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1.
Angew Chem Int Ed Engl ; 60(21): 11758-11762, 2021 05 17.
Artigo em Inglês | MEDLINE | ID: mdl-33724623

RESUMO

Extensive recent efforts have been put on the design of high-performance organic near-infrared (NIR) photothermal agents (PTAs), especially over NIR-II bio-window (1000-1350 nm). So far, the development is mainly limited by the rarity of molecules with good NIR-II response. Here, we report organic nanoparticles of intermolecular charge-transfer complexes (CTCs) with easily programmable optical absorption. By employing different common donor and acceptor molecules to form CTC nanoparticles (CT NPs), absorption peaks of CT NPs can be controllably tuned from the NIR-I to NIR-II region. Notably, CT NPs formed with perylene and TCNQ have a considerably red-shifted absorption peak at 1040 nm and achieves a good photothermal conversion efficiency of 42 % under 1064 nm excitation. These nanoparticles were used for antibacterial application with effective activity towards both Gram-negative and Gram-positive bacteria. This work opens a new avenue into the development of efficient PTAs.


Assuntos
Antibacterianos/farmacologia , Nanopartículas/química , Antibacterianos/química , Antibacterianos/efeitos da radiação , Derivados de Benzeno/química , Derivados de Benzeno/farmacologia , Derivados de Benzeno/efeitos da radiação , Escherichia coli/efeitos dos fármacos , Raios Infravermelhos , Testes de Sensibilidade Microbiana , Nanopartículas/efeitos da radiação , Nitrilas/química , Nitrilas/farmacologia , Nitrilas/efeitos da radiação , Perileno/química , Perileno/farmacologia , Perileno/efeitos da radiação , Compostos Policíclicos/química , Compostos Policíclicos/farmacologia , Compostos Policíclicos/efeitos da radiação , Solubilidade , Staphylococcus aureus/efeitos dos fármacos , Eletricidade Estática/efeitos adversos , Compostos de Sulfidrila/química , Compostos de Sulfidrila/farmacologia , Compostos de Sulfidrila/efeitos da radiação , Água/química
2.
J Chem Phys ; 153(14): 144302, 2020 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-33086833

RESUMO

Directing energy and charge transfer processes in light-harvesting antenna systems is quintessential for optimizing the efficiency of molecular devices for artificial photosynthesis. In this work, we report a novel synthetic method to construct two regioisomeric antenna molecules (1-D2A2 and 7-D2A2), in which the 4-(n-butylamino)naphthalene monoimide energy and electron donor is attached to the perylene monoimide diester (PMIDE) acceptor at the 1- and 7-bay positions, respectively. The non-symmetric structure of PMIDE renders a polarized distribution of the frontier molecular orbitals along the long axis of this acceptor moiety, which differentiates the electron coupling between the donor, attached at either the 1- or the 7-position, and the acceptor. We demonstrate that directional control of the photo-driven charge transfer process has been obtained by engineering the molecular structure of the light-harvesting antenna molecules.


Assuntos
Naftalimidas/química , Perileno/análogos & derivados , Transferência de Energia , Luz , Naftalimidas/síntese química , Naftalimidas/efeitos da radiação , Perileno/efeitos da radiação , Eletricidade Estática
3.
J Nat Prod ; 83(8): 2490-2500, 2020 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-32786877

RESUMO

Hypocrellins and hypomycins are naturally occurring fungal perylenequinones with potential photodynamic activity against cancer and microbial diseases. This project pursued three lines of research. First, the production of perylenequinones was enhanced by investigating the effect of culture medium and light exposure on their biosynthesis. Solid-fermentation cultures on rice medium allowed for enhanced production of hypocrellins as compared to Cheerios or oatmeal medium. Alternatively, increased production of hypomycins, which are structurally related to the hypocrellins, was observed on oatmeal medium. In both cases, light exposure was an essential factor for the enhanced biosynthesis. In addition, this led to the discovery of two new perylenequinones, ent-shiraiachrome A (5) and hypomycin E (8), which were elucidated based on spectroscopic data. Finally, the photocytotoxic effects of both classes of compounds were evaluated against human skin melanoma, with EC50 values at nanomolar levels for hypocrellins and micromolar levels for hypomycins. In contrast, both classes of compounds showed reduced dark toxicity (EC50 values >100 µM), demonstrating promising phototherapeutic indices.


