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Recent years have seen a lot of interest in mycosporine-like amino acids (MAAs) because of their alleged potential as a natural microbial sunscreen. Since chemical ultraviolet (UV) absorbers are unsafe for long-term usage, the demand for natural UV-absorbing substances has increased. In this situation, MAA is a strong contender for an eco-friendly UV protector. The capacity of MAAs to absorb light in the UV-A (320-400 nm) and UV-B (280-320 nm) range without generating free radicals is potentially relevant in photoprotection. The usage of MAAs for purposes other than photoprotection has now shifted in favor of medicinal applications. Aside from UV absorption, MAAs also have anti-oxidant, anti-inflammatory, wound-healing, anti-photoaging, cell proliferation stimulators, anti-cancer agents, and anti-adipogenic properties. Recently, MAAs application to combat SARS-CoV-2 infection was also investigated. In this review article, we highlight the biomedical applications of MAAs that go beyond photoprotection, which can help in utilizing the MAAs as promising bioactive compounds in both pharmaceutical and cosmetic applications. [ABSTRACT FROM AUTHOR]

Natural antioxidants have become vital to minimize macromolecular damage caused by Reactive Oxygen Species (ROS). This study investigated the antioxidant property of β-cryptoxanthin (β-CRX) extracted from Kocuria marina DAGII and its protective effect against macromolecular damages by generating ROS via two models: UV radiation and the Fenton reaction. β-cryptoxanthin exhibited the highest scavenging activity towards hydrogen peroxide radicals with an IC50 value of 38.30 ± 1.13 μg/ml, favoring the hydrogen atom transfer mechanism. The total antioxidant capacity value of 872.0101 ± 1.84 μg BHT/mg β-CRX indicated the cumulative ROS scavenging ability of β-cryptoxanthin. β-cryptoxanthin could protect against ROS-induced lipid peroxidation, protein oxidation, and DNA damage. The highest lipid peroxidation and protein oxidation inhibition values of β-cryptoxanthin against ROS were 99.371 ± 0.51% and 78.19 ± 0.15%, respectively. β-cryptoxanthin also showed a protective effect in maintaining DNA intactness against ROS-mediated DNA damage. Allium cepa test showed the non-genotoxic nature of β-cryptoxanthin and its protective effect against ROS genotoxic effects. A photo-stability study of β-cryptoxanthin toward UVA and UVB radiation showed a rapid bleaching result of UVB obeying pseudo-zero order kinetics with an average R2 value of 0.9897 and a higher k value (−6.3 × 10–11 ± 0.2 M/s) than UVA (k value −3.1 × 10–11 ± 0.17 M/s), signifying that UVB is more potent toward photo-degradation. The good SPF value of 23.1737 ± 0.15 showed the UV protection capability of β-cryptoxanthin. Thus, the present study suggests that β-cryptoxanthin could be a valuable antioxidant to protect against ROS-induced various macromolecular damages and act as a good UV protectant. [ABSTRACT FROM AUTHOR]

Far‐UVC radiation sources of wavelengths 222 nm and 233 nm represent an interesting potential alternative for the antiseptic treatment of the skin due to their high skin compatibility. Nevertheless, no studies on far‐UVC‐induced DNA damage in different skin types have been published to date, which this study aims for. After irradiating the skin with far‐UVC of the wavelengths 222 and 233 nm as well as broadband UVB, the tissue was screened for cyclobutane pyrimidine dimer‐positive (CPD+) cells using immunohistochemistry. The epidermal DNA damage was lower in dark skin types than in fair skin types after irradiation at 233 nm. Contrary to this, irradiation at 222 nm caused no skin type‐dependent differences, which can be attributed to the decreased penetration depth of radiation. UVB showed the relatively strongest differences between light and dark skin types when using a suberythemal dose of 3 mJ/cm2. As melanin is known for its photoprotective effect, we evaluated the ratio of melanin content in the stratum basale and stratum granulosum in samples of different skin types using two‐photon excited fluorescence lifetime imaging (TPE‐FLIM) finding a higher ratio up to skin type IV–V. As far‐UVC is known to penetrate only into the upper layers of the viable skin, the aforementioned melanin ratio could explain the less pronounced differences between skin types after irradiation with far‐UVC compared to UVB. [ABSTRACT FROM AUTHOR]

Laccase is a versatile enzyme widely used for the oxidation of environmental contaminants and exhibits great potential in many others applications; however, it undergoes photo-degradation when irradiated with UVB light. The photo-stability of this biomolecule can be improved by immobilization in different encapsulation media and reverse micelles have been employed with this purpose. The laccase activity using syringaldazine as substrate has been studied in the absence and in the presence of reverse micelles of 0.15 M of sodium 1,4-bis (2-ethylhexyl) sulfosuccinate (AOT) in isooctane at W0 ([H2O]/[AOT]) = 30, before and after irradiation of the enzyme with UVB light. The kinetic parameters, i.e., Michaelis–Menten constant (KM), catalytic constant (kCAT), and catalytic efficiency (kCAT/KM), were determined by spectroscopic measurements in the micellar system and in homogeneous aqueous medium. The distribution of the substrate in two pseudo-phases (micelle and organic solvent) was taking into account in the kinetic parameters' determinations. The results obtained indicate that the nano-aggregate system confers a solubilization media in the water core of the micelle, both for the enzyme and the substrate, in which the catalytic function of the enzyme is preserved. On the other hand, in homogeneous aqueous medium kCAT/KM value, it is reduced by ~50% after UVB irradiation of the enzyme, while in micellar medium, less than 10% of the activity was affected. This mean that the enzyme achieves a considerably photo-protection when it is irradiated with UVB light in reverse micelles as compared with the homogeneous aqueous medium. This phenomenon can be mainly due to the confinement of the biomolecule inside the micelle. Physical properties of the nano-environment could affect photochemical reactions. [ABSTRACT FROM AUTHOR]

