Evaluation of the photoprotective and antioxidant potential of an avobenzone derivative.

Solar radiation can cause damage to the skin, and the use of sunscreens is one of the main protective measures. However, photounstable ultraviolet (UV) filters can generate photoproducts and reactive oxygen species (ROS). Adding antioxidants, such as resveratrol, to enhance the action of UV filters in sunscreens is an interesting strategy for reducing the damage caused by UV radiation exposure. However, new compounds must have their stability, safety and efficacy guaranteed. Avobenzone, a commonly used UV filter, stands out as a promising candidate for structural modification to enhance its stability. Its molecular hybridization with other UV filters and antioxidants can lead to safer and more effective compounds. In this study, the photoprotective and antioxidant potential of a derivative of avobenzone, hybridized with resveratrol's molecule, was evaluated using in vitro models of cells in monolayer and reconstructed human skin (RHS). Phototoxic potential was assessed using fibroblasts, while the antioxidant activity was measured using the DCFH2-DA probe in HaCaT keratinocytes and in-house RHS. The derivative exhibited UV absorption and demonstrated photostability. It did not exhibit any phototoxic nor photoreactivity potential. Additionally, it was able to photo stabilize a combination of photounstable UV filters, avobenzone and octyl methoxycinnamate, and to reduce their phototoxic potential. In terms of antioxidant activity, the derivative successfully protected against UVA-induced ROS production in the HaCaT keratinocytes model, showing statistical equivalence to the antioxidant control, quercetin (10 µg/mL). Furthermore, experiments conducted in the RHS model demonstrated a significant reduction of 30.7% in ROS generation compared to the irradiated control. This study demonstrated that structural modifications of avobenzone can lead to the development of a broad spectrum (absorbing UVB and UVA II radiation, as well as a portion of the UVA I radiation), non-phototoxic, non-photoreactive and photostable derivative for sunscreen and anti-aging formulations. This derivative enhances protection against oxidative stress induced by UV radiation and improves the effectiveness of sun protection. In addition to the monolayer model, the use of a standardized in-house RHS model was highly relevant for evaluating the effects of UV radiation and skin aging. This model closely mimics human physiological conditions and enables the testing of new compounds and the investigation of protective mechanisms against skin damage.

Assessment of the photoprotective potential and structural characterization of secondary metabolites of Antarctic fungus Arthrinium sp.

Interest in Antarctic fungi has grown due to their resilience in harsh environments, suggesting the presence of valuable compounds from its organisms, such as those presenting photoprotective potential, since this environment suffers the most dangerous UV exposure in the world. Therefore, this research aimed to assess the photoprotective potential of compounds from sustainable marine sources, specifically seaweed-derived fungi from Antarctic continent. These studies led to discovery of photoprotective and antioxidant properties of metabolites from Arthrinium sp., an endophytic fungus from Antarctic brown algae Phaeurus antarcticus. From crude extract, fractions A-I were obtained and compounds 1-6 isolated from E and F fractions, namely 3-Hydroxybenzyl alcohol (1), (-)-orthosporin (2), norlichexanthone (3), anomalin B (4), anomalin A (5), and agonodepside B (6). Compounds 1, 2, and 6 were not previously reported in Arthrinium. Fraction F demonstrated excellent absorbance in both UVA and UVB regions, while compound 6 exhibited lower UVB absorbance, possibly due to synergistic effects. Fraction F and compound 6 displayed photostability and were non-phototoxic to HaCaT cells. They also exhibited antioxidant activity by reducing intracellular ROS production induced by UVA in keratinocyte monolayers and reconstructed human skin models (resulting in 34.6% and 30.2% fluorescence reduction) and did not show irritation potential in HET-CAM assay. Thus, both are promising candidates for use in sunscreens. It is noted that Fraction F does not require further purification, making it advantageous, although clinical studies are necessary to confirm its potential applicability for sunscreen formulations.

Strategies for the evaluation of the eye irritation potential of different types of surfactants and silicones used in cosmetic products.

