Avobenzone Research Articles

UV Filter NanoCapsule with Broad‐Spectrum UV Protection

AbstractIn this study, nanocapsules encapsulating avobenzone (AVB) compounded with isooctyl p‐dimethylaminobenzoate (OD‐PABA) were prepared via miniemulsion polymerization using methyl methacrylate (MMA) as the monomer, ethylene glycol dimethacrylate (EGDMA) as the cross‐linker, and poly(styrene‐co‐methacrylic acid) (P(St‐co‐MAA)) as the polymeric emulsifier. When a solid ultraviolet radiation A (UVA) filter, AVB, was encapsulated in nanocapsules (A‐UVNCs), the encapsulation and loading rates were 67.6% and 9.7%, respectively. When a liquid ultraviolet radiation B (UVB) filter, OD‐PABA, was combined with AVB, the encapsulation and loading rates of the nanocapsules (A/O‐UVNCs) of AVB and OD‐PABA increased to 90.0% and 15.6%, respectively, and 71.5% and 14.0%, respectively. The A/O‐UVNCs realized broad‐spectrum ultraviolet (UV) protection with an SPF value of 46.3. The A/O‐UVNCs have raspberry‐like nanostructures. These submicron particles can scatter and reflect a portion of the UV radiation and synergistically enhance UV protection. After exposure to simulated sunlight for four hours, the UVAPF of a sunscreen containing A‐UVNCs or A/O‐UVNCs decreased to a smaller extent than that of the sunscreen containing free AVB. Cell toxicity experiments showed that the cell viability of A‐UVNCs and A/O‐UVNCs was 85.9% and 83.0%, respectively. Therefore, UVNCs not only enhance UV protection but also improve photostability and safety.

Thyroid, neurodevelopmental, and kidney toxicities of common organic UV filters in embryo-larval zebrafish (Danio rerio), and their potential links

Organic UV filters (OUVFs) have been commonly used in sunscreen and many consumer products. Following dermal application, these compounds can enter circulation and may cause systemic effects in humans. In the present study, we chose four OUVFs frequently detected in the environment, i.e., avobenzone (AVB), benzophenone-3 (BP-3), octocrylene (OC), and octyl methoxycinnamate (OMC), and evaluated their thyroid, neurodevelopmental, and kidney toxicities. For this purpose, zebrafish embryos (<4 h post fertilization, hpf) were exposed to sublethal concentrations of AVB, BP-3, OC, or OMC until 120 hpf. Exposure to all OUVFs decreased thyroid hormone (TH) levels, probably by enhanced metabolism and excretion of THs (ugt1ab and/or sult1 st5) in the larval fish. Exposure to the OUVFs also induced hypoactivities and/or anxiety-like behaviors: Regulatory changes of mbp, gfap, c-fos, syn2a, sty1a, and stxbp1b genes, support the changes in normal neurobehavior of the larval fish. Moreover, the OUVFs exposure caused increased proteinuria in the fish, along with transcriptional changes of wt1, nephrin, podocin, and cdh17 genes, which could explain the observed reduction in kidney functions. Principal component analysis (PCA) implied the potential interplay of THs with neurogenesis, or podocyte differentiation of the larval fish. Toxicological consequences of altered TH homeostasis, neurobehavior, and kidney function at the early life stage warrant further investigations not only in humans but also in aquatic ecosystems.

Computer-aided drug design supporting sunscreen research: a showcase study using previously synthesized hybrid UV filter-antioxidant compounds.