Assuntos
Antineoplásicos/metabolismo , Antineoplásicos/farmacologia , Luz , Perileno/análogos & derivados , Quinonas/metabolismo , Quinonas/farmacologia , Antineoplásicos/química , Linhagem Celular Tumoral , Meios de Cultura , Ensaios de Seleção de Medicamentos Antitumorais , Fermentação , Humanos , Estrutura Molecular , Perileno/metabolismo , Perileno/farmacologia , Perileno/efeitos da radiação , Quinonas/efeitos da radiação , Análise Espectral/métodos , Estereoisomerismo
4.
Toxicol In Vitro ; 66: 104860, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32298799

RESUMO

The use of natural products as chemotherapeutic agents and tools for manipulation of apoptosis represent an attractive therapeutic concept. In this study, we investigated the anticancer activities of a combination of two natural compounds with different origin, hypericin (plant product) in its photoactive state and Manumycin A (yeast product) and explored the underlying mechanisms of their pro-apoptotic action using an oxaliplatin-resistant variant of human colon adenocarcinoma cell line HT-29-OxR as the experimental model. CCK-8 assay was performed to evaluate the cytotoxicity of the drugs. CalcuSyn software was used to identify the type of interaction between the two agents. BrdU incorporation assay and colony forming assay were performed to study the short- and long-term proliferation of cells. To evaluate the ability of the drug combination to induce apoptosis, PARP p85 fragment was detected using the ELISA method. Changes in apoptosis-related proteins were examined by immunoassays. Our results showed that a synergistic combination of photoactive hypericin and Manumycin A decreased viability, inhibited both short- and long-term cell proliferation, decreased levels of IAPs proteins (cIAP1, cIAP2, XIAP and survivin), induced an apoptotic PARP cleavage associated with decline in procaspase-3 level, promoted phagocytosis of cancer cells, and restored chemosensitivity to oxaliplatin.


Assuntos
Antineoplásicos/farmacologia , Neoplasias Colorretais/tratamento farmacológico , Perileno/análogos & derivados , Polienos/farmacologia , Alcamidas Poli-Insaturadas/farmacologia , Antracenos , Antineoplásicos/efeitos da radiação , Proteínas Reguladoras de Apoptose/metabolismo , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Neoplasias Colorretais/metabolismo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Sinergismo Farmacológico , Humanos , Luz , Macrófagos/efeitos dos fármacos , Macrófagos/fisiologia , Oxaliplatina/farmacologia , Perileno/farmacologia , Perileno/efeitos da radiação , Fagocitose/efeitos dos fármacos
5.
Chem Commun (Camb) ; 56(11): 1705-1708, 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-31942910

RESUMO

We report ultrathin organic photovoltaic elements optimized to run photofaradaic reactions in biological conditions. We demonstrate concurrent oxygen reduction to hydrogen peroxide and glucose oxidation. The devices are powered by deep-red irradiation in the tissue transparency window. We utilize bilayers of phthalocyanine, acting as the light absorber, and perylene diimide, functioning as both electron-acceptor and the hydrogen peroxide evolution electrocatalyst. These heterojunction bilayers are stable when irradiated in simulated physiological conditions, producing photovoltages sufficient to simultaneously drive cathodic oxygen reduction to H2O2 and anodic oxidation of glucose. We find that optimization of the anode metal is critical for sustained photofaradaic reactivity. Our results demonstrate a robust "wet" thin film photovoltaic with potential for physiological applications where localized electrochemical manipulation is desired, in particular the delivery of reactive oxygen species.