Since the possibility to biotechnologically produce melanin by Streptomycetes using plant biomass has been so far poorly investigated, Posidonia oceanica egagropili, a marine waste accumulating along the Mediterranean Sea coasts, was explored as a renewable source to enhance extracellular melanin production by Streptomyces roseochromogenes ATCC 13400. Therefore, different amounts of egagropili powder were added to a culture medium containing glucose, malt extract, and yeast extract, and their effect on the melanin biosynthesis was evaluated. A 2.5 g·L−1 supplementation in 120-h shake flask growths at 26 °C, at pH 6.0 and 250 rpm, was found to enhance the melanin production up to 3.94 ± 0.12 g·L−1, a value 7.4-fold higher than the control. Moreover, 2-L batches allowed to reach a concentration of 9.20 ± 0.12 g·L−1 in 96 h with a productivity of 0.098 g·L−1·h−1. Further studies also demonstrated that the melanin production enhancement was due to the synergistic effect of both the lignin carbohydrate complex and the holocellulose components of the egagropili. Finally, the pigment was purified from the broth supernatant by acidic precipitation and reversed-phase chromatography, characterized by UV absorbance and one- and two-dimensional NMR, and also tested for its chemical, antioxidant, and photo-protective properties. Key points: • S. roseochromogenes ATCC 13400 produces extracellular soluble melanin. • Egagropili added to the growth medium enhances melanin production and productivity. • Both the lignin carbohydrate complex and the holocellulose egagropili components influence the melanin biosynthesis. [ABSTRACT FROM AUTHOR]

Honokiol is one of the natural extracts of Magnolia officinalis. It is a small molecule, lipophilic compound with extensive biological effects. It has been used in the treatment of multisystem diseases, including digestive diseases, endocrine diseases, nervous system diseases, and various tumors. This paper reviews the biological effects of honokiol on the treatment of skin diseases in recent years, including anti‐microbial, anti‐oxidant, anti‐inflammatory, anti‐tumor, anti‐fibrosis, anti‐allergy, photo‐protection, and immunomodulation. Most current researches are focused on the effects of anti‐melanoma and photo‐protection. Therefore, we summarized the specific mechanisms about these two effects. On the other side of treating skin diseases, the advantages of topical drugs cannot be replaced. As a small molecule fat‐soluble compound, honokiol is suitable for external use. We reviewed the advantages and disadvantages of the topical mixed cream and various improved methods. These improvements include physical and chemical penetration enhancers, drug carriers, and chemical derivatives. In conclusion, honokiol has a wide range of effects, and its topical preparation provides a safe and effective way for treating skin diseases. [ABSTRACT FROM AUTHOR]

A novel oil-in-water (O/W) microemulsion (ME) loading with Ferulic acid (FA) was created, featuring transparent, thermodynamically stable, and forms spontaneously. The formula of FA-loaded microemulsion was optimized based on pseudo-ternary phase diagram, Box Behnken design (BBD) and dissolution test. The optimized formula (2 %FAME) consisted of 1-Decanol (3.98 %, w/w), Cremophor®RH40 (6.72 %, w/w), Tween 80 (0.75 %, w/w), 1,3-Butanediol (29.85 %, w/w), water (56.71, w/w) and FA (2 %, w/w). The microscopic morphology and droplet size distribution were investigated by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The unique emulsion enhanced the solubility of FA in water while demonstrating good stability, controlled release properties, significant free radical scavenging ability and ultraviolet-B (UVB) absorption capacity. Sunscreen properties were demonstrated by Carbomer®934 gel. The sunscreen gel exhibited sun protection properties, while the FA microemulsion demonstrated synergistic effect with ZnO, resulting in a significant enhancement of SPF. These results demonstrate that this novel microemulsion system not only improves the bioavailability of FA, but also provides valuable insights into the development and application of natural UV filters. [Display omitted] • The microemulsion was prepared using a new system of long and short chain alcohols. • The formula was optimized by RSM and phase diagram. • The load, stability, ABTS·+, in vitro release and sunscreen gel of microemulsion were studied. [ABSTRACT FROM AUTHOR]

Changes in pigment (chlorophyll-a, carotenoids and phycobiliproteins) and mycosporine-like amino acid (MAA) composition were studied in the red edible macroalga Palmaria palmata, harvested between February 2018 and February 2019 at 2 sites from Brittany (France). The results occuring in natural conditions revealed a high seasonal variability that can be related to a combination of environmental parameters, including light, nutrients, temperature, salinity and pH, which may have synergistic or antagonistic effects. A decrease in pigments was observed in summer, matching with the increase in irradiance at the same period. On the contrary, the increase in light from February to May has caused an increase in the total MAA content, confirming the UV-photoprotective role attributed to these compounds. Analysis of the results coupled with the biosynthesis pathway suggests that some MAAs are favoured in the occurrence of high irradiance. In this sense, asterina-330 was synthetized only between March and July and not the rest of the year, supporting its importance in photoprotection. In addition, analysis revealed that nutrient availibility could have a significant influence on MAAs since their synthesis seemed to be limited in summer, despite significant exposure to light. However, this decrease could be due to another potential role of MAAs as a nitrogen source for macroalgae. Thus, the diversity of these compounds and the different synthesis pathways could be explained by different roles including photo-protection and nitrogen source, making MAA multi-purpose protective agents which could play a key role in the adaptation of this species to its changing environment. [ABSTRACT FROM AUTHOR]

