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1.
J Phys Chem Lett ; 11(3): 1059-1067, 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-31952446

RESUMO

The interplay between active molecules and the protein environment in light-harvesting complexes tunes the photophysics and the dynamical properties of pigment-protein complexes in a subtle way, which is not fully understood. Here we characterized the photophysics and the ultrafast dynamics of four variants of the water-soluble chlorophyll protein (WSCP) as an ideal model system to study the behavior of strongly interacting chlorophylls. We found that when coordinated by the WSCP protein, the presence of the formyl group in chlorophyll b replacing the methyl group in chlorophyll a strongly affects the exciton energy and the dynamics of the system, opening up the possibility of tuning the photophysics and the transport properties of multichromophores by engineering specific interactions with the surroundings.


Assuntos
Clorofila A/química , Clorofila/química , Complexos de Proteínas Captadores de Luz/química , Modelos Moleculares , Temperatura Ambiente , Termodinâmica , Água/química
2.
J Photochem Photobiol B ; 203: 111763, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31931382

RESUMO

Photodynamic therapy (PDT) is a clinical modality that allows the destruction of tumor cells and microorganisms by reactive oxygen species, formed by the combination of photosensitizer (PS), molecular oxygen and adequate wavelength light. This research, through a clean methodology that involves pressurized liquids extraction (PLE), obtained a highly antimicrobial extract of Tetragonia tetragonoides, which rich in chlorophylls as photosensitizers. The Chlorophylls-based extract (Cbe-PLE) presented pharmacological safety, through the maintenance of cellular viability. In addition, Cbe-PLE showed great efficacy against Staphylococcus aureus, with severe dose-dependent damage to the cell wall of the pathogen. The obtained product has a high potential for the development of photostimulated phytotherapic formulations for clinical applications in localized infections, as a complementary therapeutic alternative to antibiotics.


Assuntos
Aizoaceae/química , Extratos Vegetais/química , Aizoaceae/metabolismo , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Clorofila/química , Clorofila/farmacologia , Luz , Camundongos , Testes de Sensibilidade Microbiana , Nanoestruturas/química , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Folhas de Planta/química , Folhas de Planta/metabolismo , Caules de Planta/química , Caules de Planta/metabolismo , Staphylococcus aureus/efeitos dos fármacos
3.
J Photochem Photobiol B ; 202: 111726, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31816516

RESUMO

The objective of the study was to investigate the effects of growth-stage specific lighting for the physiological homeostasis of red leaf lettuce (Lactuca sativa L. cv. Red Cos), by measuring the productivity of photosynthesis and primary metabolism. In the experiments, the main photosynthetic photon flux consisted of red (R) and blue (B) light, supplemented with blue, green (G) or UV-A wavelengths. Decrease of fructose, accompanied by significant decrease of stomatal conductance (gs), the ratio of intracellular to ambient CO2 concentration (Ci/Ca), photosynthetic rate (Pr), light adapted actual quantum yield of PSII photochemistry (ΦPSII), biomass formation and significant increase of transpiration rate (Tr) suggest that supplemental UV-A during maturity stage, after supplemental green irradiation during seedling stage (BRG to BRUV) was the least favourable condition for red leaf lettuce. However, constant irradiation with supplemental green (BRG) or supplemental green irradiation after increased blue exposure (B↑R to BRG) resulted in significant increase of Pr, gs, Ci/Ca, and light use efficiency(LUE), and decrease of Tr and Water use efficiency (WUE). Significant increase of leaf area was observed under supplemental green in both seedlings (BR; BRG) and matured plants (B↑R to BRG). Significant increase of specific leaf area was found under supplemental green (BRG) for seedlings and under increased blue (B↑R) for matured plants. Accordingly, the most favourable growth-stage specific lighting spectrum strategy for red leaf lettuce, based on photosynthetic and primary metabolite response, is supplemental green irradiation after increased blue exposure (B↑R to BRG), whereas, the most favourable condition for seedlings is BRG. According to the PCA correlation matrix, associations among the measured data indicate that WUE negatively correlated with gs and Ci/Ca, while LUE positively correlated with gs and Pr. However, weak correlations between ФPSII, LUE and photochemical reflectance index (PRI) suggest that selected light conditions were not optimal for red leaf lettuce.


