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1.
Int J Mol Sci ; 22(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34360822

RESUMO

Brillouin spectroscopy has recently gained considerable interest within the biomedical field as an innovative tool to study mechanical properties in biology. The Brillouin effect is based on the inelastic scattering of photons caused by their interaction with thermodynamically driven acoustic modes or phonons and it is highly dependent on the material's elasticity. Therefore, Brillouin is a contactless, label-free optic approach to elastic and viscoelastic analysis that has enabled unprecedented analysis of ex vivo and in vivo mechanical behavior of several tissues with a micrometric resolution, paving the way to a promising future in clinical diagnosis. Here, we comprehensively review the different studies of this fast-moving field that have been performed up to date to provide a quick guide of the current literature. In addition, we offer a general view of Brillouin's biomedical potential to encourage its further development to reach its implementation as a feasible, cost-effective pathology diagnostic tool.


Assuntos
Espalhamento de Radiação , Análise Espectral/métodos , Animais , Doenças Ósseas/diagnóstico por imagem , Humanos , Neoplasias/diagnóstico por imagem
2.
J Phys Chem Lett ; 12(30): 7085-7090, 2021 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-34292744

RESUMO

Microscopic dynamics of complex fluids in the early stage of spinodal decomposition (SD) is strongly intertwined with the kinetics of structural evolution, which makes a quantitative characterization challenging. In this work, we use X-ray photon correlation spectroscopy to study the dynamics and kinetics of a protein solution undergoing liquid-liquid phase separation (LLPS). We demonstrate that in the early stage of SD, the kinetics relaxation is up to 40 times slower than the dynamics and thus can be decoupled. The microscopic dynamics can be well described by hyper-diffusive ballistic motions with a relaxation time exponentially growing with time in the early stage followed by a power-law increase with fluctuations. These experimental results are further supported by simulations based on the Cahn-Hilliard equation. The established framework is applicable to other condensed matter and biological systems undergoing phase transitions and may also inspire further theoretical work.


Assuntos
Soroalbumina Bovina/química , Animais , Bovinos , Cinética , Transição de Fase , Soluções/química , Análise Espectral/métodos
3.
J Insect Sci ; 21(4)2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34280293

RESUMO

Protein and amino acids in pollen are important nutritional components for larval development in several insect species, especially in Apoidea. The Bradford assay is a widely used method to measure relative protein content of pollen, which can shed light on pollen quality and consequences to fitness. Prior to using the Bradford assay, protein must be released from pollen grains, often using a mixture of chemical and mechanical fracturation methods. In this study, we tested the efficacy of protein extraction without using mechanical fracturation. We used pollen collected by the solitary bee Osmia lignaria Say to compare two known buffers associated with pollen protein analysis: phosphate-buffered saline and sodium hydroxide, and deionized water, and with different pollen weights from which we quantified protein using the Bradford assay. While all buffers and deionized water were useful in releasing protein from pollen grains collected by O. lignaria, the use of sodium hydroxide resulted in significantly higher protein quantification across all pollen weights. This methodological study can inform future studies of pollen nutrition in pollen-foraging species.


Assuntos
Comportamento Alimentar , Pólen/química , Aminoácidos/química , Aminoácidos/isolamento & purificação , Animais , Abelhas/fisiologia , Proteínas/química , Proteínas/isolamento & purificação , Análise Espectral/métodos
4.
Int J Mol Sci ; 22(12)2021 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-34207189

RESUMO

Studying the interactions between lipid membranes and various bioactive molecules (e.g., polyphenols) is important for determining the effects they can have on the functionality of lipid bilayers. This knowledge allows us to use the chosen compounds as potential inhibitors of bacterial and cancer cells, for elimination of viruses, or simply for keeping our healthy cells in good condition. As studying those effect can be exceedingly difficult on living cells, model lipid membranes, such as liposomes, can be used instead. Liposomal bilayer systems represent the most basic platform for studying those interactions, as they are simple, quite easy to prepare and relatively stable. They are especially useful for investigating the effects of bioactive compounds on the structure and kinetics of simple lipid membranes. In this review, we have described the most basic methods available for preparation of liposomes, as well as the essential techniques for studying the effects of bioactive compounds on those liposomes. Additionally, we have provided details for an easy laboratory implementation of some of the described methods, which should prove useful especially to those relatively new on this research field.