Assuntos
Técnicas Eletroquímicas/métodos , Peróxido de Hidrogênio/síntese química , Imidas/química , Indóis/química , Perileno/análogos & derivados , Técnicas Eletroquímicas/instrumentação , Desenho de Equipamento , Glucose/química , Ouro/química , Imidas/efeitos da radiação , Indóis/efeitos da radiação , Isoindóis , Luz , Membranas Artificiais , Oxirredução , Oxigênio/química , Perileno/química , Perileno/efeitos da radiação , Fotoquímica/métodos
6.
Analyst ; 144(21): 6193-6196, 2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31577279

RESUMO

We here describe a photocurrent generation system exploiting gold nanoparticles (AuNPs) that cover perylenediimide-DNA complexes on electrode surfaces. Enhanced photocurrents were generated by the irradiation of the AuNPs, attributed to the efficient excitation of the perylenediimides by a local electric field on the surface of the AuNPs.


Assuntos
DNA/química , Técnicas Eletroquímicas/métodos , Nanopartículas Metálicas/química , Fotoquímica/métodos , Técnicas Eletroquímicas/instrumentação , Eletrodos , Ouro/química , Ouro/efeitos da radiação , Imidas/química , Imidas/efeitos da radiação , Luz , Nanopartículas Metálicas/efeitos da radiação , Perileno/análogos & derivados , Perileno/química , Perileno/efeitos da radiação
7.
Chembiochem ; 18(16): 1599-1603, 2017 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-28681411

RESUMO

For decades the detection of nucleic acids and their interactions at low abundances has been a challenging task that has thus far been solved by enzymatic target amplification. In this work we aimed at developing efficient tools for amplification-free nucleic acid detection, which resulted in the synthesis of new fluorescent nanoparticles. Here, the fluorescent nanoparticles were made by simple and inexpensive radical emulsion polymerization of butyl acrylate in the presence of fluorescent dyes and additional functionalization reagents. This provided ultra-bright macrofluorophores of 9-84 nm mean diameter, modified with additional alkyne and amino groups for bioconjugation. By using click and NHS chemistries, the new nanoparticles were attached to target-specific DNA probes that were used in fluorimetry and fluorescence microscopy. Overall, these fluorescent nanoparticles and their oligonucleotide derivatives have higher photostability, brighter fluorescence and hence dramatically lower limits of target detection than the individual organic dyes. These properties make them useful in approaches directed towards ultrasensitive detection of nucleic acids, in particular for imaging and in vitro diagnostics of DNA.


Assuntos
Sondas de DNA/química , Corantes Fluorescentes/química , MicroRNAs/análise , Nanopartículas/química , Acrilatos/química , Aminoacridinas/química , Aminoacridinas/efeitos da radiação , Azidas/química , Benzotiazóis/química , Benzotiazóis/efeitos da radiação , Carbocianinas/química , Carbocianinas/efeitos da radiação , Química Click , Difusão Dinâmica da Luz , Corantes Fluorescentes/efeitos da radiação , Fluorometria , Limite de Detecção , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , Nanopartículas/efeitos da radiação , Tamanho da Partícula , Perileno/química , Perileno/efeitos da radiação , Polimerização , Propilaminas/química , Quinolinas/química , Quinolinas/efeitos da radiação , Raios Ultravioleta
8.
Photochem Photobiol Sci ; 16(10): 1502-1511, 2017 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-28636018

RESUMO

The step-up photophobic response of the heterotrich ciliate Blepharisma japonicum is mediated by a hypericinic pigment, blepharismin, which is not present in any of the known six families of photoreceptors, namely rhodopsins, phytochromes, xanthopsins, cryptochromes, phototropins, and BLUF proteins. Upon irradiation, native cells become light-adapted (blue) by converting blepharismin into the photochemically stable oxyblepharismin (OxyBP). So far, OxyBP has been investigated mainly from a photophysical point of view in vitro, either alone or complexed with proteins. In this work, we exploit the vivid fluorescence of OxyBP to characterize its lifetime emission in blue B. Japonicum cells, on account of the recognized role of the fluorescence lifetime to provide physicochemical insights into the fluorophore environment at the nanoscale. In a biological context, OxyBP modifies its emission lifetime as compared to isotropic media. The phasor approach to fluorescence lifetime microscopy in confocal mode highlights that fluorescence originates from two excited states, whose relative balance changes throughout the cell body. Additionally, Cilia and kinetids, i.e., the organelles involved in photomovement, display lifetime asymmetry between the anterior and posterior part of the cell. From these data, some hypotheses on the phototransduction mechanism are proposed.