Assuntos
Alface/efeitos da radiação , Luz , Clorofila/química , Análise por Conglomerados , Gases/química , Gases/metabolismo , Alface/crescimento & desenvolvimento , Fotossíntese/efeitos da radiação , Folhas de Planta/química , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/efeitos da radiação , Análise de Componente Principal , Teoria Quântica , Raios Ultravioleta
4.
Food Chem Toxicol ; 135: 110975, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31747619

RESUMO

This paper presents innovative packaging materials made of environmentally friendly biodegradable polymers (polylactide and polyhydroxybutyrate) with the addition of natural colorants commonly used in the food industry. Colorants fulfilled the role of indicator, changing colour under the influence of external factors, and gave the materials the characteristics of intelligent packaging, where colour changes indicated the life time of the materials. The paper gives the mechanical and thermal properties of the materials obtained, and describes changes in the colour of the samples under the influence of thermooxidation, UV and weathering, as well as the biodegradability of the materials. The packaging materials presented are in line with current trends in the packaging market and legal requirements. The samples, in addition to the basic functions of packaging materials, are pro-ecological and fully biodegradable new generation materials.


Assuntos
Plásticos Biodegradáveis/química , Compostos Cromogênicos/química , Embalagem de Alimentos , /química , Plásticos Biodegradáveis/metabolismo , Chaetomium/metabolismo , Clorofila/química , Curcumina/química , Luteína/química , Fungos Mitospóricos/metabolismo , Oxirredução , Poliésteres/química , Poliésteres/metabolismo , Temperatura Ambiente , beta Caroteno/química
5.
Food Chem ; 306: 125300, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31562927

RESUMO

Chlorophyll is a valuable bioactive compound, which is used as a natural food coloring agent and a photosensitizer for photodynamic therapy because of its antioxidant properties, antimutagenic ability, and near-infrared fluorescence. However, chlorophyll is unstable when it comes to retaining its antioxidant activity, when exposed to oxygen, high temperature, or light environments. To enhance the stability of chlorophyll, a polymer encapsulation method was proposed. Polycaprolactone (PCL) was employed to encapsulate the chlorophyll, and the particles size of the composites was controlled through droplet microfluidics. The composites (chlorophyll-encapsulated PCL particles) were characterized through UV-VIS spectrometry, SEM, optical microscopy, and light exposure. The particles were spherical, with diameters adjustable from 68 to 247 µm. Additionally, the chlorophyll-encapsulated PCL particles exhibited considerably prolonged chlorophyll stability. The solid microparticle is more convenient for storage and transportation, and have great potential for application in the food industry.


Assuntos
Clorofila/química , Poliésteres/química , Microfluídica/métodos , Tamanho da Partícula
6.
J Photochem Photobiol B ; 201: 111679, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31710926

RESUMO

Plants from the family Droseraceae, especially Drosera sp. and Dionaea sp., are naturally rich in phenolic derivatives such as plumbagin, among others. Plumbagin is known both for its pharmacological significance and its protective properties against light stress. Light stress - high light intensity or/and light spectral composition - activates plants' response mechanisms including, among others, hormonal (salicylic acid, jasmonic acid) pathways and secondary metabolite (phenolic compounds, proline) pathways. Short-wavelength radiation, due to its high energy, will induce the synthesis of protective secondary metabolites, including those with pharmaceutical properties. The aim of the study was to describe and compare acclimation strategies of Drosera peltata and Dionaea muscipula to blue-red light in the context of phenolic compound accumulation, and salicylic acid, jasmonic acid and proline synthesis. For the first time, differences in the responses of D. muscipula and D. peltata to blue-red light (in the ratio 6:1) were established. In Dionaea sp., it was associated with the use of redox equivalents (in particular, plastoquinone pool) for the synthesis of primary metabolites used in the process of growth and development. In Drosera sp., a rapid adjustment of redox state led to the synthesis of secondary metabolites, constituting a reservoir of carbon skeletons and allowing for a quick defence response to stress factors. In both species, blue-red light did not induce the jasmonic acid pathway. However, the salicylic acid pathway was induced as an alternative to the phenolic compound synthesis pathway. Nevertheless, the applied blue-red light was not an effective elicitor of phenolic compounds in the plants examined.


