Safety and efficacy evaluation of gelatin-based nanoparticles associated with UV filters

Exposure to UV-B filter octylmethoxycinnamate and human health effects: Focus on endocrine disruptor actions

Human skin is the first line of photoprotection against UV radiation. However, despite having its defence mechanisms, the photoprotection that the skin exerts is not enough. To protect human skin, the inclusion of UV filters in the cosmetic industry has grown significantly as a photoprotection strategy. Octylmethoxycinnamate, also designated by octinoxate, or 2-ethylhexyl-4-methoxycinnamate (CAS number: 5466-77-3) is one of the most widely used UV-B filter in the cosmetic industry. The toxic effects of OMC have alarmed the public, but there is still no consensus in the scientific community about its use. This article aims to provide an overview of the UV filters' photoprotection, emphasizing the OMC and the possible negative effects it may have on the public health. Moreover, the current legislation will be addressed. In summary, the recommendations should be rethought to assess their risk-benefit, since the existing literature warns us to endocrine-disrupting effects of OMC. Further studies should be focus on the toxicity of OMC alone, in mixture and should consider its degradation products, to improve the knowledge of its risk assessment as EDC.

HPLC-TBARS-EVSC (high-performance liquid chromatography-thiobarbituric acid reactive substances-ex vivo stratum corneum) protocol: Selection of the subjects and approach to present the results

OBJECTIVE

Nowadays, it is recognized the need for improved safety and efficacy protocols to evaluate the human stratum corneum (SC) and its interaction with topical and cosmetic formulations by minimally or non-invasive methodologies. The aim of our research work was to streamline the HPLC-TBARS-EVSC (high-performance liquid chromatography-thiobarbituric acid reactive substances-ex vivo stratum corneum) methodology, by exploring the results of a group of 18 subjects.

METHODS

The study included nine women and nine men aged between 19 and 57 years old with phototypes from II to V. Sites in the forearm of each volunteer were randomly delimited, and the SC was collected by tape stripping. HPLC was used to quantify the MDA-TBA2 (malondialdehyde-thiobarbituric acid) adduct from the tape-stripped SC, irradiated and not by an ultraviolet (UV) simulator chamber.

RESULTS

Observing the findings of our present investigation, and the statistical approach applied, the use of the ratio between the treatment site and control would be an adequate strategy to better discriminate and evaluate the results. Additionally, an optimal selection of the volunteers to respond specifically to the purpose of the ex vivo assay also can be considered advantageous.

CONCLUSIONS

It seemed that in future studies focusing on the impact of SC UV-induced lipid peroxidation, determined by the HPLC-TBARS-EVSC, the most suitable subjects are females aged less than 35 years old, with phototype II.

In Vitro Photoprotection and Functional Photostability of Sunscreen Lipsticks Containing Inorganic Active Compounds

Titanium dioxide (TiO2) is a safe inorganic ultraviolet (UV) filter with activity against UV damage. However, the recombination of the carrier’s charge and the tendency for TiO2 aggregation are the main disadvantages. Substrate supports, such as mesoporous silica, are biocompatible strategies to incorporate TiO2, altering its interaction with the skin. Since the lips are sensitive to the adversities of the environment, including UV radiation, the application of lipstick sunscreens is of great importance and expected to provide protection for this particular area against sunburn and photoaging, among other unfavorable responses unprotected UV exposure. We investigated the in vitro photoprotective efficacy and photostability of lipstick formulations containing TiO2 incorporated into mesoporous silica (SBA-15). The samples were the lipstick base; SBA-15; TiO2 (free form); and TiO2 incorporated into SBA-15. The photoprotective efficacy was characterized in vitro using a Labsphere UV2000S. Lipsticks were irradiated in a Suntest CPS+ chamber to evaluate functional photostability. Lipstick base and SBA-15 alone did not display photoprotective efficacy. The sample containing 10.0% TiO2 incorporated into the mesoporous silica generated greater photostability and sun protection factor (SPF) value compared to the one containing only 10.0% TiO2 (free state). Our findings suggest that TiO2 + SBA-15 can be considered a broad-spectrum ingredient for innovative sunscreens, particularly for the photoprotection of the lips.