The ocular irritation potential of products that may come into contact with the eyes should be assessed by the combination of different in vitro alternative methods to determine different mechanisms of toxicity previously evaluated by the Draize in vivo assay. Thus, this study proposed to apply two strategies for the prediction of the eye irritation potential of different concentrations of surfactants and silicones, the first one involving evaluation Hen's Egg Test - Chorioallantoic Membrane (HET-CAM), and the other one using Bovine Corneal Opacity and Permeability (BCOP) followed by histopathological. HET-CAM was considered important in assessing the ocular irritation potential and, despite classifying almost all surfactants as "severe irritants", it could discriminate moderate and slight irritant SLES concentrations as well as Cocoamidopropyl Betaine as a severe irritant, when the coagulation score was taken into consideration. The BCOP assay alone also did not offer a good prediction of the irritant potential of surfactants, since almost all of them were classified as "no prediction can be made". However, the histopathological evaluation of the BCOP corneas was very important for establishing the degree and depth of damage related to reversibility. The present study also showed those strategies are sensitive to small variations in the studied anionic, cationic amphoteric surfactant concentrations and can be used for predicting their toxicity in the final product and can be used depending on the focus of the analysis.

Safety and efficacy of combined essential oils for the skin barrier properties: In vitro, ex vivo and clinical studies.

OBJECTIVE: To evaluate the safety and the synergistic effects of tea tree, lavender, eucalyptus and tangerine essential oils in combination on the skin using in vitro, ex vivo and clinical studies. METHODS: The phototoxicity was predicted using 3T3 neutral red uptake phototoxicity test (OECD TG 432). Skin penetration was evaluated by confocal Raman microspectroscopy using direct application of essential oils to pig ears. For the clinical studies, 40 participants were enrolled and randomized in three groups: (1) lavender, eucalyptus and tangerine, (2) the same essential oils plus melaleuca and (3) placebo group. The skin was evaluated by noninvasive techniques before and after a 90-day period of topical use. RESULTS: The essential oils were non-phototoxic, but the tangerine oil showed dose-dependent cytotoxicity (IC50: 33.1 µg/ml), presenting 35% of penetration in the viable epidermis. On the contrary, 17.7 µg/ml in combination was applied per day in the clinical study and the penetration rate for the combinations (10%, 1.77 µg/ml achieving the viable epidermis) guaranteed the safety, since in the clinical study, the application of the four essential oils improved skin barrier and morphologic skin characteristics, as well as increased skin hydration and decreased sebum levels, with no unwanted effects reported. CONCLUSIONS: All essential oils studied were considered non-cytotoxic or non-phototoxic separately except tangerine, which present a dose-dependent cytotoxicity. Finally, the essential oils in combination in an appropriate amount were safe and effective in the improvement of the hydrolipidic balance and morphological properties of the skin.

OBJECTIF: évaluer la sécurité d'emploi et les effets synergiques des associations d'huiles essentielles d'arbre à thé, de lavande, d'eucalyptus et de mandarine sur la peau à l'aide d'études in vitro, ex vivo et cliniques. MÉTHODES: la phototoxicité a été prédite avec le test de phototoxicité de fixation du rouge neutre 3T3 (OCDE TG 432). La pénétration cutanée a été évaluée par microspectroscopie confocale de Raman grâce à l'application directe d'huiles essentielles sur les oreilles de cochons. Pour les études cliniques, 40 participants ont été inclus et randomisés dans trois groupes : (1) lavande, eucalyptus et mandarine, (2) les mêmes huiles essentielles plus melaleuca et (3) un groupe placebo. La peau a été évaluée par des techniques non invasives avant et après une période d'utilisation topique de 90 jours. RÉSULTATS: les huiles essentielles se sont avérées non phototoxiques, mais l'huile de mandarine a montré une cytotoxicité dose-dépendante (CI 50 : 33,1 µg/ml), représentant 35 % de pénétration dans l'épiderme viable. À l'inverse, dans l'étude clinique, une quantité de 17,7 µg/ml par jour en association a été appliquée, et le taux de pénétration des associations (10 %, soit 1,77 µg/ml atteignant l'épiderme viable) a garanti la sécurité d'emploi, puisque dans l'étude clinique, l'application des quatre huiles essentielles a amélioré la barrière cutanée et les caractéristiques morphologiques de la peau, et a entraîné une augmentation de l'hydratation cutanée et une diminution des taux de sébum, sans signalement d'effets indésirables. CONCLUSIONS: chacune des huiles essentielles étudiées a été considérée comme non cytotoxique ou non phototoxique, à l'exception de la mandarine, qui présente une cytotoxicité dose-dépendante. Enfin, l'association d'huiles essentielles en quantité appropriée a démontré sa sécurité d'emploi et son efficacité dans l'amélioration de l'équilibre hydrolipidique et des propriétés morphologiques de la peau.

