vivo to the Golgi compartment. Our work provides the first systematic analysis of in vivo functions of a eukaryotic CSAS gene and sheds light on evolutionary relationships among metazoan CSAS proteins.


Assuntos
Monofosfato de Citidina/metabolismo , Proteínas de Drosophila/genética , Drosophila/enzimologia , Ligases/genética , Ácido N-Acetilneuramínico/metabolismo , N-Acilneuraminato Citidililtransferase/genética , Fenômenos Fisiológicos do Sistema Nervoso/genética , Animais , Animais Geneticamente Modificados , Drosophila/genética , Proteínas de Drosophila/metabolismo , Evolução Molecular , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Ligases/metabolismo , Longevidade/genética , N-Acilneuraminato Citidililtransferase/metabolismo , Junção Neuromuscular/genética , Junção Neuromuscular/metabolismo , Paralisia/genética , Paralisia/metabolismo , Vesículas Secretórias/fisiologia , Sialiltransferases/genética , Sialiltransferases/metabolismo , Transmissão Sináptica/genética , Transmissão Sináptica/fisiologia , Temperatura
9.
Development ; 138(8): 1595-605, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21389050

RESUMO

The spatiotemporal integration of adhesion and signaling during neuritogenesis is an important prerequisite for the establishment of neuronal networks in the developing brain. In this study, we describe the role of the L1-type CAM Neuroglian protein (NRG) in different steps of Drosophila mushroom body (MB) neuron axonogenesis. Selective axon bundling in the peduncle requires both the extracellular and the intracellular domain of NRG. We uncover a novel role for the ZO-1 homolog Polychaetoid (PYD) in axon branching and in sister branch outgrowth and guidance downstream of the neuron-specific isoform NRG-180. Furthermore, genetic analyses show that the role of NRG in different aspects of MB axonal development not only involves PYD, but also TRIO, SEMA-1A and RAC1.


Assuntos
Axônios/metabolismo , Moléculas de Adesão Celular Neuronais/metabolismo , Proteínas de Drosophila/metabolismo , Corpos Pedunculados/citologia , Corpos Pedunculados/metabolismo , Molécula L1 de Adesão de Célula Nervosa/metabolismo , Animais , Axônios/fisiologia , Moléculas de Adesão Celular Neuronais/genética , Linhagem Celular , Drosophila , Proteínas de Drosophila/genética , Feminino , Imuno-Histoquímica , Masculino , Molécula L1 de Adesão de Célula Nervosa/genética , Organogênese/genética , Organogênese/fisiologia , Reação em Cadeia da Polimerase , Transdução de Sinais/genética , Transdução de Sinais/fisiologia
10.
Proc Natl Acad Sci U S A ; 107(25): 11393-8, 2010 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-20534503

RESUMO

The endogenous signaling molecule S-nitrosoglutathione (GSNO) and other S-nitrosylating agents can cause full maturation of the abnormal gene product DeltaF508 cystic fibrosis (CF) transmembrane conductance regulator (CFTR). However, the molecular mechanism of action is not known. Here we show that Hsp70/Hsp90 organizing protein (Hop) is a critical target of GSNO, and its S-nitrosylation results in DeltaF508 CFTR maturation and cell surface expression. S-nitrosylation by GSNO inhibited the association of Hop with CFTR in the endoplasmic reticulum. This effect was necessary and sufficient to mediate GSNO-induced cell-surface expression of DeltaF508 CFTR. Hop knockdown using siRNA recapitulated the effect of GSNO on DeltaF508 CFTR maturation and expression. Moreover, GSNO acted additively with decreased temperature, which promoted mutant CFTR maturation through a Hop-independent mechanism. We conclude that GSNO corrects DeltaF508 CFTR trafficking by inhibiting Hop expression, and that combination therapies--using differing mechanisms of action--may have additive benefits in treating CF.


