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1.
Int J Mol Sci ; 25(15)2024 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-39125846

RESUMO

Lippia alba (Mill.) N.E.Br. ex Britton and P. Wilson is used in folk medicine of Central and South America for its biological activities: i.e., antifungal, antibacterial, antiviral, and anti-inflammatory. Based on ethnopharmacological information and the increasing interest in this species, this work aimed to test a possible wide use of its essential oil (EO) in pharmaceutical and horticultural applications. Therefore, we focused the attention on the antioxidant activity of the oil as a possible tool to overcome the oxidative stress in both applications. For this purpose, we have chosen three aggressive breast cancer cell lines and two horticultural species (Solanum lycopersicum L. and Phaseolus acutifolius L.) that are very sensitive to salt stress. We determined the antioxidant activity of L. alba EO through the quantification of phenols and flavonoids. Regarding tomato and bean plants under salt stress, L. alba EO was used for the first time as a seed priming agent to enhance plant salt tolerance. In this case, the seed treatment enhanced the content of phenolic compounds, reduced power and scavenger activity, and decreased membrane lipid peroxidation, thus mitigating the oxidative stress induced by salt. While in breast cancer cells the EO treatment showed different responses according to the cell lines, i.e., in SUM149 and MDA-MB-231 the EO decreased proliferation and increased antioxidant activity and lipid peroxidation, showing high cytotoxic effects associated with the release of lactate dehydrogenase, vice versa no effect was observed in MDA-MB-468. Such antioxidant activity opens a new perspective about this essential oil as a possible tool to counteract proliferation in some cancer cell lines and in horticulture as a seed priming agent to protect from oxidative damage in crops sensitive to salinity.


Assuntos
Antioxidantes , Lippia , Óleos Voláteis , Estresse Oxidativo , Lippia/química , Óleos Voláteis/farmacologia , Óleos Voláteis/química , Humanos , Antioxidantes/farmacologia , Antioxidantes/química , Estresse Oxidativo/efeitos dos fármacos , Linhagem Celular Tumoral , Fenóis/farmacologia , Solanum lycopersicum/química , Flavonoides/farmacologia , Flavonoides/química , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Sementes/química
2.
Langmuir ; 36(14): 3843-3852, 2020 04 14.
Artigo em Inglês | MEDLINE | ID: mdl-32207954

RESUMO

The production of nanostructured materials for biological and medical applications may be applied toward the conjugation of adequate substances to boost the stimulus response of sensors and diagnostic probes. In this sense, Langmuir-Blodgett films constituted of bioinspired and biomimetic materials have attracted attention because of the ease of manipulation of the molecular architecture. In this paper, we employed a nucleoside-based drug, which was linked with a sterol hydrophobic moiety (3',4'-acetonide-uridine-succinate-cholesterol conjugate) to provide it an amphiphilic character. The drug was spread on the air-water interface, alone or mixed with stearic acid, forming Langmuir monolayers, and the complex Eu(tta)3(H2O)2 was incorporated in the drug-containing monolayer. Interactions at the air-water interface between stearic acid, the drug, and the europium complex were then investigated with tensiometry, surface potential, infrared spectroscopy, and Brewster angle microscopy. The Langmuir films were transferred to solid supports as Langmuir-Blodgett films, which presented luminescent properties that could be tuned according to the molecular architecture. We believe that these results can serve as a novel approach to characterize and assemble materials organized in the molecular scale for medical applications.

3.
Biophys Chem ; 310: 107256, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38728807

RESUMO

Understanding the mechanisms by which drugs interact with cell membranes is crucial for unraveling the underlying biochemical and biophysical processes that occur on the surface of these membranes. Our research focused on studying the interaction between an ester-type derivative of tristearoyl uridine and model cell membranes composed of lipid monolayers at the air-water interface. For that, we selected a specific lipid to simulate nontumorigenic cell membranes, namely 1,2-dihexadecanoyl-sn-glycero-3-phospho-l-serine. We noted significant changes in the surface pressure-area isotherms, with a noticeable shift towards larger areas, which was lower than expected for ideal mixtures, indicating monolayer condensation. Furthermore, the viscoelastic properties of the interfacial film demonstrated an increase in both the elastic and viscous parameters for the mixed film. We also observed structural alterations using vibrational spectroscopy, which revealed an increase in the all-trans to gauche conformers ratio. This confirmed the stiffening effect of the prodrug on the lipid monolayer. In summary, this study indicates that this lipophilic prodrug significantly impacts the lipid monolayer's thermodynamic, rheological, electrical, and molecular characteristics. This information is crucial for understanding how the drug interacts with specific sites on the cellular membrane. It also has implications for drug delivery, as the drug's passage into the cytosol may involve traversing the lipid bilayer.


