Interacció entre filtres solars

Els protectors solars s'utilitzen per protegir la pell de la radiació solar ultraviolada (UV), particularment de l'UVA i UVB. Una característica important que hauria de tenir un filtre solar és la fotoestabilitat. És a dir, després d'irradiar un filtre UVA o UVB aquest hauria de romandre invariable. Tanmateix, molts filtres presenten certa reactivitat. Un conegut exemple és el del tert-butilmetoxidibenzoilmetà (BM-DBM, també conegut com avobenzona) que, malgrat la seua fotolabilitat, és un filtre UVA utilitzat habitualment. En la formulació de molts protectors solars s'utilitzen almenys dos filtres per tal de cobrir tot l'espectre UV. Això pot donar lloc bé a un efecte sinergètic que afavoreix la fotoestabilització dels filtres, o bé a una acceleració de la descomposició d'aquestos. La millora de l'estabilitat dels filtres solars UV rau en el fet d'entendre les propietats fotoquímiques i fotofísiques d'aquestes combinacions de filtres. Tot i això, fins ara no existia una metodologia generalment acceptada per tal d'estudiar de manera sistemàtica els efectes d'aquestes combinacions. En aquest treball s'ha centrat l'atenció en l'estudi de les interaccions de l'avobenzona combinada amb sis filtres UV comercials. A partir d'aquests compostos s'ha dissenyat una estratègia per tal d'investigar la fotoestabilitat dels protectors solars d'una manera més sistemàtica, tenint en compte els diferents processos que poden donar-se considerant aquestes combinacions.Sunscreens are used to protect against ultraviolet (UV) radiation reaching earth i.e. UVA and UVB regions of the solar spectrum. Among the different characteristics a sunscreen should possess, photostability is important not only to maintain an efficient protection along exposition time but also to avoid adverse effects like phototoxicity and photoallergy. However, many filters are photoreactive. This is the case of the well-known tert-butylmethoxydibenzoylmethane (BM-DBM, also known as avobenzone) which, in spite of its photolability, is a widely used UVA filter. In sunscreen formulation, at least two filters are generally present in order to cover all the UV spectra. This could produce a synergistic effect that favours filter stabilization or, on the other hand, could accelerate filter decomposition. Thus, improvement of UV filter stability is a key factor in sunscreen development that relies on the understanding of photochemical and photophysical properties of the filter combination. However, until now a general methodology to study systematically these combinations does not exist. In this work, we have focused the attention on the interactions between avobenzone and six commercial UV filters. In order to investigate the photostability of sunscreens in a more systematic way, the designed strategy takes into account all the different processes that could occur between the different single components

The Role of Photoprotection in Optimizing the Treatment of Atopic Dermatitis

Funding: The journal's Rapid Service Fee was supported by ISDIN.Atopic dermatitis (AD) is a chronic inflammatory skin disease with an estimated prevalence of 10-15% in children and 2-10% in adults. Clinically, there is notable phenotypic variability driven by a complex interaction between genetics, immune function, and the environment. Impairment of the skin barrier plays a significant role in the pathogenesis of AD. The apparent beneficial effect of sunlight in patients with atopic eczema is questioned due to its capacity to disrupt the skin barrier and generate free radicals that can damage proteins, lipids, and DNA. The sum of the external factors that an individual is exposed to throughout their lifetime is termed the exposome. Environmental factors such as sun exposure, temperature, and humidity contribute to both AD flares and regional prevalence variation. Literature on photoprotection in atopic dermatitis is very scarce. The use of adequate sunscreens in atopic dermatitis can ensure the level of photoprotection required to prevent skin photoaging and skin cancer and to mitigate skin barrier dysfunction, decrease inflammation, and neutralize facial redness. Herein we discuss and review the role of UV radiation and the exposome in the etiology of AD, as well as the role of adequate photoprotection

Role of CPI-17 in restoring skin homoeostasis in cutaneous field of cancerization: effects of topical application of a film-forming medical device containing photolyase and UV filters

Cutaneous field of cancerization (CFC) is caused in part by the carcinogenic effect of the cyclobutane pyrimidine dimers CPD and 6‐4 photoproducts (6‐4PPs). Photoreactivation is carried out by photolyases which specifically recognize and repair both photoproducts. The study evaluates the molecular effects of topical application of a film‐forming medical device containing photolyase and UV filters on the precancerous field in AK from seven patients. Skin improvement after treatment was confirmed in all patients by histopathological and molecular assessment. A gene set analysis showed that skin recovery was associated with biological processes involved in tissue homoeostasis and cell maintenance. The CFC response was associated with over‐expression of the CPI‐17 gene, and a dependence on the initial expression level was observed (P = 0.001). Low CPI‐17 levels were directly associated with pro‐inflammatory genes such as TNF (P = 0.012) and IL‐1B (P = 0.07). Our results suggest a role for CPI‐17 in restoring skin homoeostasis in CFC lesions