Photoprotective Efficacy of the Association of Rosmarinic Acid 0.1% with Ethylhexyl Methoxycinnamate and Avobenzone

Innovative prototype sunscreens with reduced ultraviolet (UV) filters are required to achieve safer, more effective, and more environmentally friendly formulations. Rosmarinic acid (RA) is a phenolic antioxidant and potential candidate for multifunctional sunscreens. We used RA (0.1% w/w) in combination with avobenzone (2.5% and 5.0% w/w), a UVA filter, and ethylhexyl methoxycinnamate (10.0% w/w), a UVB filter, to evaluate in vitro sun protection factor (SPF) and critical wavelength, photostability, and the in vivo SPF. RA, in vitro, improved the SPF of F2 (ethylhexyl methoxycinnamate 10.0% w/w + avobenzone 2.5% w/w + RA 0.1% w/w) and F3 (ethylhexyl methoxycinnamate 10.0% w/w + avobenzone 5.0% w/w + RA 0.1% w/w), which also presented broad-spectrum profiles; however, no expressive effects were observed for the critical wavelength (nm). By the in vivo trial, RA showed an increment in the F3 SPF value and maintained the F2 effectiveness, even when avobenzone was at 2.5%. Nonetheless, no increase in photostability was observed. Our findings suggest that incorporating natural molecules with antioxidant activities into sunscreens could decrease the proportion of conventional UV filters in the final product, with the advantage of providing other functional properties. Further investigation of higher RA concentrations, even from other sources, and other UV filter combinations could reveal important data for the development of multifunctional sunscreens.

UV Filters: Challenges and Prospects

The use of sunscreens is an established and recommended practice to protect skin from solar-induced damage. Around 30 UV filters can be used in sunscreen products in the European Union, which ought to follow the requirements of the regulation 1223/2009 to ensure their efficacy and safety for humans. Nevertheless, low photostability and putative toxicity for humans and environment have been reported for some UV filters. Particularly, the negative impact in marine organisms has recently raised concern on the scientific community. Therefore, it is important to develop new UV filters with improved safety profile and photostability. Over the last two decades, nearly 200 new compounds have revealed promising photoprotection properties. The explored compounds were obtained through different approaches, including exploration of natural sources, synthetic pathways, and nanotechnology. Almost 50 natural products and around 140 synthetic derivatives, such as benzimidazoles, benzotriazoles, hydroxycinnamic acids, xanthones, triazines, among others, have been studied aiming the discovery of novel, effective, and safer future photoprotective agents. Herein, we provide the reader with an overview about UV filters’ challenges and prospects, offering a forward-looking to the next-generation of UV filters.

Vaccinium myrtillus L. extract associated with octocrylene, bisoctrizole and titanium dioxide: in vitro and in vivo tests to evaluate safety and efficacy

OBJECTIVE

The harmful effects induced by ultraviolet exposition and the significant increment in skin cancer diagnosis confirm the necessity to develop effective and safe sunscreens. Limited efficacy and cutaneous adverse reactions of traditional formulations drove the incorporation of natural extracts into multifunctional sunscreens. Vaccinium myrtillus L. extract (VME), that contains anthocyanins and flavonoids, is a potential candidate for such systems.

METHODS

Considering that, we performed in vitro and in vivo tests to evaluate the sun protection factor (SPF), photostability and safety of sunscreen samples containing VME.

RESULTS

As main results, the SPF was reduced in both in vitro and in vivo evaluation in the presence of VME, nonetheless, the samples were photostable and safe.

CONCLUSION

Further investigation is required to better understand the unexpected effects of VME over photoprotection, decreasing the SPF value. As a conclusion, even with interesting findings, we highlight the importance of case-by-case investigations to develop multifunctional bioactive sunscreens.

Microalgae as a Sustainable, Natural-Oriented and Vegan Dermocosmetic Bioactive Ingredient: The Case of Neochloris oleoabundans

“Vegan” and “sustainable” characteristics are strong claim trends behind the development of innovative skincare, fragrances, and makeup products. This created a need in the market for compliant ingredients. To date, there have been no records evidencing the use of the microalgae Neochloris oleoabundans (NA) in dermocosmetics. Therefore, we studied the applicability of such a natural compound in this context. NA was cultivated, and the scavenging activity (SA) of the NA extracts was evaluated. The highest SA was from the aqueous extract (54.8% ± 2.1%), being higher than that of the positive control. Two hydrogels were prepared with 1.0% ammonium acryloyldimethyltaurate/VP copolymer: (1) control gel; and (2) gel with a 1.0% NA aqueous extract. In vivo experiments were performed in healthy male and female volunteers with skin phototypes of II–IV. The stratum corneum (SC) hydration and the transepidermal water loss (TEWL) were measured in the forearm of participants to determine their biocompatibility. This parameter was determined by skin bioengineering measurements, confirming that SC hydration and TEWL were not affected by the samples. The laser Doppler measurements results showed a delayed erythema onset in the sites, where the NA hydrogel was applied. The results confirmed the biocompatibility and the anti-inflammatory activity of an innovative ingredient derived from microalgae suitable for a natural and vegan lifestyle.

