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2.
Molecules ; 28(21)2023 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-37959728

RESUMO

Polymers, including non-linear copolymers, have great potential in the development of drug delivery systems with many advantages, but the design requires optimizing polymer-drug interactions. Molecular dynamics (MD) simulations can provide insights into polymer-drug interactions for designing delivery systems, but mimicking formulation processes such as drying is often not included in in silico studies. This study demonstrates an MD approach to model drying of systems comprising either hydrophilic tinidazole or hydrophobic clotrimazole drugs with amphiphilic hyperbranched copolyethers. The simulated drying protocol was critical for elucidating drug encapsulation and binding mechanisms. Experimentally, two polymers were synthesized and shown to encapsulate clotrimazole with up to 83% efficiency, guided by interactions with the hydrophobic core observed in simulations. In contrast, tinidazole is associated with surface regions, indicating capacity differences between drug types. Overall, this work highlights MD simulation of the drying process as an important tool for predicting drug-polymer complex behaviour. The modelled formulation protocol enabled high encapsulation efficiency and opened possibilities for the design of delivery systems based on computationally derived binding mechanisms. This demonstrates a computational-experimental approach where simulated drying was integral to elucidating interactions and developing optimized complexes, emphasizing the value of molecular modelling for the development of drug delivery formulations.


Assuntos
Micelas , Simulação de Dinâmica Molecular , Tinidazol , Clotrimazol , Polímeros/química , Interações Hidrofóbicas e Hidrofílicas , Portadores de Fármacos/química , Polietilenoglicóis/química
3.
Bioorg Chem ; 138: 106659, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37336104

RESUMO

A library of 4-substituted quinolines was synthesised based on the structural features of the privileged 4-(benzylthio)-6-methoxy-2-methylquinoline scaffold. Quinoline-based chemical probes have proven to be effective anti-tuberculosis agents with the ability of inhibiting components of Mycobacterium tuberculosis (MTB) respiratory chain including the b subunit of the cytochrome bc1 complex. Novel 4-(arylalkyl)-thio, -oxy and sulfoxy-quinoline analogues were tested for their ability to inhibit the growth of MTB H37Rv and QcrB mutant strains, and the compounds mode of action was investigated. Members of the 4-subtituted thio- and sulfoxyquinoline series exhibited significant growth inhibitory activity in the high nanomolar range against wild-type MTB and induced depletion of intracellular ATP. These probes also showed reduced potency in the QcrB T313I mutant strain, thus indicating the cytochrome bc1 oxidase complex as the molecular target. Interestingly, new 4-(quinolin-2-yl)oxy-quinoline 4i was more selective for the QcrB T313I strain compared to the wild-type strain.


Assuntos
Mycobacterium tuberculosis , Quinolinas , Antituberculosos/química , Complexo III da Cadeia de Transporte de Elétrons/farmacologia , Quinolinas/farmacologia , Citocromos/farmacologia , Testes de Sensibilidade Microbiana
4.
Int J Antimicrob Agents ; 61(5): 106774, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36893812

RESUMO

The regioisomers of the anandamide-acting drug LY2183240 exhibited specific potent and competitive inhibitory activities against class C ß-lactamases. More explicitly, the 1,5- and 2,5-regioisomers inhibited AmpC from Enterobacter hormaechei (formerly Enterobacter cloacae) with inhibitor binding affinity values of 1.8 µM and 2.45 µM, respectively. Structural molecular modelling studies revealed the interaction of the regioisomers with the relevant residues of the catalytic site of cephalosporinase from E. hormaechei P99, which included Tyr150, Lys315 and Thr316.


Assuntos
Cefalosporinase , beta-Lactamases , beta-Lactamases/metabolismo , Compostos Heterocíclicos com 1 Anel , Enterobacter cloacae/metabolismo
5.
J Struct Biol ; 214(3): 107876, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35738335

RESUMO

Botulinum Neurotoxins (BoNT) are the most potent toxins currently known. However, they also have therapeutic applications for an increasing number of motor related conditions due to their specificity, and low diffusion into the system. Although the start- and end- points for the BoNT mechanism of action are well-studied, a critical step remains poorly understood. It is theorised that BoNTs undergo a pH-triggered conformational shift, activating the neurotoxin by priming it to form a transmembrane (TM) channel. To test this hypothesis, we combined molecular dynamics (MD) simulations and small-angle x-ray scattering (SAXS), revealing a new conformation of serotype E (BoNT/E). This conformation was exclusively observed in simulations below pH 5.5, as determined by principal component analysis (PCA), and its theoretical SAXS profile matched an experimental SAXS profile obtained at pH 4. Additionally, a localised secondary structural change was observed in MD simulations below pH 5.5, in a region previously identified as instrumental for membrane insertion for serotype A (BoNT/A). These changes were found at a critical pH value for BoNTs in vivo, and may be relevant for their therapeutic use.