Basis for enhanced barrier function of pigmented skin

Humans with darkly-pigmented skin display superior permeability barrier function in comparison to humans with lightly-pigmented skin. The reduced pH of the stratum corneum (SC) of darkly-pigmented skin could account for enhanced function, because acidifying lightly-pigmented human SC resets barrier function to darkly-pigmented levels. In SKH1 (non-pigmented) vs. SKH2/J (pigmented) hairless mice, we evaluated how a pigment-dependent reduction in pH could influence epidermal barrier function. Permeability barrier homeostasis is enhanced in SKH2/J vs. SKH1 mice, correlating with a reduced pH in the lower SC that co-localizes with the extrusion of melanin granules. Darkly-pigmented human epidermis also shows substantial melanin extrusion in the outer epidermis. Both acute barrier disruption and topical basic pH challenges accelerate re-acidification of SKH2/J (but not SKH1) SC, while inducing melanin extrusion. SKH2/J mice also display enhanced expression of the SC acidifying enzyme, secretory phospholipase A2f (sPLA2f). Enhanced barrier function of SKH2/J mice could be attributed to enhanced activity of two acidic pH-dependent, ceramide-generating enzymes, β-glucocerebrosidase and acidic sphingomyelinase, leading to accelerated maturation of SC lamellar bilayers. Finally, organotypic cultures of darkly-pigmented-bearing human keratinocytes display enhanced barrier function in comparison to lightly-pigmented cultures. Together, these results suggest that the superior barrier function of pigmented epidermis can be largely attributed to the pH-lowering impact of melanin persistence/extrusion and enhanced sPLA2f expression

Cell and tissue-based models for evaluating the cutaneous impact of visible light

Owing to its low energy, visible light (VIS) was previously considered to have no photobiological effects and research was focused on the ultraviolet (UV) end of the solar spectrum. However, the discovery that exposure of skin to VIS leads to clinical changes in skin reminiscent of those of UV led to a reassessment of its effects. Driving our understanding have been cell and tissue-based models that permit a thorough dissection of the molecular events in skin cells following exposure to specific wavelengths and intensities of VIS. Here we explore how these models have been used to understand the cutaneous impact of VIS and identify substances that protect skin from its damaging effects

Inhibition of Nematocyst Discharge from Pelagia noctiluca (Cnidaria: Scyphozoa)-Prevention Measures against Jellyfish Stings

16 pages, 4 figures, 3 tables, supplementary materials: https://www.mdpi.com/article/10.3390/md20090571/s1.--Data Availability Statement: Not applicablePelagia noctiluca stings are common in Mediterranean coastal areas and, although the venom is non-lethal, they are painful. Due to its high toxicity and abundance, P. noctiluca is considered a target species for the focus of research on active ingredients to reduce the symptoms of its sting. To determine the effect of 31 substances and formulations on nematocyst discharge, we performed three tests: (1) screening of per se discharge activator solutions, (2) inhibitory test with nematocyst chemical stimulation (5% acetic acid) and (3) inhibitory test quantifying the hemolytic area. Ammonia, barium chloride, bleach, scented ammonia, carbonated cola, lemon juice, sodium chloride and papain triggered nematocyst discharge. All of them were ruled out as potential inhibitors. Butylene glycol showed a reduction in nematocyst discharge, while the formulations of 10% lidocaine in ethanol, 1.5% hydroxyacetophenone in distilled water + butylene glycol, and 3% Symsitive® in butylene glycol inhibited nematocyst discharge. These last results were subsequently correlated with a significant decrease in hemolytic area in the venom assays versus seawater, a neutral solution. The presented data represent a first step in research to develop preventive products for jellyfish stings while at the same time attempting to clarify some uncertainties about the role of various topical solutions in P. noctiluca first-aid protocolsThis research was funded by ISDIN (Spain, Barcelona). [...] Authors A.B. and J-M.G. acknowledge the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)Peer reviewe

Photoprotection Beyond Ultraviolet Radiation: A Review of Tinted Sunscreens

Both ultraviolet radiation and visible light have biologic effects on the skin. Visible light can induce erythema in light skinned individuals and pigmentation in dark skinned individuals. Broad spectrum sunscreens protect against ultraviolet radiation and do not adequately protect against visible light. For a sunscreen to protect against visible light, it must be visible on the skin. Inorganic filters (also known as mineral filters), namely, zinc oxide and titanium dioxide, are used in the form of nanoparticles in sunscreens to minimize the chalky and white appearance on the skin; as such, they do not protect against visible light. Tinted sunscreens use different formulations and concentrations of iron oxides and pigmentary titanium dioxide to provide protection against visible light. Many shades of tinted sunscreens are available by combining different amounts of iron oxides and pigmentary titanium dioxide to cater to all skin phototypes. Therefore, tinted sunscreens are beneficial for patients with visible light-induced photodermatoses and those with hyperpigmentation disorders such as melasma and post-inflammatory hyperpigmentation

