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Frontiers in Plant Science 2016Regulation of photosynthetic light harvesting in the thylakoids is one of the major key factors affecting the efficiency of photosynthesis. Thylakoid membrane is... (Review)
Review
Regulation of photosynthetic light harvesting in the thylakoids is one of the major key factors affecting the efficiency of photosynthesis. Thylakoid membrane is negatively charged and influences both the structure and the function of the primarily photosynthetic reactions through its electrical double layer (EDL). Further, there is a heterogeneous organization of soluble ions (K, Mg, Cl) attached to the thylakoid membrane that, together with fixed charges (negatively charged amino acids, lipids), provides an electrical field. The EDL is affected by the valence of the ions and interferes with the regulation of "state transitions," protein interactions, and excitation energy "spillover" from Photosystem II to Photosystem I. These effects are reflected in changes in the intensity of chlorophyll fluorescence, which is also a measure of photoprotective non-photochemical quenching (NPQ) of the excited state of chlorophyll . A triggering of NPQ proceeds via lumen acidification that is coupled to the export of positive counter-ions (Mg, K) to the stroma or/and negative ions (e.g., Cl) into the lumen. The effect of protons and anions in the lumen and of the cations (Mg, K) in the stroma are, thus, functionally tightly interconnected. In this review, we discuss the consequences of the model of EDL, proposed by Barber (1980b) Biochim Biophys Acta :253-308) in light of light-harvesting regulation. Further, we explain differences between electrostatic screening and neutralization, and we emphasize the opposite effect of monovalent (K) and divalent (Mg) ions on light-harvesting and on "screening" of the negative charges on the thylakoid membrane; this effect needs to be incorporated in all future models of photosynthetic regulation by ion channels and transporters.
PubMed: 28018387
DOI: 10.3389/fpls.2016.01849 -
Current Medicinal Chemistry 2018Excessive human exposure to solar ultraviolet radiation (UVR) continues to be a major public health concern, with skin cancer rates increasing year on year. The major... (Review)
Review
BACKGROUND
Excessive human exposure to solar ultraviolet radiation (UVR) continues to be a major public health concern, with skin cancer rates increasing year on year. The major protective measure is the use of synthetic UVR filters formulated into sunscreens, but there is a growing concern that some of these chemicals cause damage to delicate marine ecosystems. One alternative is the use of biocompatible mycosporine-like amino acids (MAA), which occur naturally in a wide range of marine species. Their role within nature is mainly thought to be photoprotective. However, their potential for human photoprotection is largely understudied.
OBJECTIVE
To review the role of MAA in nature and assess their potential as natural sunscreens for human skin photoprotection.
METHOD
A literature review of all relevant papers was conducted.
CONCLUSION
MAA are natural photostable compounds that are thought to offer photoprotection to marine species. Initially thought of as protective based on their absorption properties in the solar UVR spectrum, it is clear that MAA are multifunctional photoprotective compounds acting as chemical and biological anti-oxidants. This suggests that MAA may offer a novel eco-friendly approach to human skin photoprotection. Most studies have been carried out in vitro and current data strongly suggest that MAA have potential for development as natural biocompatible sunscreens that protect against a diverse range of solar UVR induced adverse effects on human health.
Topics: Amino Acids; Animals; Humans; Radiation Protection; Skin; Ultraviolet Rays
PubMed: 28554325
DOI: 10.2174/0929867324666170529124237 -
Antioxidants (Basel, Switzerland) Jan 2023Ultraviolet (UV) radiation promotes the generation of reactive oxygen species (ROS) and nitrogen species (RNS), resulting in skin damage. Cosmetic industries have...
Ultraviolet (UV) radiation promotes the generation of reactive oxygen species (ROS) and nitrogen species (RNS), resulting in skin damage. Cosmetic industries have adopted a strategy to incorporate antioxidants in sunscreen formulations to prevent or minimize UV-induced oxidative damage, boost photoprotection effectiveness, and mitigate skin photoaging. Many antioxidants are naturally derived, mainly from terrestrial plants; however, marine organisms have been increasingly explored as a source of new potent antioxidant molecules. This work aims to characterize the frequency of the use of antioxidants in commercial sunscreens. Photoprotective formulations currently marketed in parapharmacies and pharmacies were analyzed with respect to the composition described on the label. As a result, pure compounds with antioxidant activity were found. The majority of sunscreen formulations contained antioxidants, with vitamin E and its derivatives the most frequent. A more thorough analysis of these antioxidants is also provided, unveiling the top antioxidant ingredients found in sunscreens. A critical appraisal of the scientific evidence regarding their effectiveness is also performed. In conclusion, this work provides an up-to-date overview of the use of antioxidants in commercial sunscreens for a better understanding of the advantages associated with their use in photoprotective formulations.