Assuntos
Membrana Celular , Pró-Fármacos , Uridina , Pró-Fármacos/química , Pró-Fármacos/farmacologia , Pró-Fármacos/metabolismo , Membrana Celular/química , Membrana Celular/metabolismo , Uridina/química , Uridina/farmacologia , Fosfatidilserinas/química , Termodinâmica , Propriedades de Superfície , Viscosidade , Elasticidade
4.
Colloids Surf B Biointerfaces ; 244: 114129, 2024 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-39121572

RESUMO

Molecular Recognition in nucleotides is crucial for medicine, underpinning precise interactions in genetic replication and therapy. Alkylated nucleotides, in particular, play a key role in modifying DNA to inhibit cancer cell growth. In this study, we focused on an alkylated nucleotide, PNM2 (3',4',6'-O-tristearoyl uridine or uridine tri-stearate), to investigate the interaction between adenine molecules in the aqueous subphase and PNM2 Langmuir monolayers. Utilizing techniques such as tensiometry, Brewster angle microscopy, infrared spectroscopy, surface potential measurements, and dilatational surface rheology, we found compelling evidence of molecular Recognition between the polar head of the insoluble amphiphile (uridine) in the monolayer and adenine in the aqueous subphase, attributed to hydrogen bonding. These interactions significantly influenced the physicochemical properties of the air-water interface, including monolayer expansion upon molecular recognition, decreased dilatational modulus, increased tensiometric stability of the monolayer when compressed to relevant surface pressures, and decreased surface potential. These findings are noteworthy for drug development, providing crucial insights into the mechanisms of nucleotide interactions.


Assuntos
Propriedades de Superfície , Alquilação , Ligação de Hidrogênio , Nucleotídeos/química , Nucleotídeos/metabolismo , Água/química , Uridina/química , Adenina/química , Reologia
5.
Sci Rep ; 14(1): 26533, 2024 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-39489758

RESUMO

It has been shown recently, without an explanation of the possible molecular mechanisms involved, that 4-(2-hydroxyethyl)-1-piperazinepropanesulphonic (EPPS) acid effectively protects from the neurotoxicity induced by oligomers and plaques formed by the protein amyloid-ß protein. Here we report the same protective effect, obtained in vitro (HT22-diff cell line) and ex vivo (hippocampal slices) models, against amyloid neurotoxicity induced by oligomers of salmon Calcitonin (sCT), which has been shown to be a good model for the study of neurodegenerative diseases. Based on biophysical studies focusing on the protein aggregation kinetic and the interaction of the aggregates with model membranes, we propose a possible molecular mechanism underlying the protective effects. Taken together, our results indicate that EPPS is able to counteract the direct association (primary aggregation) of harmless low-molecular weight aggregates (dimers and trimers) or their aggregation catalysed by surfaces present in the solution (secondary aggregation). Thus, EPPS stabilizes harmless aggregates and hinders the formation of toxic and metastable prefibrillar oligomers. Overall, our data demonstrate that EPPS is an excellent drug candidate for the treatment of neurodegeneration due to misfolded proteins, such as Alzheimer's or Parkinson's disease.


Assuntos
Peptídeos beta-Amiloides , Animais , Peptídeos beta-Amiloides/metabolismo , Fármacos Neuroprotetores/farmacologia , Camundongos , Linhagem Celular , Hipocampo/metabolismo , Hipocampo/efeitos dos fármacos , Calcitonina/metabolismo , Calcitonina/química , Humanos , Agregados Proteicos/efeitos dos fármacos , Piperazinas/farmacologia , Doenças Neurodegenerativas/metabolismo , Agregação Patológica de Proteínas/metabolismo , Amiloide/metabolismo , Multimerização Proteica/efeitos dos fármacos
6.
Nanoscale ; 15(26): 11107-11114, 2023 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-37337765