Assuntos
Droseraceae/efeitos da radiação , Luz , Fenóis/metabolismo , Catalase/metabolismo , Clorofila/química , Droseraceae/química , Droseraceae/metabolismo , Peroxidação de Lipídeos , Malondialdeído/análise , Peroxidases/metabolismo , Fenóis/química , Prolina/química
7.
Chem Biodivers ; 16(12): e1900459, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31535771

RESUMO

This study was conducted to analyze the bioactive compounds and in vitro antioxidant capacity of tea infusions prepared from whole and ground medicinal fruits, including gardenia, jujube, magnolia, quince, and wolfberries. The dried medicinal fruit samples were ground, and then passed through a 60-mesh sieve (pore size, 250 µm). Hot water (80 °C) infusions of whole and ground fruits were examined. In average of both whole and ground tea infusions, the maximum bioactive compounds were found in gardenia (ß-carotene, lycopene, and vitamin C), magnolia (total chlorophyll and anthocyanin), quince (flavonoid), and wolfberries (phenolic), and the maximum antioxidant capacity was found in quince (ABTS and DPPH) and wolfberries (NSA). Whole fruit tea infusions showed a higher brightness than the ground fruit tea infusions. The total chlorophyll, anthocyanin, ß-carotene, lycopene, phenolic, flavonoid, and vitamin C contents were found to be significantly (p≤0.001) higher in the ground fruit tea infusions than in the whole fruit tea infusions; additionally, the ground fruit tea infusions had a higher antioxidant capacity especially ABTS, DPPH and NSA. Therefore, the ground fruit tea infusions appeared to be more powerful with regard to the contents of bioactive compounds and antioxidant capacities than the whole fruit tea infusions.


Assuntos
Antioxidantes/química , Plantas Medicinais/química , Chá/química , Antocianinas/análise , Clorofila/química , Flavonoides/análise , Frutas/química , Frutas/metabolismo , Temperatura Alta , Licopeno/análise , Fenóis/análise , Extratos Vegetais/química , Plantas Medicinais/metabolismo , beta Caroteno/análise
8.
Chem Commun (Camb) ; 55(76): 11410-11413, 2019 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-31482869

RESUMO

Graphene-based composite materials are versatile but not easily procurable. Cyanobacterial cells, an outgrowth of eutrophic freshwater lake, were simultaneously employed as a template for the growth of ZnO nanoparticles and as a biomass carbon source for graphene sheets, resulting in chlorophyll-containing graphene-wrapped ZnO nanospheres.


Assuntos
Cianobactérias/química , Cianobactérias/citologia , Grafite/química , Nanosferas/química , Óxido de Zinco/química , Clorofila/química
9.
Photochem Photobiol Sci ; 18(11): 2673-2681, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31482917

RESUMO

The utilization of the light-harvesting and electron-transferring function of chlorophylls (Chls) has received attention for visible-light driven hydrogen production. In this work, a series of Chl derivatives based on pyropheophorbide-a (Pyro-a) conjugated with a viologen moiety, including a Pyro-a methyl ester directly bonded with the viologen at the 3-position 1, its 31-methylene analog 2 and Pyro-a connected with the viologen in the 17-substituent 3, were synthesized from chemical modification of naturally occurring Chl-a and characterized in terms of their photochemical and photophysical properties. As the photoexcited singlet state of the Pyro-a moiety was strongly quenched by the viologen moiety in a molecule, the effective photoinduced intramolecular electron transfer from Pyro-a to the bonded viologen moiety occurred. Moreover, these molecules were applied as a photosensitizer in the system for visible-light driven hydrogen production with platinum nanoparticles via intramolecular reduction of the bonded viologen moiety. Efficient photoreduction of external methyl viologen and successive hydrogen production on platinum nanoparticles were achieved using the synthetic conjugate of Pyro-a with the viologen moiety as a photosensitizer. In particular, effective visible-light driven hydrogen production was accomplished using 3 and platinum nanoparticles via the reduction of external methyl viologen.