Assuntos
Toxinas Botulínicas Tipo A , Toxinas Botulínicas , Toxinas Botulínicas Tipo A/química , Concentração de Íons de Hidrogênio , Espalhamento a Baixo Ângulo , Difração de Raios X
6.
Biomolecules ; 12(3)2022 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-35327564

RESUMO

Vascular endothelial growth factors (VEGFs) are the key regulators of blood and lymphatic vessels' formation and function. Each of the proteins from the homologous family VEGFA, VEGFB, VEGFC and VEGFD employs a core cysteine-knot structural domain for the specific interaction with one or more of the cognate tyrosine kinase receptors. Additional diversity is exhibited by the involvement of neuropilins-transmembrane co-receptors, whose b1 domain contains the binding site for the C-terminal sequence of VEGFs. Although all relevant isoforms of VEGFs that interact with neuropilins contain the required C-terminal Arg residue, there is selectivity of neuropilins and VEGF receptors for the VEGF proteins, which is reflected in the physiological roles that they mediate. To decipher the contribution made by the C-terminal sequences of the individual VEGF proteins to that functional differentiation, we determined structures of molecular complexes of neuropilins and VEGF-derived peptides and examined binding interactions for all neuropilin-VEGF pairs experimentally and computationally. While X-ray crystal structures and ligand-binding experiments highlighted similarities between the ligands, the molecular dynamics simulations uncovered conformational preferences of VEGF-derived peptides beyond the C-terminal arginine that contribute to the ligand selectivity of neuropilins. The implications for the design of the selective antagonists of neuropilins' functions are discussed.


Assuntos
Neuropilinas , Fator A de Crescimento do Endotélio Vascular , Ligantes , Neuropilinas/química , Neuropilinas/genética , Neuropilinas/metabolismo , Peptídeos , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismo , Fatores de Crescimento do Endotélio Vascular
7.
J Biomol Struct Dyn ; 40(4): 1671-1691, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-33047663

RESUMO

Recently, we designed and synthesized a subnanomolar, reversible, dual-binding site acetylcholinesterase (AChE) inhibitor which consists of the tacrine and aroylacrylic acid phenylamide moieties, mutually linked by eight methylene units. To further investigate the process of the molecular recognition between the AChE and its inhibitor, we performed six unconstrained molecular dynamics (MD) simulations, where the compound in three possible protonation states was placed inside binding sites of two available AChE crystal structures. In all six MD trajectories, the ligand generally occupied similar space inside the AChE active site, but the pattern of the interactions between the ligand functional groups and the amino acid residues was significantly different and highly dependent upon the crystal structure used to generate initial systems for simulation. The greatest differences were observed between the trajectories obtained with different AChE crystal structures used as starting target conformations. In some trajectories, several unusual positions and dynamic behavior of the tacrine moiety were observed. Therefore, this study provides important structure-based data useful in further optimization of the reversible, dual binding AChE inhibitors, and also emphasizes the importance of the starting crystal structure used for dynamics as well as the protonation state of the reversible inhibitors.Communicated by Ramaswamy H. Sarma.


Assuntos
Acetilcolinesterase , Tacrina , Acetilcolinesterase/química , Sítios de Ligação , Domínio Catalítico , Inibidores da Colinesterase/química , Simulação de Acoplamento Molecular , Tacrina/química
8.
Eur J Med Chem ; 225: 113734, 2021 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-34418786