RESUMO

Nanopores and nanocavities are promising single molecule tools for investigating the behavior of individual molecules within confined spaces. For single molecule analysis, the total duration of time the analyte remains within the pore/cavity is highly important. However, this dwell time is ruled by a complex interplay among particle-surface interactions, external forces on the particle and Brownian diffusion, making the prediction of the dwell time challenging. Here, we show how the dwell time of an analyte in a nanocavity that is connected to the external environment by two nanopore gates depends on the sizes of the nanocavity/nanopore, as well as particle-wall interactions. For this purpose, we used a coarse-grained model that allowed us to simulate hundreds of individual analyte trajectories within a nanocavity volume. We found that by increasing the attraction between the particle and the wall, the diffusion process transforms from a usual 3D scenario (repulsive wall) to a 2D motion along the cavity surface (highly attractive wall). This results in a significant reduction of the average dwell time. Additionally, the comparison of our results with existing theories on narrow escape problem allowed us to quantify the reliability of theory derived for ideal conditions to geometries more similar to actual devices.

7.
Membranes (Basel) ; 12(12)2022 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-36557189

RESUMO

Investigation of the interaction between drugs and biomembrane models, as a strategy to study and eventually improve drug/substrate interactions, is a crucial factor in preliminary screening. Synthesized peptides represent a source of potential anticancer and theragnostic drugs. In this study, we investigated the interaction of a novel synthesized peptide, called RH-23, with a simplified dimyristoylphosphatidylcholine (DMPC) model of the cellular membrane. The interaction of RH-23 with DMPC, organized either in multilamellar vesicles (MLVs) and in Langmuir-Blodgett (LB) monolayers, was assessed using thermodynamic techniques, namely differential scanning calorimetry (DSC) and LB. The calorimetric evaluations showed that RH-23 inserted into MLVs, causing a stabilization of the phospholipid gel phase that increased with the molar fraction of RH-23. Interplay with LB monolayers revealed that RH-23 interacted with DMPC molecules. This work represents the first experimental thermodynamic study on the interaction between RH-23 and a simplified model of the lipid membrane, thus providing a basis for further evaluations of the effect of RH-23 on biological membranes and its therapeutic/diagnostic potential.

8.
Membranes (Basel) ; 12(10)2022 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-36295696

RESUMO

Cell membrane models are useful for obtaining molecular-level information on the interaction of biologically active molecules whose activity is believed to depend also on their effects on the membrane. Cytarabine was conjugated with fatty acids to improve the drug lipophilicity and the interaction with the biomembrane model. Cytarabine was conjugated with fatty acids of different lengths to form the trimyristoyl cytarabine and the tristearoyl cytarabine derivatives. Their interaction with biomembrane models constituted by dimyristoylphosphatidylcholine (DMPC) monolayers was studied by employing the Langmuir-Blodgett technique. DMPC/cytarabine, DMPC/trimyristoyl cytarabine and DMPC/tristearoyl cytarabine mixed monolayers at increasing molar fractions of the compound were prepared and placed on the subphase. The mean molecular area/surface pressure isotherms were recorded at 37 °C. Between the molecules of DMPC and those of cytarabine or prodrugs, repulsive forces act. However, these forces are very weak between DMPC and cytarabine and stronger between DMPC and the cytarabine derivatives, thus avoiding the expulsion of the compounds at higher surface pressure and modifying the stability of the mixed monolayer. The fatty acid moieties could then modulate the affinity of cytarabine for biomembranes.

9.
Plants (Basel) ; 11(15)2022 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-35956490

RESUMO

Patagonia is a geographical area characterized by a wide plant biodiversity. Several native plant species are traditionally used in medicine by the local population and demonstrated to be sources of biologically active compounds. Due to the massive need for green and sustainable pesticides, this study was conducted to evaluate the insecticidal activity of essential oils (EOs) from understudied plants growing in this propitious area. Ciprés (Pilgerodendron uviferum), tepa (Laureliopsis philippiana), canelo (Drimys winteri), and paramela (Adesmia boronioides) EOs were extracted through steam distillation, and their compositions were analyzed through GC−MS analysis. EO contact toxicity against Musca domestica L., Spodoptera littoralis (Boisd.), and Culex quinquefasciatus Say was then evaluated. As a general trend, EOs performed better on housefly males over females. Ciprés EO showed the highest insecticidal efficacy. The LD50(90) values were 68.6 (183.7) and 11.3 (75.1) µg adult−1 on housefly females and males, respectively. All EOs were effective against S. littoralis larvae; LD50 values were 33.2−66.7 µg larva−1, and tepa EO was the most effective in terms of LD90 (i.e., <100 µg larva−1). Canelo, tepa, and paramela EOs were highly effective on C. quinquefasciatus larvae, with LC50 values < 100 µL L−1. Again, tepa EO achieved LD90 < 100 µL L−1. This EO was characterized by safrole (43.1%), linalool (27.9%), and methyl eugenol (6.9%) as major constituents. Overall, Patagonian native plant EOs can represent a valid resource for local stakeholders, to develop effective insecticides for pest and vector management, pending a proper focus on their formulation and nontarget effects.