Assuntos
Clorofila/análogos & derivados , Hidrogênio/química , Luz , Nanopartículas Metálicas/química , Platina/química , Clorofila/química , Transporte de Elétrons , Fármacos Fotossensibilizantes/química , Teoria Quântica , Viologênios/química
10.
J Agric Food Chem ; 67(38): 10624-10636, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31483633

RESUMO

The freshness and color quality of postharvest tea leaves can be markedly prolonged and retained by proper preservation measures. Here, we investigated the dynamic changes of chlorophyll and its derivatives in postharvest tea leaves under different low-temperature treatments using natural withering as a control. Chlorophyll decomposition was found closely related with chlorophyllide, pheophorbide, and pheophytin. Low-temperature withering could slow chlorophyll degradation in postharvest tea leaves via significant inhibition on the enzyme activity and gene expression of Mg-dechelatase, chlorophyllase, and pheophorbide a oxygenase. At the initial stage of withering, a significant increase was observed in the chlorophyll content, expression of chlorophyll-synthesis-related enzymes (such as glutamyl-tRNA synthetase, etc.), and chlorophyll synthase activity in newly picked tea leaves. Moreover, an obvious decrease was found in the content of l-glutamate as the foremost precursor substance of chlorophyll synthesis. Hence, our findings revealed that the chlorophyll synthesis reaction was induced by the light-dehydration-stress in the initial withering of tea leaves. This study provides a theoretical basis for exploring preservation technology in actual green tea production.


Assuntos
Camellia sinensis/genética , Camellia sinensis/metabolismo , Clorofila/metabolismo , Manipulação de Alimentos/métodos , Regulação da Expressão Gênica de Plantas , Camellia sinensis/química , Camellia sinensis/crescimento & desenvolvimento , Hidrolases de Éster Carboxílico/genética , Hidrolases de Éster Carboxílico/metabolismo , Clorofila/química , Cor , Enzimas/genética , Enzimas/metabolismo , Oxigenases/genética , Oxigenases/metabolismo , Folhas de Planta/química , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Temperatura Ambiente
11.
Sensors (Basel) ; 19(15)2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31366151

RESUMO

Nondestructive plant growth measurement is essential for researching plant growth and health. A nondestructive measurement system to retrieve plant information includes the measurement of morphological and physiological information, but most systems use two independent measurement systems for the two types of characteristics. In this study, a highly integrated, multispectral, three-dimensional (3D) nondestructive measurement system for greenhouse tomato plants was designed. The system used a Kinect sensor, an SOC710 hyperspectral imager, an electric rotary table, and other components. A heterogeneous sensing image registration technique based on the Fourier transform was proposed, which was used to register the SOC710 multispectral reflectance in the Kinect depth image coordinate system. Furthermore, a 3D multiview RGB-D image-reconstruction method based on the pose estimation and self-calibration of the Kinect sensor was developed to reconstruct a multispectral 3D point cloud model of the tomato plant. An experiment was conducted to measure plant canopy chlorophyll and the relative chlorophyll content was measured by the soil and plant analyzer development (SPAD) measurement model based on a 3D multispectral point cloud model and a single-view point cloud model and its performance was compared and analyzed. The results revealed that the measurement model established by using the characteristic variables from the multiview point cloud model was superior to the one established using the variables from the single-view point cloud model. Therefore, the multispectral 3D reconstruction approach is able to reconstruct the plant multispectral 3D point cloud model, which optimizes the traditional two-dimensional image-based SPAD measurement method and can obtain a precise and efficient high-throughput measurement of plant chlorophyll.