In Vitro Evaluation of the Photoprotective Potential of Quinolinic Alkaloids Isolated from the Antarctic Marine Fungus Penicillium echinulatum for Topical Use.

Marine-derived fungi proved to be a rich source of biologically active compounds. The genus Penicillium has been extensively studied regarding their secondary metabolites and biological applications. However, the photoprotective effects of these metabolites remain underexplored. Herein, the photoprotective potential of Penicillium echinulatum, an Antarctic alga-associated fungus, was assessed by UV absorption, photostability study, and protection from UVA-induced ROS generation assay on human immortalized keratinocytes (HaCaT) and reconstructed human skin (RHS). The photosafety was evaluated by the photoreactivity (OECD TG 495) and phototoxicity assays, performed by 3T3 neutral red uptake (3T3 NRU PT, OECD TG 432) and by the RHS model. Through a bio-guided purification approach, four known alkaloids, (-)-cyclopenin (1), dehydrocyclopeptine (2), viridicatin (3), and viridicatol (4), were isolated. Compounds 3 and 4 presented absorption in UVB and UVA-II regions and were considered photostable after UVA irradiation. Despite compounds 3 and 4 showed phototoxic potential in 3T3 NRU PT, no phototoxicity was observed in the RHS model (reduction of cell viability < 30%), which indicates their very low acute photoirritation and high photosafety potential in humans. Viridicatin was considered weakly photoreactive, while viridicatol showed no photoreactivity; both compounds inhibited UVA-induced ROS generation in HaCaT cells, although viridicatol was not able to protect the RHS model against UVA-induced ROS production. Thus, the results highlighted the photoprotective and antioxidant potential of metabolites produced by P. echinulatum which can be considered a new class of molecules for photoprotection, since their photosafety and non-cytotoxicity were predicted using recommended in vitro methods for topical use.

Effects of UV-filter Photostabilizers in the Photostability and Phototoxicity of Vitamin A Palmitate Combined with Avobenzone and Octyl Methoxycinnamate.

A challenge for cosmetic and dermatologic products is to develop new high-performance and safer anti-aging products based on new compounds to enhance the stability of retinyl palmitate combined with broad-spectrum UV-filters. Consequently, the aim of this work was to evaluate the effects of three often used avobenzone photostabilizers-ethylhexyl methoxycrylene (EHMCR), tris(tetramethylhydroxypiperidinol) citrate (TTMHP) and tris-biphenyl triazine (TBPT)-on the photostability and phototoxicity of the combination of avobenzone (AVO), octyl methoxycinnamate (OMC) and retinyl palmitate (RP). The photostability studies were performed by the exposure of formulations to UVA radiation. The phototoxicity was evaluated by the 3T3 neutral red uptake phototoxic assay (OECD TG 432). The addition of EHMCR, TBPT, and TTMHP in the formulations, with/or without RP, improved the photostability of AVO and RP, but EHMCR was the most effective in stabilizing RP. In the phototoxicity assay, the combinations AVO-OMC containing or not RP showed phototoxic potential. EHMCR and TTMHP reduced the phototoxicity of the combination AVO-OMC, whereas EHMCR also decreased the phototoxicity of the combination containing RP. Therefore, EHMCR might be used to the photostabilization of formulations of AVO-OMC with/or not RP, while TTMHP can be added to this photounstable UV-filter combination.

Fucoxanthin for Topical Administration, a Phototoxic vs. Photoprotective Potential in a Tiered Strategy Assessed by In Vitro Methods.