10.
Membranes (Basel) ; 12(5)2022 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-35629809

RESUMO

Histoplasma capsulatum is a dimorphic, thermal, and nutritional fungus. In the environment and at an average temperature of 28 °C, it develops as a mold that is composed of infecting particles. Once in the host or in cultures at 37 °C, it undergoes a transition into the parasitic form. In the present work, we performed chemical extraction and characterization using chromatography techniques of the associated lipid composition of the external surface of the cell wall of the mycelial phase of two isolates of the H. capsulatum: one clinical and one environmental. Several differences were evidenced in the fatty acids in the phospholipid composition. Surface pressure-area isotherms and compression module curves of the Amphotericin B and lipid extract monolayers, as well as (AmB)-lipid extract mixed monolayers were recorded. Results show a high affinity of AmB towards lipid extracts. The most stable monolayers were formed by AmB + environmental with a mass ratio of 1:3 and AmB + clinical with a mass ratio of 1:2. Knowledge of the AmB aggregation processes at a molecular level and the characterization of the lipid extracts allows the possibility to understand the interaction between the AmB and the lipid fractions of H. capsulatum.

11.
Langmuir ; 27(7): 3749-53, 2011 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-21370902

RESUMO

Supported dipalmitoylphosphatidylcholine (DPPC) bilayers are widely used membrane systems in biophysical and biochemical studies. Previously, short-range positional and orientational order of lipid headgroups of supported DPPC bilayers was observed at room temperature using low deflection noise frequency modulation atomic force microscopy (FM-AFM). While this ordering was supported by X-ray diffraction studies, it conflicted with diffusion coefficient measurements of gel-phase bilayers determined from fluorescence photobleaching experiments. In this work, we have directly imaged mica-supported DPPC bilayers with submolecular resolution over scan ranges up to 146 nm using low deflection noise FM-AFM. Both orientational and positional molecular ordering were observed in the mesoscale, indicative of crystalline order. We discuss these results in relation to previous biophysical studies and propose that the mica support induces mesoscopic crystalline order of the DPPC bilayer at room temperature. This study also demonstrates the recent advance in the scan range of submolecular scale AFM imaging.


Assuntos
1,2-Dipalmitoilfosfatidilcolina/química , Bicamadas Lipídicas/química , Microscopia de Força Atômica/métodos
12.
Nat Prod Res ; 35(22): 4746-4752, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31965826

RESUMO

Nowadays, only a little part of essential oils produced at an industrial level is employed for insecticidal formulations, while thousand tons are used for perfumery purposes. This research explores the insecticidal potential of two essential oils largely used in perfumery, ylang ylang (Cananga odorata) and frankincense (Boswellia spp.) on three insects of economic importance, Culex quinquefasciatus, Musca domestica and Spodoptera littoralis, comparing their performances with a commercial pyrethrum extract. GC-MS showed that the ylang ylang and frankincense essential oils were mainly composed of α-thujene (73.8%), benzyl salicylate (24.4%) and linalool (21.9%), respectively. Ylang-ylang and frankincense essential oils showed significant insecticidal activity against C. quinquefasciatus larvae (LC50 < 70 ppm) and M. domestica adults (LD50 < 80 µg/female), respectively, while no relevant toxicity was detected on S. littoralis. As highly available from the fragrance industry, these essential oils may be further considered as promising ingredients to be used in botanical formulations against mosquitoes and houseflies.