Although quantum mechanical calculations have proven effective in accurately predicting UV absorption and assessing the antioxidant potential of compounds, the utilization of computer-aided drug design (CADD) to support sustainable synthesis research of new sunscreen active ingredients remains an area with limited exploration. Furthermore, there are ongoing concerns about the safety and effectiveness of existing sunscreens. Therefore, it remains crucial to investigate photoprotection mechanisms and develop enhanced strategies for mitigating the harmful effects of UVR exposure, improving both the safety and efficacy of sunscreen products. A previous study conducted synthesis research on eight novel hybrid compounds (I-VIII) for use in sunscreen products by molecular hybridization of trans-resveratrol (RESV), avobenzone (AVO), and octinoxate (OMC). Herein, time-dependent density functional theory (TD-DFT) calculations performed in the gas phase on the isolated hybrid compounds (I-VIII) proved to reproduce the experimental UV absorption. Resveratrol-avobenzone structure-based hybrids (I-IV) present absorption maxima in the UVB range with slight differences between them, while resveratrol-OMC structure-based hybrids (V-VIII) showed main absorption in the UVA range. Among RESV-OMC hybrids, compounds V and VI exhibited higher UV absorption intensity, and compound VIII stood out for its broad-spectrum coverage in our simulations. Furthermore, both in silico and in vitro analyses revealed that compounds VII and VIII exhibited the highest antioxidant activity, with compound I emerging as the most reactive antioxidant within RESV-AVO hybrids. The study suggests a preference for the hydrogen atom transfer (HAT) mechanism over single-electron transfer followed by proton transfer (SET-PT) in the gas phase. With a strong focus on sustainability, this approach reduces costs and minimizes effluent production in synthesis research, promoting the eco-friendly development of new sunscreen active ingredients. The SPARTAN'20 program was utilized for the geometry optimization and energy calculations of all compounds. Conformer distribution analysis was performed using the Merck molecular force field 94 (MMFF94), and geometry optimization was carried out using the parametric method 6 (PM6) followed by density functional theory (DFT/B3LYP/6-31G(d)). The antioxidant behavior of the hybrid compounds (I-VIII) was determined using the highest occupied molecular orbital (εHOMO) and the lowest unoccupied molecular orbital (εLUMO) energies, as well as the bond dissociation enthalpy (BDE), ionization potential (IP), and proton dissociation enthalpy (PDE) values, all calculated at the same level of structural optimization. TD-DFT study is carried out to calculate the excitation energy using the B3LYP functional with the 6-31G(d) basis set. The calculated transitions were convoluted with a Gaussian profile using the Gabedit program.

Prospecting toxicity of the avobenzone sunscreen in plants.

Avobenzone (AVO) is a sunscreen with high global production and is constantly released into the environment. Incorporating sewage biosolids for fertilization purposes, the leaching from cultivated soils, and the use of wastewater for irrigation explain its presence in the soil. There is a lack of information about the impact of this sunscreen on plants. In the present study, the ecotoxicity of AVO was tested at concentrations 1, 10, 100, and 1,000ng/L. All concentrations caused a reduction in root growth of Allium cepa, Cucumis sativus, and Lycopersicum esculentum seeds, as well as a mitodepressive effect, changes in the mitotic spindle and a reduction in root growth of A. cepa bulbs. The cell cycle was disturbed because AVO disarmed the enzymatic defense system of root meristems, leading to an accumulation of hydroxyl radicals and superoxides, besides lipid peroxidation in cells. Therefore, AVO shows a high potential to cause damage to plants and can negatively affect agricultural production and the growth of non-cultivated plants.

Distinguishing the transitions of fluorescence spectra of tryptophan-134 and 213 in BSA induced by bindings of UV filters, oxybenzone-3, and avobenzone

Abstract Oxybenzone-3 (OBZ) and avobenzone (ABZ), commercially available ultraviolet-light filters for sunscreens, are known to induce photosensitizing allergy as an adverse effect, similar to an analgesic ketoprofen (KTP) due to their benzophenone moiety. The present study focused on OBZ and ABZ's protein binding compared to the related analgesics, KTP, diclofenac (DCF), and ibuprofen (IBP). The bovine serum albumin (BSA) was used as a protein model, measuring the fluorescent spectral peak shifts (i) and Stern–Volmer analysis (i) of its intrinsic tryptophans. Moreover, their adsorption types (iii) were verified using the singular value decomposition (SVD) computation of fluorescence spectra. For (i), (ii), and (iii), KTP and DCF caused a no-shift peak, an ordinary dynamic quenching, and a simple Langmuir adsorption. We found OBZ exhibiting (i) red-shift and (ii) including static quenching, ABZ suggesting (i) blue-shift and (iii) binding to multiple bind sites, and IBP indicating (i) blue-shift and (iii) multivalent bindings. Integrating the results, it can be understood that OBZ interacts with subdomain IA (around W134) in BSA, while ABZ interacts with subdomain IIA (around W213) in BSA. Moreover, IBP is bound to BSA with a cooperative effect, certified by Hill's plot. OBZ and ABZ had their individual binding sites on a protein, suggesting the exchange between OBZ and ABZ might reduce their own adverse effect. The present study verified the effectiveness of the SVD computation in distinguishing the details of the adsorption manner of ligands around the intrinsic fluorescent probes.