Assuntos
Cilióforos/química , Cilióforos/efeitos da radiação , Cor , Luz , Perileno/análogos & derivados , Células Fotorreceptoras/química , Células Fotorreceptoras/efeitos da radiação , Cilióforos/citologia , Microscopia de Fluorescência , Estrutura Molecular , Perileno/química , Perileno/efeitos da radiação , Processos Fotoquímicos
9.
Int J Pharm ; 503(1-2): 56-67, 2016 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-26940808

RESUMO

By means of fluorescence microscopy the intracellular distribution of fluorescent drugs with different hydrophobicity (quinizarin, emodin and hypericin) was studied. Selective photoactivation of these drugs in precisely defined position (nuclear envelope) allowed moderately hydrophobic emodin enter the nucleus. Highly hydrophobic hypericin was predominantly kept in the membranes with no fluorescence observed in the nucleus. The redistribution of quinizarin, emodin and hypericin between lipids, proteins and DNA was studied in solutions and cells. Based on these results was proposed theoretical model of hydrophobic drugs' nuclear internalization after photo-activation. Molecular docking models showed that hypericin has the strongest affinity to P-glycoprotein involved in the cell detoxification. Presence of 10 µM quinizarin, emodin or hypericin increased P-glycoprotein function in U87 MG cells. Moreover, emodin pretreatment allowed quinizarin nuclear internalization without photo-activation, which was not the case for hypericin. The synergy of such pretreatment and photo-activation should lessen the drug doses with simultaneous increase of drug efficacy triggering cell apoptosis/necrosis.


Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Antraquinonas/farmacologia , Emodina/farmacologia , Perileno/análogos & derivados , Antracenos , Antraquinonas/química , Antraquinonas/efeitos da radiação , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Núcleo Celular/efeitos da radiação , LDL-Colesterol/química , DNA/química , Emodina/química , Emodina/efeitos da radiação , Glioma/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Luz , Simulação de Acoplamento Molecular , Perileno/química , Perileno/farmacologia , Perileno/efeitos da radiação , Albumina Sérica/química
10.
Gen Physiol Biophys ; 35(2): 223-30, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26891274

RESUMO

The study was designed to test the potential photogenotoxicity of hypericin (HYP) at three different levels: primary DNA damages, gene mutations and chromosome aberrations. Primary genetic changes were detected using the comet assay. The potential mutagenic activity of HYP was assessed using the Ames/Salmonella typhimurium assay. Finally, the ability of photoactivated HYP to induce chromosome aberrations was evaluated by the in vitro mammalian chromosome aberration test and compared to that of non-photoactivated HYP. The results have shown that photoactivated HYP can only induce primary DNA damages (single-strand DNA breaks), acting in a dose-response manner. This activity depended both on HYP concentrations and an intensity of the light energy needed for its photoactivation. However, mutagenic effect of photoactivated HYP evaluated in the Ames assay using three bacterial strains S. typhimurium (TA97, TA98 and TA100) was not confirmed. Moreover, photoactivated HYP in the range of concentrations (0.005-0.01 µg/ml) was not found to be clastogenic against HepG2 cells. Our findings from both the Ames assay and the chromosome aberrations test provide evidence that photoactivated HYP is not genotoxic, which might be of great importance mainly in terms of its use in the photodynamic therapy.