To cope with the biotic and abiotic stresses experienced within their environment, marine macroalgae have developed certain defence mechanisms including the synthesis of photo-protective molecules against light and particularly harmful UV radiation. The aim of this study was to screen selected red algae, a highly diverse phylogenetic group, for the production of photo-protective molecules. The pigment content and composition (i.e. chlorophyll- a , phycobiliproteins and carotenoids) and the composition of mycosporine-like amino acids (MAAs) were studied in 40 species of red macroalgae collected in Brittany (France), at two distinct periods (i.e. February and July 2017). A high inter-specific variability was demonstrated in terms of pigment content and MAA composition. Twenty-three potential MAAs were detected by HPLC, and six were identified by LC-MS (i.e. shinorine, palythine, asterina-330, porphyra-334, usurijene and palythene). This is the first study to report on the composition of pigments and MAAs in a diverse group of red seaweeds from Brittany, including some species for which the MAA composition has never been studied before. Nevertheless, the results suggested that some species of red algae are more likely to cope with high levels of light radiation since those species such as Bostrychia scorpioides, Porphyra dioica , Gracilaria vermiculophylla and Vertebrata lanosa are living in environments exposed to higher levels of irradiation, and had various MAAs in addition to their photo-protective pigments. Image 1 • Detection of 23 potential MAAs in 40 red macroalgae, including 6 already identified. • First report on the MAAs composition for some red seaweeds. • High variability in MAAs composition between the different species, with no link with phylogeny or morphology. • A MAAs extraction method using 70% ethanol being less toxic than conventional methanol. [ABSTRACT FROM AUTHOR]

Purpose: To develop a stable emulgel formulation from Manilkara zapota fruit extract (MZFE) and evaluate its sun-protective factor (SPF) and its physical retention on facial skin. Methods: Active test formulations containing MZFE and placebo (containing no active ingredients) were prepared by dispersing the primary emulsion into a gel phase. Both test and placebo emulgel formulations were subjected to physicochemical evaluation, stability studies, and assessment of possible photo-protective properties. The sun-protective factor (SPF) was determined in vitro by spectrophotometric analysis. Non-invasive in vivo skin bioengineering technique was used to assess the UV-quenching effects of the test and placebo emulgel formulations. Results: A stable and cosmetically acceptable emulgel formulation loaded with MZFE was obtained. The formulation and control exhibited optimum physicochemical stability in stress stability tests. The formulation exhibited promising photo-protective effects both in vitro (SPF = 14.215 ± 0.140) and in vivo (lasted for approximately 120 min). Conclusion: The developed MZFE-loaded test emulgel formulation possesses suitable photoprotection capability in vitro, and displays quenching effects against specific wavelengths of UV light, indicating a UV-filtering property. [ABSTRACT FROM AUTHOR]

The formation, characterization, photo-protective properties and release profiles of folic acid-loaded nanolaminated films were investigated by UV–visible spectroscopy, FTIR, Raman and SEM microscopy. Food-grade alginate/chitosan nanolaminates were obtained by the layer-by-layer technique and folic acid (FA) was incorporated by post-diffusion. The FA concentration of loading solutions and immersion time significantly affected the FA content in nanolaminates. The maximum FA loading was reached using FA solutions at 10 mg/mL for 30 min (54.4 μg/cm 2 ), or 12.5 mg/mL for 120 min (≈70 μg/cm 2 ). Nanolaminates containing FA were more stable under ultraviolet light exposure than non-encapsulated FA. The rate and concentration of FA released from nanolaminates were greater at buffer pH 7 than at pH 3, which might play a key role in the delivery and bioavailability of nutraceuticals. These results provide important information for the design of nanolaminates containing hydrophilic active compounds for food applications. [ABSTRACT FROM AUTHOR]

The formation, characterization, photo-protective properties and release profiles of folic acid-loaded nanolaminated films were investigated by UV–visible spectroscopy, FTIR, Raman and SEM microscopy. Food-grade alginate/chitosan nanolaminates were obtained by the layer-by-layer technique and folic acid (FA) was incorporated by post-diffusion. The FA concentration of loading solutions and immersion time significantly affected the FA content in nanolaminates. The maximum FA loading was reached using FA solutions at 10 mg/mL for 30 min (54.4 μg/cm 2 ), or 12.5 mg/mL for 120 min (≈70 μg/cm 2 ). Nanolaminates containing FA were more stable under ultraviolet light exposure than non-encapsulated FA. The rate and concentration of FA released from nanolaminates were greater at buffer pH 7 than at pH 3, which might play a key role in the delivery and bioavailability of nutraceuticals. These results provide important information for the design of nanolaminates containing hydrophilic active compounds for food applications. [ABSTRACT FROM AUTHOR]

To more thoroughly characterize the mechanism regulating the conversion of red maple tree ( Acer rubrum L. ‘Brandywine’) foliar coloration in autumn, we analyzed the leaf coloration process using the Lab color space scale, and compared the anthocyanin concentrations, photosynthetic pigment contents, soluble sugar contents, and the phenylalanine ammonia lyase and polyphenol oxidase activities between control and band-treated red maple seedlings. We observed that stem banding enhanced the development of leaves exhibiting brilliant red coloration in the upper treated branches, and weakened the brightness of yellow leaves. Additionally, studies also revealed that leaf anthocyanin contents increased significantly. Moreover, carotenoid contents and polyphenol oxidase activity decreased considerably by banding. In contrast, the chlorophyll pigment, phenylalanine ammonia lyase activity and soluble sugar contents were only minimally affected by the long-term banding of trees. Our results indicate that the Lab color model is appropriate for quantifying leaf coloration changes, and for revealing the relationship between leaf coloration and internal physiological changes. Changes to leaf coloration are a consequence of the actions of photosynthetic pigments and anthocyanins. Our results also demonstrate that anthocyanin accumulation influences the underlying biochemical mechanism. The successful manipulation of leaf coloration changes highlights the significance of anthocyanins in this process, and is consistent with the possibility that anthocyanin accumulation influences the underlying biochemical activities. [ABSTRACT FROM AUTHOR]

