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Internal photoprotection

Lewis A Baker, Sarah L Clark, Scott Habershon, Vasilios G Stavros
The ultrafast photoprotection mechanisms in operation in ethylhexyl triazone (EHT, octyl triazone), an approved ultraviolet-B (UV-B) chemical filter for commercial sunscreens, remain elusive, with a notable absence of ultrafast time-resolved measurements. These large organic molecules are of increasing interest as they are suspected to be less likely to penetrate the skin than some of the smaller approved filters, thereby reducing the possible adverse effects from sunscreen products. We apply femtosecond transient absorption spectroscopy with electronic structure calculations to unravel the complete photodeactivation mechanism that EHT undergoes after UV-B irradiation...
April 28, 2017: Journal of Physical Chemistry Letters
Pierre Çarçabal, Dominique Descamps, Stéphane Petit, Yann Mairesse, Valérie Blanchet, Raluca Cireasa
5-Fluorouracil (5FU) is a radiosensitiser molecule routinely used in combined chemo- and radio-therapies to enhance and localize cancer treatments. We have employed ultra-short XUV pulses produced by high harmonic generation (HHG) as a pump pulse to study the dynamics underlying the photo-stability and the radiation damage of this molecule. This work shows that it is possible to resolve individual dynamics even when using unselected HH. By comparing the results with those obtained in the multiphoton absorption at 400 nm, we were able to identify the frequencies of the HH comb relevant to the recorded dynamics: HH5 and HH3...
December 16, 2016: Faraday Discussions
Yi Xiao, Danny Tholen, Xin-Guang Zhu
Leaf photosynthesis is determined by biochemical properties and anatomical features. Here we developed a three-dimensional leaf model that can be used to evaluate the internal light environment of a leaf and its implications for whole-leaf electron transport rates (J). This model includes (i) the basic components of a leaf, such as the epidermis, palisade and spongy tissues, as well as the physical dimensions and arrangements of cell walls, vacuoles and chloroplasts; and (ii) an efficient forward ray-tracing algorithm, predicting the internal light environment for light of wavelengths between 400 and 2500nm...
October 4, 2016: Journal of Experimental Botany
Yazhe Wang, Cheng Wang, Yang Ding, Jing Li, Min Li, Xiao Liang, Jianping Zhou, Wei Wang
Photodynamic therapy has emerged as a promising strategy for cancer treatment. To ensure the efficient delivery of a photosensitizer to tumor for anticancer effect, a safe and tumor-specific delivery system is highly desirable. Herein, we introduce a novel biomimetic nanoparticle named rHDL/ICG (rHDL/I), by loading amphiphilic near-infrared (NIR) fluorescent dye indocyanine green (ICG) into reconstituted high density lipoproteins (rHDL). In this system, rHDL can mediate photoprotection effect and receptor-guided tumor-targeting transportation of cargos into cells...
December 1, 2016: Colloids and Surfaces. B, Biointerfaces
Nuria Blázquez-Sánchez, Magdalena De Troya-Martín, Francisco Rivas-Ruiz, Sara Bueno-Fernández, Maria Teresa Fernández-Morano, Salvador Arias-Santiago
Sun exposure in childhood is the main risk determinant for skin cancer in adulthood. Several questionnaires have been used to examine behaviour patterns in terms of sun exposure in childhood, but none have been subjected to a rigorous analysis of their measurement properties. To evaluate the psychometric properties of a questionnaire adapted to investigate children's sun exposure behaviour, a two-stage validation study was carried out. First, in a transverse study, the questionnaire was administered to a sample of 333 children recruited from schools, and the validity and internal consistency were analysed...
September 23, 2016: European Journal of Cancer Prevention
Federico Gonzalez-Fernandez, Brandi Betts-Obregon, Andrew T Tsin, Richard J DeSa
PURPOSE: Assaying photodecomposition is challenging because light must be used to initiate the photodamage and light must be used to monitor the photodecomposition. The experimental requirements are as follows: 1) During exposure of the actinic beam, continuously monitor the spectral characteristics of the sample, 2) uniformly expose the reactants to the actinic source, 3) obtain informative spectra in the presence of light scatter, and 4) achieve sufficient sensitivity for dilute reactants...
2016: Molecular Vision
Marko Kojić, Milena Petković, Mihajlo Etinski
Avobenzone (4-tert-butyl-4'-methoxydibenzoylmethane, AB) is one of the most widely used filters in sunscreens for skin photoprotection in the UVA band. The photochemistry of AB includes keto-enol tautomerization, cis-trans isomerization, rotation about the single bond and α bond cleavages of carbonyl groups. In this contribution we study chelated and non-chelated enol, rotamers Z and E, and keto tautomers of AB in the ground and excited states in gas phase and acetonitrile by means of a coupled cluster method...