Assuntos
Técnicas Biossensoriais , Clorofila/isolamento & purificação , Lycopersicon esculentum/química , Folhas de Planta/química , Clorofila/química , Humanos , Imagem Tridimensional , Solo/química
12.
Molecules ; 24(15)2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31374946

RESUMO

Arthrospira platensis (spirulina) is considered a source of natural molecules with nutritional and health benefits. As the different storage forms can affect the quantity and quality of bioactive ingredients, the aim of the present work was to evaluate the effects of freezing, oven-drying and freeze-drying on chemical composition of spirulina biomass. Total proteins, photosynthetic pigments and antioxidants, were analyzed and compared to respective quantities in fresh biomass. The frozen sample exhibited the highest content of phycocyanin-C, phenols, and ascorbic acid, also respect to the fresh biomass. The highest total flavonoid amount was in the freeze-dried biomass. HPLC-DAD analysis of phenolic acids revealed the presence of the isoflavone genistein, known for its therapeutic role, in all the spirulina samples. The phosphomolybdenum method (TAC) and DPPH scavenging activity were applied to determine the antioxidant activity of different samples. The highest DPPH scavenging activity was detected in fresh and freeze-dried biomass and it was positively related to carotenoid content. A positive correlation indicated that carotenoids, chlorophyll, ascorbic acid and all phenolic compounds were the major contributors to the TAC activity in spirulina biomass. The results highlighted a different functional value of spirulina biomass, depending on the processing methods used for its storage.


Assuntos
Antioxidantes/química , Liofilização/métodos , Fotossíntese , Spirulina/química , Ácido Ascórbico/química , Carotenoides/química , Clorofila/química , Dessecação/métodos , Flavonoides/química , Fenóis/química , Ficocianina/química , Pigmentação
13.
Biochim Biophys Acta Bioenerg ; 1860(10): 148054, 2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31336104

RESUMO

In cyanobacteria, Glu-244 and Tyr-246 of the Photosystem II (PS II) D1 protein are hydrogen bonded to two water molecules that are part of a hydrogen-bond network between the bicarbonate ligand to a non-heme iron and the cytosol. Ala substitutions were introduced in Synechocystis sp. PCC 6803 to investigate the roles of these residues and the hydrogen-bond network on electron transfer between the primary plastoquinone acceptor, QA, and the secondary plastoquinone acceptor, QB, of the quinone-Fe-acceptor complex. All mutants assembled PS II; however, an increase in the PS II to PS I ratio was apparent, particularly in the E244A:Y246A double mutant. The mutants also showed impaired oxygen evolution and retarded chlorophyll a fluorescence decays following single turnover actinic flashes, which appeared to be primarily due to reduced QB binding in the E244A strain and an enhanced back reaction with the S2 state of the oxygen-evolving complex in the Y246A mutant. Impaired PS II in the Y246A and E244A:Y246A mutants resulted in inactivation of the psbA gene encoding D1. The Y246A and E244A:Y246A mutants also showed high light sensitivity whereas the E244A mutant showed enhanced resilience towards photodamage. Unlike the control strain, all of the mutants were insensitive to the addition of formate or bicarbonate in assays following chlorophyll decay kinetics that reflect electron transfer between QA and QB, suggesting the bicarbonate binding environment was perturbed. Our data also indicate that waters W582 and W622 (PDB: 4UB6) have essential roles in maintaining the architecture of the acceptor side of PS II.