Objectives These were two-fold: (i) to assess the possible changes in some facial signs induced in a 6-month period by the periodical shift from winter to summer in Caucasian women and (ii) to appraise the preventive effects of a strong photo-protective product. Methods The facial signs of two cohorts of French women ( N= 40 and 42), of comparable ages were graded between winter to summer. One group was left unprotected whereas the other daily applied a strong photo-protective product for 6 months. Facial signs (structural and pigmentation-related) were graded in blind by a panel of 12 experts from photographs taken under standard conditions. A global and focused analysis of the skin colour or dark spots, when present, was carried out through spectro-radiometry under diffuse and standardized visible light, using the L*, a*, b* referential system. Results The unprotected group showed significant changes in summer as compared to winter on 10 facial signs (two-third of the studied signs) that presented an increased severity, of variable respective amplitude. Five signs among the 10 were particularly and significantly affected by the seasonal transition, of an amplitude above the precision of the grading scale. Three of these five signs concerned structural elements (wrinkles), the two others being related to vascular disorders (redness). These season-induced alterations appear efficiently reduced in the photo-protected group. The colour of the facial skin then appears more homogeneous, less red, less dull, all criteria being quantified by the L*, a*, b* referential system. The comparison with a previous work carried out on Chinese women, through a similar protocol, shows that the photo-protective product brings, in Caucasian women, a more important effect upon structural and vascular features than upon pigmentation disorders, inversely to the results previously observed in Chinese women. Conclusion The alterations in some facial signs occurring in a 6-month period between winter and summer are confirmed in Caucasian women, mostly related to structural (wrinkles) and vascular elements. Such changes appear alleviated or prevented by daily applications of a strong sun photo-protective product. [ABSTRACT FROM AUTHOR]

Due to its characteristic of high biomass yield potential, there is considerable interest in cultivating Phalaris arundinacea L. cv. ‘chuancaoyin No.3' (reed canary grass) on the Qinghai-Tibet Plateau where there is an abundance of alpine steppe meadow and a potential large market for animal husbandry. In this study, we 1) investigate whether reed canary grass exhibits superior productive capacity to Elymus nutans ‘Aba' ( E. nutans ), ordinary common pasture, during the long warm days of summer at high-altitude; and 2) compare the cold tolerance between reed canary grass and E. nutans , including photosynthesis, photo-inhibition, and photo-protection. The results suggest that reed canary grass exhibits higher photosynthetic capacity compared to E. nutans at latitudes of the cool temperate zone. Meanwhile, cold-induced photo-inhibition and photo-damage at high altitudes in reed canary grass were due to both stomatal and non-stomatal limitation, and the enhancement in photo-respiration, thermal dissipation, and Mehler reaction are important processes to minimize the negative effects of high elevation and a cold environment. [ABSTRACT FROM AUTHOR]

Objectives These were two-fold: (i) to record through standardized pictures, the possible changes in 31 facial signs induced, in a 6-month period, by the periodical shift from winter to summer in a group of 43 Chinese women and (ii) to appraise the preventive effects of a strong photo-protective product, daily applied to the faces of an additional group ( N = 40) of women of same age-range and presenting same severities of facial signs in winter. Methods Facial signs (structural and pigmentation-related) were scored in blind by a panel of 12 experts from photographs taken under standard conditions. Scorings were performed under specific scales as established by a previously published referential Skin Aging Atlas, Volume 2, Asian Type. Results A significant seasonal impact was found for more than 60% of facial signs, that is presenting a higher severity in summer in the unprotected group. Some changes are of a low or subtle extent, whereas some others show significant amplitudes. The latter comprise eight signs, among the 31, that became, far above scoring threshold, indeed affected during this 6-month period. The observed changes in six of these eight signs, in majority related to pigmentation, appeared efficiently alleviated in the photo-protected group. Conclusion The shift from winter to summer exposure is confirmed in altering some facial pigmented signs among Chinese women. Such changes appear much alleviated by a daily strong photo-protective regimen. [ABSTRACT FROM AUTHOR]

The ability of Rhodopseudomonas palustris cells to rapidly acclimate to high light irradiance is an essential issue when cells are grown under sunlight. The aim of this study was to investigate the photo-acclimation process in Rhodopseudomonas palustris 42OL under different culturing conditions: (i) anaerobic (AnG), (ii) aerobic (AG), and (iii) under H 2 -producing (HP) conditions both at low (LL) and high light (HL) irradiances. The results obtained clearly showed that the photosynthetic unit was significantly affected by the light irradiance at which Rp. palustris 42OL was grown. The synthesis of carotenoids was affected by both illumination and culturing conditions. At LL, lycopene was the main carotenoid synthetized under all conditions tested, while at HL under HP conditions, it resulted the predominant carotenoid. Oppositely, under AnG and AG at HL, rhodovibrin was the major carotenoid detected. The increase in light intensity produced a deeper variation in light-harvesting complexes (LHC) ratio. These findings are important for understanding the ecological distribution of PNSB in natural environments, mostly characterized by high light intensities, and for its growth outdoors. [ABSTRACT FROM AUTHOR]

Background: As the predominant secondary metabolic pathway in tea plants, flavonoid biosynthesis increases with increasing temperature and illumination. However, the concentration of most flavonoids decreases greatly in lightsensitive tea leaves when they are exposed to light, which further improves tea quality. To reveal the metabolism and potential functions of flavonoids in tea leaves, a natural light-sensitive tea mutant (Huangjinya) cultivated under different light conditions was subjected to metabolomics analysis. Results: The results showed that chlorotic tea leaves accumulated large amounts of flavonoids with ortho-dihydroxylated B-rings (e.g., catechin gallate, quercetin and its glycosides etc.), whereas total flavonoids (e.g., myricetrin glycoside, epigallocatechin gallate etc.) were considerably reduced, suggesting that the flavonoid components generated from different metabolic branches played different roles in tea leaves. Furthermore, the intracellular localization of flavonoids and the expression pattern of genes involved in secondary metabolic pathways indicate a potential photoprotective function of dihydroxylated flavonoids in light-sensitive tea leaves. Conclusions: Our results suggest that reactive oxygen species (ROS) scavenging and the antioxidation effects of flavonoids help chlorotic tea plants survive under high light stress, providing new evidence to clarify the functional roles of flavonoids, which accumulate to high levels in tea plants. Moreover, flavonoids with ortho-dihydroxylated B-rings played a greater role in photo-protection to improve the acclimatization of tea plants. [ABSTRACT FROM AUTHOR]