Fucoxanthin possesses a well-described antioxidant activity that might be useful for human skin photoprotection. However, there is a lack of scientific information regarding its properties when applied onto human skin. Thus, the objective of the present study was to assess the photoprotective and phototoxicity potential of fucoxanthin based on its ultraviolet (UVB 280-320 nm; UVA 320-400 nm) and visible (VIS 400-700 nm) absorption, photostability, phototoxicity in 3T3 mouse fibroblast culture vs. full-thickness reconstructed human skin (RHS), and its ability to inhibit reactive oxygen species formation that is induced by UVA on HaCaT keratinocytes. Later, we evaluated the antioxidant properties of the sunscreen formulation plus 0.5% fucoxanthin onto RHS to confirm its bioavailability and antioxidant potential through the skin layers. The compound was isolated from the alga Desmarestia anceps. Fucoxanthin, despite presenting chemical photo-instability (dose 6 J/cm2: 35% UVA and 21% VIS absorbance reduction), showed acceptable photodegradation (dose 27.5 J/cm2: 5.8% UVB and 12.5% UVA absorbance reduction) when it was added to a sunscreen at 0.5% (w/v). In addition, it increased by 72% of the total sunscreen UV absorption spectra, presenting UV-booster properties. Fucoxanthin presented phototoxic potential in 3T3 fibroblasts (mean photo effect 0.917), but it was non-phototoxic in the RHS model due to barrier function that was provided by the stratum corneum. In addition, it showed a significant inhibition of ROS formation at 0.01% (p < 0.001), in HaCat, and in a sunscreen at 0.5% (w/v) (p < 0.001), in RHS. In conclusion, in vitro results showed fucoxanthin protective potential to the skin that might contribute to improving the photoprotective potential of sunscreens in vivo.

Skin Irritation Testing beyond Tissue Viability: Fucoxanthin Effects on Inflammation, Homeostasis, and Metabolism.

UV light catalyzes the ozone formation from air pollutants, like nitrogen oxides. Since ozone reacts with cutaneous sebum lipids to peroxides and, thus, promotes inflammation, tumorigenesis, and aging, even broad-spectrum sunscreens cannot properly protect skin. Meanwhile, xanthophylls, like fucoxanthin, proved their antioxidant and cytoprotective functions, but the safety of their topical application in human cell-based models remains unknown. Aiming for a more detailed insight into the cutaneous fucoxanthin toxicity, we assessed the tissue viability according to OECD test guideline no. 439 as well as changes in inflammation (IL-1α, IL-6, IL-8), homeostasis (EGFR, HSPB1) and metabolism (NAT1). First, we proved the suitability of our 24-well-based reconstructed human skin for irritation testing. Next, we dissolved 0.5% fucoxanthin either in alkyl benzoate or in ethanol and applied both solutions onto the tissue surface. None of the solutions decreased RHS viability below 50%. In contrast, fucoxanthin ameliorated the detrimental effects of ethanol and reduced the gene expression of pro-inflammatory interleukins 6 and 8, while increasing NAT1 gene expression. In conclusion, we developed an organ-on-a-chip compatible RHS, being suitable for skin irritation testing beyond tissue viability assessment. Fucoxanthin proved to be non-irritant in RHS and already showed first skin protective effects following topical application.

Antioxidant role on the protection of melanocytes against visible light-induced photodamage.

Visible light can induce the generation of singlet oxygen and can cause oxidative stress, especially in melanocytes due to melanin photosensitization. Currently, there is no organic UV-filter that provide visible light protection. Previous studies showed that some antioxidants, such as apigenin (API), chrysin (CRI) and beta-carotene (BTC) besides neutralizing radical chain reactions can also quench singlet oxygen via physical or chemical quenching and exhibit potential for use in photoprotection. Therefore, the aim of this study is to evaluate the efficacy of API, CRI and BTC on the protection against cell death induced by melanin photosensitization and understand the underlying mechanisms that are involved in the protection. Precise protocols of melanogenesis and quantification of singlet oxygen generation were developed. Viability of B16-F10 cells with melanin basal levels and after melanogenesis induction was evaluated after visible light exposure in the presence and absence of API, CRI and BTC. Results showed that API and BTC protected cells from photoinduced cell death API exhibiting superior photoprotective effect. We noticed that the efficiency of cell protection and the rate of singlet oxygen suppression are not well correlated, at least for the studied series of antioxidants, indicating that the anti-radical capacity should be playing a major role in protecting cells against the damage induced by melanin photosensitization. In terms of sun care strategies, both API and BTC offer protection against visible light-induced damages and may be effective topical antioxidants to be added to sunscreens.

Photoprotective potential of metabolites isolated from algae-associated fungi Annulohypoxylon stygium.