Assuntos
Bicarbonatos/química , Cianobactérias/química , Transporte de Elétrons , Complexo de Proteína do Fotossistema II/química , Plastoquinona/química , Benzoquinonas , Sítios de Ligação , Chlamydomonas reinhardtii , Clorofila/química , Clorofila/metabolismo , Ligações de Hidrogênio , Ferro , Proteínas Mutantes , Oxigênio/química , Oxigênio/metabolismo , Plastoquinona/metabolismo , Synechocystis/genética
14.
Plant Mol Biol ; 101(3): 257-268, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31302867

RESUMO

KEY MESSAGE: The C-terminal cysteine-rich motif of NYE1/SGR1 affects chlorophyll degradation likely by mediating its self-interaction and conformational change, and somehow altering its Mg-dechelating activity in response to the changing redox potential. During green organ senescence in plants, the most prominent phenomenon is the degreening caused by net chlorophyll (Chl) loss. NON-YELLOWING1/STAY-GREEN1 (NYE1/SGR1) was recently reported to be able to dechelates magnesium (Mg) from Chl a to initiate its degradation, but little is known about the domain/motif basis of its functionality. In this study, we carried out a protein truncation assay and identified a conserved cysteine-rich motif (CRM, P-X3-C-X3-C-X-C2-F-P-X5-P) at its C terminus, which is essential for its function. Genetic analysis showed that all four cysteines in the CRM were irreplaceable, and enzymatic assays demonstrated that the mutation of each of the four cysteines affected its Mg-dechelating activity. The CRM plays a critical role in the conformational change and self-interaction of NYE1 via the formation of inter- and intra-molecular disulfide bonds. Our results may provide insight into how NYE1 responds to rapid redox changes during leaf senescence and in response to various environmental stresses.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Clorofila/química , Proteínas de Cloroplastos/metabolismo , Motivos de Aminoácidos , Quelantes/química , DNA Complementar/metabolismo , Dissulfetos , Regulação da Expressão Gênica de Plantas , Magnésio/química , Oxirredução , Fenótipo , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas/metabolismo , Conformação Proteica , Domínios Proteicos , Estresse Fisiológico
15.
J Photochem Photobiol B ; 197: 111551, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31306954

RESUMO

Heavy metal pollution as one of the most serious pollution problems of marine environment, seriously threatens the safety of marine organism and human health, and will lead to potential risks for the marine ecological environment. In order to develop a rapid and sensitive toxicity detection method for marine heavy metals, in this study, marine diatom Nitzschia closterium was used as the test organism, and the effects of different concentrations of lead (Pb) on the five chlorophyll fluorescence parameters of N. closterium including the maximum photochemical quantum yield of PSII (Fv/Fm), the effective quantum yield of PSII photochemical energy conversion (ΦPSII), the effective absorption cross section of PSII photochemistry (σPSII'), the relative electron transfer rate of PSII (rP), and the PSII electron flux per unit volume (JVPII) at different exposure times were investigated based on chlorophyll fluorescence technology. By comparing with the photosynthetic activity fluorescence parameter Fv/Fm which is commonly used for toxicity analysis of pollutants using algae as test organisms, the optimal chlorophyll fluorescence parameter that could rapidly and sensitively determine Pb toxicity to N. closterium was selected. The results indicate that all the five chlorophyll fluorescence parameters of Fv/Fm, ΦPSII, σPSII', rP and JVPII showed good dose-response relationships with Pb within 8 h exposure time, and they all could be used as endpoints to rapidly determine Pb toxicity to N. closterium. Among the five chlorophyll fluorescence parameters, JVPII was the most sensitive fluorescence parameter for detecting the toxicity of Pb to N. closterium within 6 h exposure. And for JVPII, the median effective concentration (EC50) values of Pb at 2, 4 and 6 h were 0.329, 0.068 and 0.040 mmol L-1, respectively. However, when the exposure time was 8 h, ΦPSII was the most sensitive fluorescence parameter for the toxicity detection of Pb, and the EC50 value of Pb at 8 h was 0.038 mmol L-1. This study will provide an important basis for the development of a rapid and sensitive detection method for the biological toxicity of marine heavy metals, and those results will be helpful for ecological risk assessment in marine environment.