Propanediol (and) Caprylic Acid (and) Xylitol as a New Single Topical Active Ingredient against Acne: In Vitro and In Vivo Efficacy Assays

In addition to dermatological complications, acne can affect the quality of life of individuals in numerous ways, such as employment, social habits and body dissatisfaction. According to our expertise, caprylic acid and propanediol would not have a direct action on Cutibacterium acnes. Despite this, we investigated the existence of a synergistic effect among xylitol, caprylic acid and propanediol as a mixture of compounds representing a single topical active ingredient that could benefit the treatment against acne. In vitro and in vivo assays were performed to challenge and to prove the efficacy of propanediol, xylitol and caprylic acid (PXCA) against acne. PXCA had its MIC challenged against C. acnes (formerly Propionibacterium acnes) and Staphylococcus aureus, resulting in concentrations of 0.125% and 0.25%, respectively, and it also developed antimicrobial activity against C. acnes (time-kill test). PXCA was able to reduce the 5-alpha reductase expression in 24% (p < 0.01) in comparison with the testosterone group. By the end of 28 days of treatment, the compound reduced the skin oiliness, porphyrin amount and the quantity of inflammatory lesions in participants. According to the dermatologist evaluation, PXCA improved the skin's general appearance, acne presence and size.

Preclinical and clinical studies to evaluate cutaneous biodistribution, safety and efficacy of UV filters encapsulated in mesoporous silica SBA-15

Innovative technologies have been designed to improve efficacy and safety of chemical UV filters. Encapsulation can enhance efficacy and reduce transdermal permeation and systemic exposure. The aims of this work were (i) to determine the cutaneous biodistribution of avobenzone (AVO), oxybenzone (OXY), and octyl methoxycinnamate (OMC) incorporated in mesoporous silica SBA-15 and (ii) to perform preclinical (in vitro) and (iii) clinical safety studies to demonstrate their innocuity and to evaluate sun protection factor (SPF) in humans. Skin penetration studies showed that deposition of OXY and AVO in porcine and human skin after application of stick formulation with incorporated filters (stick incorporated filters) was significantly lower than from a marketed (non-encapsulated) stick. Cutaneous deposition and transdermal permeation of OXY in and across human skin were 3.8-and 13.4- fold lower, respectively, after application of stick entrapped filters. Biodistribution results showed that encapsulation in SBA-15 decreased AVO and OXY penetration reaching porcine and human dermis. Greater deposition (and permeation) of OXY in porcine skin than in human skin, pointed to the role of follicular transport. Stick incorporated filters had good biocompatibility in vivo and safety profiles, even under sun-exposed conditions. Entrapment of UV filters improved the SPF by 26% and produced the same SPF profile as a marketed stick. Overall, the results showed that SBA-15 enabled safety and efficacy of UV filters to be increased.

Evaluation of antioxidant, photoprotective and antinociceptive activities of Marcetia macrophylla extract: potential for formulation of sunscreens

The antioxidant, photoprotective and antinociceptive Marcetia macrophylla active extract was investigated as an active ingredient in a sunscreen cream formulation. Thus, the M. macrophylla extract showed IC50 of 3.43 mg/ml of the antioxidant (DPPH∙ scavenging test) and Sun Protection Factor of 20.25 (SPF/UV-B, at 250 µg/ml) and UV-A of 78.09% (photobleaching trans-resveratrol test). The antinociceptive activity was superior to all standards tested using the in vivo acetic acid-induced writhing test (99.14% at the dose of 200 mg/kg) and the high-performance liquid chromatography coupled with diode array detector and mass spectroscopy multi-stage (HPLC-DAD-MS/MS) enabled the structural characterization of the quercetin-3-O-hexoside, quercetin-3-O-pentoside and quercetin-3-O-desoxihexoside. The pharmaceutical formulation containing the Marcetia macrophylla crude active extract was prepared and the physicochemical tests (organoleptic characteristics, pH analysis and centrifugation), the in vitro UVB (sun protection factor, SPF) and UVA (β-carotene) using the spectroscopic method were investigated. The formulation showed satisfactory results concerning the physicochemical parameters evaluated and active against the UV test. Thus, M. macrophylla showed biological activities with potential use in pharmaceutical preparations.