Natural products, or secondary metabolites, obtained from fungal species associated with marine algae have been widely used in sunscreens due to their antioxidant activity and protective potential against solar radiation. The endophytic fungus isolated from Bostrychia radicans algae collected in the Rio Escuro mangrove, São Paulo State, Brazil, Annulohypoxylon stygium (Xylariaceae family) was studied to evaluate the photoprotective potential of its metabolites. The Annulohypoxylon genus can produce secondary metabolites with interesting cytotoxic, antibacterial and antioxidant properties and was never isolated before from a marine alga or had its metabolites studied for UV protection. The fungal culture (code As) extracted with dichloromethane: methanol (2:1) yielded 9 fractions (Asa to Asi) which were submitted to different chromatographic methodologies to obtain pure compounds, and to spectroscopic methodologies to elucidate their structures. Also, a screening was conducted to evaluate the qualitative production of the metabolites, besides the absorption in the UVA/UVB range, their photostability and phototoxicity potential using the 3T3 NRU phototoxicity test (OECD TG 432). This study led to the isolation of a novel compound, 3-benzylidene-2-methylhexahydropyrrolo [1,2-α] pyrazine-1,4-dione (1), from fractions Ase3 and Asf3; Ase1 was identified as 1-(1,3-Benzodioxol-5-yl)-1,2-propanediol (2), two metabolites were isolated as diastereomers (1S,2R)-1-phenyl-1,2-propanediol (3) from Asd2 and (1R,2R)-1-phenyl-1,2-propanediol (4) from Asd3, and Ase1 and 1,3-benzodioxole-5-methanol (5) from Asc1. The results obtained showed a great potential source of new molecules to be used as UVB filters in sunscreens, since substances 1-2 presented UVB absorption, had no phototoxic potential and were considered photostable. In conclusion, these compounds can be considered as a potential new class of molecules for photoprotection, since their photosafety and non-cytotoxicity were predicted using in vitro methods for topical use. Meanwhile, further efficacy assays shall be conducted for the establishment of their Sun Protection Factor (SPF). Also, this work provided new information concerning the metabolic profile of A. stygium, since it was possible to obtain two enantiomer compounds (3) and (4). One of them belonged to the same skeleton, but with a methylenedioxy moiety, showing the richest enzymatic pattern for this microorganism.

Novel benzophenone-3 derivatives with promising potential as UV filters: Relationship between structure, photoprotective potential and phototoxicity.

Benzophenone-3 (BP-3) is a UV filter with absorption at the UVB and UVA wavelengths which has not been extensively studied in experiments involving its absorbing effects and toxicity. We synthetized four BP-3 derivatives and characterized their photoprotective potential by UV absorption and photodegradation, their phototoxicity potential by 3T3 Neutral Red Uptake (3T3 NRU PT) and their photoreactivity by the reactive oxygen species (ROS) assay. The UV absorption, photodegradation, phototoxicity and photoreactivity of the four BP-3 derivatives (BP-3 carbonate, BP-3 carbazole, BP-3 phenylamine and BP-3 methoxy-phenylamine) were evaluated and compared to those of BP-3. Results showed that all derivatives were photostable, except BP-3 carbonate, which did not absorb in the UVA range. BP-3 phenylamine and BP-3 methoxy-phenylamine were considered non-phototoxic and weakly photoreactive in the ROS assay, while the carbazole derivative was considered phototoxic and non-photoreactive due to its rigid structure. The UV spectra of BP-3 carbonate, BP-3 phenylamine and BP-3 methoxy-phenylamine showed the influence of hydrogen bonding on their UV absorption. Based on these results, we concluded that BP-3 phenylamine and BP-3 methoxy-phenylamine could be promising UVA filters.

Diethylamino hydroxybenzoyl hexyl benzoate (DHHB) as additive to the UV filter avobenzone in cosmetic sunscreen formulations - Evaluation of the photochemical behavior and photostabilizing effect.

The aim of the present study was to investigate the photochemical behavior of DHHB and its photostabilizing effect on avobenzone (AVO) in different sunscreen formulations. The formulations were subjected to photostability studies by HPLC and spectrophotometry. In vitro phototoxicity was assessed using 3T3 fibroblast cultures. The mechanism of interaction between DHHB and AVO was investigated by steady state and time-resolved fluorescence spectroscopy. All formulations provided ultra-protection against UVA radiation. HPLC results demonstrated that DHHB did not present a photostabilizing effect on AVO. Fluorescence spectroscopy showed that AVO and DHHB interact by a static quenching mechanism and DHHB did not affect the AVO excited state lifetime. In addition, the energy transfer by Förster mechanism (FRET), which is the most often mechanism responsible for singlet-singlet quenching, is unlikely in this work. These results suggest why DHHB did not work as a photostabilizer on AVO singlet excited state. Phototoxicity results demonstrated that combinations containing DHHB (C2) did not show a phototoxic potential. Finally, although DHHB was considered to be photostable for all formulations studied (F2 and F3) it did not increase the photostability of AVO (F3). Thus, we suggested that formulations containing DHHB (F2) should be considered more advantageous than formulations containing AVO and AVO/DHHB (F1 and F3 respectively).