Assuntos
Proteínas de Transporte/genética , Proteínas de Transporte/fisiologia , Fibrose Cística/terapia , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Mutação , Nitrogênio/química , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/fisiologia , Linhagem Celular , Membrana Celular/metabolismo , Fibrose Cística/genética , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Retículo Endoplasmático/metabolismo , Terapia Genética/métodos , Humanos , Modelos Biológicos , S-Nitrosoglutationa/química , Transdução de Sinais
11.
Pestic Biochem Physiol ; 106(3): 79-84, 2013 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-24003261

RESUMO

Conventional insecticides targeting acetylcholinesterase (AChE) typically show high mammalian toxicities and because there is resistance to these compounds in many insect species, alternatives to established AChE inhibitors used for pest control are needed. Here we used a fluorescence method to monitor interactions between various AChE inhibitors and the AChE peripheral anionic site, which is a novel target for new insecticides acting on this enzyme. The assay uses thioflavin-T as a probe, which binds to the peripheral anionic site of AChE and yields an increase in fluorescent signal. Three types of AChE inhibitors were studied: catalytic site inhibitors (carbamate insecticides, edrophonium, and benzylpiperidine), peripheral site inhibitors (tubocurarine, ethidium bromide, and propidium iodide), and bivalent inhibitors (donepezil, BW284C51, and a series of bis(n)-tacrines). All were screened on murine AChE to compare and contrast changes of peripheral site conformation in the TFT assay with catalytic inhibition. All the inhibitors reduced thioflavin-T fluorescence in a concentration-dependent manner with potencies (IC50) ranging from 8 nM for bis(6)-tacrine to 159 µM for benzylpiperidine. Potencies in the fluorescence assay were correlated well with their potencies for enzyme inhibition (R2 = 0.884). Efficacies for reducing thioflavin-T fluorescence ranged from 23-36% for catalytic site inhibitors and tubocurarine to near 100% for ethidium bromide and propidium iodide. Maximal efficacies could be reconciled with known mechanisms of interaction of the inhibitors with AChE. When extended to pest species, we anticipate these findings will assist in the discovery and development of novel, selective bivalent insecticides acting on AChE.

12.
Neurobiol Dis ; 46(1): 137-46, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22266335

RESUMO

Parkinson's disease (PD), caused by selective loss of dopaminergic (DA) neurons in the substantia nigra pars compacta, is the most common movement disorder. While its etiology remains unknown, mitochondrial dysfunction is recognized as one of the major cellular defects contributing to PD pathogenesis. Mitochondrial uncoupling protein 2 (UCP2) has been implicated in neuroprotection in several neuronal injury models. Here we show that hucp2 expression in Drosophila DA neurons under the control of the tyrosine hydroxylase (TH) promoter protects those flies against the mitochondrial toxin rotenone-induced DA neuron death, head dopamine depletion, impaired locomotor activity and energy deficiency. Under normal conditions, hUCP2 flies maintain an enhanced locomotor activity and have higher steady-state ATP levels suggesting improved energy homeostasis. We show that while no increased mitochondrial DNA content or volume fraction is measured in hUCP2 flies, augmented mitochondrial complex I activity is detected. Those results suggest that it is increased mitochondrial function but not mitochondrial biogenesis that appears responsible for higher ATP levels in hUCP2 flies. Consistent with this notion, an up-regulation of Spargel, the Drosophila peroxisome proliferator-activated receptor gamma coactivator 1 (PGC-1) homologue is detected in hUCP2 flies. Furthermore, a Spargel target gene Tfam, the mitochondrial transcription factor A is up-regulated in hUCP2 flies. Taken together, our results demonstrate a neuroprotective effect of hUCP2 in DA neurons in a Drosophila sporadic PD model. Moreover, as the TH promoter activity is present in both DA neurons and epidermis, our results reveal that hucp2 expression in those tissues may act as a stress signal to trigger Spargel activation resulting in enhanced mitochondrial function and increased energy metabolism.


Assuntos
Neurônios Dopaminérgicos/fisiologia , Canais Iônicos/fisiologia , Proteínas Mitocondriais/fisiologia , Transtornos Parkinsonianos/genética , Transtornos Parkinsonianos/fisiopatologia , Animais , Animais Geneticamente Modificados , Modelos Animais de Doenças , Neurônios Dopaminérgicos/citologia , Neurônios Dopaminérgicos/efeitos dos fármacos , Drosophila melanogaster , Feminino , Humanos , Canais Iônicos/genética , Masculino , Proteínas Mitocondriais/genética , Transtornos Parkinsonianos/metabolismo , Proteína Desacopladora 2
13.
Bioorg Med Chem Lett ; 22(14): 4593-8, 2012 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-22738634

RESUMO

To identify potential human-safe insecticides against the malaria mosquito we undertook an investigation of the structure-activity relationship of aryl methylcarbamates inhibitors of acetylcholinesterase (AChE). Compounds bearing a ß-branched 2-alkoxy or 2-thioalkyl group were found to possess good selectivity for inhibition of Anopheles gambiae AChE over human AChE; up to 530-fold selectivity was achieved with carbamate 11d. A 3D QSAR model is presented that is reasonably consistent with log inhibition selectivity of 34 carbamates. Toxicity of these compounds to live Anopheles gambiae was demonstrated using both tarsal contact (filter paper) and topical application protocols.