Assuntos
Aberrações Cromossômicas/efeitos da radiação , Dano ao DNA/fisiologia , Linfócitos/efeitos da radiação , Mutação/efeitos da radiação , Perileno/análogos & derivados , Antracenos , Células Cultivadas , Relação Dose-Resposta à Radiação , Humanos , Linfócitos/citologia , Linfócitos/fisiologia , Testes de Mutagenicidade , Mutação/genética , Perileno/administração & dosagem , Perileno/efeitos da radiação , Fármacos Fotossensibilizantes/administração & dosagem , Fármacos Fotossensibilizantes/efeitos da radiação , Doses de Radiação
11.
Chem Commun (Camb) ; 48(31): 3751-3, 2012 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-22398407

RESUMO

Visible light-harvesting perylenebisimide (PBI)-C(60) dyads were prepared as organic triplet photosensitizers for photooxidation of 1,5-dihydroxynaphthalene and the efficiency of the dyads is 6-fold of the conventional Ir(III) complex triplet photosensitizer.


Assuntos
Fulerenos/química , Imidas/química , Naftóis/química , Naftóis/efeitos da radiação , Perileno/análogos & derivados , Oxigênio Singlete/química , Transferência de Energia , Fulerenos/efeitos da radiação , Imidas/efeitos da radiação , Irídio/química , Luz , Oxirredução , Perileno/química , Perileno/efeitos da radiação
12.
Int J Pharm ; 386(1-2): 131-7, 2010 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-19922781

RESUMO

We report a facile silica nanovehicle preparation procedure for hydrophobic drug delivery, which is carried out in water without adding any surfactant and additional catalyst. This strategy includes hydrophobic drug nanopaticle preparation by reprecipitation method and in situ hydrolyzation and polymerization to encapsulate this naoparticle using only N-(beta-amimoethyl)-gamma-aminopropyltriethoxysilane (AETPS). To demonstrate this technique hypocrellin A (HA), a hydrophobic photosensitizing anticancer drug, is embedded into silica nanovehicle using this simple method. The resulting HA encapsulated nanovehicles (HANV) are monodisperse and stable in aqueous solution. Comparative studies with free HA and entrapped HA have demonstrated that the encapsulation effect on the embedded photosensitizer nanoparticle significantly enhances the efficacy of singlet oxygen generation and, thereby, the in vitro photodynamic efficacy.


Assuntos
Portadores de Fármacos , Nanopartículas , Perileno/análogos & derivados , Veículos Farmacêuticos/química , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/farmacologia , Quinonas/farmacologia , Silanos/química , Apoptose/efeitos dos fármacos , Transporte Biológico , Sobrevivência Celular/efeitos dos fármacos , Precipitação Química , Química Farmacêutica , Composição de Medicamentos , Estabilidade de Medicamentos , Géis , Células HeLa , Humanos , Ligação de Hidrogênio , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Microscopia Eletrônica de Transmissão , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Tamanho da Partícula , Perileno/química , Perileno/metabolismo , Perileno/farmacologia , Perileno/efeitos da radiação , Veículos Farmacêuticos/toxicidade , Fenol , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/metabolismo , Fármacos Fotossensibilizantes/efeitos da radiação , Propilaminas , Quinonas/química , Quinonas/metabolismo , Quinonas/efeitos da radiação , Espécies Reativas de Oxigênio/metabolismo , Reprodutibilidade dos Testes , Silanos/toxicidade , Oxigênio Singlete/química , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Tecnologia Farmacêutica/métodos , Fatores de Tempo
13.
J Chem Phys ; 128(12): 124516, 2008 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-18376952