Assuntos
Bicamadas Lipídicas/química , Lipossomos/química , Polifenóis/química , Fluidez de Membrana , Análise Espectral/métodos
5.
Molecules ; 26(11)2021 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-34063773

RESUMO

Flaky graphene oxide (GO) nanoparticles (NPs) were synthesized using Hummer's method and then capped with polyethylene glycol (PEG) by an esterification reaction, then loaded with Nigella sativa (N. sativa) seed extract. Aiming to investigate their potential use as a smart drug delivery system against Staphylococcus aureus and Escherichia coli, the spectral and structural characteristics of GO-PEG NPs were comprehensively analyzed by XRD, AFM, TEM, FTIR, and UV- Vis. XRD patterns revealed that GO-PEG had different crystalline structures and defects, as well as a higher interlayer spacing. AFM results showed GONPs with the main grain size of 24.41 nm, while GONPs-PEG revealed graphene oxide aggregation with the main grain size of 287.04 nm after loading N. sativa seed extract, which was verified by TEM examination. A strong OH bond appeared in FTIR spectra. Furthermore, UV- Vis absorbance peaks at (275, 284, 324, and 327) nm seemed to be correlated with GONPs, GO-PEG, N. sativa seed extract, and GO -PEG- N. sativa extract. The drug delivery system was observed to destroy the bacteria by permeating the bacterial nucleic acid and cytoplasmic membrane, resulting in the loss of cell wall integrity, nucleic acid damage, and increased cell-wall permeability.


Assuntos
Antibacterianos/farmacologia , Sistemas de Liberação de Medicamentos , Grafite/química , Nanopartículas/química , Nigella sativa/química , Extratos Vegetais/farmacologia , Polietilenoglicóis/química , Antibacterianos/administração & dosagem , Escherichia coli/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Transmissão , Extratos Vegetais/administração & dosagem , Análise Espectral/métodos , Staphylococcus aureus/efeitos dos fármacos , Difração de Raios X
6.
Molecules ; 26(11)2021 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-34064288

RESUMO

The correct recognition of sweet orange (Citrus sinensis L. Osbeck) variety accessions at the nursery stage of growth is a challenge for the productive sector as they do not show any difference in phenotype traits. Furthermore, there is no DNA marker able to distinguish orange accessions within a variety due to their narrow genetic trace. As different combinations of canopy and rootstock affect the uptake of elements from soil, each accession features a typical elemental concentration in the leaves. Thus, the main aim of this work was to analyze two sets of ten different accessions of very close genetic characters of three varieties of fresh citrus leaves at the nursery stage of growth by measuring the differences in elemental concentration by laser-induced breakdown spectroscopy (LIBS). The accessions were discriminated by both principal component analysis (PCA) and a classifier based on the combination of classification via regression (CVR) and partial least square regression (PLSR) models, which used the elemental concentrations measured by LIBS as input data. A correct classification of 95.1% and 80.96% was achieved, respectively, for set 1 and set 2. These results showed that LIBS is a valuable technique to discriminate among citrus accessions, which can be applied in the productive sector as an excellent cost-benefit tool in citrus breeding programs.


Assuntos
Citrus/genética , Lasers , Análise Espectral/métodos , Análise de Componente Principal
7.
Molecules ; 26(11)2021 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-34073711

RESUMO

Digital farming is a modern agricultural concept that aims to maximize the crop yield while simultaneously minimizing the environmental impact of farming. Successful implementation of digital farming requires development of sensors to detect and identify diseases and abiotic stresses in plants, as well as to probe the nutrient content of seeds and identify plant varieties. Experimental evidence of the suitability of Raman spectroscopy (RS) for confirmatory diagnostics of plant diseases was previously provided by our team and other research groups. In this study, we investigate the potential use of RS as a label-free, non-invasive and non-destructive analytical technique for the fast and accurate identification of nutrient components in the grains from 15 different rice genotypes. We demonstrate that spectroscopic analysis of intact rice seeds provides the accurate rice variety identification in ~86% of samples. These results suggest that RS can be used for fully automated, fast and accurate identification of seeds nutrient components.