Assuntos
Acetilcolinesterase/metabolismo , Anopheles/enzimologia , Inibidores da Colinesterase/síntese química , Animais , Anopheles/efeitos dos fármacos , Carbamatos , Inibidores da Colinesterase/farmacologia , Humanos , Modelos Moleculares , Estrutura Molecular , Relação Quantitativa Estrutura-Atividade
14.
Sci Rep ; 12(1): 19280, 2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36369317

RESUMO

A wet chemical route is reported for synthesising organic molecule stabilized lead sulfide nanoparticles. The dielectric capacitance, energy storage performances and field-driven polarization of the organic-inorganic hybrid system are investigated in the form of a device under varying temperature and frequency conditions. The structural analysis confirmed the formation of the monoclinic phase of lead sulfide within the organic network. The band structure of lead sulfide was obtained by density functional theory calculation that supported the semiconductor nature of the material with a direct band gap of 2.27 eV. The dielectric performance of the lead sulfide originated due to the dipolar and the space charge polarization. The energy storage ability of the material was investigated under DC-bias conditions, and the device exhibited the power density values 30 W/g and 340 W/g at 100 Hz and 10 kHz, respectively. The electric field-induced polarization study exhibited a fatigue-free behaviour of the device for 103 cycles with a stable dielectric strength. The study revealed that the lead sulfide-based system has potential in energy storage applications.

15.
Chemosphere ; 291(Pt 2): 132788, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34742761

RESUMO

The present study utilized discarded tea leaf waste to produce 'Tea leaf biochar' (TLB) as the functional matrix for the fabrication of hybrid nanocomposite (nAg-TC), with colloidal deposition of silver nanoparticles (nAg) via modified chemical co-precipitation, for treatment of dye-laden wastewater. The chemical composition, physicochemical properties, and morphology of nAg-TC, and active surface functional groups involved in adsorption were identified using BET, FESEM-EDX, FTIR, TGA, XPS, and XRD. The nAg-TC matrix was found to be heterogeneous, mesoporous, thermostable, with rich in active surface functional groups (-OH, =NH, =CH, CC, CO, CN, and CC), and nAg as a dopant material. The dye adsorption results indicated the maximum removal efficiency (RhB = 95.89%, CR = 94.10%) at 300 K for rhodamine B (RhB) and Congo red (CR) concentrations of 25 mg L-1 and 22.5 mg L-1, respectively. The present investigation agreed with Freundlich isotherm (R2CR:0.991; R2RhB:0.993) and pseudo-second order kinetic (R2CR:0.999; R2RhB:0.999) model, indicating overall adsorption of RhB and CR through spontaneous and exothermic chemisorption on the heterogeneous surface of nAg-TC. The mechanism of RhB and CR adsorption was complex where nAg-TC, possessing the synergistic effects of TLB and nAg, showed surface complexation, electrostatic attraction, and H-bonding, leading to chemisorption. Study showed excellent reusability of spent nAg-TC, and commendable treatment efficiency for dye-laden real industrial effluents. The study exhibits substantial techno-economic feasibility of adsorbent and translates the principles of circular economy into synthesis of value-added products through sustainable management of biowaste and bioresource.