RESUMO

Antimicrobial resistance is a main concern in tuberculosis treatment and is often associated with the emergence of Mycobacterium tuberculosis strains resistant to rifampicin (RIF), which is one of the cornerstones of tuberculosis chemotherapy. In this study, aminoalkyl-aromatic ring tails were appended to the C3 position of rifamycin core to assess the role of C3 substitutions to the anti-mycobacterial activity of the rifamycin antibiotics. The typical hydrazone unit of RIF was replaced by an amino-alkyl linkage to connect the aromatic ring tails with the rifamycin naphthoquinone core. Eight novel C3-(N-alkyl-aryl)-aminoalkyl analogues of rifamycin SV were synthesised and screened in vitro against wild-type HR37Rv and "hypervirulent" HN-878 strains, and a panel of rifampicin-resistant M. tuberculosis clinical isolates carrying mutations at the 522, 531 and 455 positions of the rpoB gene (RpoBS522L, RpoBS531L and RpoBH455D strains). The analogues exhibited anti-tubercular activity against H37Rv and HN-878 at submicromolar or nanomolar concentrations, and against clinical H37Rv isolates bearing the S522L mutations at low micromolar concentration. Benzylamine moiety-including analogue 8 was as active as rifampicin against HN-878 with a MIC90 value of 0.02 µM, whereas 14 and 15, which included tryptamine and para-methyl-sulfonylbenzylamine C3-substituents, respectively, showed higher anti-tubercular activity (MIC90 = 3 µM) compared to rifampicin against the S522L mutated H37Rv strain. Detailed in silico analysis of different RNAP molecular systems predicted a distinct, possibly novel, binding mode for the new rifamycin analogues. These were found to occupy a different space in the binding pockets of both wild type and mutated RNAP proteins compared to that of rifampicin. Moreover, the molecular modelling experiments investigated the ability of the novel analogues aromatic tails to establish key interactions at the RNAP binding site. These interesting findings might pave the way for generating rifamycin analogues that can overcome anti-microbial resistance in M. tuberculosis.


Assuntos
Antituberculosos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Rifamicinas/farmacologia , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Antituberculosos/síntese química , Antituberculosos/química , Sítios de Ligação/efeitos dos fármacos , Relação Dose-Resposta a Droga , Testes de Sensibilidade Microbiana , Estrutura Molecular , Rifamicinas/síntese química , Rifamicinas/química , Relação Estrutura-Atividade
9.
Biomolecules ; 11(3)2021 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-33810011

RESUMO

Antimicrobial resistance is an increasing issue in healthcare as the overuse of antibacterial agents rises during the COVID-19 pandemic. The need for new antibiotics is high, while the arsenal of available agents is decreasing, especially for the treatment of infections by Gram-negative bacteria like Escherichia coli. Antimicrobial peptides (AMPs) are offering a promising route for novel antibiotic development and deep learning techniques can be utilised for successful AMP design. In this study, a long short-term memory (LSTM) generative model and a bidirectional LSTM classification model were constructed to design short novel AMP sequences with potential antibacterial activity against E. coli. Two versions of the generative model and six versions of the classification model were trained and optimised using Bayesian hyperparameter optimisation. These models were used to generate sets of short novel sequences that were classified as antimicrobial or non-antimicrobial. The validation accuracies of the classification models were 81.6-88.9% and the novel AMPs were classified as antimicrobial with accuracies of 70.6-91.7%. Predicted three-dimensional conformations of selected short AMPs exhibited the alpha-helical structure with amphipathic surfaces. This demonstrates that LSTMs are effective tools for generating novel AMPs against targeted bacteria and could be utilised in the search for new antibiotics leads.


Assuntos
Aprendizado Profundo , Escherichia coli/efeitos dos fármacos , Proteínas Citotóxicas Formadoras de Poros/química , Sequência de Aminoácidos , Área Sob a Curva , Teorema de Bayes , Aprendizado de Máquina , Conformação Molecular , Proteínas Citotóxicas Formadoras de Poros/farmacologia , Conformação Proteica em alfa-Hélice , Curva ROC
10.
J Mater Chem B ; 9(15): 3371-3376, 2021 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-33881429

RESUMO

The presence of genotoxic impurities in active pharmaceutical ingredients (APIs) is a major concern for the pharmaceutical industry. Acetamide is a common genotoxic byproduct found in synthetic routes of many APIs, mainly due to acetonitrile hydrolysis, and selective scavenging is a still a challenging task. Herein, as a proof-of-concept, we evaluate polyurea (PURE) biodendrimers as strategic nanopolymers to prepare safe drug nanoformulations from mixtures containing acetamide, using (S)-ibuprofen (IBF) as a model drug. Furthermore, computational molecular dynamics (MD) simulations were conducted to rationalize in vitro results and to identify the key intermolecular interactions within mixtures. Experimental data were corroborated by MD simulations which showed that acetamide, IBF and carboxyfluorescein interactions with PURE biodendrimers are mostly at the surface. Also, PURE nanoformulations appear to be driven by hydrogen bonding, electrostatic and hydrophobic interactions.


