In Vitro and In Vivo Photoprotective Effects of (-)-Loliode Isolated from the Brown Seaweed, Sargassum horneri.

Skin is the largest organ of humans. Overexposure to ultraviolet (UV) is the primary environmental factor that causes skin damage. The compound, (-)-loliode, isolated from the brown seaweed Sargassum horneri, showed strong antioxidant and anti-inflammatory activities in in vitro and in vivo models. To further explore the potential of (-)-loliode in cosmetics, in the present study, we investigated the photoprotective effect of (-)-loliode in vitro in skin cells and in vivo in zebrafish. The results indicated that (-)-loliode significantly reduced intracellular reactive oxygen species (ROS) level, improved cell viability, and suppressed apoptosis of UVB-irradiated human keratinocytes. In addition, (-)-loliode remarkably attenuated oxidative damage, improved collagen synthesis, and inhibited matrix metalloproteinases expression in UVB-irradiated human dermal fibroblasts. Furthermore, the in vivo test demonstrated that (-)-loliode effectively and dose-dependently suppressed UVB-induced zebrafish damage displayed in decreasing the levels of ROS, nitric oxide, lipid peroxidation, and cell death in UVB-irradiated zebrafish. These results indicate that (-)-loliode possesses strong photoprotective activities and suggest (-)-loliode may an ideal ingredient in the pharmaceutical and cosmeceutical industries.

Anti-Photoaging and Potential Skin Health Benefits of Seaweeds.

The skin health benefits of seaweeds have been known since time immemorial. They are known as potential renewable sources of bioactive metabolites that have unique structural and functional features compared to their terrestrial counterparts. In addition, to the consciousness of green, eco-friendly, and natural skincare and cosmetics products, their extracts and bioactive compounds such as fucoidan, laminarin, carrageenan, fucoxanthin, and mycosporine like amino acids (MAAs) have proven useful in the skincare and cosmetic industries. These bioactive compounds have shown potential anti-photoaging properties. Furthermore, some of these bioactive compounds have been clinically tested and currently available in the market. In this contribution, the recent studies on anti-photoaging properties of extracts and bioactive compounds derived from seaweeds were described and discussed.

Biotechnological Production of the Sunscreen Pigment Scytonemin in Cyanobacteria: Progress and Strategy.

Scytonemin is a promising UV-screen and antioxidant small molecule with commercial value in cosmetics and medicine. It is solely biosynthesized in some cyanobacteria. Recently, its biosynthesis mechanism has been elucidated in the model cyanobacterium Nostoc punctiforme PCC 73102. The direct precursors for scytonemin biosynthesis are tryptophan and p-hydroxyphenylpyruvate, which are generated through the shikimate and aromatic amino acid biosynthesis pathway. More upstream substrates are the central carbon metabolism intermediates phosphoenolpyruvate and erythrose-4-phosphate. Thus, it is a long route to synthesize scytonemin from the fixed atmospheric CO2 in cyanobacteria. Metabolic engineering has risen as an important biotechnological means for achieving sustainable high-efficiency and high-yield target metabolites. In this review, we summarized the biochemical properties of this molecule, its biosynthetic gene clusters and transcriptional regulations, the associated carbon flux-driving progresses, and the host selection and biosynthetic strategies, with the aim to expand our understanding on engineering suitable cyanobacteria for cost-effective production of scytonemin in future practices.

Characterization of a lignin from Crataeva tapia leaves and potential applications in medicinal and cosmetic formulations.

Lignins are phenolic macromolecules that have several applications. In this work, we examine some biological activities of a lignin-like macromolecule isolated from the Crataeva tapia leaves, not yet studied to evaluate its potential applications in medicinal and cosmetic formulations. Lignin was obtained by alkaline delignification and its physical-chemical characterization was made by means of FT-IR, UV-Vis, NMR spectroscopy, elementary analysis, molecular mass determination and thermal analysis. Lignin is of the GSH type, with levels of hydrogen (5.10%), oxygen (27.18%), carbon (67.60%), nitrogen (0.12%) and phenolic content of 189.6 ± 9.6 mg GAE/g. In addition, it is a thermally stable macromolecule with low antioxidant activity. Cytotoxicity and cytokine production were assessed by flow cytometry. The photoprotective activity was evaluated by adding different concentrations of lignin to a commercial cream. Lignin was not cytotoxic, it stimulated the production of TNF-α, IL-6 and IL-10 and did not promote a significant change in nitric oxide levels. In addition, this macromolecule was able to promote increased absorption of ultraviolet light from a commercial cream. These results reinforce the ethnopharmacological use of C. tapia leaves and suggest the need for further studies to determine the potential medicinal and cosmetic applications (sunscreen) of lignin from C. tapia leaves.