A Survey of UV Filters Used in Sunscreen Cosmetics

The aim of this study was to determine the types of UV filters used in adult and children’s sunscreen products sold in Poland (part of the EU market) and their frequency of use. The INCI compositions of sunscreen products were collected and analyzed for the presence of UV filters. The study included 150 randomly selected preparations for adults (from 71 brands) and 50 for children (from 33 brands). The survey concerned the UV filters listed in Annex VI to Regulation (EC) No 1223/2009 of the European Parliament and Council of 30 November 2009 on cosmetic products. The most frequently used UV filters in the child sunscreens were triazine derivatives: bis-ethylhexyloxyphenol methoxyphenyl triazine (60.0%) and ethylhexyl triazone (52.0%), and ethylhexyl salicylate (46.0%), a derivative of salicylic acid. The most common in adult sunscreens were butyl methoxydibenzoylmethane (56.0%), a dibenzoylmethane derivative, followed by the salicylic acid derivative ethylhexyl salicylate (54.7%) and the triazine derivatives bis-ethylhexyloxyphenol methoxyphenyl triazine (54.7%) and ethylhexyl triazone (50.0%). Physical filters, including their nano and non-nano forms, were more popular in sunscreens for children, i.e., 50.0% (TiO2) and 22.0% (ZnO), than for adults: 21.3% (TiO2) and 6.7% (ZnO). For both adults and children, many cosmetic products contained four or five UV filters per preparation; however, the child preparations often used two UV filters. To summarize, the following UV filters dominate in photoprotectors for both adults and children: butyl methoxydibenzoylmethane, bis-ethylhexyloxyphenol methoxyphenyl triazine, ethylhexyl triazone, ethylhexyl salicylate, and diethylamino hydroxybenzoyl hexyl benzoate.

Assessing the Fate of Benzophenone-Type UV Filters and Transformation Products during Soil Aquifer Treatment: The Biofilm Compartment as Bioaccumulator and Biodegrader in Porous Media.

The fate of selected UV filters (UVFs) was investigated in two soil aquifer treatment (SAT) systems, one supplemented with a reactive barrier containing clay and vegetable compost and the other as a traditional SAT reference system. We monitored benzophenone-3 (BP-3) and its transformation products (TPs), including benzophenone-1 (BP-1), 4,4'-dihydroxybenzophenone (4DHB), 4-hydroxybenzophenone (4HB), and 2,2'-dihydroxy-4-methoxybenzophenone (DHMB), along with benzophenone-4 (BP-4) and avobenzone (AVO) in all involved compartments (water, aquifer sediments, and biofilm). The reactive barrier, which enhances biochemical activity and biofilm development, improved the removal of all detected UVFs in water samples. Among monitored UVFs, only 4HB, BP-4, and AVO were detected in sediment and biofilm samples. But the overall retained amounts were several orders of magnitude larger than those dissolved. These amounts were quantitatively reproduced with a specifically developed simple analytical model that consists of a mobile compartment and an immobile compartment. Retention and degradation are restricted to the immobile water compartment, where biofilm absorption was simulated with well-known compound-specific Kow values. The fact that the model reproduced observations, including metabolites detected in the biofilm but not in the (mobile) water samples, supports its validity. The results imply that accumulation ensures significant biodegradation even if the degradation rates are very low and suggest that our experimental findings for UVFs and TPs can be extended to other hydrophobic compounds. Biofilms act as accumulators and biodegraders of hydrophobic compounds.