Cyclic electron flow (CEF) alleviates PSII photo-inhibition under high light by at least two different mechanisms: one is liked to thermal energy dissipation (qE) and the other one is independent of qE. However, the latter mechanism is unclear. Because the photodamage to PSII primarily occurred at the oxygen-evolving complex (OEC), and the stability of OEC is dependent on proton gradient across thylakoid membrane (ΔpH), we hypothesize that the CEF-dependent generation of ΔpH can alleviate photodamage to OEC. To test this hypothesis, we determined the effects of antimycin A (AA), methyl viologen (MV), chloramphenicol (CM), nigericin (Nig) on PSII activity and the stability of OEC for leaves of a light-demanding tropical tree species Erythrophleum guineense by the analysis of OKJIP chlorophyll a fluorescence transient. After high light treatment, the stronger decrease in F v / F m in the AA-, CM-, MV-, and Nig-treated samples was accompanied with larger photo damage of OEC. The AA-treated samples significantly showed lower CEF activity than the H 2 O-treated samples. Although the AA-treated leaves significantly showed stronger PSII photo-inhibition and photo-damage of OEC compared to the H 2 O-treated leaves, the value of non-photochemical quenching did not differ between them. Therefore, CEF activity was partly inhibited in the AA-treated samples, and the stronger PSII photo-inhibition in the AA-treated leaves was independent of qE. Taking together, we propose a hypothesis that CEF-dependent generation of ΔpH under high light plays an important role in photoprotection for the OEC activity. [ABSTRACT FROM AUTHOR]

We have prepared a chitosan polymer modified with gallic acid in order to develop an efficient protection strategy biological membranes against photodamage. Lipid bilayers were challenged with photoinduced damage by photosensitization with methylene blue, which usually causes formation of hydroperoxides, increasing area per lipid, and afterwards allowing leakage of internal materials. The damage was delayed by a solution of gallic acid in a concentration dependent manner, but further suppressed by the polymer at very low concentrations. The membrane of giant unilamellar vesicles was covered with this modified macromolecule leading to a powerful shield against singlet oxygen and thus effectively protecting the lipid membrane from oxidative stress. The results have proven the discovery of a promising strategy for photo protection of biological membranes. [ABSTRACT FROM AUTHOR]

Mistletoe plants that are positioned on the canopy of their hosts are more susceptible to UV radiation exposure. These aerial plants are resistant to damage by UV radiation due the presence of epidermal constituents such as the cuticle, cork layer, trichomes and antioxidant secondary metabolites. In response to the photo-oxidative stress associated with UV exposure, plants generally deploy photo-protective responsive mechanisms that involve the biosynthesis of UV absorbing phenolic compounds such as chlorogenic acids (CGAs). The hydroxycinnamic acid moieties of these CGAs are predominantly in the trans configuration, naturally. However, excessive sunlight exposure of plants containing these compounds can result in geometrical isomerisation, characterized by the formation of cis isomers. Therefore, in this study, the effect of UV light radiation on the CGA composition of Viscum combreticola Engl. (Santalacaeae) plants using an in vitro model was unravelled through UHPLC-q-TOF-MS-based metabolic profiling. Interestingly, the findings of this study revealed that this plant has a diverse chemical composition of CGAs that is characterized by epimerization, monoacylation, homodiacylation and heterodiacylation of the quinic acid (QA), thereby, contributing to the state of readiness in these plants against sunlight or UV exposure. In addition to the commonly reported cinnamoyl containing heterodiacylated CGAs, hydroxybenzoyl containing heterodiacylated CGAs were also reported in this study. Moreover, cis isomers (24 in total) of some CGAs were identified in the non-irradiated samples and the formation of these compounds has been reported to help plants in the mitigation of photo-oxidative stress. An additional 28 cis isomers of CGAs and HCA derivatives were observed in the UV-irradiated samples, hence, further increasing the complexity of the metabolome of this plant, with a total of 108 compounds identified in this study. The presence of epimers, positional and geometrical isomers of these compounds could be a biochemical strategy to maximize the chemical arsenal of this plant to withstand the photo-oxidative stress posed by UV radiation from the sunlight. Due to purported pharmacological properties associated with the identified compounds these parasitic plants can be a rich source of prospective therapeutic compounds that can be employed as drug discovery leads. Moreover, UV radiation might be essential in future to produce potent drugs since plants naturally produce these compounds in low quantities. • The semi-parasitic plant, Viscum combreticola Engl. contains structurally diverse cinnamic acid derivatives. • The cinnamic acid derivatives of Viscum combreticola Engl. undergo trans/cis isomerization upon UV exposure. • The presence of chlorogenic acids protect Viscum combreticola Engl. against excessive sunlight or UV light exposure. • The use of the LC-MS and molecular networking approach helps in identification of UV-responsive metabolites in plants. [ABSTRACT FROM AUTHOR]

This study investigated the feasibility of using photosynthetic bacteria (PSB) to produce biomass and carotenoid while treating wastewater. The effects of light intensity on the biomass, carotenoid and bacteriochlorophyll accumulation in together with pollutant removal were studied. Results showed that it was feasible to use PSB to treat wastewater as well as to produce biomass or carotenoid. 2000 lux was an optimal intensity for biomass production and COD removal, and the corresponding values were 2645 mg/L and 94.7%. 8000 lux was an optimal light intensity for carotenoid production (1.455 mg/L). Mechanism analysis displayed that the greater the bacteriochlorophyll and carotenoid were secreted, the lower the light conversion efficiency turned out to be. The highest light conversion efficiency was achieved at 500 lux; the ATP production, biomass production, and COD removal were the highest at 2000 lux, but the bacteriochlorophyll and carotenoid content were the lowest at 2000 lux. [ABSTRACT FROM AUTHOR]