Assuntos
Clorofila/química , Chumbo/toxicidade , Microalgas/efeitos dos fármacos , Microalgas/química , Microalgas/metabolismo , Complexo de Proteína do Fotossistema II/química , Complexo de Proteína do Fotossistema II/metabolismo , Teoria Quântica , Espectrometria de Fluorescência , Poluentes Químicos da Água/química , Poluentes Químicos da Água/toxicidade
16.
Adv Mater ; 31(35): e1901586, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31259438

RESUMO

Hydrophile-lipophile balance (HLB) has a great influence on the self-assembly and physicochemical properties of amphiphiles, thus affecting their biological effects. It is shown that amphiphilic nanoparticles (NPs) with a moderate HLB value display enhanced stability and highly efficient tumor retention. 2,2-Bis(hydroxymethyl)propionic acid hyperbranched poly(ethylene glycol) (PEG)-pyropheophorbide-a (Ppa) amphiphiles (G320P, G310P, G220P, and G210P) are synthesized with a tunable HLB value from 6.1 to 9.9 by manipulating the number of generation of dendrons (G2 or G3) and the molecular weight of PEG chains (10 or 20 kDa). Molecular dynamics simulations reveal that G320P and G210P with a moderate HLB value (8.0 and 7.8) self-assemble into very stable NPs with a small solvent accessible surface area and high nonbonding interactions. G320P with a moderate HLB value (8.0) and a long PEG chain excels against other NPs in prolonging the blood circulation time of Ppa (up to 13-fold), penetrating deeply into multicellular tumor spheroids and accumulating in tumors, and enhancing the PDT efficacy with a tumor growth inhibition of 96.0%. Rational design of NPs with a moderate HLB value may be implemented in these NP-derived nanomedicines to achieve high levels of retention in tumors.


Assuntos
Dendrímeros/química , Dendrímeros/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Nanopartículas/química , Animais , Linhagem Celular Tumoral , Clorofila/análogos & derivados , Clorofila/química , Camundongos , Simulação de Dinâmica Molecular , Polietilenoglicóis/química , Propionatos/química , Conformação Proteica
17.
Plant Physiol Biochem ; 141: 172-182, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31174034

RESUMO

Chickpea (Cicer arietinum L.), a cool season crop is severely affected by heat stress, predicted to increase due to warming climates. Research for identifying heat tolerance markers for potential chickpea genotype selection is imperative. The study assessed the response of four chickpea genotypes to a natural temperature gradient in the field using chlorophyll fluorescence, non-structural carbohydrate, chlorophyll concentrations, gas exchange and grain yield. Field experiments were carried out in two winter seasons at three locations with known differences in temperature in NE South Africa. Results showed two genotypes were tolerant to heat stress with an Fv/Fm of 0.83-0.85 at the warmer site, while the two sensitive genotypes showed lower Fv/Fm of 0.78-0.80. Both dark-adapted Fv/Fm and Fq'/Fm' (where Fq' = Fm' -F) measured at comparable high light levels correlated positively with grain yield. The two tolerant genotypes also showed higher photosynthetic rates, starch, sucrose and grain yield than the sensitive genotypes at the warmer site. However, these parameters were consistently higher at the cooler sites than at the warmer. These results were further validated by a climate chamber experiment, where higher Fv/Fm decline in the sensitive compared to tolerant genotypes was observed when they were exposed to short-term heat treatments of 30/25 °C and 35/30 °C. Tolerant genotypes had higher Fv/Fm (0.78-0.81) and grain yield plant-1(1.12-2.37g) compared to sensitive genotypes (0.74-0.75) and (0.32-0.89g plant-1) respectively in the 35/30 °C. It is concluded that chlorophyll fluorescence and leaf carbohydrates are suitable tools for selection of heat tolerant chickpea genotypes under field conditions, while the coolest site showed favourable conditions for chickpea production.