RESUMO

Electronic excitation energy transfer has been studied by single molecule spectroscopy in donor/acceptor dyads composed of a perylenediimide donor and a terrylenediimide acceptor linked by oligo(phenylene) bridges of two different lengths. For the shorter bridge (three phenylene units) energy is transferred almost quantitatively from the donor to the acceptor, while for the longer bridge (seven phenylene units) energy transfer is less efficient as indicated by the occurrence of donor and acceptor emission. To determine energy transfer rates and efficiencies at the single molecule level, several methods have been employed. These comprise time-correlated single photon counting techniques at room temperature and optical linewidth measurements at low temperature (1.4 K). For both types of measurement we obtain broad distributions of the rate constants of energy transfer. These distributions are simulated in the framework of Forster theory by properly taking into account static disorder and the flexibility of the dyads, as both effects can substantially contribute to the distributions of energy transfer times. The rate constants of energy transfer obtained from the calculated distributions are smaller on average than those extracted from the experimental distributions, whereby the discrepancy is larger for the shorter bridge. Furthermore, by plotting the experimentally determined transfer rates against the individual spectral overlaps, approximately linear dependencies are found being indicative of a Forster-type contribution to the energy transfer. For a given single molecule such a linear dependence could be followed by spectral diffusion induced fluctuations of the spectral overlap. The discrepancies between measured energy transfer rates and rates calculated by Forster theory are briefly discussed in light of recent results of quantum chemical calculations, which indicate that a bridge-mediated contribution is mainly responsible for the deviations from Forster theory. The availability of the inhomogeneous distributions of donor and acceptor electronic transition frequencies allows for comparing the energy transfer process at liquid helium and room temperature for the same set of molecules via simple simulations. It is found that on average the energy transfer is by a factor of approximately 3 faster at room temperature, which is due to an increase of spectral overlap.


Assuntos
Transferência de Energia , Imidas/química , Hidrocarbonetos Policíclicos Aromáticos/química , Antracenos/química , Antracenos/efeitos da radiação , Elétrons , Imidas/efeitos da radiação , Luz , Estrutura Molecular , Perileno/análogos & derivados , Perileno/química , Perileno/efeitos da radiação , Fotoquímica , Hidrocarbonetos Policíclicos Aromáticos/efeitos da radiação , Espectrometria de Fluorescência/métodos , Temperatura , Fatores de Tempo
14.
J Org Chem ; 72(23): 8990-3, 2007 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-17935352

RESUMO

3-(1-Alkynyl)perylenes undergo oxygenation when subjected to irradiation with visible light under aerated conditions. The structures of novel oxygenated products formed in this manner are assigned as regioisomeric dibenzo[jk,mn]phenanthrene-4,5-diones.


Assuntos
Luz , Oxigênio/química , Oxigênio/efeitos da radiação , Perileno , Fenantrenos/química , Fenantrenos/síntese química , Fenantrenos/efeitos da radiação , Espectroscopia de Ressonância Magnética/métodos , Estrutura Molecular , Oxirredução , Perileno/análogos & derivados , Perileno/síntese química , Perileno/efeitos da radiação , Fotoquímica
15.
J Biomol Struct Dyn ; 25(3): 321-6, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17937493

RESUMO

Elsinochrome A (EA) is one of the important perylenequinonoid photosensitizers (PQPs); however, its photophysical and photochemical properties were given less attention in comparsion with other PQPs. In view of the successful use of quantum chemical methods, especially time-dependent density functional theory (TD-DFT), in investigating the photo-physicochemical characters of various photosensitizers, we attempt to explore the photophysical and photosensitive properties of EA by theoretical methods. Firstly, the absorption spectra and lowest-lying T(1) excitation energy of EA were estimated by TD-DFT calculations. Then, the photosensitizing mechanisms of EA were explored. It was found that EA can photo-generate (1)O(2) through energy transfer in both benzene and DMSO. However, EA gives birth to O(2)(.-) only in DMSO, and it is E(A)(.-) generated from autoionization reactions that is responsible for the O(2)(.-)-generation, which gains some deeper insights into the photosensitive behaviors of EA.


Assuntos
Simulação por Computador , Perileno/análogos & derivados , Quinonas/química , Luz , Modelos Biológicos , Estrutura Molecular , Perileno/química , Perileno/efeitos da radiação , Fotoquímica , Fármacos Fotossensibilizantes/química , Quinonas/efeitos da radiação
16.
Phytochem Anal ; 18(3): 204-8, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17500362