Zeofilters for potentially innovative sunscreen products: formulation, stability and spectroscopic studies

Exposure to both UVA and UVB radiation from the sun stands as the primary cause of skin cancers, contributing to the escalating yearly count of diagnosed cases. Sunscreen products, (i.e. organic and inorganic UV filters) have become ubiquitous in personal-care products, packaging, plastics, dyes, and many other sectors. Ideal UV filters should be photostable and dissipate the absorbed energy efficiently. However, most organic UV filters are photolabile upon protracted UV exposure, leading to the formation of photoproducts of unknown toxicity for human health and environment. The chemical environment surrounding UV filters may strongly affect their behaviour: the interaction with other components of sunscreen formulations may enhance their degradation. Particularly, the interaction between photochemically incompatible ingredients must be avoided. Therefore, much effort has been invested in developing more effective and safe sunscreens.Our team recently focused on the preparation and characterization of hybrid UVfs obtained by the encapsulation of organic UV filters into various zeolites differing for topology. The zeolite most efficient for the encapsulation of organic UV filters, in term of stability and efficiency in radiation filtration, resulted to be LTL zeolite. Here, hybrid materials realized after the encapsulation of octinoxate (OMC) and avobenzone (AVO) in LTL zeolite were tested in terms of skin permeation profiles, cytotoxicity and photostability once the materials are dispersed in cream formulations, so to mimicking the real condition of use.The results show that the hybrids were successfully incorporated into oil-in-water emulsions and the skin permeation tests displayed a very low UV filter permeation through pig skin and no UV filter accumulation in dermis layer.The photostability of the hybrid-based emulsions were compared with that of emulsions containing a mixture of bare OMC and AVO, highlighting a reduced decrease in UV screening efficiency upon irradiation for the samples containing the hybrid materials with respect to the free filters. This evidence confirms that the encapsulation in the zeolite frameworks prevents some of the photodegradation reactions. The result of this paper highlights that zeolite encapsulation is increasingly establishing as a viable way to stabilize UV filters and other photoactive molecules.

Hybrid radical coupling during MnO2-mediated transformation of a mixture of organic UV filters: Chemistry and toxicity assessment

Manganese oxide (MnO2) is one of the most abundant metal oxides, and it is renowned for its ability to degrade various phenolic micropollutants. However, under MnO2-mediated transformation, BP-3 transforms into 12 different radical-coupled transformation products (TPs) out of 15 identified TPs. These radical-coupled TPs are reported with adverse environmental impacts. This study explored the effects of MnO2 on organic UV filter mixtures and different water constituents (i.e., bicarbonate ion (HCO3−), humic acid (HA) and halide ions) in terms of degradation efficiency and transformation chemistry. When a mixture of benzophenone-3 (BP-3) and avobenzone (AVO) underwent transformation by MnO2, hybrid radical-coupled TPs derived from both organic UV filters were generated. These hybrid radical-coupled TPs were evaluated by an in silico prediction tool and Vibrio fischeri bioluminescence inhibition assay (VFBIA). Results showed that these TPs were potentially toxic to aquatic organisms, even more so than their parent compounds. The higher the concentration of HCO3−, HA, chloride ion (Cl−) and bromide ion (Br−), the greater the reduction in the efficiencies of degrading BP-3 and AVO. Contrastingly, in the presence of iodide ion (I−), degradation efficiencies of BP-3 and AVO were enhanced; however, iodinated TPs and iodinated radical-coupled TPs were formed, with questionable toxicity. This study has revealed the environmental risks of hybrid radical-coupled TPs, iodinated TPs and iodinated radical-coupled TPs when the organic UV filters BP-3 and AVO are transformed by MnO2.

Dynamic macromolecular material design: the versatility of cucurbituril over cyclodextrin in host-guest chemistry.

The keto-enol tautomerism of avobenzone (AVO) is pivotal to its photostability, influenced by microenvironmental factors, such as, the type of solvent and complexation with macrocyclic compounds. This study explores the effect of host-guest complexation on AVO photostabilization, employing cucurbit[7]uril (CB[7]) and β-cyclodextrin (β-CD) to form inclusion complexes. CB[7] exhibits a higher affinity to the keto form of AVO, a UVC radiation absorber. The complexed keto form facilitates the regeneration of the enol form, reducing skin permeation. Spectroscopic and thermal analyses confirm 1 : 1 AVO-CB[7] and AVO-β-CD complex formation. Computational and MD simulations show that host-guest complex is favored over isolated AVO and β-CD or CB[7] molecules by 95-125 kJ mol-1, depending on the presence of implicit solvent. Both macrocycles enhance AVO photostabilization in aqueous environments, with CB[7] displaying greater selectivity for the keto form, while β-CD shows ethanol concentration-dependent binding.