Assuntos
Acetamidas/química , Dendrímeros/química , Polímeros/química , Simulação de Dinâmica Molecular , Estrutura Molecular
11.
Nat Prod Res ; 35(11): 1881-1886, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31303068

RESUMO

This study seeks to discover flavonoids from a traditional Chinese herb, Artemisia rupestris L., with synergistic antibacterial effects against multidrug-resistant Staphylococcus aureus. Five flavonoids, artemetin (1), chrysosplenetin (2), pachypodol (3), penduletin (4) and chrysoeriol (5) were obtained by various column chromatographic methods. Their chemical structures were determined on the basis of comprehensive spectroscopic analysis and comparison with literature data. Three of the compounds (2, 4 and 5) exhibited synergistic activity when combined with norfloxacin against SA1199B, an effluxing fluoroquinolone-resistant strain. The fractional inhibitory concentration indices (FICIs) of 2, 4 and 5 in combination with norfloxacin were 0.375, 0.079 and 0.266 respectively, suggesting synergy. Compound 5 also showed synergistic effects against EMRSA-15 and EMRSA-16 when combined with ciprofloxacin and oxacillin exhibiting FICIs of 0.024 and 0.375 respectively. Real time ethidium bromide (EtBr) efflux assay, qRT-PCR and molecular docking were employed to explore the mechanisms of the synergistic effects.


Assuntos
Antibacterianos/farmacologia , Artemisia/classificação , Flavonoides/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Sinergismo Farmacológico , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Ligação de Hidrogênio , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Extratos Vegetais/química , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
12.
Int J Mol Sci ; 21(23)2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-33266278

RESUMO

Cationic antimicrobial peptides have attracted interest, both as antimicrobial agents and for their ability to increase cell permeability to potentiate other antibiotics. However, toxicity to mammalian cells and complexity have hindered development for clinical use. We present the design and synthesis of very short cationic peptides (3-9 residues) with potential dual bacterial membrane permeation and efflux pump inhibition functionality. Peptides were designed based upon in silico similarity to known active peptides and efflux pump inhibitors. A number of these peptides potentiate the activity of the antibiotic novobiocin against susceptible Escherichia coli and restore antibiotic activity against a multi-drug resistant E. coli strain, despite having minimal or no intrinsic antimicrobial activity. Molecular modelling studies, via docking studies and short molecular dynamics simulations, indicate two potential mechanisms of potentiating activity; increasing antibiotic cell permeation via complexation with novobiocin to enable self-promoted uptake, and binding the E. coli RND efflux pump. These peptides demonstrate potential for restoring the activity of hydrophobic drugs.


Assuntos
Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/farmacologia , Técnicas de Química Sintética , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Modelos Moleculares , Novobiocina/química , Novobiocina/farmacologia , Peptídeos Catiônicos Antimicrobianos/síntese química , Desenho de Fármacos , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Novobiocina/síntese química , Relação Estrutura-Atividade
13.
Expert Opin Drug Discov ; 15(9): 1015-1024, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32452244

RESUMO

INTRODUCTION: Dendrimers are well-defined hyperbranched polymers built from a variety of different monomers and with tuneable properties that make them suitable for different biomedical applications. Their three-dimensional (3D) structure cannot be usually determined experimentally due to their inherent nature of repeating patterns in the topology, failure to crystalize, and/or high flexibility. Therefore, their conformations and interactions at the atomistic level can be studied only by using computational chemistry methods, including molecular dynamics, Monte Carlo simulations, and molecular docking. AREAS COVERED: In this review, the methods that could be utilized in computer-aided dendrimer design are considered, providing a list of approaches to generate initial 3D coordinates and selected examples of applications of relevant molecular modeling methods. EXPERT OPINION: Computational chemistry provides an invaluable set of tools to study dendrimers and their interactions with drugs and biological targets. There is a gap in the software development that is dedicated to study of these highly variable and complex systems that could be overcome by the integration of already established approaches for topology generation and open source molecular modeling libraries. Furthermore, it would be highly beneficial to collate already built 3D models of various dendrimers with corresponding relevant experimental data.