RESUMO

An analytical procedure was developed for the simultaneous determination of total hypericin (protopseudohypericin, pseudohypericin, protohypericin and hypericin) and hyperforin in Hypericum perforatum (St. John's wort) extracts and its preparations. The determination of total hypericin and hyperforin in one step was achieved by exposing the samples to artificial daylight in amber glass vials. This procedure allows both the photoconversion of the protoforms into the appropriate hypericins and the protection of the photosensitive hyperforin. For quantification, an HPLC method with electrochemical detection was applied. As an example of the application of the principle, two preparations containing St. John's wort were assayed.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Eletroquímica/métodos , Hypericum/química , Perileno/análogos & derivados , Floroglucinol/análogos & derivados , Terpenos/análise , Antracenos , Antidepressivos/química , Compostos Bicíclicos com Pontes/análise , Compostos Bicíclicos com Pontes/química , Compostos Bicíclicos com Pontes/efeitos da radiação , Luz , Perileno/análise , Perileno/química , Perileno/efeitos da radiação , Floroglucinol/análise , Floroglucinol/química , Floroglucinol/efeitos da radiação , Extratos Vegetais/química , Pós/química , Comprimidos/química , Terpenos/química , Terpenos/efeitos da radiação
17.
J Phys Chem B ; 111(14): 3742-9, 2007 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-17388539

RESUMO

Three long-wavelength absorbing dipeptide-modified hypocrellin B (HB) derivatives, Gly-HB, Tyr-HB, and Trp-HB, were prepared for application in photodynamic therapy (PDT). Their abilities to produce free radicals and singlet oxygen were compared in detail with EPR technique, and their binding interactions with calf thymus DNA (CT DNA) were studied by absorption spectra and DNA melting temperature measurements. Tyr-HB and Trp-HB distinguish themselves from Gly-HB and HB remarkably by their significantly improved efficiencies to generate semiquinone anion radicals, superoxide anion radicals, and hydroxyl radicals, as well as their affinity to CT DNA, as the result of the electron-donating properties and intercalating abilities of tyrosine and tryptophan groups. Tyr-HB and Trp-HB show remarkably enhanced photodamage capabilities on CT DNA than their parent HB in aerobic conditions. Moreover, they possess moderate photodamage abilities on CT DNA even in anaerobic conditions, indicating the role of Type I mechanism in their photodynamic behaviors.


Assuntos
Perileno/análogos & derivados , Quinonas/química , Triptofano/química , Tirosina/química , Ânions/química , Ânions/efeitos da radiação , DNA/química , DNA/efeitos da radiação , Espectroscopia de Ressonância de Spin Eletrônica/métodos , Radicais Livres/química , Radicais Livres/efeitos da radiação , Estrutura Molecular , Oxigênio/química , Oxigênio/efeitos da radiação , Perileno/química , Perileno/efeitos da radiação , Fotoquímica , Fotoquimioterapia , Teoria Quântica , Quinonas/efeitos da radiação , Sensibilidade e Especificidade , Triptofano/efeitos da radiação , Tirosina/efeitos da radiação , Raios Ultravioleta
18.
J Phys Chem B ; 110(50): 25163-73, 2006 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-17165960

RESUMO

Photoexcitation of a series of donor-bridge-acceptor (D-B-A) systems, where D = phenothiazine (PTZ), B = p-phenylene (Phn), n = 1-5, and A= perylene-3,4:9,10-bis(dicarboximide) (PDI) results in rapid electron transfer to produce 1(PTZ+*-Phn-PDI-*). Time-resolved EPR (TREPR) studies of the photogenerated radical pairs (RPs) show that above 150 K, when n = 2-5, the radical pair-intersystem crossing mechanism (RP-ISC) produces spin-correlated radical ion pairs having electron spin polarization patterns indicating that the spin-spin exchange interaction in the radical ion pair is positive, 2J > 0, and is temperature dependent. This temperature dependence is most likely due to structural changes of the p-phenylene bridge. Charge recombination in the RPs generates PTZ-Phn-3*PDI, which exhibits a spin-polarized signal similar to that observed in photosynthetic reaction-center proteins and some biomimetic systems. At temperatures below 150 K and/or at shorter donor-acceptor distances, e.g., when n = 1, PTZ-Phn-3*PDI is also formed from a competitive spin-orbit-intersystem crossing (SO-ISC) mechanism that is a result of direct charge recombination: 1(PTZ+*-Phn-PDI-*) --> PTZ-Phn-3*PDI. This SO-ISC mechanism requires the initial RP intermediate and depends strongly on the orientation of the molecular orbitals involved in the charge recombination as well as the magnitude of 2J.