Assuntos
Grão Comestível/química , Nutrientes/química , Agricultura , Análise Espectral/métodos
8.
Molecules ; 26(11)2021 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-34073936

RESUMO

Crocins are highly valuable natural compounds for treating human disorders, and they are also high-end spices and colorants in the food industry. Due to the limitation of obtaining this type of highly polar compound, the commercial prices of crocins I and II are expensive. In this study, macroporous resin column chromatography combined with high-speed counter-current chromatography (HSCCC) was used to purify crocins I and II from natural sources. With only two chromatographic steps, both compounds were simultaneously isolated from the dry fruit of Gardenia jasminoides, which is a cheap herbal medicine distributed in a number of countries. In an effort to shorten the isolation time and reduce solvent usage, forward and reverse rotations were successively utilized in the HSCCC isolation procedure. Crocins I and II were simultaneously obtained from a herbal resource with high recoveries of 0.5% and 0.1%, respectively, and high purities of 98.7% and 99.1%, respectively, by HPLC analysis. The optimized preparation method was proven to be highly efficient, convenient, and cost-effective. Crocins I and II exhibited inhibitory activity against ATP citrate lyase, and their IC50 values were determined to be 36.3 ± 6.24 and 29.7 ± 7.41 µM, respectively.


Assuntos
ATP Citrato (pro-S)-Liase/antagonistas & inibidores , Carotenoides/isolamento & purificação , Distribuição Contracorrente/métodos , Inibidores Enzimáticos/farmacologia , Gardenia/química , Carotenoides/farmacologia , Análise Espectral/métodos
9.
Methods Mol Biol ; 2277: 101-124, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34080147

RESUMO

This chapter describes the complementary experimental techniques Electron Transmission Spectroscopy and Dissociative Electron Attachment Spectroscopy, two of the most suitable means for investigating interactions between electrons and gas-phase molecules, resonance formation of temporary molecular negative ions, and their possible decay through the dissociative electron attachment (DEA) mechanism. The latter can be seen as the gas-phase counterpart of the transfer of a solvated electron in solution, accompanied by dissociation of the molecular anion, referred to as dissociative electron transfer (DET). DET takes place in vivo under reductive conditions, for instance, in the intermembrane space of mitochondria under interaction of xenobiotic molecules possessing high electron affinity with electrons "leaked" from the mitochondrial respiratory chain. A likely mechanism of the toxic activity of dichlorodiphenyltrichloroethane based on its DEA properties is briefly outlined, and compared with the well-established harmful effects of the model toxicant carbon tetrachloride ascribed to reductive dechlorination in a cellular ambient. A possible mechanism of the antioxidant activity of polyphenolic compounds present near the main site of superoxide anion production in mitochondria is also briefly discussed.


Assuntos
Mitocôndrias/química , Mitocôndrias/metabolismo , Análise Espectral/métodos , Antioxidantes/química , Antioxidantes/metabolismo , DDT/química , DDT/toxicidade , Transporte de Elétrons , Elétrons , Membranas Mitocondriais , Polifenóis/química , Polifenóis/metabolismo , Análise Espectral/instrumentação , Xenobióticos/química , Xenobióticos/toxicidade
10.
Molecules ; 26(10)2021 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-34065476