August 10, 2016: Physical Chemistry Chemical Physics: PCCP
Vera Slaveykova, Bettina Sonntag, Juan Carlos Gutiérrez
We report a summary of the symposium "Stress and Protists: No life without stress", which was held in September 2015 on the VII European Congress of Protistology in partnership with the International Society of Protistologists (Seville, Spain). We present an overview on general comments and concepts on cellular stress which can be also applied to any protist. Generally, various environmental stressors may induce similar cell responses in very different protists. Two main topics are reported in this manuscript: (i) metallic nanoparticles as environmental pollutants and stressors for aquatic protists, and (ii) ultraviolet radiation - induced stress and photoprotective strategies in ciliates...
August 2016: European Journal of Protistology
I Aloisi, G Cai, D Serafini-Fracassini, S Del Duca
Transglutaminases (TGases) are ubiquitous enzymes catalyzing many biological reactions. The best-known TGase activity, namely the transamidation of specific proteins by polyamines (PAs), has been studied in plants to verify if TGase is a mediator of PAs mechanism of action to re-interpret some of PAs effects. Usually, the TGase activity is present at basal level in plant cells, but it can be induced by internal or external events or stresses, like rehydration, wounding, light, developmental differentiation and programmed cell death (PCD)...
October 2016: Amino Acids
Michele De Luca, Giuseppina Ioele, Claudia Spatari, Gaetano Ragno
1,4-dihydropyridine antihypertensives (DHPs) are almost all dispensed in solid pharmaceutical formulations for their easy lability when exposed to light. This paper reports a study on the photoprotective effect of containers in different glassy or polymeric matrices with regard to four known DHPs when in solutions. The samples were subjected to forced degradation by means of a Xenon lamp, in accordance with the international rules on drug stability evaluation. The simultaneous determination of the drugs and their photoproducts was carried out by applying the multivariate curve resolution (MCR) methodology to the spectral data recorded along the irradiation test...
May 30, 2016: International Journal of Pharmaceutics
Lewis A Baker, Michael D Horbury, Simon E Greenough, Florent Allais, Patrick S Walsh, Scott Habershon, Vasilios G Stavros
We explore the ultrafast photoprotective properties of a series of sinapic acid derivatives in a range of solvents, utilizing femtosecond transient electronic absorption spectroscopy. We find that a primary relaxation mechanism displayed by the plant sunscreen sinapoyl malate and other related molecular species may be understood as a multistep process involving internal conversion of the initially photoexcited 1(1)ππ* state along a trans-cis photoisomerization coordinate, leading to the repopulation of the original trans ground-state isomer or the formation of a stable cis isomer...
January 7, 2016: Journal of Physical Chemistry Letters
Timothy S Murbach, Erzsébet Béres, Adél Vértesi, Róbert Glávits, Gábor Hirka, John R Endres, Amy E Clewell, Ilona Pasics Szakonyiné
A battery of toxicological studies was conducted in accordance with internationally accepted standards to investigate the genotoxicity and repeated-dose oral toxicity of Fernblock(®), a commercial aqueous extraction of the leaves of the tropical fern Polypodium leucotomos used for its oral and topical photoprotective properties. No evidence of mutagenicity was observed in a bacterial reverse mutation test or in vitro mammalian chromosomal aberration test nor was any genotoxic activity observed in an in vivo mouse micronucleus test...
December 2015: Food and Chemical Toxicology
Mickael Baqué, Cyprien Verseux, Ute Böttger, Elke Rabbow, Jean-Pierre Paul de Vera, Daniela Billi
The space mission EXPOSE-R2 launched on the 24th of July 2014 to the International Space Station is carrying the BIOMEX (BIOlogy and Mars EXperiment) experiment aimed at investigating the endurance of extremophiles and stability of biomolecules under space and Mars-like conditions. In order to prepare the analyses of the returned samples, ground-based simulations were carried out in Planetary and Space Simulation facilities. During the ground-based simulations, Chroococcidiopsis cells mixed with two Martian mineral analogues (phyllosilicatic and sulfatic Mars regolith simulants) were exposed to a Martian simulated atmosphere combined or not with UV irradiation corresponding to the dose received during a 1-year-exposure in low Earth orbit (or half a Martian year on Mars)...
June 2016: Origins of Life and Evolution of the Biosphere
Thaisa Baccarin, Montserrat Mitjans, David Ramos, Elenara Lemos-Senna, Maria Pilar Vinardell
There has been an increase in the use of botanicals as skin photoprotective agents. Pomegranate (Punica granatum L.) is well known for its high concentration of polyphenolic compounds and for its antioxidant and anti-inflammatory properties. The aim of this study was to analyze the photoprotection provided by P. granatum seed oil nanoemulsion entrapping the polyphenol-rich ethyl acetate fraction against UVB-induced DNA damage in the keratinocyte HaCaT cell line. For this purpose, HaCaT cells were pretreated for 1h with nanoemulsions in a serum-free medium and then irradiated with UVB (90-200 mJ/cm(2)) rays...