Assuntos
Boswellia , Cananga , Franquincenso , Inseticidas , Óleos Voláteis , Animais , Larva , Óleos Voláteis/farmacologia , Óleos de Plantas
13.
Nat Prod Res ; 34(4): 449-455, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31135192

RESUMO

The in vitro antifungal activity of extracts obtained from 14 medicinal plants of the mongolian flora were investigated by measuring their minimal inhibitory concentration (MIC) against fungi cause of cutaneous diseases such as Candida species, dermatophytes and Malassezia furfur. Among the species examined, Stellaria dichotoma L., Scutellaria scordifolia L. Aquilegia sibirica Fisch. Et Schrenk. and Hyoscyamus niger L. extracts demonstrated antifungal activity against all studied fungi. In particular, S. scordifolia L. methanol extract, obtained at room temperature, showed the best activity against Candida spp., Malassezia furfur and dermatophytes with GMMIC50 values of 22 µg/mL, 64 µg/mL and 32 µg/mL, respectively. The flavones, luteolin and apigenin, identified in S. scordifolia extracts, and rutin identified in S. dichotoma and Hyoscyamus niger L. extracts, could be responsible of the observed antifungal activity.


Assuntos
Antifúngicos/isolamento & purificação , Extratos Vegetais/farmacologia , Plantas Medicinais/química , Antifúngicos/farmacologia , Arthrodermataceae/efeitos dos fármacos , Candida/efeitos dos fármacos , Flavonas/farmacologia , Malassezia/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Mongólia , Extratos Vegetais/uso terapêutico , Scutellaria/química , Dermatopatias Infecciosas/tratamento farmacológico , Dermatopatias Infecciosas/microbiologia
14.
Food Chem Toxicol ; 138: 111207, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32074492

RESUMO

In this work, the essential oils (EOs) from Litchi chinensis, Clausena anisata, Heracleum sphondylium, Pimpinella anisum, Lippia alba, Crithmum maritimum and Syzygium aromaticum were tested for their contact toxicity against the poultry red mite, Dermanyssus gallinae, a deleterious ectoparasite of aviary systems. In addition, in order to give insights on their mode of action and effectiveness, the vapor phase and residual toxicity tests were also performed. Results showed that amongst all the tested EOs, that of S. aromaticum demonstrated the highest contact toxicity, with a LC50 value of 8.9 µg/mL, followed by C. maritimum and L. chinensis EOs, with LC50 values of 23.7 and 24.7 µg/mL, respectively. L. chinensis and C. anisata EOs showed higher vapor toxicity than the other EOs. L. chinensis and S. aromaticum EOs showed promising toxic effects up to 4 days post-application. Taken together, these results highlighted L. chinensis and S. aromaticum as two promising sources of biopesticides, able to cause severe contact, vapor and residual toxicity in the poultry red mites. Given the wide plant cultivation and uses in foodstuffs, cosmetics, flavour and fragrances, these EOs may be considered cheap and ready-to-use products as valid, eco-friendly alternatives to pesticides currently used in the aviary systems.


Assuntos
Acaricidas/toxicidade , Ácaros/efeitos dos fármacos , Óleos Voláteis/farmacologia , Doenças das Aves Domésticas/prevenção & controle , Aves Domésticas/parasitologia , Animais , Camarões , Clausena , Destilação , Inocuidade dos Alimentos , Itália , Litchi/química , Extratos Vegetais/farmacologia , Óleos de Plantas/farmacologia , Syzygium/química
15.
J Pharm Pharmacol ; 71(3): 329-337, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30456846

RESUMO

OBJECTIVES: Uridine was conjugated with fatty acids to improve the drug lipophilicity and the interaction with phospholipid bilayers. METHODS: The esterification reaction using carbodiimides compounds as coupling agents and a nucleophilic catalyst allowed us to synthesize tri-acyl ester derivatives of uridine with fatty acids. Analysis of molecular interactions between these tri-acyl ester derivatives and l-α-dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles (MLV) - as a mammalian cell membrane model - have been performed by differential scanning calorimetry (DSC). KEY FINDINGS: The DSC thermograms suggest that nucleoside and uridine triacetate softly interact with phospholipidic multilamellar vesicles which are predominantly located between the polar phase, whereas the tri-acyl ester derivatives with fatty acids (myristic and stearic acids) present a strongly interaction with the DMPC bilayer due to the nucleoside and aliphatic chains parts which are oriented towards the polar and lipophilic phases of the phospholipidic bilayer, respectively. However, the effects caused by the tri-myristoyl uridine and tri-stearoyl uridine are different. CONCLUSIONS: We show how the structural changes of uridine modulate the calorimetric behaviour of DMPC shedding light on their affinity with the phospholipidic biomembrane model.