RESUMO

A series of novel 5-[(Z,2Z)-2-chloro-3-(4-nitrophenyl)-2-propenylidene]-thiazolidinones (Ciminalum-thiazolidinone hybrid molecules) have been synthesized. Anticancer activity screening toward the NCI60 cell lines panel, gastric cancer (AGS), human colon cancer (DLD-1), and breast cancer (MCF-7 and MDA-MB-231) cell lines allowed the identification of 3-{5-[(Z,2Z)-2-chloro-3-(4-nitrophenyl)-2-propenylidene]-4-oxo-2-thioxothiazolidin-3-yl}propanoic acid (2h) with the highest level of antimitotic activity with mean GI50/TGI values of 1.57/13.3 µM and a certain sensitivity profile against leukemia (MOLT-4, SR), colon cancer (SW-620), CNS cancer (SF-539), melanoma (SK-MEL-5), gastric cancer (AGS), human colon cancer (DLD-1), and breast cancers (MCF-7 and MDA-MB-231) cell lines. The hit compounds 2f, 2i, 2j, and 2h have been found to have low toxicity toward normal human blood lymphocytes and a fairly wide therapeutic range. The significant role of the 2-chloro-3-(4-nitrophenyl)prop-2-enylidene (Ciminalum) substituent in the 5 position and the substituent's nature in the position 3 of core heterocycle in the anticancer cytotoxicity levels of 4-thiazolidinone derivatives have been established.


Assuntos
Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Tiazolidinas/química , Tiazolidinas/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Análise Espectral/métodos , Relação Estrutura-Atividade
11.
Molecules ; 26(10)2021 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-34065538

RESUMO

New Co(II), Ni(II), and Cu(II) complexes were synthesized with the Schiff base ligand obtained by the condensation of sulfathiazole with salicylaldehyde. Their characterization was performed by elemental analysis, molar conductance, spectroscopic techniques (IR, diffuse reflectance and UV-Vis-NIR), magnetic moments, thermal analysis, and calorimetry (thermogravimetry/derivative thermogravimetry/differential scanning calorimetry), while their morphological and crystal systems were explained on the basis of powder X-ray diffraction results. The IR data indicated that the Schiff base ligand is tridentate coordinated to the metallic ion with two N atoms from azomethine group and thiazole ring and one O atom from phenolic group. The composition of the complexes was found to be of the [ML2]∙nH2O (M = Co, n = 1.5 (1); M = Ni, n = 1 (2); M = Cu, n = 4.5 (3)) type, having an octahedral geometry for the Co(II) and Ni(II) complexes and a tetragonally distorted octahedral geometry for the Cu(II) complex. The presence of lattice water molecules was confirmed by thermal analysis. XRD analysis evidenced the polycrystalline nature of the powders, with a monoclinic structure. The unit cell volume of the complexes was found to increase in the order of (2) < (1) < (3). SEM evidenced hard agglomerates with micrometric-range sizes for all the investigated samples (ligand and complexes). EDS analysis showed that the N:S and N:M atomic ratios were close to the theoretical ones (1.5 and 6.0, respectively). The geometric and electronic structures of the Schiff base ligand 4-((2-hydroxybenzylidene) amino)-N-(thiazol-2-yl) benzenesulfonamide (HL) was computationally investigated by the density functional theory (DFT) method. The predictive molecular properties of the chemical reactivity of the HL and Cu(II) complex were determined by a DFT calculation. The Schiff base and its metal complexes were tested against some bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis). The results indicated that the antibacterial activity of all metal complexes is better than that of the Schiff base.


Assuntos
Cobalto/química , Cobre/química , Níquel/química , Bases de Schiff/química , Sulfatiazóis/química , Antibacterianos/química , Análise Espectral/métodos
12.
Molecules ; 26(11)2021 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-34070610

RESUMO

As a significant co-activator involved in cell cycle and cell growth, differentiation and development, p300/CBP has shown extraordinary potential target in cancer therapy. Herein we designed new compounds from the lead compound A-485 based on molecular dynamic simulations. A series of new spirocyclic chroman derivatives was prepared, characterized and proven to be a potential treatment of prostate cancer. The most potent compound B16 inhibited the proliferation of enzalutamide-resistant 22Rv1 cells with an IC50 value of 96 nM. Furthermore, compounds B16-P2 displayed favorable overall pharmacokinetic profiles, and better tumor growth inhibition than A-485 in an in vivo xenograft model.