Adaptations to freezing air temperature in temperate understory species of Rhododendron include physiological processes, anatomical changes, and thermonastic leaf movements. Leaves roll transversely and leaf-lamina angle decreases in relation to horizontal as temperatures decrease below a critical freezing temperature. Within the genus Rhododendron, tolerance of cold conditions is greater in species with thermonastic leaf movements than species without. The leaf movements protect critical physiological processes such as photosynthesis from damage due to the synergistic effects of cold temperatures, and high light common to winter conditions in temperate forests. In particular, the absence of these leaf movements increases photoinhibition, and species that lack these adaptations exhibit distinctly different physiological and anatomical mechanisms of photo-protection during cold conditions. The biomechanical or physiological causes for thermonastic leaf movements have been difficult to resolve because of the lack of distinctive anatomical and morphological features associated with these leaf movements. Nevertheless, it is firmly established that the lower the petiole turgor potential the lower the leaf-lamina angle in relation to horizontal. However, the cause of leaf rolling is unclear. In this study, experiments on sectioned leaves implicate both longitudinal and lateral thermonastic rolling forces, likely driven by water redistribution between apoplast and symplast, and regulated by aquaporins. This should result in abaxial-adaxial differential turgor pressures that vary markedly along the mediolateral direction. We postulate that the combined effect of the leaf morphology, anisotropy in rolling forces and the geometrical constraints due to the relatively stiff midrib causes leaf rolling, consistent with the mechanics of a thin plate with anisotropic spontaneous curvature. We expect a correlation between the rolling forces and veination microstructure that remains to be explored for a complete understanding of leaf adaptations to freezing in understory evergreen Rhododendron species, as well as more general thermonastic responses. [ABSTRACT FROM AUTHOR]

This study aims to investigate the photoprotective properties of a Lomentaria hakodatensis ethanol extract (LHE) against ultraviolet B (UVB) radiation-induced cellular damage in human HaCaT keratinocytes. LHE exhibited scavenging activity against intracellular reactive oxygen species (ROS), which were generated by either hydrogen peroxide (HO) or UVB radiation. Moreover, LHE scavenged superoxide anion generated by the xanthine/xanthine oxidase system and hydroxyl radical generated by the Fenton reaction (FeSO + HO). Furthermore, LHE exhibited UVB absorptive properties and attenuated injury to cellular components ( e.g., lipids, proteins and DNA), resulting from UVB-induced oxidative stress. In addition, LHE reduced apoptosis in response to UVB, as shown by decreased DNA fragmentation and the formation of apoptotic bodies. These results suggest that LHE protects human keratinocytes against UVB-induced oxidative stress by scavenging ROS and absorbing UVB rays; thereby reducing damage to biological components. [ABSTRACT FROM AUTHOR]

With the aim to establish a novel nanocarrier system with higher payload and higher photo-protection for deltamethrin (active ingredient) compared to solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC) were prepared by combining hot homogenization and sonication with different ratios of corn oil (liquid lipid) and beeswax (solid lipid). Compared to SLN, the incorporation of corn oil gave a higher payload, slower release rate and higher photo-protection for deltamethrin. Particularly, compared to beeswax solid lipid nanoparticles (BSLN), NLC gave a higher payload (approximately 1.79 times) with a high encapsulation efficiency (83.6%), higher photo-protection in direct photolysis (1.8 times) after 12 h exposure of ultraviolet light (UV) and in indirect photolysis (1.37 times) after 2 h exposure of UV in 2% (v/v) acetone solution used as a photosensitizer. This study demonstrated that novel nanocarrier possesses a wide range of applicability in protecting photo-labile compounds for the crop, food and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

Abstract: Some solar-powered sea slugs are capable of incorporating chloroplasts directly in their cell cytosol sustaining photosynthesis for significant time periods. This phenomenon is known as kleptoplasty. Kleptoplastids show high functionality levels but little is known about their photo-regulatory mechanisms. The main objective was to investigate the functionality of the xanthophyll cycle using the sacoglossan Elysia timida that acquires kleptoplasts from Acetabularia acetabulum. Xanthophyll cycle functionality was tested using a combination of PAM fluorescence and HPLC pigment analysis. Rapid light curves (RLC) and steady state light curves were carried out in both organisms. E. timida RLC showed a rETR inflexion point after 700μmolE−1 m−2 s−1 that was not visible on A. acetabulum. This was attributed to the fact that the animal closed the parapodia in high light intensities, thus shading the kleptoplasts leading to higher PSII quantum efficiencies. This behaviour also resulted in Ek values being significantly higher in E. timida (ANOVA, F(1, 27) =7.49, p<0.05). The xanthophyll cycle was shown to be functional with kleptoplasts xanthophyll ratio, i.e. zea/(vio+ant+zea) increasing with exposure to higher light intensities (F(1, 23) =122.83, p<0.01) and showing a strong linear relationship with non-photochemical quenching measurements. The present study showed that E. timida was capable of combining a behavioural photo-regulation mechanism (opening/closing the parapodia) with a functional physiological photo-regulation mechanism (xanthophyll cycle) increasing their photo-regulation capacity, keeping their maximum photosynthetic capacity for longer periods than their food source. [ABSTRACT FROM AUTHOR]