Natural components in sunscreens: Topical formulations with sun protection factor (SPF).

Artificial sunscreens are already gaining traction in order to protect the skin from sunburns, photoaging and photocarcinogenesis. However, the efficacy and safety of most artificial sunscreen constituents are hindered by their photostability, toxicity and damage to marine ecosystems. Natural selection and evolution have ensured that plants and animals have developed effective protective mechanisms against the deleterious side effects of oxidative stress and ultraviolet radiation (UV). Hence, natural antioxidants such as sun blockers are drawing considerable attention. The exact mechanism by which natural components act as sunscreen molecules has not been clearly established. However, conjugated π system is reported to play an important role in protecting the vital genetic material within the organism. Compared to artificial sunscreens, natural sunscreens with strong UV absorptive capacities are largely limited by low specific extinction value and by their inability to spread in large-scale sunscreen cosmetic applications. Previous studies have documented that natural components exert their photoprotective effects (such as improved skin elasticity and hydration, skin texture, and wrinkles) through their antioxidant effects, and through the regulation of UV-induced skin inflammation, barrier impairment and aging. This review focuses on natural antioxidant topical formulations with sun protection factor (SPF). Lignin, melanin, silymarin and other ingredients have been added to high sun protection nature sunscreens without any physical or chemical UV filters. This paper also provides a reference for adopting novel technical measures (extracting high content components, changing the type of solution, optimizing formulation, applying Nano technology, et al) to design and prepare nature sunscreen formulations equated with commercial sunscreen formulations. Another strategy is to add natural antioxidants from plants, animals, microorganisms and marine organisms as special enhancer or modifier ingredients to reinforce SPF values. Although the photoprotective effects of natural components have been established, their deleterious side effects have not been elucidated.

Protective Effect of a Fucose-Rich Fucoidan Isolated from Saccharina japonica against Ultraviolet B-Induced Photodamage In Vitro in Human Keratinocytes and In Vivo in Zebrafish.

A fucose-rich fucoidan was purified from brown seaweed Saccharina japonica, of which the UVB protective effect was investigated in vitro in keratinocytes of HaCaT cells and in vivo in zebrafish. The intracellular reactive oxygen species levels and the viability of UVB-irradiated HaCaT cells were determined. The results indicate that the purified fucoidan significantly reduced the intracellular reactive oxygen species levels and improved the viability of UVB-irradiated HaCaT cells. Furthermore, the purified fucoidan remarkably decreased the apoptosis by regulating the expressions of Bax/Bcl-xL and cleaved caspase-3 in UVB-irradiated HaCaT cells in a dose-dependent manner. In addition, the in vivo UV protective effect of the purified fucoidan was investigated using a zebrafish model. It significantly reduced the intracellular reactive oxygen species level, the cell death, the NO production, and the lipid peroxidation in UVB-irradiated zebrafish in a dose-dependent manner. These results suggest that purified fucoidan has a great potential to be developed as a natural anti-UVB agent applied in the cosmetic industry.

Cosmetic potential of lignin extracts from alkaline-treated sugarcane bagasse: Optimization of extraction conditions using response surface methodology.

Each year, sugarcane bagasse, a low-priced by-product of the sugar industry, is generated in large quantities. The aim of this study was to optimize the alkaline hydrolysis condition for the extraction of lignin from sugarcane bagasse using response surface methodology combined with Box-Behnken design, and to evaluate functional properties of lignin extracts for cosmetic applications. Three process parameters were varied (NaOH solution concentrations (3-7% w/v), temperatures (115-135 °C), and times (30-60 min)). The second-order polynomial model developed and the subsequent ANOVA test showed that the optimal conditions providing the highest total phenolic content (69.41 ± 0.32 mg gallic acid equivalent/g extract), antioxidant activity (262.30 ± 2.98 mg Trolox equivalent/g extract), and sun protection factor (8.65 ± 0.21) were as follows: NaOH solution concentration of 7% w/v, temperature of 135 °C, and time of 47.92 min. Fourier-transform infrared spectroscopy analysis revealed the functional groups present in the lignin extract that affected its activities. The extract showed both UVA and UVB-absorbing properties and tyrosinase-inhibitory properties. The results suggested that the lignin extract obtained from alkaline hydrolysis of sugarcane bagasse has great potential as a bioactive multi-functional ingredient that can offer anti-ageing, sun-protection, and skin-whitening properties for sun care formulations.