PubMed: 36670999
DOI: 10.3390/antiox12010138 -
Journal of Evolutionary Biology Oct 2022Yellow and red autumn leaves are typical of many temperate/boreal woody plants. Since the 19 century, it has been either considered the non-functional outcome of... (Review)
Review
Yellow and red autumn leaves are typical of many temperate/boreal woody plants. Since the 19 century, it has been either considered the non-functional outcome of chlorophyll degradation that unmasks the pre-existing yellow and red pigments or that the de novo synthesis of red anthocyanins in autumn leaves indicated that it should have a physiological function, although it was commonly ignored. Defending free amino acids and various other resources released especially following the breakdown of the photosynthetic system, and mobilizing them for storage in other organs before leaf fall, is the cornerstone of both the physiological and anti-herbivory hypotheses about the functions of yellow and red autumn leaf colouration. The complicated phenomenon of conspicuous autumn leaf colouration has received significant attention since the year 2000, especially because ecologists started paying attention to its anti-herbivory potential. The obvious imperfection of the hypotheses put forth in several papers stimulated many other scientists. Hot debates among physiologists, among ecologists, and between physiologists and ecologists have been common since the year 2000, first because the various functions of yellow and red autumn leaf colouration are non-exclusive, and second because many scientists were trained to focus on a single subject. Here, I will review the debates, especially between the photoprotective and the anti-herbivory hypotheses, and describe both the progress in their understanding and the required progress.
Topics: Amino Acids; Anthocyanins; Chlorophyll; Plant Leaves; Seasons
PubMed: 35975328
DOI: 10.1111/jeb.14069 -
Nanomaterials (Basel, Switzerland) Jan 2022Despite the health benefits of the sun, overexposure to solar radiation without proper precautions can cause irreversible damage to exposed skin. In the search for... (Review)
Review
Despite the health benefits of the sun, overexposure to solar radiation without proper precautions can cause irreversible damage to exposed skin. In the search for balance between the risks and benefits of exposure to solar radiation in human health, a technological alternative was found, the incorporation of photoprotective products in lipid nanoparticulate systems for topical application. These nanometric systems have demonstrated several advantages when used as adjuvants in photoprotection compared to chemical and/or physical sunscreens alone. The increase in the sun protection factor (SPF), photostability and UV action spectrum are parameters that have benefited from the application of these systems in order to increase the effectiveness and safety of photoprotective formulations containing organic and/or inorganic sunscreens.
PubMed: 35159721
DOI: 10.3390/nano12030377 -
Molecules (Basel, Switzerland) Dec 2020Conversion of sunlight into photochemistry depends on photoprotective processes that allow safe use of sunlight over a broad range of environmental conditions. This... (Review)
Review
Conversion of sunlight into photochemistry depends on photoprotective processes that allow safe use of sunlight over a broad range of environmental conditions. This review focuses on the ubiquity of photoprotection associated with a group of interconvertible leaf carotenoids, the xanthophyll cycle. We survey the striking plasticity of this process observed in nature with respect to (1) xanthophyll cycle pool size, (2) degree and speed of interconversion of its components, and (3) flexibility in the association between xanthophyll cycle conversion state and photoprotective dissipation of excess excitation energy. It is concluded that the components of this system can be independently tuned with a high degree of flexibility to produce a fit for different environments with various combinations of light, temperature, and other factors. In addition, the role of genetic variation is apparent from variation in the response of different species growing side-by-side in the same environment. These findings illustrate how field studies can generate insight into the adjustable levers that allow xanthophyll cycle-associated photoprotection to support plant photosynthetic productivity and survival in environments with unique combinations of environmental factors.
Topics: Biosynthetic Pathways; Carotenoids; Environment; Nutritional Physiological Phenomena; Photosynthesis; Phytochemicals; Plant Leaves; Plant Physiological Phenomena; Protective Agents; Sunlight; Weather; Zeaxanthins
PubMed: 33321863
DOI: 10.3390/molecules25245825 -
The Plant Journal : For Cell and... Feb 2020Photoprotection refers to a set of well defined plant processes that help to prevent the deleterious effects of high and excess light on plant cells, especially within... (Review)
Review
Photoprotection refers to a set of well defined plant processes that help to prevent the deleterious effects of high and excess light on plant cells, especially within the chloroplast. Molecular components of chloroplast photoprotection are closely aligned with those of photosynthesis and together they influence productivity. Proof of principle now exists that major photoprotective processes such as non-photochemical quenching (NPQ) directly determine whole canopy photosynthesis, biomass and yield via prevention of photoinhibition and a momentary downregulation of photosynthetic quantum yield. However, this phenomenon has neither been quantified nor well characterized across different environments. Here we address this problem by assessing the existing literature with a different approach to that taken previously, beginning with our understanding of the molecular mechanism of NPQ and its regulation within dynamic environments. We then move to the leaf and the plant level, building an understanding of the circumstances (when and where) NPQ limits photosynthesis and linking to our understanding of how this might take place on a molecular and metabolic level. We argue that such approaches are needed to fine tune the relevant features necessary for improving dynamic NPQ in important crop species.