Assuntos
Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Cromanos/química , Neoplasias da Próstata/tratamento farmacológico , Proliferação de Células/efeitos dos fármacos , Cromanos/farmacologia , Xenoenxertos , Humanos , Concentração Inibidora 50 , Masculino , Simulação de Acoplamento Molecular , Neoplasias da Próstata/patologia , Análise Espectral/métodos , Relação Estrutura-Atividade
13.
Molecules ; 26(11)2021 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-34070629

RESUMO

Densazalin, a polycyclic alkaloid, was isolated from the marine sponge Haliclona densaspicula collected in Korea. The complete structure of the compound was determined by spectroscopic methods, including 1D and 2D nuclear magnetic resonance techniques, high-resolution mass spectrometry, and comparison of the calculated and measured electronic circular dichroism spectra. Densazalin possesses a unique 5,11-diazatricyclo[7.3.1.02,7]tridecan-2,4,6-triene moiety, which is connected by two linear carbon chains. This compound was derived from the biogenetic precursor bis-1,3-dialkylpyridnium. Densazalin exhibited cytotoxic activity on two human tumor cell lines (AGS and HepG2) in the Cell Counting Kit-8 (CCK-8) bioassay, with IC50 values ranging from 15.5 to 18.4 µM.


Assuntos
Alcaloides/isolamento & purificação , Biologia Marinha , Poríferos/química , Alcaloides/química , Alcaloides/farmacologia , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Análise Espectral/métodos
14.
Nat Commun ; 12(1): 3246, 2021 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-34059690

RESUMO

Biosensors are indispensable tools for public, global, and personalized healthcare as they provide tests that can be used from early disease detection and treatment monitoring to preventing pandemics. We introduce single-wavelength imaging biosensors capable of reconstructing spectral shift information induced by biomarkers dynamically using an advanced data processing technique based on an optimal linear estimator. Our method achieves superior sensitivity without wavelength scanning or spectroscopy instruments. We engineered diatomic dielectric metasurfaces supporting bound states in the continuum that allows high-quality resonances with accessible near-fields by in-plane symmetry breaking. The large-area metasurface chips are configured as microarrays and integrated with microfluidics on an imaging platform for real-time detection of breast cancer extracellular vesicles encompassing exosomes. The optofluidic system has high sensing performance with nearly 70 1/RIU figure-of-merit enabling detection of on average 0.41 nanoparticle/µm2 and real-time measurements of extracellular vesicles binding from down to 204 femtomolar solutions. Our biosensors provide the robustness of spectrometric approaches while substituting complex instrumentation with a single-wavelength light source and a complementary-metal-oxide-semiconductor camera, paving the way toward miniaturized devices for point-of-care diagnostics.


Assuntos
Técnicas Biossensoriais , Neoplasias da Mama/diagnóstico , Técnicas Analíticas Microfluídicas/instrumentação , Testes Imediatos , Refratometria/instrumentação , Neoplasias da Mama/sangue , Exossomos/química , Feminino , Humanos , Técnicas Analíticas Microfluídicas/métodos , Nanopartículas/química , Refratometria/métodos , Análise Espectral/instrumentação , Análise Espectral/métodos
15.
Molecules ; 26(10)2021 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-34069463

RESUMO

In this investigation, for the first time, we used Fragaria ananassa (strawberry) leaf extract as a source of natural reducing, capping or stabilizing agents to develop an eco-friendly, cost-effective and safe process for the biosynthesis of metal-based nanoparticles including silver, copper, iron, zinc and magnesium oxide. Calcinated and non-calcinated zinc oxide nanoparticles also synthesized during a method different from our previous study. To confirm the successful formation of nanoparticles, different characterization techniques applied. UV-Vis spectroscopy, X-ray Diffraction (XRD) spectroscopy, Field Emission Scanning Electron Microscopy (FESEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS), Photon Cross-Correlation Spectroscopy (PCCS) and Fourier Transformed Infrared Spectroscopy (FT-IR) were used to study the unique structure and properties of biosynthesized nanoparticles. The results show the successful formation of metal-based particles in the range of nanometer, confirmed by different characterization techniques. Finally, the presented approach has been demonstrated to be effective in the biosynthesis of metal and metal oxide nanoparticles.