Health Properties and Composition of Honeysuckle Berry Lonicera caerulea L. An Update on Recent Studies.

Lonicera caerulea L., also known as haskap or honeysuckle berry, is a fruit commonly planted in eastern Europe, Canada and Asia. The fruit was registered as a traditional food from a third country under European Union regulations only on December 2018. It is resistant to cold, pests, various soil acidities and diseases. However, its attractiveness is associated mostly with its health properties. The fruit shows anticancer, anti-inflammatory, and antioxidant activity-important factors in improving health. These features result from the diverse content of phytochemicals in honeysuckle berries with high concentrations of phytocompounds, mainly hydroxycinnamic acids, hydroxybenzoic acids, flavanols, flavones, isoflavones, flavonols, flavanones and anthocyanins but also iridoids, present in the fruit in exceptional amounts. The content and health properties of the fruit were identified to be dependent on cultivar, genotype and the place of harvesting. Great potential benefits of this nutritious food are its ability to minimize the negative effects of UV radiation, diabetes mellitus and neurodegenerative diseases, and to exert hepato- and cardioprotective activity.

Seasonal Variation of Mycosporine-Like Amino Acids in Three Subantarctic Red Seaweeds.

UV-absorbing compounds, such as mycosporine-like amino acids (MAAs), are a group of secondary metabolites present in many marine species, including red seaweeds. In these organisms, the content and proportion of the composition of MAAs vary, depending on the species and several environmental factors. Its high cosmetic interest calls for research on the content and composition of MAAs, as well as the dynamics of MAAs accumulation in seaweeds from different latitudes. Therefore, this study aimed to survey the content of UV-absorbing MAAs in three Subantarctic red seaweeds during a seasonal cycle. Using spectrophotometric and HPLC techniques, the content and composition of MAAs of intertidal Iridaea tuberculosa, Nothogenia fastigiate, and Corallina officinalis were assessed. Some samples were also analyzed using high-resolution mass spectrometry coupled with HPLC-ESI-MS in order to identify more precisely the MAA composition. I. tuberculosa exhibited the highest MAA values (above 1 mg g-1 of dried mass weight), while C. officinalis showed values not exceeding 0.4 mg g-1. Porphyra-334 was the main component in N. fastigiata, whereas I. tuberculosa and C. officinalis exhibited a high content of palythine. Both content and composition of MAAs varied seasonally, with high concentration recorded in different seasons, depending on the species, i.e., winter (I. tuberculosa), spring (N. fastigiata), and summer (C. officinalis). HPLC-ESI-MS allowed us to identify seven different MAAs. Two were recorded for the first time in seaweeds from Subantarctic areas (mycosporine-glutamic acid and palythine-serine), and we also recorded an eighth UV-absorbing compound which remains unidentified.

Photoprotection assessment of olive (Olea europaea L.) leaves extract standardized to oleuropein: In vitro and in silico approach for improved sunscreens.

Olive leaves contain higher amount of polyphenols than olive oil and represent a waste product from olive harvest and pruning of olive trees. The most abundant compound in olive leaves is oleuropein. Benefits of the topical application of olive leaves extract were previously reported, but little information is available on its photoprotective potential and the result of the association of this extract with organic UV filters in topical sunscreen formulations. The olive leaves extract photoprotective potential is less explored for both oral and topical photoprotection in comparison with other plants extracts and polyphenols, such as Polypodium leucotomos extract and resveratrol. There are increasing efforts towards developing more efficient sunscreens and a photoprotection assessement along with a better understanding of the photochemistry of naturally occurring sunscreens could aid the design of new and improved commercial sunscreen formulations. This study was designed to investigate the photoprotective potential of olive leaves extract standardized for oleuropein performing a set of in vitro and in silico tools as an innovative approach, highlighting yeast assays, in vitro Sun Protection Factor (SPF) and molecular modelling studies of UV absorption. This study supports the use of olive leaves extract for photoprotection, as an effective photoprotective, anti-mutagenic and antioxidant active, also showing a synergistic effect in association with UV filters with an improvement on in vitro SPF of sunscreen formulations.

UVA and UVB Photoprotective Capabilities of Topical Formulations Containing Mycosporine-like Amino Acids (MAAs) through Different Biological Effective Protection Factors (BEPFs).