December 2015: Journal of Photochemistry and Photobiology. B, Biology
Lewis A Baker, Michael D Horbury, Simon E Greenough, Philip M Coulter, Tolga N V Karsili, Gareth M Roberts, Andrew J Orr-Ewing, Michael N R Ashfold, Vasilios G Stavros
Oxybenzone is a common constituent of many commercially available sunscreens providing photoprotection from ultraviolet light incident on the skin. Femtosecond transient electronic and vibrational absorption spectroscopies have been used to investigate the nonradiative relaxation pathways of oxybenzone in cyclohexane and methanol after excitation in the UVA region. The present data suggest that the photoprotective properties of oxybenzone can be understood in terms of an initial ultrafast excited state enol → keto tautomerization, followed by efficient internal conversion and subsequent vibrational relaxation to the ground state (enol) tautomer...
April 16, 2015: Journal of Physical Chemistry Letters
Giuseppina Ioele, Lorena Tavano, Rita Muzzalupo, Michele De Luca, Gaetano Ragno
Photostability tests applied on topical commercial formulations containing non-steroidal anti-inflammatory drugs have demonstrated a clear degradation of the active compounds when exposed to light. The photodegradation profile of these drugs is usually monitored by spectrophotometric or chromatographic techniques according to the international ICH rules for photostability testing. In the last years, the data are processed ever more by multivariate analysis, as principal component analysis, partial least squares, multivariate curve resolution...
2016: Mini Reviews in Medicinal Chemistry
Michael D Horbury, Lewis A Baker, Wen-Dong Quan, Jamie D Young, Michael Staniforth, Simon E Greenough, Vasilios G Stavros
Eumelanin is a naturally synthesized ultraviolet light absorbing biomolecule, possessing both photoprotective and phototoxic properties. We infer insight into these properties of eumelanin using a bottom-up approach, by investigating an ultraviolet absorbing motif of eumelanin, 4-tert-butylcatechol. Utilizing a combination of femtosecond transient electronic absorption spectroscopy and time-resolved velocity map ion imaging, our results suggest an environmental-dependent relaxation pathway, following irradiation at 267 nm to populate the S1 ((1)ππ*) state...
December 17, 2015: Journal of Physical Chemistry. A
Gwladys Surget, Valérie Stiger-Pouvreau, Klervi Le Lann, Nelly Kervarec, Céline Couteau, Laurence J M Coiffard, Fanny Gaillard, Karine Cahier, Fabienne Guérard, Nathalie Poupart
In temperate saltmarshes, halophytic plants have to daily protect their internal tissues against sunlight and UV rays. Consequently, they develop adaptive responses such as the synthesis of secondary metabolites, including polyphenols. The present study focused on the biological activities of fractions enriched in polyphenols from Salicornia ramosissima. Three different extracts were obtained by purification processes to concentrate polyphenols: a crude hydroalcoholic extract, and two purified fractions: an ethyl acetate fraction (EAF) and an aqueous fraction...
February 2015: Journal of Photochemistry and Photobiology. B, Biology
Steven C Holland, Anthony D Kappell, Robert L Burnap
Inorganic carbon (Ci) is the major sink for photosynthetic reductant in organisms capable of oxygenic photosynthesis. In the absence of abundant Ci, the cyanobacterium Synechocystis sp. strain PCC6803 expresses a high affinity Ci acquisition system, the CO2-concentrating mechanisms (CCM), controlled by the transcriptional regulator CcmR and the metabolites NADP+ and α-ketoglutarate, which act as co-repressors of CcmR by modulating its DNA binding. The CCM thus responds to internal cellular redox changes during the transition from Ci-replete to Ci-limited conditions...
March 2015: Biochimica et Biophysica Acta
Lipan Hu, Lixia Xiang, Li Zhang, Xiaoting Zhou, Zhirong Zou, Xiaohui Hu
Polyamines are small, ubiquitous, nitrogenous compounds that scavenge reactive oxygen species and stabilize the structure and function of the photosynthetic apparatus in response to abiotic stresses. Molecular details underlying polyamine-mediated photoprotective mechanisms are not completely resolved. This study investigated the role of spermidine (Spd) in the structure and function of the photosynthetic apparatus. Tomato seedlings were subjected to salinity-alkalinity stress with and without foliar application of Spd, and photosynthetic and morphological parameters were analyzed...
2014: PloS One
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