Modulation of excimer formation and photostability of avobenzone inside the nanocavities of cyclodextrins

Avobenzone (AVZ), a UVA filter, is extensively used in sunscreen lotion and protects the skin from harmful UVA radiation. Despite their importance in sunscreen formulation, less attention has been given to its light induced excited state properties. Herein, we have explored the photophysical properties of AVZ in aqueous solutions and cyclodextrins (CDs) complexes by employing steady-state, time-resolved fluorescence, and molecular modelling tools followed by photostability analysis. AVZ exhibits dual emission from monomer and excimer forms in aqueous solutions. Spectroscopic studies revealed that AVZ forms multiple inclusion complexes with β-CD and γ-CD depending upon the host’s cavity size. These versatile host–guest complexes resulted in the modulation of the excimer formation of AVZ. The presence of α-CD and β-CD complexes with AVZ inhibited the excimer forms. In contrast, γ-CD facilitated excimer formation because its larger cavity could encapsulate the AVZ dimer. Stoichiometry and association constants for multiple host–guest complexes were determined using Benesi-Hildebrand (BH) plot. Job’s plot was used to confirm the stoichiometry of complexes. Time correlated single photon counting (TCSPC) technique was used to depict the excited state lifetime values of AVZ:CD inclusion complexes. Furthermore, these inclusion complexes were characterized by Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Molecular docking followed by semiempirical calculations confirm the experimental results on stoichiometries and binding constants of host–guest complexes. UV light-induced absorption kinetics revealed that the photostability of AVZ inside the β-CD cavity is much better than other inclusion complexes of CDs. Overall, the present study helps us in further understanding of excited state behavior of AVZ inside hydrophobic nanocavities.

UV filters in everyday cosmetic products, a comparative study.

Today, UV filters are found as contaminants in a variety of biological fluids and environment, e.g. in vegetable crops and surface water. This is because UV filters are widely used in everyday products. In this context, we focused this study on cosmetic products, in order to assess the importance of this source of contamination. The study of 742 cosmetic products, excluding actual sunscreen products, but including hygiene, personal care and make-up products and perfumes revealed that the most common UV filters present are butyl methoxydibenzoylmethane (90 products or 12.1% of products tested), octyl methoxycinnamate (75 products or 10.1% of products tested), octocrylene (62 products or 8.3% of products tested), octyl salicylate (43 products or 5.8% of products tested) and titanium dioxide (33 products or 4.4% of products tested). Very few UV filters are found in the hygiene products (only in 12 shampoos/conditioners and in 2 shower gels) and deodorants and toothpastes are completely free of them. Conversely, make-up and perfumes are frequently formulated with at least one UV filter. Seventy-five of the two hundred and forty-four (or 30.7%) skincare products studied contained at least one UV filter. 49.1 of the makeup products studied and 74.3% of perfumes contained it.

Microbial consortia degrade several widely used organic UV filters, but a number of hydrophobic filters remain recalcitrant to biodegradation

Organic UV filters are important ingredients in many personal care products, including sunscreens. Evaluating the biodegradability of organic UV filters is key to estimate their recalcitrance and environmental fate and thus central to their overall environmental risk assessment. In order to further understand the degradation process, the aim was to investigate whether specific consortia could degrade certain UV filters. Several bacterial strains were isolated from enrichment cultures actively degrading octocrylene (OC), butyl methoxydibenzoylmethane (BM), homosalate (HS), and 2-ethylhexyl salicylate (ES) and were utilized to construct an in-house consortium. This synthetic consortium contained 27 bacterial strains and degraded OC, BM, HS, and ES 60–80% after 12 days, but not benzophenone-3 (BP3), methoxyphenyl triazine (BEMT), methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), diethylhexyl butamido triazone (DBT), ethylhexyl triazone (EHT), or diethylamino hydroxybenzoyl hexyl benzoate (DHHB). Furthermore, several commercial microbial mixtures from Greencell were tested to assess their degradation activity toward the same organic UV filters. ES and HS were degraded by some of the commercial consortia, but to a lesser extent. The rest of the tested UV filters were not degraded by any of the commercial bacterial mixes. These results confirm that some organic UV filters are recalcitrant to biodegradation, while others are degraded by a specific set of microorganisms.