Topics: Carbon Dioxide; Photochemical Processes; Photosynthesis; Photosystem II Protein Complex; Plant Leaves; Plant Physiological Phenomena
PubMed: 31686424
DOI: 10.1111/tpj.14601 -
Archives of Biochemistry and Biophysics Apr 2011The skin is the largest organ of the body that produces a flexible and self-repairing barrier and protects the body from most common potentially harmful physical,... (Review)
Review
The skin is the largest organ of the body that produces a flexible and self-repairing barrier and protects the body from most common potentially harmful physical, environmental, and biological insults. Solar ultraviolet (UV) radiation is one of the major environmental insults to the skin and causes multi-tiered cellular and molecular events eventually leading to skin cancer. The past decade has seen a surge in the incidence of skin cancer due to changes in life style patterns that have led to a significant increase in the amount of UV radiation that people receive. Reducing excessive exposure to UV radiation is desirable; nevertheless this approach is not easy to implement. Therefore, there is an urgent need to develop novel strategies to reduce the adverse biological effects of UV radiation on the skin. A wide variety of natural agents have been reported to possess substantial skin photoprotective effects. Numerous preclinical and clinical studies have elucidated that natural agents act by several cellular and molecular mechanisms to delay or prevent skin cancer. In this review article, we have summarized and discussed some of the selected natural agents for skin photoprotection.
Topics: Animals; Biological Products; Cells; Cytoprotection; Humans; Light; Radiation Protection
PubMed: 21147060
DOI: 10.1016/j.abb.2010.12.007 -
Biophysical Reviews Aug 2022Variable fluorescence of chlorophyll (CF) of the photosynthetic apparatus is an ample source of valuable information on physiological condition of photosynthetic... (Review)
Review
Variable fluorescence of chlorophyll (CF) of the photosynthetic apparatus is an ample source of valuable information on physiological condition of photosynthetic organisms. Currently, the most widespread CF-based technique is represented by recording pulse-amplitude modulated (PAM) induction of CF by saturating light. The CF-based monitoring techniques are increasingly employed for characterization of performance and stress resilience of microalgae in microalgal biotechnology. Analysis of CF induction curves reveals the fate of light energy absorbed by photosynthetic apparatus, the proportions of the energy that have been utilized for photochemistry (culture growth), and heat dissipated by photoprotective mechanisms. Hence CF and its derived parameters are an accurate proxy of the metabolic activity of the photosynthetic cell and the engagement of photoprotective mechanisms. This information is a solid foundation for making decisions on the microalgal culture management during the lab-scale and industrial-scale cultivation. Applications of CF and PAM include the monitoring of stressor (high light, nutrient deprivation, extreme temperatures, etc.) effects for assessment of the culture robustness. It also serves as a non-invasive express test for gauging the effect of assorted toxicants in microalgae. This approach is becoming widespread in ecological toxicology and environmental biotechnology, particularly for bioprospecting strains capable of the destruction of dangerous pollutants such as pharmaceuticals. In the review, we discuss the advantages and drawbacks of using CF-based methods for assessment of the culture conditions. Special attention is paid to the potential caveats and applicability of different variations of CF and PAM measurements for solving problems of microalgal biotechnology.
PubMed: 36124274
DOI: 10.1007/s12551-022-00951-9 -
Antioxidants (Basel, Switzerland) Nov 2021The aim of this study was to develop a new hybrid biomaterial that could photo-stabilize and improve the photoprotective capacity of a extract. Different combinations...
The aim of this study was to develop a new hybrid biomaterial that could photo-stabilize and improve the photoprotective capacity of a extract. Different combinations of lignin/gelatin/natural extract were applied to prepare hybrid biomaterial nanoparticles (NPs), which were then incorporated into an emulsion. The in vitro photoprotection and photostability were evaluated. The methanolic extract showed high phenolic content (646.4 ± 9.5 mg GAE/g dry extract) and a DPPH radical assay revealed that the antiradical capacity of the extract (0.13 to 0.05 g extract/mmol DPPH) was even better than that of BHT. The particle size of the hybrid biomaterial ranged from 100 to 255 nm; a polydispersity index (PdI) between 0.416 and 0.788 is suitable for topical use in dermocosmetic products. The loading capacity of the extract ranged from 27.0 to 44.5%, and the nanoparticles (NPs) showed electrostatic stability in accordance with the zeta potential value. We found that the formulation based on lignin: extract (1:1 ratio) and gelatin: lignin: extract (0.5:0.5:1 ratio) demonstrated photoprotection qualities with a sun protection factor (SPF) ranging from 9.4 to 22.6. In addition, all the hybrid NP-formulations were time-stable with %SPFeff and %UVAPFeff greater than 80% after exposure to 2 h of radiation. These results suggest that the hybrid biopolymer-natural extract improved the photoprotection and photostability properties, as well as the antiradical capacity, of the extract, and may be useful for trapping high polyphenol content from natural extracts, with potential application in cosmeceutical formulations.
PubMed: 34943007
DOI: 10.3390/antiox10121904