Assuntos
Nanopartículas Metálicas , Nanocompostos , Poluentes Químicos da Água , Adsorção , Carvão Vegetal , Cinética , Folhas de Planta/química , Prata , Chá , Poluentes Químicos da Água/análise
16.
Chemosphere ; 308(Pt 2): 136413, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36103924

RESUMO

In this study, (hemi)cellulosic biochar-based environment-friendly non-toxic nanocomposite (nAg-AC) was fabricated for an inordinate overlook of toxic dye-laden wastewater depollution. This hybrid nanocomposite grafted with silver nanoparticles, numerous hydroxyl and π-bond containing functional groups exhibited outstanding physicochemical properties. FESEM images indicated the heterogeneous porous structure of nAg-AC, while BET analysis revealed mesoporous property with a significant increment of overall surface area (132%). Imbedding of silver nanoparticles and the presence of multiple hydroxyl groups was evident from the XRD and XPS spectrum. Further, the TGA result indicated excellent thermal stability, and FTIR analysis suggested the involvement of surface functional groups like -OH, =C = O, =NH, =C = C = , and -CH in Rhodamine B (RhB) adsorption. The adsorbent matrix provided the overall mechanical strength and facilitated recycling, while the functional matrix (biochar) provided the adsorptive locus for augmented RhB adsorption efficiency (92.77%). Experiments pertaining to adsorption isotherms and kinetics modeling suggested that RhB was removed through multilayer chemisorption on the heterogeneous nAg-AC surface. The main RhB adsorption mechanism included cumulative efforts of H-bindings, π-π stacking interaction, pore-filling, and electrostatic interactions. The nAg-AC maintained mechanical robustness with significant RhB adsorption even after three consecutive regeneration cycles signifying facile recycling. The nAg-AC displayed an outstanding efficacy for the real industrial wastewater depollution, indicating high effectiveness for practical environmental applications. Finally, the cost analysis (incorporating economic, environmental, and social dimensions) suggested a significant role of the nAg-AC in promoting and establishing sustainable development with the circular economy.


Assuntos
Nanopartículas Metálicas , Nanocompostos , Poluentes Químicos da Água , Adsorção , Carvão Vegetal , Cinética , Nanocompostos/química , Prata/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise
17.
Chemosphere ; 289: 133243, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34896417

RESUMO

Dual functional innovative approaches were developed to tackle the algal scum problem in water by utilizing the algal (Spirogyra sp.) biomass waste for organic dye-laden industrial wastewater treatment, a global problem, and challenge. Therefore, an algal biochar-based nanocomposite (nAgBC) was synthesized and employed as a low-cost adsorbent for Congo red (CR) removal. Surface morphology, physicochemical characteristics, elemental composition, phase, and stability of the nanocomposite was analyzed using BET, FESEM-EDX, FTIR, XRD, XPS, and TGA. The nanocomposite was found to be thermostable, mesoporous with large and heterogeneous surface area, containing nAg as doped material, where -OH, NH, CO, CC, SO, and CH are the surface binding active functional groups. Maximum adsorption efficiency of 95.92% (18 mg L-1 CR) was achieved (qe = 34.53 mg g-1) with 0.5 g L-1 of nanocomposite after 60 min, at room temperature (300 K) at pH 6. Isotherm and kinetic model suggested multilayer chemisorption, where adsorption thermodynamics indicated spontaneous reaction. Fluorescens spectral analysis of CR confirmed the formation of CR supramolecule, supporting enhanced adsorption. Furthermore, the result suggested a 5th cycle reusability and considerable efficacy towards real textile industrial effluents. Synergistic effects of the active surface functional groups of the biochar and nAg, along with the overall surface charge of the composite lead to chemisorption, electrostatic attraction, H-bonding, and surface complexation with CR molecules. Thus, synthesized nAgBC can be applicable to mitigate the wastewater for cleaner production and environment.


Assuntos
Nanocompostos , Poluentes Químicos da Água , Purificação da Água , Adsorção , Biomassa , Carvão Vegetal , Concentração de Íons de Hidrogênio , Cinética , Águas Residuárias , Poluentes Químicos da Água/análise
18.
Int J Cardiol ; 358: 88-93, 2022 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-35436557

RESUMO

BACKGROUND: In the United States, African Americans (AAs) have greater risk for Class III obesity and cardiovascular disease (CVD). Previous reports suggest that AAs have a different immune cell profile when compared to Caucasians. METHODS: The immune cell profile of AAs was characterized by flow cytometry using two experimental setups: ex vivo (N = 40) and in vitro (N = 10). For ex vivo experiments, PBMC were treated with participant serum to understand how lipid contents may contribute to monocyte phenotypic differences. For in vitro experiments, monocytes were low-density lipoprotein (LDL)- or vehicle-treated for four hours and subsequently analyzed by flow cytometry and RT-qPCR. RESULTS: When PBMCs were treated with participant sera, subsequent multivariable regression analysis revealed that serum triglycerides and LDL levels were associated with monocyte subset differences. In vitro LDL treatment of monocytes induced a phenotypic switch in monocytes away from classical monocytes accompanied by subset-specific chemokine receptor CCR2 and CCR5 expression changes. These observed changes are partially translation-dependent as determined by co-incubation with cycloheximide. CONCLUSIONS: LDL treatment of monocytes induces a change in monocyte subsets and increases CCR2/CCR5 expression in a subset-specific manner. Understanding the molecular mechanisms could prove to have CVD-related therapeutic benefits, especially in high-risk populations with hyperlipidemia and increased risk for CVD.