In vitro photosafety and efficacy screening of apigenin, chrysin and beta-carotene for UVA and VIS protection.

Currently most of sunscreens provide effective protection in the full UV range but lack VIS protection. The addition of effective antioxidants to sunscreens might afford suitable UV-VIS protection. Apigenin (API), chrysin (CRI) and beta-carotene (BTC) have shown potential for UV-VIS protection. This paper reports a photosafety and efficacy screening of such antioxidants through evaluation of the photostability, photoreactivity and phototoxicity as well as UVA/UVB ratio and critical wavelength. The assessment of the photostability, photoreactivity and phototoxicity of API, CRI and BTC, isolated and combined (CMB) was performed by HPLC, ROS assay and 3T3 NRU phototoxicity test, respectively. The phototoxicity test was also performed for CMB plus bemotrizinol (BMZ). The in vitro evaluation of the UVA protection was assessed by the determination of the UVA/UVB ratio and the critical wavelength. The antioxidants API, CRI, BTC and CMB were stable under UVA/VIS and VIS light. However weak photoreactivity after UVA/VIS irradiation was observed for API, CRI and CMB in the ROS assay. In the 3T3 NRU phototoxicity test, phototoxic potential was observed for CRI, BTC, CMB and CMB+BMZ after UVA/VIS exposure, and for BTC and CMB after VIS exposure. BMZ reduced the phototoxic potential of CMB in the VIS range. In the in vitro evaluation of UVA protection API, CRI, BTC, CMB and CMB+BMZ presented ultra UVA protection (UVA/UVB ratio>0.9) and exhibited critical wavelength close to or above 370nm. In conclusion, the use of API, CRI, BTC and their CMB aiming skin photoprotection could be considered safer in the VIS range. Furthermore, API presented the best performance in the photosafety screening among the studied antioxidants, since it was photostable and non-phototoxic in UVA/VIS and photostable, non-photoreactive and non-phototoxic in VIS range.

Mangiferin and naringenin affect the photostability and phototoxicity of sunscreens containing avobenzone.

Efficient UV-absorbing molecules are designed to protect against UV-light exposure. However, the development of photostable sunscreens is important to preserve the photoprotective efficacy and to prevent the formation of reactive oxygen species (ROS) and photodegradation products, which can promote phototoxic or photoallergic contact dermatitis. The aim of this study was to evaluate the effects of mangiferin and naringenin on the photostability and phototoxicity of sunscreens containing avobenzone. Cosmetic sunscreen formulations containing octocrylene (OCT), octyl methoxycinnamate (OMC) and avobenzone (AVO) were prepared and supplemented or not with mangiferin, naringenin, or with both compounds in combination. For photostability studies, samples of the formulations were spread onto glass plates, exposed to UVA radiation and then analyzed by high performance liquid chromatography (HPLC) to determine UV filters and the antioxidants recovery. The phototoxicity of the UV filters and antioxidants was evaluated using 3T3 fibroblast cultures that were subjected (or not) to irradiation according to OECD TG 432. The photostability studies demonstrated that AVO and naringenin showed the highest photodegradation when present in formulation FN (containing octocrylene, avobenzone, octyl methoxycinnamate and naringenin). The addition of mangiferin to this combination (FMN) resulted in an improved photostability of both substances compared to FN. The in vitro phototoxicity test showed that only avobenzone was considered phototoxic. The combination containing AVO/naringenin exhibited phototoxic potential; however, this was reduced by the addition of mangiferin (combination CMN). The results of this study are promising because it was demonstrated that mangiferin could increase the photostability and reduce the phototoxic potential of the combination of naringenin and AVO.

Photostability evaluation of five UV-filters, trans-resveratrol and beta-carotene in sunscreens.

