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Suppressing Effect of 2-Nitrobenzaldehyde on Singlet Oxygen Generation, Fatty Acid Photooxidation, and Dye-Sensitizer Degradation
摘要： 2-Nitrobenzaldehyde was found to efficiently block singlet oxygen generation in a series of different test samples upon exposure to UV and visible light under aerobic conditions. The effect of quenching singlet oxygen formation was monitored in the presence of 1, 4-diazabicyclo [2.2.2] octane (DABCO) acting as a well-known singlet oxygen scavenger. A comparison of different nitrobenzaldehyde isomers with other highly effective synthetic antioxidants used in the food industry such as butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), tert-butylhydroquinone (TBHQ) revealed that the protection of materials from singlet oxygen decreases in the order of 2-nitrobenzaldehyde > DABCO > TBHQ > 3-nitrobenzaldehyde > BHA > 4-nitrobenzaldehyde > BHT. Upon addition of 2-nitrobenzaldehyde, the oxidation of fatty acids and the degradation of photosensitizers was found to be considerably diminished, which indicates that the presence of 2-nitrobenzaldehyde has a significant protective influence by restricting the singlet oxygen generation and photodegradation of dyes. Moreover, the compound turned out to display its highly suppressing effects on typical singlet oxygen-dependent reactions, such as fatty acid photooxidation and dye photosensitizer degradation, in a rather broad spectral region covering wavelengths from 300 nm (UV-B) to 575 nm (close to the maximum of ambient solar radiation).
关键词： photostabilization,singlet oxygen scavenger,inhibition of fatty acid photooxidation,UV photoprotection,2-nitrobenzaldehyde
更新于2025-09-19 17:15:36
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The Unique Photophysical Properties of the Peridinin-Chlorophyll-a-Protein
摘要： Peridinin-Chlorophyll-a-Proteins (PCPs) are water-soluble light harvesting complexes from dinoflagellates. They have unique light-harvesting and energy transfer properties which have been studied in details in the last 15 years. This review aims to give an overview on all the main aspects of PCPs photophysics, with an emphasis on some aspects which have not been reviewed in details so far, such as vibrational spectroscopy studies, theoretical calculations, and magnetic resonance studies. A paragraph on the present development of PCPs towards technological applications is also included.
关键词： peridinin-chlorophyll-protein,peridinin,Carotenoids,photoprotection.,light-harvesting
更新于2025-09-11 14:15:04
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ROLE OF CYCLIC AND PSEUDO-CYCLIC ELECTRON TRANSPORT IN RESPONSE TO DYNAMIC LIGHT CHANGES IN PHYSCOMITRELLA PATENS
摘要： Photosynthetic organisms support cell metabolism by harvesting sunlight and driving the electron transport chain at the level of thylakoid membranes. Excitation energy and electron flow in the photosynthetic apparatus is continuously modulated in response to dynamic environmental conditions. Alternative electron flow around photosystem I plays a seminal role in this regulation contributing to photo-protection by mitigating over-reduction of the electron carriers. Different pathways of alternative electron flow coexist in the moss Physcomitrella patens, including cyclic electron flow mediated by the PGRL1/PGR5 complex and pseudo-cyclic electron flow mediated by the flavodiiron proteins FLV. In this work we generated P. patens plants carrying both pgrl1 and flva knock-out (KO) mutations. A comparative analysis of the WT, pgrl1, flva and pgrl1 flva lines suggests that cyclic and pseudo-cyclic processes have a synergic role in the regulation of photosynthetic electron transport. However, while both contribute to photosystem I protection from over-reduction by modulating electron flow following changes in environmental conditions, FLV activity is particularly relevant in the first seconds after a light change while PGRL1 has a major role upon sustained strong illumination.
关键词： Photosynthetic Reaction Center Complex Proteins,Photosynthesis,photoprotection,Energy metabolism,Evolution, Molecular,Bryophyta
更新于2025-09-10 09:29:36
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A review of inorganic UV filters zinc oxide (ZnO) and titanium dioxide (TiO <sub/>2</sub> )
摘要： Photoprotection has become integral in the prevention of keratinocyte cancer and photoaging. Organic UV filters such as oxybenzone and octinoxate have become controversial due to their potential impact on the environmental and their potential human health risks. As such, inorganic UV filters, ZnO and TiO2, have become paramount in discussions about photoprotection. ZnO and TiO2 are used in sunscreens as nanoparticles, which denotes a size less than 100nm. The smaller size of these mineral particles increases their cosmetic acceptability by users as they are much less visible after application. ZnO has a broad UVA-UVB absorption curve, while TiO2 provides better UVB protection. Overall, the human health risks with inorganic filters are extremely low given a lack of percutaneous absorption; however, there is potential risk when exposed via inhalation, prompting recommendations against spray sunscreen products with nanoparticles. At this time, the known risk to the environment is low though the risk stratification may evolve with increasing usage of these filters and higher environmental concentrations. The continued practice of photoprotection is critical. The public should be counseled to seek shade, use photoprotective clothing including hats and glasses in addition to sunscreens on sun-exposed skin. For those concerned about emerging evidence of environmental impact of organic UV filters, based on current evidence, ZnO and TiO2-containing sunscreens are safe alternatives.
关键词： environmental impact,titanium dioxide,photoprotection,inorganic UV filters,nanoparticles,zinc oxide,health risks,sunscreen
更新于2025-09-09 09:28:46
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ZnO nanoparticles modified with an amphipathic peptide show improved photoprotection in skin
摘要： ZnO nanoparticles of different sizes were functionalized with an amphipathic peptide and its effect on nanoparticle stabilization and UV photoprotective activity was studied in this article. The peptide modified nanoparticles exhibited lower aggregation, significant reduction in Zn2+ leaching in-vitro and even inside the cells for smaller particle sizes, reduced photocatalytic activity and reduced cellular toxicity under UV-B treated conditions. In addition, the peptide modified 60 nm sized ZnO nanoparticles showed lower genotoxicity, lower oxidative stress induction levels, less DNA damage responses and less immunogenic potential than the bare counterparts in presence of UV-B rays. They localized more in the stratum corneum and epidermis ex-vivo indicating better retention in epidermis and demonstrated improved UV-B protection and/or skin integrity in SKH-1 mice in-vivo as compared to unmodified nanoparticles and commercial UV protective agents tested. To our knowledge, this is the first report on application of peptide modified ZnO nanoparticles for improved photoprotection.
关键词： UV-B rays,ZnO nanoparticles,cytotoxicity,cell penetrating peptide,photoprotection
更新于2025-09-09 09:28:46