Assuntos
Doenças Cardiovasculares , Receptores de Quimiocinas , Negro ou Afro-Americano , Doenças Cardiovasculares/metabolismo , Proteínas de Transporte/metabolismo , Quimiocinas/metabolismo , Humanos , Leucócitos Mononucleares/metabolismo , Monócitos/metabolismo , Receptores de Quimiocinas/metabolismo
19.
Appl Nanosci ; 11(11): 2625-2660, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34745812

RESUMO

Silver nanoparticle (AgNP) has been one of the most commonly used nanoparticles since the past decade for a wide range of applications, including environmental, agricultural, and medical fields, due to their unique physicochemical properties and ease of synthesis. Though chemical and physical methods of fabricating AgNPs have been quite popular, they posed various environmental problems. As a result, the bioinspired route of AgNP synthesis emerged as the preferred pathway for synthesis. This review focuses extensively on the biosynthesis of AgNP-mediated through different plant species worldwide in the past 10 years. The most popularly utilized application areas have been highlighted with their in-depth mechanistic approach in this review, along with the discussion on the different phytochemicals playing an important role in the bio-reduction of silver ions. In addition to this, the environmental factors which govern their synthesis and stability have been reviewed. The paper systematically analyses the trend of research on AgNP biosynthesis throughout the world through bibliometric analysis. Apart from this, the feasibility analysis of the plant-mediated synthesis of nanoparticles and their applications have been intrigued considering the perspectives of engineering, economic, and environmental limitations. Thus, the review is not only a comprehensive summary of the achievements and current status of plant-mediated biosynthesis but also provides insight into emerging future research frontier. Supplementary Information: The online version contains supplementary material available at 10.1007/s13204-021-02135-5.

20.
BMJ Open ; 10(12): e040702, 2020 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-33371027

RESUMO

INTRODUCTION: Although physical activity (PA) reduces cardiovascular disease (CVD) risk, physical inactivity remains a pressing public health concern, especially among African American (AA) women in the USA. PA interventions focused on AA women living in resource-limited communities with scarce PA infrastructure are needed. Mobile health (mHealth) technology can increase access to PA interventions. We describe the development of a clinical protocol for a multilevel, community-based, mHealth PA intervention for AA women. METHODS AND ANALYSIS: An mHealth intervention targeting AA women living in resource-limited Washington, DC communities was developed based on the socioecological framework for PA. Over 6 months, we will use a Sequential Multi-Assignment, Randomized Trial approach to compare the effects on PA of location-based remote messaging (named 'tailored-to-place') to standard remote messaging in an mHealth intervention. Participants will be randomised to a remote messaging intervention for 3 months, at which point the intervention strategy will adapt based on individuals' PA levels. Those who do not meet the PA goal will be rerandomised to more intensive treatment. Participants will be followed for another 3 months to determine the contribution of each mHealth intervention to PA level. This protocol will use novel statistical approaches to account for the adaptive strategy. Finally, effects of PA changes on CVD risk biomarkers will be characterised. ETHICS AND DISSEMINATION: This protocol has been developed in partnership with a Washington, DC-area community advisory board to ensure feasibility and acceptability to community members. The National Institutes of Health Intramural IRB approved this research and the National Heart, Lung, and Blood Institute provided funding. Once published, results of this work will be disseminated to community members through presentations at community advisory board meetings and our quarterly newsletter. TRIAL REGISTRATION NUMBER: NCT03288207.


Assuntos
Aplicativos Móveis , Telemedicina , Adulto , Idoso , Exercício Físico , Feminino , Humanos , Pessoa de Meia-Idade , Gravidez , Estudos Prospectivos , Resultado do Tratamento
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