Trans-resveratrol (RES) is used in cosmetic formulations and beta-carotene (BTC) is a classical sunscreen antioxidant, but their photostability in sunscreens, a property directly correlated to performance and safety has not been addressed in the literature. This paper reports the assessment of RES and/or BTC influence on the photostability of five UV-filters (octyl methoxycinnamate - OMC, avobenzone -AVO, octocrylene - OCT, bemotrizinole - BMZ, octyltriazone - OTZ) in three different combinations after UVA exposure followed by the identification of degradation products and the assessment of photoreactivity. The evaluation of sunscreen photostability was performed by HPLC and spectrophotometric analysis, and degradation products were identified by GC-MS analysis. Components RES, BTC, OMC and AVO were significantly degraded after UV exposure (reduction of around 16% in recovery). According to HPLC analysis, all formulations presented similar photostability profiles. Eleven degradation products were identified in GC-MS analysis, among them products of RES, BTC, OMC and AVO photodegradation. All evaluated formulations were considered photoreactive, as well as the isolated compounds RES and AVO. Considering HPLC, spectrophotometric and GC-MS results, it is suggested that formulations containing BMZ were considered the most photostable. The combination RES+BTC in a sunscreen improved the photostability of AVO. The benefits of using a combination of antioxidants in sunscreens was demonstrated by showing that using RES+BTC+studied UV-filters led to more photostable formulations, which in turn implies in better safety and efficacy.

Comparative effects of retinoic acid or glycolic acid vehiculated in different topical formulations.

Retinoids and hydroxy acids have been widely used due to their effects in the regulation of growth and in the differentiation of epithelial cells. However, besides their similar indication, they have different mechanisms of action and thus they may have different effects on the skin; in addition, since the topical formulation efficiency depends on vehicle characteristics, the ingredients of the formulation could alter their effects. Thus the objective of this study was to compare the effects of retinoic acid (RA) and glycolic acid (GA) treatment on the hairless mouse epidermis thickness and horny layer renewal when added in gel, gel cream, or cream formulations. For this, gel, gel cream, and cream formulations (with or without 6% GA or 0.05% RA) were applied in the dorsum of hairless mice, once a day for seven days. After that, the skin was analyzed by histopathologic, morphometric, and stereologic techniques. It was observed that the effects of RA occurred independently from the vehicle, while GA had better results when added in the gel cream and cream. Retinoic acid was more effective when compared to glycolic acid, mainly in the cell renewal and the exfoliation process because it decreased the horny layer thickness.

Combination of retinyl palmitate and UV-filters: phototoxic risk assessment based on photostability and in vitro and in vivo phototoxicity assays.

This study aimed to assess the phototoxic potential of combined UV-filters and retinyl palmitate (RP) in the presence or not of bemotrizinol (BMTZ), employing photostability and in vitro and in vivo phototoxicity assays. The formulations tested contained octocrylene (OCT), octyl methoxycinnamate (OMC), benzophenone-3 (BZP-3) and RP (photostable) or octocrylene (OCT), octyl methoxycinnamate (OMC), avobenzone (AVO) and RP (less photostable). Both formulations were supplemented with bemotrizinol. Photostability was evaluated by exposing, or not, formulations spread on a glass plate to UVA/UVB irradiation. The resulting products were quantified by HPLC analysis. In vitro phototoxicity of UV-filters and combinations were evaluated using 3T3 viable monolayer fibroblast cultures submitted, or not, to irradiation according to OECD TG 432. In vivo photoallergy and photoxicity were assessed by clinical studies (photopatch test). Photostability assays showed that UV-filter bemotrizinol was a better photostabilizer for RP/benzophenone-3 than for RP/avobenzone. The in vitro phototoxicity of the combination RP/avobenzone was reduced by bemotrizinol. Clinical studies did not indicate phototoxic or photoallergenic potentials in all formulations tested. It is concluded that the 3T3 NRU phototoxicity test may be considered a supplementary assay in formulation developments, since it can detect chemically unstable and potentially phototoxic combinations. However, extrapolation of in vitro positive results to human photopatch tests may be performed only to a limited extent.

Benefits of combinations of vitamin A, C and E derivatives in the stability of cosmetic formulations.

Chemically stable ester derivatives of vitamins A, C and E have become a focus of interest for their role in the satisfactory results in skin aging treatments. Accordingly, the aim of this study was to evaluate the physical and chemical stability of a cosmetic formulation containing 1% retinyl palmitate, ascorbyl tetraisopalmitate and tocopheryl acetate, alone or in combination. In the studies of physical stability, a Brookfield rheometer was used to determine rheological behavior of formulations containing the vitamins. Chemical stability was determined by HPLC on a Shimadzu system with UV detection. Results showed that formulations had pseudoplastic behavior and that vitamins did not alter their apparent viscosity and thixotropy. In the chemical stability studies, first-order reaction equations were used for determinations of the shelf-life of vitamins derivatives considering a remaining concentration of 85%. Combined vitamins in a single formulation had a slightly lower degradation rate as compared to different preparations containing only one of the vitamins. Considering that many cosmetic formulations contain vitamin combinations it is suggested that the present study may contribute to the development of more stable formulations containing liposoluble vitamins.