We demonstrated a direct correlation between melanogenic and catalase activities on in vitro and ex vivo models. Here, we investigated whether the stimulation of Melanocortin-1 Receptor (MC1R) could influence catalase expression, activity and cellular localization. For this purpose, we treated B16-F0 melanoma cells with α-Melanocyte Stimulating Hormone (α-MSH) and we showed a rapid induction of catalase through a cAMP/PKA-dependent, microphthalmia-associated transcription factor (MITF) independent mechanism, acting at post-transcriptional level. Moreover, α-MSH promoted a partial re-distribution of catalase to the cell periphery and dendrites. This work strengthens the correlation between melanogenesis and anti-oxidants, demonstrating the induction of catalase in response to a melanogenic stimulation, such as α-MSH-dependent MC1R activation. Moreover, this study highlights catalase regulatory mechanisms poorly known, and attributes to α-MSH a protective role in defending melanocytes, and possibly keratinocytes, not only on the basis of its pigmentary action, but also for its capacity to stimulate a quick anti-oxidant defence. [ABSTRACT FROM AUTHOR]

Proton motive force (pmf) across thylakoid membranes is not only for harnessing solar energy for photosynthetic CO2 fixation, but also for triggering feedback regulation of photosystem II antenna. The mechanisms for balancing these two roles of the proton circuit under the long-term environmental stress, such as prolonged drought, have been poorly understood. In this study, we report on the response of wild watermelon thylakoid ‘proton circuit’ to drought stress using both in vivo spectroscopy and molecular analyses of the representative photosynthetic components. Although drought stress led to enhanced proton flux via a ∼34% increase in cyclic electron flow around photosystem I (PS I), an observed ∼fivefold decrease in proton conductivity, gH+, across thylakoid membranes suggested that decreased ATP synthase activity was the major factor for sustaining elevated qE. Western blotting analyses revealed that ATP synthase content decreased significantly, suggesting that quantitative control of the complex plays a pivotal role in down-regulation of gH+. The expression level of cytochrome b6 f complex – another key control point in photosynthesis – also declined, probably to prevent excess-reduction of PS I electron acceptors. We conclude that plant acclimation to long-term environmental stress involves global changes in the photosynthetic proton circuit, in which ATP synthase represents the key control point for regulating the relationship between electron transfer and pmf. [ABSTRACT FROM AUTHOR]

Abstract: Low-temperature crystalline deposition techniques are important, especially for coating polymer films that cannot tolerate high temperatures. In this work, crystalline anatase titanium dioxide (TiO2) thin films were deposited by reactive radio-frequency (RF) magnetron sputtering on unheated poly(ethylene terephthalate) (PET) films. The stability of the polymer film under UV-light irradiation in air was then studied. With only a TiO2 layer the polymer film was degraded by in-air, UV radiation. However, a transparent bilayer coating, consisting of a TiO2 layer on top of an ultra-thin sputtered alumina (Al2O3) layer, on the PET film effectively protected the polymer layer from photo-oxidation. Furthermore, the top anatase TiO2 layer has very good photo-catalytic activity, as shown by its ability to photo-degrade rhodamine B dye solution. The combination of these two properties allows photo-stable and transparent polymer/ceramic layered media with a self-cleaning surface. [Copyright &y& Elsevier]

Using in vivo thermoluminescence, we examined the effects of growth irradiance and growth temperature on charge recombination events in photosystem II reaction centres of the model green alga Chlamydomonas reinhardtii. We report that growth at increasing irradiance at either 29 or 15 °C resulted in comparable downward shifts in the temperature peak maxima (TM) for S2QB– charge pair recombination events, with minimal changes in S2QA– recombination events. This indicates that such growth conditions decrease the activation energy required for S2QB– charge pair recombination events with no concomitant change in the activation energy for S2QA– recombination events. This resulted in a decrease in the ΔTM between S2QA– and S2QB– recombination events, which was reversible when shifting cells from low to high irradiance and back to low irradiance at 29 °C. We interpret these results to indicate that the redox potential of QB was modulated independently of QA, which consequently narrowed the redox potential gap between QA and QB in photosystem II reaction centres. Since a decrease in the ΔTM between S2QA– and S2QB– recombination events correlated with growth at increasing excitation pressure, we conclude that acclimation to growth under high excitation pressure narrows the redox potential gap between QA and QB in photosystem II reaction centres, enhancing the probability for reaction center quenching in C. reinhardtii. We discuss the molecular basis for the modulation of the redox state of QB, and suggest that the potential for reaction center quenching complements antenna quenching via the xanthophyll cycle in the photoprotection of C. reinhardtii from excess light. [ABSTRACT FROM AUTHOR]

Gametophytes of Jamesoniella colorata (jungermanniaceae) and Isotachis lyallii (isotachidaceae) produce red leaves in exposed habitats, but green leaves in shaded environments. To understand the functional significance of this colour polymorphism, the anatomy, pigment composition, optical properties, and kinetics of chlorophyll a fluorescence were compared for red and green gametophytes. Both colour morphs were structurally similar, but the red leaves held unidentified red pigment(s) firmly associated with the cell wall. Green morphs contained more chlorophylls and carotenoids, and had higher ratios of chlorophylls to carotenoids, than did the red morphs. Red leaves absorbed 10% more photosynthetically active radiation, with a maximum at 540 nm, than did the green leaves. Under high irradiance, the red leaves maintained higher apparent quantum efficiencies for photosynthesis, and had larger photochemical and non-photochemical quenching values. The data indicate that red gametophytes have the greater potential to mitigate the damaging effects of high irradiance. [ABSTRACT FROM AUTHOR]