The safety and stability of synthetic UV-filters and the procedures for evaluating the photoprotective capability of commercial sunscreens are under continuous review. The influence of pH and temperature stressors on the stability of certain Mycosporine-like amino acids (MAAs) isolated at high purity levels was examined. MAAs were highly stable at room temperature during 24 h at pH 4.5⁻8.5. At 50 °C, MAAs showed instability at pH 10.5 while at 85 °C, progressive disappearances were observed for MAAs through the studied pH range. In alkaline conditions, their degradation was much faster. Mycosporine-serinol and porphyra-334 (+shinorine) were the most stable MAAs under the conditions tested. They were included in four cosmetically stable topical sunscreens, of which the Sun Protection Factor (SPF) and other Biological Effective Protection Factors (BEPFs) were calculated. The formulation containing these MAAs showed similar SPF and UVB-BEPFs values as those of the reference sunscreen, composed of synthetic UV absorbing filters in similar percentages, while UVA-BEPFs values were slightly lower. Current in vitro data strongly suggest that MAAs, as natural and safe UV-absorbing and antioxidant compounds, have high potential for protection against the diverse harmful effects of solar UV radiation. In addition, novel complementary in vitro tests for evaluation of commercial sunscreens efficacy are proposed.

Cosmeceutical potential of geranium and calendula essential oil: Determination of antioxidant activity and in vitro sun protection factor.

The present investigation was aimed to find out the sun protection factor (SPF) and antioxidant potential of geranium essential oil (GEO) and calendula essential oil (CEO) because having a combination of these two properties moves up the oils as an active ingredient of various cosmeceutical formulations for their preventive and protective properties. Essential oils were obtained by hydrodistillation of Pelargonium graveolens leaves (GEO) and Calendula officinalis flowers (CEO). The composition and identification of chemical constituents of oils were determined by GCMS analysis. Free radical scavenging activity was measured by nitric oxide scavenging activity and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. It was observed that both GEO and CEO have the potential to reduce or prevent oxidative stress and can be used in skin care regimen to slow down skin aging via its antioxidant properties. In vitro SPF was determined by a very simple and rapid spectroscopic method. SPF value of GEO and CEO was found to 6.45 and 8.36, respectively. The SPF of CEO was higher than GEO, and the results of SPF show that these essential oils can be employed in sunscreen formulations to protect the skin from sunburn. From the results, it can be concluded that the combined antioxidant and SPF property of GEO and CEO can provide synergistic photoprotective effect or lift up the additional value of the cosmeceutical formulation.

Ganoderma lucidum polysaccharide inhibits UVB-induced melanogenesis by antagonizing cAMP/PKA and ROS/MAPK signaling pathways.

Ultraviolet (UV)-induced pigmentation is very common in clinical practice, but the current treatments are rarely effective, accompanied by some side effects. Ganoderma lucidum polysaccharide (GLP) is a natural antioxidant with no toxic side effects, which can antagonize UVB-induced fibroblast photo aging. The study aims to explore the role of GLP in inhibiting UVB-induced melanogenesis and its possible mechanism. The expression of melanogenesis genes such as microphthalmia-associated transcription factor (MITF), tyrosine (TYR), tyrosinase related protein 1 (TYRP1), tyrosinase related protein 2 (TYRP2), ras-related protein Rab-27A (Rab27A), and Myosin shows an upward trend after exposure of B16F10 and PIG1 cells to UVB irradiation, but GLP can downregulate the expression of genes related to UVB-induced melanogenesis. GLP can inhibit UVB-activated protein kinase A (PKA) and mitogen-activated protein kinase (MAPK) signaling pathways. Besides, GLP protects mitochondria from UVB damage and inhibits reactive oxygen species (ROS) production. Also, UVB-induced cyclic adenosine monophosphate (cAMP) can be inhibited. It has been found in the experiments of UVB-induced skin pigmentation in zebrafish that GLP is capable of inhibiting UVB-induced skin pigmentation. Meanwhile, it can greatly relieve erythema reaction in guinea pig skin caused by high-dosage UVB irradiation. In conclusion, this study shows that GLP can inhibit UVB-induced melanogenesis by antagonizing cAMP/PKA and ROS/MAPK signaling pathways and is a potential natural safe whitening sunscreen additive.

In vitro antioxidant activity and solar protection factor of blackberry and raspberry extracts in topical formulation.