Assuntos
Fragaria/química , Nanopartículas Metálicas/química , Extratos Vegetais/química , Folhas de Planta/química , Vias Biossintéticas , Microscopia Eletrônica de Varredura , Análise Espectral/métodos
16.
Molecules ; 26(10)2021 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-34069585

RESUMO

This study aimed to design an effective nanoparticle-based carrier for the oral delivery of fisetin (FST) with improved biopharmaceutical properties. FST-loaded nanoparticles were prepared with polyvinyl alcohol (PVA) and poly(lactic-co-glycolic acid) (PLGA) by the interfacial deposition method. A central composite design of two independent variables, the concentration of PVA and the amount of PLGA, was applied for the optimization of the preparative parameter. The responses, including average particle size, polydispersity index, encapsulation efficiency, and zeta potential, were assessed. The optimized formulation possessed a mean particle size of 187.9 nm, the polydispersity index of 0.121, encapsulation efficiency of 79.3%, and zeta potential of -29.2 mV. The morphological observation demonstrated a globular shape for particles. Differential scanning calorimetry and powder X-ray diffraction studies confirmed that the encapsulated FST was presented as the amorphous state. The dissolution test indicated a 3.06-fold increase for the accumulating concentrations, and the everted gut sac test showed a 4.9-fold gain for permeability at the duodenum region. In conclusion, the optimized FST-loaded nanoparticle formulation in this work can be developed as an efficient oral delivery system of FST to improve its biopharmaceutic properties.


Assuntos
Composição de Medicamentos , Flavonóis/farmacologia , Nanotecnologia , Varredura Diferencial de Calorimetria , Cromatografia Líquida de Alta Pressão/métodos , Desenho de Fármacos , Concentração de Íons de Hidrogênio , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/metabolismo , Tamanho da Partícula , Difração de Pó , Reprodutibilidade dos Testes , Análise Espectral/métodos
17.
Molecules ; 26(10)2021 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-34069639

RESUMO

Phosphodiesterase 2 (PDE2) has been regarded as a novel target for the treatment of Alzheimer's disease (AD). In this study, we obtained (R)-LZ77 as a hit compound with moderate PDE2 inhibitory activity (IC50 = 261.3 nM) using a high-throughput virtual screening method based on molecular dynamics. Then, we designed and synthesized 28 dihydropyranopyrazole derivatives as PDE2 inhibitors. Among them, compound (+)-11h was the most potent PDE2 inhibitor, with an IC50 value of 41.5 nM. The molecular docking of PDE2-(+)-11h reveals that the 4-(trifluoromethyl)benzyl)oxyl side chain of the compound enters the H-pocket and forms strong hydrophobic interactions with L770/L809/F862, which improves inhibitory activity. The above results may provide insight for further structural optimization of highly potent PDE2 inhibitors and may lay the foundation for their use in the treatment of AD.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Inibidores de Fosfodiesterase/farmacologia , Pirazóis/química , Pirazóis/farmacologia , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Humanos , Concentração Inibidora 50 , Simulação de Acoplamento Molecular , Inibidores de Fosfodiesterase/uso terapêutico , Pirazóis/síntese química , Análise Espectral/métodos
18.
Molecules ; 26(10)2021 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-34069653

RESUMO

Microbial biotransformation is an important tool in drug discovery and for metabolism studies. To expand our bioactive natural product library via modification and to identify possible mammalian metabolites, a cytotoxic cardenolide (gitoxigenin) was biotransformed using the endophytic fungus Alternaria eureka 1E1BL1. Initially, oleandrin was isolated from the dried leaves of Nerium oleander L. and subjected to an acid-catalysed hydrolysis to obtain the substrate gitoxigenin (yield; ~25%). After 21 days of incubation, five new cardenolides 1, 3, 4, 6, and 8 and three previously- identified compounds 2, 5 and 7 were isolated using chromatographic methods. Structural elucidations were accomplished through 1D/2D NMR, HR-ESI-MS and FT-IR analysis. A. eureka catalyzed oxygenation, oxidation, epimerization and dimethyl acetal formation reactions on the substrate. Cytotoxicity of the metabolites were evaluated using MTT cell viability method, whereas doxorubicin and oleandrin were used as positive controls. Biotransformation products displayed less cytotoxicity than the substrate. The new metabolite 8 exhibited the highest activity with IC50 values of 8.25, 1.95 and 3.4 µM against A549, PANC-1 and MIA PaCa-2 cells, respectively, without causing toxicity on healthy cell lines (MRC-5 and HEK-293) up to concentration of 10 µM. Our results suggest that A. eureka is an effective biocatalyst for modifying cardenolide-type secondary metabolites.