Unveiling the toxic effects, physiological responses and molecular mechanisms of tobacco (Nicotiana tabacum) in exposure to organic ultraviolet filters

Exposure to organic ultraviolet (UV) filters has raised concerns due to their potential adverse effects on environments. However, their toxic mechanisms on plants remain elusive. In this study, using integrative physiological and transcriptomic approaches we investigated the physiological and molecular responses to three representative UV filters, namely oxybenzone (OBZ), avobenzone (AVB), and octinoxate (OMC), in an agricultural model plant tobacco. The exposure to UV filters disrupts the functionality of photosystem reaction centers and the light-harvesting apparatus. Concurrently, UV filters exert a suppressive effect on the expression of genes encoding Rubisco and Calvin-Benson cycle enzymes, resulting in a decreased efficiency of the Calvin-Benson cycle and consequently hampering the process of photosynthesis. Exposure to UV filters leads to significant generation of reactive oxygen species within tobacco leaves and downregulation of oxidoreductase activities. Moreover, UV filters promote abscisic acid (ABA) accumulation by inducing the expression of ABA biosynthesis genes whereas repress indole-3-acetic acid (IAA) biosynthesis gene expression, which induce leaf yellowing and slow plant growth. In summary, the organic UV filters exert toxic effects on tobacco growth by inhibiting chlorophyll synthesis, photosynthesis, and the Calvin-Benson cycle, while generating excessive reactive oxygen species. This study sheds light on the toxic and tolerance mechanisms of UV filters in agricultural crops.

Evaluation of cytotoxic and genotoxic potential of avobenzone and octocrylene on human skin fibroblast cells

We investigated the cytotoxic and genotoxic effects of the organic UVA filter avobenzone (AVB), and the UVB filter octocrylene (OCT), found alone or in combination in different sunscreen formulations, on normal human skin fibroblast cells (CCD-1118Sk). To achieve this purpose, we used XTT viability assay, single cell gel electrophoresis (comet) assay and reactive oxygen species (ROS) assay. For cytotoxicity, CCD-1118Sk cells were exposed to various concentrations of AVB (32–800 µM), and OCT (130–6500 μM). The IC50 values were 100.2 and 1390.95 µM for AVB and OCT, respectively. IC12.5, IC25 and IC50 concentrations were chosen for genotoxicity testing. The comet assay revealed DNA damage at the two highest concentrations of AVB and all OCT concentrations. The rate of DNA damage was significantly higher than in the control groups. Co-treatment with AVB and OCT increased the level of DNA damage and intracellular oxidative stress compared with AVB and OCT treatment alone. Finally, our study showed that the UVA filter AVB, with the UVB filter OCT, may induce cytotoxic and genotoxic effects on human skin fibroblast cells. Highlights Avobenzone and octocrylene are UV filters used in sunscreen products. Healthy human skin fibroblast cell line CCD-1118Sk was used for cytotoxic and genotoxic assays. Cotreatment with avobenzone and octocrylene caused more severe DNA damage than their treatment alone. Our findings will contribute to the limited number of cytotoxicity and genotoxicity studies and lead to more detailed studies on the use of these two chemicals.