BACKGROUND: Berries are known for their antioxidant activity due to the presence of flavonoids. Antioxidants' usage guarantees skin protection against free radicals and, flavonoids, especially, can act as sunscreen. The aim of this paper was to evaluate solar protection factor (SPF) and antioxidant activity in vitro of blackberry and raspberry extracts incorporated in topical formulation and study their stability. RESULTS: Raspberry presented 29.93 mg of anthocyanins/100 g of fruit and blackberry 65.58 mg of anthocyanins/100 g of fruit. In vitro solar protection factor was 54.57 to blackberry and 37.32 to raspberry. When incorporated in O/W emulsions, final formulations showed light pink color, creamy aspect, and typical fruity odor. Formulations submitted to indirect light and stove showed odor and color alterations. CONCLUSIONS: Based on the results, formulations containing extracts should be kept under refrigeration in opaque package to ensure stability due to the presence of flavonoids. In addition, blackberry and raspberry extracts are potential natural alternatives to be used as sunscreen and to prevent skin aging.

Elicited ROS Scavenging Activity, Photoprotective, and Wound-Healing Properties of Collagen-Derived Peptides from the Marine Sponge Chondrosia reniformis.

Recently, the bioactive properties of marine collagen and marine collagen hydrolysates have been demonstrated. Although there is some literature assessing the general chemical features and biocompatibility of collagen extracts from marine sponges, no data are available on the biological effects of sponge collagen hydrolysates for biomedical and/or cosmetic purposes. Here, we studied the in vitro toxicity, antioxidant, wound-healing, and photoprotective properties of four HPLC-purified fractions of trypsin-digested collagen extracts-marine collagen hydrolysates (MCHs)-from the marine sponge C. reniformis. The results showed that the four MCHs have no degree of toxicity on the cell lines analyzed; conversely, they were able to stimulate cell growth. They showed a significant antioxidant activity both in cell-free assays as well as in H2O2 or quartz-stimulated macrophages, going from 23% to 60% of reactive oxygen species (ROS) scavenging activity for the four MCHs. Finally, an in vitro wound-healing test was performed with fibroblasts and keratinocytes, and the survival of both cells was evaluated after UV radiation. In both experiments, MCHs showed significant results, increasing the proliferation speed and protecting from UV-induced cell death. Overall, these data open the way to the use of C. reniformis MCHs in drug and cosmetic formulations for damaged or photoaged skin repair.

UV Protection by Natural Products: C. myrrha Oil Versus Sunscreen.

Exposure to various types of ultraviolet (UV) radiation from the sun has been linked to skin cancer. Use of sunscreen can reduce the damaging and carcinogenic effects of UV radiation. However, multiple chemicals in sunscreen can trigger allergic responses, making people less inclined to use sunscreen. Thus, finding natural, plant-based alternatives to sunscreen with similar efficacy has become an important area of research. Myrrh oil, extracted from the shrub Commiphora myrrha, has been used in the treatment of topical wounds and studies have shown that it may provide protection against solar radiation. This study sought to further investigate if C. myrrha oil can confer protection against UV radiation. A UV-sensitive strain of Saccharomyces cerevisiae was grown in petri dishes with one half covered by aluminum foil and the other half covered by clear polyethylene food wrap. The polyethylene half was treated with either SPF 15 or SPF 30 sunscreen, C. myrrha oil or a combination of C. myrrha oil and either sunscreen. The plates were exposed to sunlight. Colony death was quantified using visual estimation. While UV blocking by C. myrrha oil alone was not as effective as that by the synthetic sunscreen, the 1:1 combination of C. myrrha oil and SPF 15 sunblock was significantly more effective than SPF 15 sunblock alone to prevent S. cerevisiae death. These data suggest that naturally-based sunscreens supplemented with synthetic UV deterrents may provide a more holistic approach to prevent UV-induced skin damage. J Drugs Dermatol. 2018;17(8):905-907.

Development and optimization of a solid-phase microextraction gas chromatography-tandem mass spectrometry methodology to analyse ultraviolet filters in beach sand.