Assuntos
Acetatos/química , Dimiristoilfosfatidilcolina/química , Ésteres/química , Membranas/química , Nucleosídeos/química , Uridina/análogos & derivados , Varredura Diferencial de Calorimetria/métodos , Ácidos Graxos/química , Modelos Teóricos , Fosfolipídeos/química , Uridina/química
16.
Biomolecules ; 10(1)2019 12 29.
Artigo em Inglês | MEDLINE | ID: mdl-31905804

RESUMO

To investigate the interaction between amyloid assemblies and "lipid-rafts", we performed functional and structural experiments on salmon calcitonin (sCT) solutions rich in prefibrillar oligomers, proto- and mature-fibers interacting with liposomes made of monosialoganglioside-GM1 (4%), DPPC (48%) and cholesterol (48%). To focus on the role played by electrostatic forces and considering that sCT is positive and GM1 is negative at physiologic pH, we compared results with those relative to GM1-free liposomes while, to assess membrane fluidity effects, with those relative to cholesterol-free liposomes. We investigated functional effects by evaluating Ca2+-influx in liposomes and viability of HT22-DIFF neurons. Only neurotoxic solutions rich in unstructured prefibrillar oligomers were able to induce Ca2+-influx in the "lipid-rafts" model, suggesting that the two phenomena were correlated. Thus, we investigated protein conformation and membrane modifications occurring during the interaction: circular dichroism showed that "lipid-rafts" fostered the formation of ß-structures and energy filtered-transmission electron microscopy that prefibrillar oligomers formed pores, similar to Aß did. We speculate that electrostatic forces between the positive prefibrillar oligomers and the negative GM1 drive the initial binding while the hydrophobic profile and flexibility of prefibrillar oligomers, together with the membrane fluidity, are responsible for the subsequent pore formation leading to Ca2+-influx and neurotoxicity.


Assuntos
Amiloide/metabolismo , Calcitonina/química , Calcitonina/toxicidade , Cálcio/metabolismo , Microdomínios da Membrana/metabolismo , Neurônios/metabolismo , Neurônios/patologia , Amiloide/química , Amiloide/efeitos dos fármacos , Animais , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Interações Hidrofóbicas e Hidrofílicas , Microdomínios da Membrana/química , Microdomínios da Membrana/efeitos dos fármacos , Camundongos , Modelos Biológicos , Neurônios/efeitos dos fármacos
17.
J Phys Chem B ; 112(9): 2622-8, 2008 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-18257564

RESUMO

The locational and orientational structure and the dynamics of cholesterol in the bilayer membrane were studied by using the solution-state NMR. The intermolecular nuclear Overhauser effect (NOE) was analyzed for large unilamellar vesicles (100 nm in diameter) composed of dimyristoylphosphatidylcholine (DMPC) and cholesterol at cholesterol concentrations of 9-33 mol %. The DMPC headgroups show (1)H-{(1)H}-NOEs with the methyl groups at the hydrophobic terminals of both cholesterol and DMPC, illustrating the significant fluctuation of the bilayer membrane in the vertical (bilayer normal) direction. Cholesterol was found to keep the hydroxyl (OH) group toward the outer water pool on the basis of the following observations: (1) the cross correlation between the DMPC headgroup and the cholesterol terminal methyl group is weaker than those between the DMPC headgroups and (2) the methyl group at the hydrophobic terminal of cholesterol shows strong correlation with the terminal group of the DMPC chain portion. The OH group plays a crucial role in orienting cholesterol with its OH group outward, since cholestane, which has a molecular structure similar to that of cholesterol except for the absence of the OH group, was found to have no orientational preference in the bilayer membrane. The dynamic slowdown at high cholesterol concentrations is demonstrated on the basis of the correlation times for NOE as well as the broadening of the proton linewidths.