Prunus domestica L. has green leaves, whereas Prunus cerasifera Ehrh. var. atropurpurea has red leaves due to the presence of mesophyll anthocyanins. We compared morphological and photosynthetic characteristics of leaves of these species, which were sampled from shoots grafted in pairs on P. domestica rootstocks, each pair comprising one shoot of each species. Two hypotheses were tested: (1) anthocyanins protect red leaves against photo-inhibition; and (2) red leaves display shade characteristics because of light attenuation by anthocyanins. Parameters were measured seasonally, during a period of increasing water stress, which caused a similar drop in shoot water potential in each species. As judged by predawn measurements of maximum PSII yield, chronic photo-inhibition did not develop in either species and, despite the anthocyanic screen, the red leaves of P. cerasifera displayed lower light-adapted PSII yields and higher non-photochemical quenching than the green leaves of P. domestica. Thus, it appears that, in this system, anthocyanins afford little photo-protection. As predicted by the shade acclimation hypothesis, red leaves were thinner and had a lower stomatal frequency, area-based CO2 assimilation rate, apparent carboxylation efficiency and chlorophyll a:b ratio than green leaves. However, red leaves were similar to green leaves in conductivity to water vapor diffusion, dry-mass-based chlorophyll concentrations and carotenoid:chlorophyll ratios. The data for red leaves indicate adaptations to a green-depleted, red-enriched shade, rather than a neutral or canopy-like shade. Thus, green light attenuation by anthocyanins may impose a limitation on leaf thickness. Moreover, the selective depletion of light at wavelengths that are preferentially absorbed by PSII and chlorophyll b may lead to adjustments in chlorophyll pigment ratios to compensate for the uneven spectral distribution of internal light. The apparent photosynthetic cost associated with lost photons and reduced leaf thickness, and the absence of a photo-protective advantage, suggest that there are other, yet to be identified, benefits for permanently anthocyanic leaves of P. cerasifera. [ABSTRACT FROM AUTHOR]

Skin cancer is the most common human malignancy worldwide and solar ultraviolet (UV) radiation is known to serve an important role in its pathogenesis. Natural candidate compounds with antioxidant, photoprotective and anti-melanogenic effects were investigated against the background of skin photoprotective and anti-melanogenic properties. Gomisin D, J and O are dibenzocyclooctadiene lignans present in Kadsura medicinal plants and possess several pharmacological activities. In this study, the functions and mechanisms underlying the effects of gomisin D, J and O in UVA-and UVB-irradiated keratinocytes and α-melanocyte stimulating hormone (α-MSH)-stimulated melanocytes were explored. Following UVA and UVB irradiation, keratinocytes were treated with gomisin D, J and O, and keratinocyte viability, lactate dehydrogenase (LDH) release, intracellular reactive oxygen species (ROS) production and apoptosis were examined. The results demonstrated that gomisin D and J improved keratinocyte viability and reduced LDH release under UVA and UVB irradiation. Intracellular ROS production induced by UVA and UVB irradiation was suppressed by gomisin D and J. In addition, Annexin V and TUNEL staining analysis indicated that gomisin D and J have significant anti-apoptotic effects on UVA-and UVB-irradiated keratinocytes. After α-MSH stimulation, melanocytes were treated with gomisin D, J and O, and the changes in melanocyte viability, intracellular melanin content, intracellular tyrosinase activity, and mechanisms underlying these changes were examined. Gomisin D markedly inhibited the α-MSH-induced increase in intracellular melanin content and tyrosinase activity. Mechanistically, gomisin D reduced the protein and mRNA expression levels of microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein (TRP)-1 and TRP-2 in α-MSH-stimulated melanocytes. In addition, gomisin D markedly downregulated α-MSH-induced phosphorylation of protein kinase A and cAMP response element binding protein, which are known to be present upstream of the MITF, tyrosinase, TRP-1 and TRP-2 genes. Overall, gomisin D has photoprotective and anti-melanogenic effects; these findings provide a basis for the production of potential brightening and photoprotective agents using natural compounds such as gomisin D. [ABSTRACT FROM AUTHOR]

Background: As yields of major crops such as wheat (T. aestivum) have begun to plateau in recent years, there is growing pressure to efficiently phenotype large populations for traits associated with genetic advancement in yield. Photosynthesis encompasses a range of steady state and dynamic traits that are key targets for raising Radiation Use Efficiency (RUE), biomass production and grain yield in crops. Traditional methodologies to assess the full range of responses of photosynthesis, such a leaf gas exchange, are slow and limited to one leaf (or part of a leaf) per instrument. Due to constraints imposed by time, equipment and plant size, photosynthetic data is often collected at one or two phenological stages and in response to limited environmental conditions. Results: Here we describe a high throughput procedure utilising chlorophyll fluorescence imaging to phenotype dynamic photosynthesis and photoprotection in excised leaves under controlled gaseous conditions. When measured throughout the day, no significant differences (P > 0.081) were observed between the responses of excised and intact leaves. Using excised leaves, the response of three cultivars of T. aestivum to a user—defined dynamic lighting regime was examined. Cultivar specific differences were observed for maximum PSII efficiency (Fv′/Fm′—P < 0.01) and PSII operating efficiency (Fq′/Fm′—P = 0.04) under both low and high light. In addition, the rate of induction and relaxation of non-photochemical quenching (NPQ) was also cultivar specific. A specialised imaging chamber was designed and built in-house to maintain gaseous conditions around excised leaf sections. The purpose of this is to manipulate electron sinks such as photorespiration. The stability of carbon dioxide (CO2) and oxygen (O2) was monitored inside the chambers and found to be within ± 4.5% and ± 1% of the mean respectively. To test the chamber, T. aestivum 'Pavon76' leaf sections were measured under at 20 and 200 mmol mol−1 O2 and ambient [CO2] during a light response curve. The Fv′/Fm′was significantly higher (P < 0.05) under low [O2] for the majority of light intensities while values of NPQ and the proportion of open PSII reaction centers (qP) were significantly lower under > 130 μmol m−2 s−1 photosynthetic photon flux density (PPFD). Conclusions: Here we demonstrate the development of a high-throughput (> 500 samples day−1) method for phenotyping photosynthetic and photo-protective parameters in a dynamic light environment. The technique exploits chlorophyll fluorescence imaging in a specifically designed chamber, enabling controlled gaseous environment around leaf sections. In addition, we have demonstrated that leaf sections do not different from intact plant material even > 3 h after sampling, thus enabling transportation of material of interest from the field to this laboratory based platform. The methodologies described here allow rapid, custom screening of field material for variation in photosynthetic processes. [ABSTRACT FROM AUTHOR]