Assuntos
Desenho Assistido por Computador , Dendrímeros/química , Modelos Moleculares , Química Computacional , Humanos , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Método de Monte Carlo
14.
RSC Adv ; 10(67): 41047-41057, 2020 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-35519189

RESUMO

Steatosis is the accumulation of triglycerides in hepatic cells wherein fats exceed 5% of the entire liver weight. Although steatotic liver damage is reversible due to the liver's regenerative capability, protracted damage often and typically leads to irreversible conditions such as cirrhosis and hepatocellular carcinoma (HCC). Therefore, early steatotic detection is critical for preventing progression to advanced liver diseases. This also becomes particularly important given the higher prevalence of drug usage, as drugs are a frequent cause of liver damage. Currently, the recommendation to diagnose steatosis is using liver enzymes and performing a liver biopsy. Liver biopsy remains the gold standard method of detection, but the procedure is invasive and an unreliable diagnostic tool. Non-invasive, specific and sensitive diagnostic solutions such as biomarkers are therefore needed for the early detection of steatosis. Our aim is to identify changes in urinary metabolites in tetracycline-induced hepatic steatotic rats at different stages of the diseases using metabolomic-based techniques. Sprague Dawley male rats are treated by intraperitoneal injection (I.P.) with either 62.5 mg kg-1 or 125 mg kg-1 tetracycline, an antibiotic previously known to induce steatosis. We analyse the metabolic profile of the urinary tetracycline induced hepatic steatotic rats using 1H nuclear magnetic resonance (NMR), 2D 1H-1H TOCSY (total correlation spectroscopy) and electrospray liquid chromatography-mass spectrometry (ESI-LC-MS/MS) based metabolomics. The combined analysis of haematoxylin & eosin (H&E), oil red O (ORO) and direct measurement of triglyceride content in the liver tissues of the control samples against 125 mg kg-1 and 62.5 mg kg-1 treated samples, reveals that 125 mg kg-1 tetracycline exposure potentially induces steatosis. The combination of 1H NMR, 2D 1H-1H TOCSY and ESI-LC-MS/MS alongside multivariate statistical analysis, detected a total of 6 urinary metabolites changes, across 6 metabolic pathways. Furthermore, lysine concentration correlates with liver damage as tetracycline dose concentration increases, whilst both H&E and ORO fail to detect hepatocellular damage at the lowest dose concentration. We conclude that the combination of 1H NMR and ESI-LC-MS/MS suggests that these are suitable platforms for studying the pathogenesis of steatosis development, prior to morphological alterations observed in staining techniques and offer a more detailed description of the severity of the steatotic disease.

15.
Int J Mol Sci ; 20(8)2019 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-31013627

RESUMO

Overcoming P-glycoprotein (P-gp) efflux is a strategy to improve the absorption and pharmacokinetics of its substrate drugs. Berberine inhibits P-gp and thereby increases the bioavailability of the P-gp substrate digoxin in rodents. However, the effects of berberine on P-gp in chickens are still unclear. Here, we studied the role of berberine in modulating broilers P-gp expression and function through both in situ and in vitro models. In addition, molecular docking was applied to analyze the interactions of berberine with P-gp as well as with chicken xenobiotic receptor (CXR). The results showed that the mRNA expression levels of chicken P-gp and CXR decreased in the ileum following exposure to berberine. The absorption rate constant of rhodamine 123 increased after berberine treatment, as detected using an in situ single-pass intestinal perfusion model. Efflux ratios of P-gp substrates (tilmicosin, ciprofloxacin, clindamycin, ampicillin, and enrofloxacin) decreased and the apparent permeability coefficients increased after co-incubation with berberine in MDCK-chAbcb1 cell models. Bidirectional assay results showed that berberine could be transported by chicken P-gp with a transport ratio of 4.20, and this was attenuated by verapamil (an inhibitor of P-gp), which resulted in a ratio of 1.13. Molecular docking revealed that berberine could form favorable interactions with the binding pockets of both CXR and P-gp, with docking scores of -7.8 and -9.5 kcal/mol, respectively. These results indicate that berberine is a substrate of chicken P-gp and down-regulates P-gp expression in chicken tissues, thereby increasing the absorption of P-gp substrates. Our findings suggest that berberine increases the bioavailability of other drugs and that drug-drug interactions should be considered when it is co-administered with other P-gp substrates with narrow therapeutic windows.


Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Berberina/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/química , Animais , Proteínas Aviárias/genética , Proteínas Aviárias/metabolismo , Berberina/química , Galinhas , Cães , Células Madin Darby de Rim Canino , Modelos Moleculares , Conformação Proteica , RNA Mensageiro/genética , Receptores Citoplasmáticos e Nucleares/genética , Receptores Citoplasmáticos e Nucleares/metabolismo , Relação Estrutura-Atividade
16.
ADMET DMPK ; 7(4): 242-251, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-35359618

RESUMO

Determination of physico-chemical properties of compounds is one of the corner-stones in selection of hit molecules for further progression into lead development in the modern drug discovery process. The speed of traditional analyses and limited quantities of hit molecules are obstacles for efficient acquisition of experimental data. Herein, the range of applications of quantitative nuclear magnetic resonance (NMR) spectroscopy as a fast technique used to evaluate solubility, log P and pKa are discussed.

17.
Int J Mol Sci ; 19(10)2018 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-30326566

RESUMO

Florfenicol (FFC) is a valuable synthetic fluorinated derivative of thiamphenicol widely used to treat infectious diseases in food animals. The aims of the study were to investigate whether FFC is a substrate for the breast cancer resistance protein (BCRP) and whether the transporter influences oral availability of FFC. In vitro transport assays using MDCK-chAbcg2 cells were conducted to assess chicken BCRP-mediated transport of FFC, while in vivo pharmacokinetic experiments with single or combined BCRP inhibitor gefitinib were employed to study the role of BCRP in oral FFC disposition. According to U.S. Food and Drug Administration (FDA) criteria, FFC was found to be a potential BCRP substrate due to the net efflux ratio being over 2.0 (2.37) in MDCK cells stably transfected with chicken BCRP and the efflux completely reversed by a BCRP inhibitor (Gefitinib). The molecular docking results indicated that florfenicol can form favorable interactions with the binding pocket of homology modeled chicken BCRP. Pharmacokinetic studies of FFC in different aged broilers with different expression levels of BCRP showed that higher BCRP expression would cause a lower Area Under Curve (AUC) and a higher clearance of FFC. In addition, more extensive absorption of florfenicol after the co-administration with gefitinib (a BCRP inhibitor) was observed. The overall results demonstrated that florfenicol is a substrate of the chicken breast cancer resistant protein which in turn affects its pharmacokinetic behavior.


Assuntos
Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Antibacterianos/metabolismo , Antibacterianos/farmacocinética , Tianfenicol/análogos & derivados , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/química , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Fatores Etários , Animais , Antibacterianos/administração & dosagem , Linhagem Celular , Galinhas , Cães , Expressão Gênica , Modelos Moleculares , Conformação Molecular , Ligação Proteica , Relação Estrutura-Atividade , Especificidade por Substrato , Tianfenicol/administração & dosagem , Tianfenicol/metabolismo , Tianfenicol/farmacocinética
18.
Pharmaceutics ; 10(4)2018 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-30248922

RESUMO

Protein-based therapeutics are considered to be one of the most important classes of pharmaceuticals on the market. The growing need to prolong stability of high protein concentrations in liquid form has proven to be challenging. Therefore, significant effort is being made to design formulations which can enable the storage of these highly concentrated protein therapies for up to 2 years. Currently, the excipient selection approach involves empirical high-throughput screening, but does not reveal details on aggregation mechanisms or the molecular-level effects of the formulations under storage conditions. Computational modelling approaches have the potential to elucidate such mechanisms, and rapidly screen in silico prior to experimental testing. Nuclear Magnetic Resonance (NMR) spectroscopy can also provide complementary insights into excipient⁻protein interactions. This review will highlight the underpinning principles of molecular modelling and NMR spectroscopy. It will also discuss the advancements in the applications of computational and NMR approaches in investigating excipient⁻protein interactions.