Assuntos
Colesterol/química , Espectroscopia de Ressonância Magnética/métodos , Modelos Moleculares , Fosfolipídeos/química , Lipossomas Unilamelares/química , Água/química , Colestanos/química , Colesterol/análogos & derivados , Dimiristoilfosfatidilcolina/química , Interações Hidrofóbicas e Hidrofílicas , Fluidez de Membrana
18.
PLoS One ; 13(10): e0200998, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30289918

RESUMO

Birdsong is a complex learned behavior regulated by Neuromuscular coordination of different muscle sets necessary for producing relevant sounds. We developed a heterogeneous and stochastically connected neural network representing the pathway from the high vocal center (HVC) to the robust nucleus of the arcopallium (RA) neurons that drive the muscles to generate sounds. We show that a single active neuron is sufficient to initiate a chain of spiking events that results to excite the entire network system. The network could synthesize realistic bird sounds spectra, with spontaneous generation of intermittent sound bursts typical of birdsong (song syllables). This study confirms experiments on animals and on humans, where results have shown that single neurons are responsible for the activation of complex behavior or are associated with high-level perception events.


Assuntos
Aves/fisiologia , Tentilhões/fisiologia , Vias Neurais/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Vocalização Animal/fisiologia , Animais , Simulação por Computador , Modelos Neurológicos , Redes Neurais de Computação , Probabilidade , Prosencéfalo/fisiologia , Processos Estocásticos
19.
Colloids Surf B Biointerfaces ; 166: 203-209, 2018 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-29597153

RESUMO

Differential scanning calorimetry (DSC) is a thermoanalytical technique which provides information on the interaction between drugs and models of cell membranes. Studies on the calorimetric behavior of hydrated phospholipids within liposomes are employed to shed light on the changes in the physico-chemical properties when interacting with drugs. In this report, new potential anti-cancer drugs such as uridine and uridine derivatives (acetonide and its succinate), 3ß-5α,8α-endoperoxide-cholestan-6-en-3-ol (5,8-epidioxicholesterol) and conjugate (uridine acetonide-epidioxicholesterol succinate) have been synthesized. Steglich esterification method using coupling agents allowed to obtain the uridine acetonide-sterol conjugate. The study on the interaction between the drugs and dimiristoyl-phophatidilcholine (DMPC) liposomes has been conducted by the use of DSC. The analysis of the DSC curves indicated that the uridine and derivatives (acetonide and its succinate) present a very soft interaction with the DMPC liposomes, whereas the 5,8-epidioxicholesterol and the conjugate showed a strong effect on the thermotropic behavior. Our results suggested that the lipophilic character of uridine acetonide-sterol conjugate improves the affinity with the DMPC liposomes.


Assuntos
Varredura Diferencial de Calorimetria/métodos , Dimiristoilfosfatidilcolina/química , Lipossomos/química , Pró-Fármacos/química , Esteróis/química , Uridina/química
20.
Artigo em Inglês | MEDLINE | ID: mdl-28684709

RESUMO

Essential oils are complex mixtures of volatile components produced by the plant secondary metabolism and consist mainly of monoterpenes and sesquiterpenes and, to a minor extent, of aromatic and aliphatic compounds. They are exploited in several fields such as perfumery, food, pharmaceutics, and cosmetics. Essential oils have long-standing uses in the treatment of infectious diseases and parasitosis in humans and animals. In this regard, their therapeutic potential against human African trypanosomiasis (HAT) has not been fully explored. In the present work, we have selected six medicinal and aromatic plants (Azadirachta indica, Aframomum melegueta, Aframomum daniellii, Clausena anisata, Dichrostachys cinerea, and Echinops giganteus) traditionally used in Cameroon to treat several disorders, including infections and parasitic diseases, and evaluated the activity of their essential oils against Trypanosma brucei TC221. Their selectivity was also determined with Balb/3T3 (mouse embryonic fibroblast cell line) cells as a reference. The results showed that the essential oils from A. indica, A. daniellii, and E. giganteus were the most active ones, with half maximal inhibitory concentration (IC50) values of 15.21, 7.65, and 10.50 µg/mL, respectively. These essential oils were characterized by different chemical compounds such as sesquiterpene hydrocarbons, monoterpene hydrocarbons, and oxygenated sesquiterpenes. Some of their main components were assayed as well on T. brucei TC221, and their effects were linked to those of essential oils.


Assuntos
Magnoliopsida , Óleos Voláteis/farmacologia , Trypanosoma brucei brucei/efeitos dos fármacos , Animais , Células 3T3 BALB , Camarões , Humanos , Camundongos , Testes de Sensibilidade Microbiana , Monoterpenos/análise , Óleos Voláteis/química , Plantas Medicinais , Sesquiterpenos/análise , Trypanosoma brucei brucei/crescimento & desenvolvimento
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