A methodology based on solid-phase microextraction (SPME) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) has been developed for the simultaneous analysis of eleven multiclass ultraviolet (UV) filters in beach sand. To the best of our knowledge, this is the first time that this extraction technique is applied to the analysis of UV filters in sand samples, and in other kind of environmental solid samples. Main extraction parameters such as the fibre coating, the amount of sample, the addition of salt, the volume of water added to the sand, and the temperature were optimized. An experimental design approach was implemented in order to find out the most favourable conditions. The final conditions consisted of adding 1 mL of water to 1 g of sample followed by the headspace SPME for 20 min at 100 °C, using PDMS/DVB as fibre coating. The SPME-GC-MS/MS method was validated in terms of linearity, accuracy, limits of detection and quantification, and precision. Recovery studies were also performed at three concentration levels in real Atlantic and Mediterranean sand samples. The recoveries were generally above 85% and relative standard deviations below 11%. The limits of detection were in the pg g-1 level. The validated methodology was successfully applied to the analysis of real sand samples collected from Atlantic Ocean beaches in the Northwest coast of Spain and Portugal, Canary Islands (Spain), and from Mediterranean Sea beaches in Mallorca Island (Spain). The most frequently found UV filters were ethylhexyl salicylate (EHS), homosalate (HMS), 4-methylbenzylidene camphor (4MBC), 2-ethylhexyl methoxycinnamate (2EHMC) and octocrylene (OCR), with concentrations up to 670 ng g-1.

Nanostructured hybrid monolith with integrated stirring for the extraction of UV-filters from water and urine samples.

This article presents a monolithic extraction unit with integrated stirring using carbon nanohorns and methacrylate-based compounds as monomers. The hybrid monolithic material was prepared by thermal polymerization at 70 °C for 24 h, and was applied for the extraction of UV-filters from waters and human urine samples. To achieve the integrated stirring unit, the monolith was grown over an ironware. Variables dealing with the polymerization mixture composition and the microextraction procedure were studied in depth. The resulting hybrid monolithic polymer was also characterized by scanning electron microscopy (SEM) and nitrogen intrusion porosimetry. The target analytes were quantified by UPLC-DAD, and the limits of detection were between 1 and 10 µg/L. The precision of the method (inter extraction units) expressed as relative standard deviation ranged from 5.4% and 7.9%. Also, relative recoveries values of the analyte spiked to swimming pool water and urine samples varied in the interval 72-124 and 71-114%, respectively.

Stability and removal of selected avobenzone's chlorination products.

Stability studies of two avobenzone transformation products: chloro-avobenzone [2-chloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione] and dichloro-avobenzone [2,2-dichloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione] have been performed at different pHs values as well as under UV A light and compared with the stability of avobenzone, one of the mostly used UV A filter present in sunscreens. We have additionally investigated the possibility of application of TiO2 photocatalysis as a method for the removal of them. Results have shown the differences in pH stability of all three studied compounds with much slower degradation rate under neutral conditions in comparison to the acidic ones for all three studied compounds. In the case of photolytic experiment, performed under UV A light, dichloro-avobenzone exhibited the lowest UVA stability (half-life 22.4 ± 0.7 min), while avobenzone and chloro-avobenzone are much more stable and have shown quite similar degradation pattern (half-lives 126 ± 16 min and 128 ± 25 min). Under the photocatalytic conditions the less stable was dichloro-avobenzone (half-life 14.1 ± 0.6 min), while chloro-avobenzone and avobenzone were much more stable (half-lives 41 ± 3 min and 79 ± 13 min). Dichloroavobenzone is significantly more reactive than avobenzone and its monochloro-derivative. On the basis of the formation of various stable degradation products, including substituted acetophenones, benzoic acids and phenols, identified by GC-MS, the degradation pathway has been proposed.

Environmental behavior of 12 UV filters and photocatalytic profile of ethyl-4-aminobenzoate.

Ethyl-4-aminobenzoate (Et-PABA) is currently used as a substitute for 4-aminobenzoate (PABA) in sunscreens and anesthetic ointments. Despite its widespread use and hydrophilicity, Et-PABA has never been found in environmental waters. This study, probed the occurrence of Et-PABA in both seawater and drinking water sources in Hong Kong, and evaluated its transformation products (TPs) and environmental fate via cumulative potency and photocatalytic profile analyses. Another 11 UV filters used in skin-care products were also studied. Et-PABA was not detected in any water sample. Four other UV filters were dominant at ng/L level in both seawater and drinking water sources. UHPLC-QTOF-MS was used to elucidate the structure of TPs. With high resolution accurate mass data and fragment rationalization, 11 Et-PABA TPs were characterized, including seven intermediates firstly proposed as TPs; two compounds were reported for the first time. It is proposed that photocatalysis induces transformation pathways of (de)hydroxylation, demethylation and molecular rearrangement. Luminescent bacteria tests showed decreasing toxicity with increasing irradiation of Et-PABA, suggesting that irradiation TPs are less toxic than the parent compound. Transformation of Et-PABA appears to explain why Et-PABA has not been detected in the natural environment.