Repurposing sunscreen as an antibiotic: zinc-activated avobenzone inhibits methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major healthcare concern with associated healthcare costs reaching over ${\$}$1 billion in a single year in the USA. Antibiotic resistance in S. aureus is now observed against last line of defense antibiotics, such as vancomycin, linezolid, and daptomycin. Unfortunately, high throughput drug discovery approaches to identify new antibiotics effective against MRSA have not resulted in much tangible success over the last decades. Previously, we demonstrated the feasibility of an alternative drug discovery approach, the identification of metallo-antibiotics, compounds that gain antibacterial activity only after binding to a transition metal ion and as such are unlikely to be detected in standard drug screens. We now report that avobenzone, the primary active ingredient of most sunscreens, can be activated by zinc to become a potent antibacterial compound against MRSA. Zinc-activated avobenzone (AVB-Zn) potently inhibited a series of clinical MRSA isolates [minimal inhibitory concentration (MIC): 0.62-2.5 µM], without pre-existing resistance and activity without zinc (MIC: >10 µM). AVB-Zn was also active against clinical MRSA isolates that were resistant against the commonly used zinc-salt antibiotic bacitracin. We found AVB-Zn exerted no cytotoxicity on human cell lines and primary cells. Last, we demonstrate AVB-Zn can be deployed therapeutically as lotion preparations, which showed efficacy in a mouse wound model of MRSA infection. AVB-Zn thus demonstrates Zn-activated metallo-antibiotics are a promising avenue for future drug discovery.

Voltammetric determination of organic UV filters by carbon paste electrodes modified with pyridinium-based ionic liquids

The rapid and sensitive voltammetric determination of organic UV filters benzophenone-3 (BP-3) and avobenzone (AVO) was performed by an ionic liquid carbon paste electrode (IL-CPE). Namely, the synthesized pyridinium-based ILs, 1-butyl-3-methylpyridinium chloride ([N–C4–3C1Py]Cl) and 1-ethoxyethyl-3-methylpyridinium chloride ([N–C2OC2–3C1Py]Cl) were compared as bulk CPE modifiers for BP-3 determination. [N–C4–3C1Py]Cl-CPE showed more favorable interactions with the target analyte, and it was tested for AVO determination, too. Cyclic voltammetric (CV) studies suggested that the irreversible electrode reaction is adsorption controlled in the case of both UV filters. Also, the square-wave adsorptive stripping voltammetric (SW-AdSV) method was optimized for quantifying selected UV filters. In the model solutions, the linear calibration curve was obtained by the SW-AdSV method in the concentration range from 0.05 to 0.89 μg mL−1 at pH 3.0 for BP-3 (Eacc = −0.7 V, tacc = 100 s), and from 0.05 to 1.77 μg mL−1 at pH 11.98 for AVO (Eacc = 0.2 V, tacc = 100 s). The evaluated limit of detection (LOD) was 0.015 μg mL−1 in both cases, while the relative standard deviation (RSD) was lower than 1.5%. The affordable IL-based voltammetric sensor fulfills the main requirements for application in real samples due to an adequate selectivity towards selected analytes in the presence of interferents usually found in swimming pool water. Therefore, the BP-3 and AVO were quantified in a swimming pool water matrix with good repeatability and recovery. The obtained results demonstrate an excellent potential of the IL-CPEs, especially of the [N–C4–3C1Py]Cl-CPE, for determining selected UV filters in various real samples.

Design of Proanthocyanidins and TiO2 Nanoparticles-Based Novel Emulsions as a Platform for UV Protection.

A white oil-in-water novel emulsion stabilized by TiO2 nanoparticles with UVB shielding properties and proanthocyanidins with antioxidant activity was prepared, where the proanthocyanidins aggregated at the oil-water interface to reduce interfacial tension while TiO2 nanoparticles were dispersed in the continuous water phase to hinder droplet coalescence. It was found that the average oil droplet size was less than 10 μm and decreased with the increase of proanthocyanidins concentration, but the increase of the content of TiO2 nanoparticles had little effect on it. The combination of TiO2 nanoparticles and proanthocyanidins was versatile for oil phases with different polarities, and the resulting emulsion exhibited high stability in the face of centrifugation, heating and prolonging storage time. After encapsulating the UVA filter avobenzone in white oil, the emulsion was endowed with the ability to resist UVB and UVA. Further, the emulsion showed great free radical scavenging ability for superoxide anion radical (⋅O2 - ), hydroxyl radical (⋅OH) with the clearance rate of over 70 %, indicating the good antioxidant activity. The ingenious combination of UVB, UVA filter and antioxidant with emulsion as carrier provides a new idea for the preparation of full-band sunscreen emulsion.