Sunscreen interactions (DOI: 10.2436/20.2003.01.32)

Els protectors solars s’utilitzen per protegir la pell de la radiació solar ultraviolada (UV), particularment de l’UVA i UVB. Una característica important que hauria de tenir un filtre solar és la fotoestabilitat. És a dir, després d’irradiar un filtre UVA o UVB aquest hauria de romandre invariable. Tanmateix, molts filtres presenten certa reactivitat. Un conegut exemple és el del tert-butilmetoxidibenzoilmetà (BM-DBM, també conegut com avobenzona) que, malgrat la seua fotolabilitat, és un filtre UVA utilitzat habitualment. En la formulació de molts protectors solars s’utilitzen almenys dos filtres per tal de cobrir tot l’espectre UV. Això pot donar lloc bé a un efecte sinergètic que afavoreix la fotoestabilització dels filtres, o bé a una acceleració de la descomposició d’aquestos. La millora de l’estabilitat dels filtres solars UV rau en el fet d’entendre les propietats fotoquímiques i fotofísiques d’aquestes combinacions de filtres. Tot i això, fins ara no existia una metodologia generalment acceptada per tal d’estudiar de manera sistemàtica els efectes d’aquestes combinacions. En aquest treball s’ha centrat l’atenció en l’estudi de les interaccions de l’avobenzona combinada amb sis filtres UVcomercials. A partir d’aquests compostos s’ha dissenyat unaestratègia per tal d’investigar la fotoestabilitat dels protectorssolars d’una manera més sistemàtica, tenint en compte elsdiferents processos que poden donar-se considerant aquestescombinacions.Paraules clau: Fotòlisi de Flaix Làser, Filtres UV, Avobenzona, Oxigen singlet, Estat excitat triplet, fotostabilitat.Sunscreens are used to protect against ultraviolet (UV) radiation reaching earth i.e. UVA and UVB regions of the solar spectrum. Among the different characteristics a sunscreen should possess, photostability is important not only to maintain an efficient protection along exposition time but also to avoid adverse effects like phototoxicity and photoallergy. However, many filters are photoreactive. This is the case of the well-known tert-butylmethoxydibenzoylmethane (BM-DBM, also known asavobenzone) which, in spite of its photolability, is a widely usedUVA filter. In sunscreen formulation, at least two filters are generally present in order to cover all the UV spectra. This couldproduce a synergistic effect that favours filter stabilization or, onthe other hand, could accelerate filter decomposition. Thus, improvement of UV filter stability is a key factor in sunscreendevelopment that relies on the understanding of photochemicaland photophysical properties of the filter combination. However,until now a general methodology to study systematically thesecombinations does not exist.In this work, we have focused the attention on the interactionsbetween avobenzone and six commercial UV filters. In order toinvestigate the photostability of sunscreens in a more systematicway, the designed strategy takes into account all the differentprocesses that could occur between the different single components.Keywords: Laser Flash Photolysis, UV-filters, Avobenzone,Singlet oxygen, Triplet excited state, Photostability

Effect of Rinse Solutions on Rhizostoma pulmo (Cnidaria: Scyphozoa) Stings and the Ineffective Role of Vinegar in Scyphozoan Jellyfish Species

9 pages, 2 figures, 2 tables.-- Data Availability Statement: Data sharing is not applicable. In this study, no new data were created or analyzedRhizostoma pulmo is a widely distributed scyphozoan in the Mediterranean Sea. Their stings result mainly in erythema, small vesicles, or/and pain, and cause a high number of bathers to seek assistance from first-aid services during the summer season. Despite the threat that jellyfish stings represent to public health, there is disagreement in the scientific community on first-aid protocols, with the dispute largely centered around the effectiveness of vinegar. In the present research, we investigated the effect of commonly used rinse solutions on nematocyst discharge in R. pulmo and the effect of vinegar on three more scyphozoans (Aurelia sp., Cassiopea sp., and Rhizostoma luteum). Scented ammonia, vinegar, and acetic acid triggered nematocyst discharge in R. pulmo. Vinegar also caused nematocyst discharge in Aurelia sp., Cassiopea sp., and R. luteum. In contrast, seawater, baking soda, freshwater, urine, and hydrogen peroxide were considered neutral solutions that did not induce nematocyst discharge. These results indicate that the use of vinegar, acetic acid, or commercial products based on these compounds is counterproductive. Their use can worsen pain and discomfort caused not only by R. pulmo stings but also by those of any scyphozoan. The use of seawater is recommended for cleaning the R. pulmo sting site until an inhibitor solution that irreversibly prevents nematocyst discharge is discoveredThe authors A.B., M.M., and J.-M.G. acknowledge the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)Peer reviewe