Assuntos
Alternaria/metabolismo , Antineoplásicos Fitogênicos/farmacologia , Cardenolídeos/isolamento & purificação , Biotransformação , Cardenolídeos/farmacocinética , Cardenolídeos/farmacologia , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , Células HEK293 , Humanos , Análise Espectral/métodos
19.
Int J Mol Sci ; 22(10)2021 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-34067690

RESUMO

The melanin fluorescence emitted by pigment cells of the human skin has been a central research topic for decades, because melanin, on the one hand, protects against (solar) radiation in the near-UV range, whereas on the other hand, melanocytes are the starting point for the malignant transformation into melanoma. Until recently, however, melanin fluorescence was not accessible in the context of conventional spectroscopy, because it is ultraweak and is overshadowed by the more intense so-called autofluorescence of endogenous fluorophores. The advent of a new method of laser spectroscopy has made this melanin fluorescence measurable in vivo. A stepwise two-photon absorption with 800 nm photons is used, which more selectively excites melanin (dermatofluoroscopy). Our review summarizes the experimental results on melanin fluorescence of the four types of cutaneous pigment cells from healthy and malignant tissues. Outstanding is the finding that different types of melanocytes (i.e., melanocytes of common nevi, versus dysplastic nevi or versus melanoma cells) show characteristically different fluorescence spectra. The possibilities of using this melanin fluorescence for melanoma diagnosis are shown. Moreover, the uniform fluorescence spectra emitted by different melanoma subtypes are essential. Conclusions are drawn about the molecular processes in the melanosomes that determine fluorescence. Finally, experimental suggestions for further investigations are given.


Assuntos
Melaninas/metabolismo , Melanócitos/metabolismo , Melanoma/metabolismo , Transformação Celular Neoplásica/patologia , Fluorescência , Humanos , Melaninas/análise , Melanoma/classificação , Melanoma/fisiopatologia , Pele/patologia , Neoplasias Cutâneas/patologia , Análise Espectral/métodos
20.
J Phys Chem Lett ; 12(23): 5526-5533, 2021 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-34096727

RESUMO

Despite extensive study, mysteries remain regarding the highly efficient ultrafast charge separation processes in photosynthetic reaction centers (RCs). In this work, transient Stark signals were found to be present in ultrafast two-dimensional electronic spectra recorded for purple bacterial RCs at 77 K. These arose from the electric field that is inherent to the intradimer charge-transfer intermediate of the bacteriochlorophyll pair (P), PA+PB-. By comparing three mutated RCs, a correlation was found between the efficient formation of PA+PB- and a fast charge separation rate. Importantly, the energy level of P* was changed due to the Stark shift, influencing the driving force for P* → P+BA- electron transfer and hence its rate. Furthermore, the orientation and amplitude of the inherent electric field varied in different ways upon different mutation, leading to contrasting changes in the rates. This mechanism of modulation provides a solution to a long-lasting inconsistency between experimental observations and activation energy theory.


Assuntos
Complexo de Proteínas do Centro de Reação Fotossintética/química , Rhodobacter sphaeroides/química , Cromatografia de Afinidade/métodos , Transporte de Elétrons/genética , Mutação/genética , Complexo de Proteínas do Centro de Reação Fotossintética/análise , Rhodobacter sphaeroides/genética , Análise Espectral/métodos , Fatores de Tempo
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