Efficacy of cosmetic formulations containing dispersion of liposome with magnesium ascorbyl phosphate, alpha-lipoic acid and kinetin.

The present study aimed to evaluate the photoprotective effects of cosmetic formulations containing a dispersion of liposome with magnesium ascorbyl phosphate (MAP), alpha-lipoic acid (ALA) and kinetin, as well as their effects on the hydration and viscoelastic skin properties. The photoprotection was determined in vitro (antioxidant activity) and in vivo on UV-irradiated hairless mouse skin. The hydration effects were performed with the application of the formulations under study on the forearm of human volunteers and skin conditions were analyzed before and after a single application and daily applications during 4 weeks in terms of transepidermal water loss (TEWL), skin moisture and viscoelastic properties. The raw material under study possessed free-radical scavenging activity and the formulation with it protected hairless mouse skin barrier function against UV damage. After 4 weeks of application on human skin, the formulation under study enhanced stratum corneum skin moisture and also showed hydration effects in deeper layers of the skin. Thus, it can be concluded that the cosmetic formulation containing a dispersion of liposome with MAP, ALA and kinetin under study showed photoprotective effects in skin barrier function as well as pronounced hydration effects on human skin, which suggests that this dispersion has potential antiaging effects.

Immediate and long-term effects of polysaccharides-based formulations on human skin

A new trend in cosmetic formulations is the use of biotechnological raw materials as the polysaccharides from Klebsiella pneumoniae, which are supposed to enhance cell renewal, improve skin hydration and micro-relief. Botanical extracts of Myrtus communis leaves contain different sugars, which may provide the same benefits. Thus, the objective of this study was to evaluate through objective and subjective analysis the immediate and long-term effects of cosmetic formulations containing polysaccharides biotechnologically-originated and / or the ones contained in Myrtus communis extracts. Three polysaccharide-based and placebo formulations were applied on the forearm skin of 40 volunteers. Skin hydration, transepidermal water loss (TEWL), viscoelasticity and skin micro-relief measurements were made before and 2 hours after a single application and after 15 and 30 day-periods of daily applications. Answers to a questionnaire about perceptions of formulation cosmetic features constituted the subjective analysis. All polysaccharide-based formulations enhanced skin hydration. Formulations with isolated or combined active substances improved skin barrier function as compared to placebo, in the short and long term studies. Formulations containing Myrtus communis extracts had the highest acceptance. Results suggest that daily use of formulations containing these substances is important for protection of the skin barrier function.

Uma nova tendência em formulações cosméticas é a utilização de matérias-primas biotecnológicas como os polissacarídeos de Klebsiella pneumoniae, que pode aumentar a renovação celular e melhor a hidratação e micro-relevo da pele. Por outro lado, o extrato vegetal de Myrtus communis contém diferentes polissacarídeos, que também podem proporcionar benefícios à pele. Assim, o objetivo do estudo foi a avaliação dos efeitos imediatos e em longo prazo, de formulações cosméticas contendo polissacarídeos obtidos por processo biotecnológico e/ou de extrato de M. communis por meio de análises objetivas e subjetivas. Três formulações contendo os polissacarídeos e um placebo foram aplicadas na pele dos antebraços de 40 voluntários. As medidas foram realizadas antes e após 2 horas da aplicação das formulações e após 15 e 30 dias de aplicações diárias em termos de hidratação da pele, perda transepidérmica de água (TEWL), viscoelasticidade e micro-relevo da pele. Para a análise subjetiva, os voluntários responderam um questionário a fim de obter-se informações sobre a percepção relativa à qualidade de cosméticos. Todas as formulações provocaram aumento da hidratação cutânea. As formulações que continham os polissacarídeos melhoraram a função barreira da pele, em curto e em longo prazo. A formulação contendo extrato de M. communis apresentou maior aceitação. Os resultados sugerem que o uso diário dos polissacarídeos avaliados é importante na proteção da função barreira da pele.