19.
Acta Biomater ; 76: 193-207, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29940370

RESUMO

α-Galactosylceramide (GalCer) is a glycolipid widely known as an activator of Natural killer T (NKT) cells, constituting a promising adjuvant against cancer, including melanoma. However, limited clinical outcomes have been obtained so far. This study evaluated the synergy between GalCer and major histocompatibility complex (MHC) class I and MHC class II melanoma-associated peptide antigens and the Toll-Like Receptor (TLR) ligands CpG and monophosphoryl lipid A (MPLA), which we intended to maximize following their co-delivery by a nanoparticle (NP). This is expected to improve GalCer capture by dendritic cells (DCs) and subsequent presentation to NKT cells, simultaneously inducing an anti-tumor specific T-cell mediated immunity. The combination of GalCer with melanoma peptides and TLR ligands successfully restrained tumor growth. The tumor volume in these animals was 5-fold lower than the ones presented by mice immunized with NPs not containing GalCer. However, tumor growth was controlled at similar levels by GalCer entrapped or in its soluble form, when mixed with antigens and TLR ligands. Those two groups showed an improved infiltration of T lymphocytes into the tumor, but only GalCer-loaded nano-vaccine induced a prominent and enhanced infiltration of NKT and NK cells. In addition, splenocytes of these animals secreted levels of IFN-γ and IL-4 at least 1.5-fold and 2-fold higher, respectively, than those treated with the mixture of antigens and adjuvants in solution. Overall, the combined delivery of the NKT agonist with TLR ligands and melanoma antigens via this multivalent nano-vaccine displayed a synergistic anti-tumor immune-mediated efficacy in B16F10 melanoma mouse model. STATEMENT OF SIGNIFICANCE: Combination of α-galactosylceramide (GalCer), a Natural Killer T (NKT) cell agonist, with melanoma-associated antigens presented by MHC class I (Melan-A:26) and MHC class II (gp100:44) molecules, and Toll-like Receptor (TLR) ligands (MPLA and CpG), within nanoparticle matrix induced a prominent anti-tumor immune response able to restrict melanoma growth. An enhanced infiltration of NKT and NK cells into tumor site was only achieved when the combination GalCer, antigens and TLR ligands were co-delivered by the nanovaccine.


Assuntos
Vacinas Anticâncer , Galactosilceramidas , Imunidade Celular/efeitos dos fármacos , Melanoma Experimental/terapia , Nanopartículas , Peptídeos , Animais , Vacinas Anticâncer/química , Vacinas Anticâncer/farmacocinética , Vacinas Anticâncer/farmacologia , Linhagem Celular Tumoral , Células Dendríticas/imunologia , Células Dendríticas/patologia , Galactosilceramidas/química , Galactosilceramidas/farmacocinética , Galactosilceramidas/farmacologia , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/patologia , Masculino , Melanoma Experimental/imunologia , Melanoma Experimental/patologia , Camundongos , Camundongos Endogâmicos C57BL , Nanopartículas/química , Nanopartículas/uso terapêutico , Peptídeos/química , Peptídeos/farmacocinética , Peptídeos/farmacologia , Linfócitos T/imunologia , Linfócitos T/patologia , Receptores Toll-Like/imunologia
20.
Pharmaceutics ; 10(3)2018 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-29933540

RESUMO

Cationic peptides with antimicrobial properties are ubiquitous in nature and have been studied for many years in an attempt to design novel antibiotics. However, very few molecules are used in the clinic so far, sometimes due to their complexity but, mostly, as a consequence of the unfavorable pharmacokinetic profile associated with peptides. The aim of this work is to investigate cationic peptides in order to identify common structural features which could be useful for the design of small peptides or peptido-mimetics with improved drug-like properties and activity against Gram negative bacteria. Two sets of cationic peptides (AMPs) with known antimicrobial activity have been investigated. The first reference set comprised molecules with experimentally-known conformations available in the protein databank (PDB), and the second one was composed of short peptides active against Gram negative bacteria but with no significant structural information available. The predicted structures of the peptides from the first set were in excellent agreement with those experimentally-observed, which allowed analysis of the structural features of the second group using computationally-derived conformations. The peptide conformations, either experimentally available or predicted, were clustered in an “all vs. all” fashion and the most populated clusters were then analyzed. It was confirmed that these peptides tend to assume an amphipathic conformation regardless of the environment. It was also observed that positively-charged amino acid residues can often be found next to aromatic residues. Finally, a protocol was evaluated for the investigation of the behavior of short cationic peptides in the presence of a membrane-like environment such as dodecylphosphocholine (DPC) micelles. The results presented herein introduce a promising approach to inform the design of novel short peptides with a potential antimicrobial activity.

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