Assuntos
Carboidratos/química , Clorofila/química , Cicer/genética , Produção Agrícola/métodos , Fluorescência , Genótipo , Aclimatação , África ao Sul do Saara , Metabolismo dos Carboidratos , Cicer/química , Genes de Plantas , Temperatura Alta , Fenótipo , Fotossíntese , Complexo de Proteína do Fotossistema II/química , Folhas de Planta/química
18.
Food Chem ; 295: 537-547, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31174793

RESUMO

Black cumin seed (BCS) is a novel oil source with potential health benefits. This study investigates the influence of infrared (IR) and dry air (DA) roasting (140, 160 and 180 °C for 5 and 10 min) on BCS oil quality characteristics. Results revealed that the oxidative stability index (OSI), Maillard reaction products (MRPs), chlorophyll and carotenoid contents were increased while acid value (AV), peroxide value (PV) and color values were decreased in DA roasted (180°C for 10 min) BCS oil compared to other DA and IR treatments. DA and IR roasting slightly influenced the fatty acid composition (FAC) of BCS oils. FTIR spectra showed minor changes in peak intensities (at 2854, 2929 and 3008 cm-1) of DA and IR roasted BCS oils. DA roasting proved more effective than IR roasting. The oil from the DA roasted BCS at 180°C for 10 min had significantly higher oil quality and oxidative stability.


Assuntos
Ar , Ácidos Graxos/análise , Raios Infravermelhos , Nigella sativa/metabolismo , Óleos Vegetais/análise , Carotenoides/química , Clorofila/química , Culinária/métodos , Produtos Finais de Glicação Avançada/análise , Nigella sativa/química , Oxirredução , Análise de Componente Principal , Sementes/química , Sementes/metabolismo , Sementes/efeitos da radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura Ambiente
19.
Food Chem ; 295: 94-100, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31174814

RESUMO

The present work aimed at examining the combined effect of chlorophyll content and light filtering packaging material on the photo-stability of virgin olive oil (VOO) via mesh cell-FTIR spectroscopy monitoring. Four different VOOs of Koroneiki cultivar differing in total chlorophyll content (∼12-46 mg/kg) were exposed in parallel to direct visible light (6000 lx, 24 °C, 344 h) and FTIR spectra were recorded periodically with or without applying light protection by an industrial filter used for packaging. Findings suggested that the protective role of light filtering material was more evident in the VOO with the lowest total chlorophyll content. Real time monitoring of VOO by mesh cell-FTIR was found to be a useful tool to follow the combined effect of pro-oxidant chlorophylls and the protective light filtering materials on the photo-oxidation process of VOO employing a minute sample amount.


Assuntos
Clorofila/química , Embalagem de Alimentos/métodos , Azeite de Oliva/química , Espectroscopia de Infravermelho com Transformada de Fourier , Ácidos Graxos/química , Luz , Oxirredução
20.
Plant Physiol Biochem ; 141: 279-290, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31202192

RESUMO

Codonopsis tangshen Oliv. (C. tangshen Oliv.), a famous medicinal herb in China, is seriously affected by continuous cropping (C-cro). The physiological and biochemical results indicated that C-cro significantly affected the malonaldehyde (MDA) and chlorophyll content, as well as activities of catalase (CAT) and superoxide dismutase (SOD) when compared with the non-continuous cropping (NC-cro) group. Transcriptome profiling found 762 differentially expressed genes, including 430 up-regulated and 332 down-regulated genes by C-cro. In addition, pathway enrichment analysis revealed that genes related to 'Tyrosine degradation I', 'Glycogen synthesis' and 'Phenylalanine and tyrosine catabolism' were up-regulated, and genes associated with 'Signal transduction', 'Immune system', etc. were down-regulated by C-cro. The expression of target genes was further validated by Q-PCR. In this study, we demonstrated the effects of C-cro on C. tangshen at the transcriptome level, and found possible C-cro responsive candidate genes. These findings could be further beneficial for improving the continuous cropping tolerance.


Assuntos
Codonopsis/genética , Medicamentos de Ervas Chinesas/química , Herbivoria , Plantas Medicinais/genética , China , Clorofila/química , Análise por Conglomerados , Codonopsis/química , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Malondialdeído/química , Fotossíntese , Raízes de Plantas/química , Reação em Cadeia da Polimerase , Análise de Sequência de RNA , Transcriptoma
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