Assuntos
Compostos de Bifenilo/química , Perileno/análogos & derivados , Perileno/química , Espectroscopia de Ressonância de Spin Eletrônica/métodos , Radicais Livres/química , Radicais Livres/efeitos da radiação , Imidas/química , Lasers , Magnetismo , Estrutura Molecular , Perileno/efeitos da radiação , Fotoquímica , Sensibilidade e Especificidade , Temperatura , Fatores de Tempo
19.
J Phys Chem B ; 110(50): 25430-40, 2006 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-17165990

RESUMO

The efficiencies of organic solar cells that incorporate light-harvesting arrays of organic pigments were calculated under 1 sun of air mass 1.5 solar irradiation. In one set of calculations, photocurrent efficiencies were evaluated for porphyrin, phthalocyanine, chlorin, bacteriochlorin, and porphyrin-bis(perylene) pigment arrays of different length and packing densities under the assumption that each solar photon absorbed quantitatively yielded one electron in the external circuit. In another more realistic set of calculations, solar conversion efficiencies were evaluated for arrays comprising porphyrins or porphyrin-(perylene)2 units taking into account competitive excited-state relaxation pathways. A system of coupled differential equations for all reactions in the arrays was solved on the basis of previously published rate constants for (1) energy transfer between the perylene and porphyrin pigments, (2) excited-state relaxation of the perylene and porphyrin pigments, and (3) excited-state electron injection into the semiconductor. This formal analysis enables determination of the optimal number of pigments in an array for solar-to-electrical energy conversion. The optimal number of pigments depends on the molar absorption coefficient and the density at which the arrays can be packed on an electrode surface. Taken together, the ability to employ fundamental photophysical, kinetic, and structural parameters of modular molecular architectures in assessments of the efficiency of solar-to-electrical energy conversion should facilitate the design of molecular-based solar cells.


Assuntos
Luz , Metaloporfirinas/química , Modelos Químicos , Perileno/química , Porfirinas/química , Elétrons , Transferência de Energia , Indóis/química , Indóis/efeitos da radiação , Isoindóis , Cinética , Metaloporfirinas/efeitos da radiação , Estrutura Molecular , Perileno/efeitos da radiação , Fotoquímica , Porfirinas/efeitos da radiação , Semicondutores , Sensibilidade e Especificidade , Análise Espectral , Propriedades de Superfície
20.
Biochim Biophys Acta ; 1760(3): 333-9, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16481115

RESUMO

In the current work, the molecular recognition and interaction were studied by taking advantages of the environmentally sensitive fluorescence of hypocrellin B (HB) and the structural knowledge of hyaluronan (HYA), a polysaccharide over-expressed in tumor cells or tissues. Interestingly, it was found that, binding to HYA, the absorbance of HB would be greatly strengthened, suggesting HB fitting to a hydrophobic environment in HYA, while the fluorescence seriously quenched at pH 7.0, which was very distinct from the binding of HB to proteins, liposome, other polysaccharide molecules or HYA at pH 2.0. Synchronously, the particle size of HYA would become bigger after interaction with HB, suggesting an aggregation of HYA. Considering the spectral responses of HB and the particle size change of HYA, a specific interaction of HB with HYA was proposed, that is, an HB molecule would link two HYA molecules not only by hydrophobic interaction but also by formations of intermolecular hydrogen bonds at physiological pH values. Furthermore, the estimated binding constant suggests a quite high affinity of HB to HYA. Besides, an oxygen-dependent degradation of HYA and photobleaching of HB were observed via photosensitization of HB.


Assuntos
Ácido Hialurônico/química , Perileno/análogos & derivados , Fármacos Fotossensibilizantes/química , Quinonas/química , Ácido Hialurônico/efeitos da radiação , Luz , Peso Molecular , Perileno/química , Perileno/efeitos da radiação , Quinonas/efeitos da radiação , Espectrometria de Fluorescência
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