Distribution of Nine Organic UV Filters along the Shore Next to the Harbor Canals in the Middle Pomeranian Region (Northern Poland)

Spatiotemporal changes in the concentration of UV filters were investigated along the shore according to increasing distance from breakwaters, from the shoreline, as well as according to seasonality in three locations of different anthropogenic pressures, involving those from cosmetic products being released during touristic activity. Nine organic UV filters (benzophenone-1 (BP-1), benzophenone-2 (BP-2), benzophenone-3 (BP-3), octocrylene (OCR), 4-methoxy benzylidene camphor (4-MBC), ethylhexyl methoxycinnamate (EHMC), ethylhexyl salicylate (EHS), homosalate (HMS), and butyl methoxydibenzoylmethane (BMDM)) were determined in core sediments, and the range of determined concentrations above the limit of quantification was between 19.2 ng·kg−1 d.w. (HMS) and 539.5 μg·kg−1 d.w. (4-MBC). Unexpectedly, contrary to the level of anthropogenic pressure, the concentrations of four (BP-1, BP-2, BP-3, OCR) UV filters decreased in the following order: Darłówko &gt; Ustka &gt; Rowy. Higher concentrations of BP-1, BP-2, BP-3, and OCR were determined in spring than in summer and autumn. The maximal concentration of HMS and EHMC/EHS was found in the summer and in the autumn, respectively. BMDM was determined occasionally only in two samples collected in Ustka. The higher maximal concentration range of all UV filters was determined in core sediments taken from the eastern (539.5 μg·kg−1 d.w.) rather than from the western (11.3 μg·kg−1 d.w.) parts of the beaches. According to increasing distance from the breakwaters, higher concentrations of UV filters were determined in sites located up to 100 m away in all locations and seasons. Spatial variation in the concentration of UV filters was observed in profiles perpendicular to the water line. Typically, higher concentrations were determined at sites having contact with water, although incidentally, high concentrations were also noticed at sites located further into the beach. The Polish coast of the Baltic Sea is not free from organic UV filters, and expectations concerning the abundance of UV filters in a given location are far from recorded data due to the impact of hydro-technical treatments (i.e., stony and wooden breakwaters, artificial reefs, nourishment) and coastal littoral drift.

Acute toxicity assessment of nine organic UV filters using a set of biotests

UV filters in environmental compartments are a source of concern related to their ecotoxicological effects. However, little is known about UV filters’ toxicity, particularly those released into the environment as mixtures. Acute toxicity of nine organic UV filters benzophenone-1, benzophenone-2, benzophenone-3, 4-methoxy benzylidene camphor, octocrylene, ethylhexyl methoxycinnamate, 2-ethylhexyl salicylate, homosalate, and butyl methoxydibenzoylmethane was determined. UV filter solutions were tested as single, binary, and ternary mixtures of various compositions. Single solutions were tested using a set of bio tests, including tests on saline crustaceans (Artemia franciscana), freshwater crustaceans (Daphnia magna), marine bacteria (Aliivibrio fischeri), and freshwater plants (Lemna minor). The tests represent different stages of the trophic chain, and hence their overall results could be used to risk assessment concerning various water reservoirs. The toxicity of binary and ternary mixtures was analyzed using the standardized Microtox® method. Generally, organic UV filters were classified as acutely toxic. Octocrylene was the most toxic for Arthemia franciscana (LC50 = 0.55 mg L–1) and Daphnia magna (EC50 = 2.66–3.67 mg L–1). The most toxic against freshwater plants were homosalate (IC50 = 1.46 mg L–1) and octocrylene (IC50 = 1.95 mg L–1). Ethylhexyl methoxycinnamate (EC50 = 1.38–2.16 mg L–1) was the most toxic for marine bacteria. The least toxic for crustaceans and plants were benzophenone-1 (EC50 = 6.15–46.78 mg L–1) and benzophenone-2 (EC50 = 14.15–54.30 mg L–1), while 4-methoxy benzylidene camphor was the least toxic for marine bacteria (EC50 = 12.97–15.44 mg L–1). Individual species differ in their sensitivity to the tested organic UV filters. An assessment of the toxicity of mixtures indicates high and acute toxicity to marine bacteria after exposition to a binary mixture of benzophenone-2 with octocrylene, 2-ethylhexyl salicylate, or homosalate. The toxicity of mixtures was lower than single solutions predicting antagonistic interaction between chemicals.Graphical abstract