Development and Characterization of Fe3O4@Carbon Nanoparticles and Their Biological Screening Related to Oral Administration

The current study presents the effect of naked Fe3O4@Carbon nanoparticles obtained by the combustion method on primary human gingival fibroblasts (HGFs) and primary gingival keratinocytes (PGKs)-relevant cell lines of buccal oral mucosa. In this regard, the objectives of this study were as follows: (i) development via combustion method and characterization of nanosized magnetite particles with carbon on their surface, (ii) biocompatibility assessment of the obtained magnetic nanoparticles on HGF and PGK cell lines and (iii) evaluation of possible irritative reaction of Fe3O4@Carbon nanoparticles on the highly vascularized chorioallantoic membrane of a chick embryo. Physicochemical properties of Fe3O4@Carbon nanoparticles were characterized in terms of phase composition, chemical structure, and polymorphic and molecular interactions of the chemical bonds within the nanomaterial, magnetic measurements, ultrastructure, morphology, and elemental composition. The X-ray diffraction analysis revealed the formation of magnetite as phase pure without any other secondary phases, and Raman spectroscopy exhibit that the pre-formed magnetic nanoparticles were covered with carbon film, resulting from the synthesis method employed. Scanning electron microscopy shown that nanoparticles obtained were uniformly distributed, with a nearly spherical shape with sizes at the nanometric level; iron, oxygen, and carbon were the only elements detected. While biological screening of Fe3O4@Carbon nanoparticles revealed no significant cytotoxic potential on the HGF and PGK cell lines, a slight sign of irritation was observed on a limited area on the chorioallantoic membrane of the chick embryo.

Scaffold-Type Structure Dental Ceramics with Different Compositions Evaluated through Physicochemical Characteristics and Biosecurity Profiles

The design and development of ceramic structures based on 3D scaffolding as dental bone substitutes has become a topic of great interest in the regenerative dentistry research area. In this regard, the present study focuses on the development of two scaffold-type structures obtained from different commercial dental ceramics by employing the foam replication method. At the same time, the study underlines the physicochemical features and the biological profiles of the newly developed scaffolds, compared to two traditional Cerabone^® materials used for bone augmentation, by employing both the in vitro Alamar blue proliferation test at 24, 48 and 96 h poststimulation and the in ovo chick chorioallantoic membrane (CAM) assay. The data reveal that the newly developed scaffolds express comparable results with the traditional Cerabone^® augmentation masses. In terms of network porosity, the scaffolds show higher pore interconnectivity compared to Cerabone^® granules, whereas regarding the biosafety profile, all ceramic samples manifest good biocompatibility on primary human gingival fibroblasts (HGFs); however only the Cerabone^® samples induced proliferation of HGF cells following exposure to concentrations of 5 and 10 µg/mL. Additionally, none of the test samples induce irritative activity on the vascular developing plexus. Thus, based on the current results, the preliminary biosecurity profile of ceramic scaffolds supports the usefulness for further testing of high relevance for their possible clinical dental applications.

Preliminary Protocol Development of a HPLC-TBARS-EVSC (Ex Vivo Stratum Corneum) Assay for Skin Research: Application in a Sunscreen System

Considering the importance of the cutaneous tissue investigation and the need for the development of new protocols to non-invasively establish the safety and efficacy of dermocosmetics and topical products, we aimed at developing an HPLC-TBARS-EVSC (high performance liquid chromatography–thiobarbituric acid reactive species–ex vivo stratum corneum) assay for the lipid peroxidation measurement on subjects’ stratum corneum (SC) obtained by tape stripping; additionally, we applied the HPLC-TBARS-EVSC assay in an emulsified sunscreen system containing ethylhexyl triazone and bemotrizinol as UV filters. HPLC analysis was performed in isocratic mode with 35% methanol/65% phosphate buffer (pH 7.0) as the mobile phase. The diode detector was set at 532 nm to quantify the malondialdehyde (MDA)-TBA adduct. An ex vivo tape stripping method was applied in 10 volunteers in three pre-defined regions of the volar forearms: the control; the irradiated; and the site containing the sunscreen (2.0 mg·cm−2). Ten adhesive tapes per region were used for SC removal. An exclusive ex vivo protocol to measure SC lipid peroxidation was preliminarily developed with linearity and selectivity. The protocol suggested the use of an artificial irradiation dose (5506 KJ·m−2) to improve the assay response from the SC. The sunscreen system had a significative decrease in SC lipoperoxidative damage compared to the control. Our protocol can aid in the efficacy establishment of anti-UV and antioxidant agents, for instance, in studies that aim at elucidating the level of SC lipid peroxidation and even in carrying out baseline investigations characterizing different ethnicities and genders.

A rutin nanocrystal gel as an effective dermal delivery system for enhanced anti-photoaging application

As a natural flavonoid compound, rutin could scavenge free radicals effectively to achieve remarkable antioxidant and anti-photoaging activity. Unfortunately, the extremely low water solubility of rutin often leads to the poor percutaneous permeability and unsatisfactory bioavailability, which has greatly restricted its clinical application. In this study, a novel freeze-dried rutin nanocrystal was developed to improve its saturation solubility, which was further redispersed in carbopol gel to formulate the targeted rutin nanocrystal gel (NC-gel) for enhanced transdermal delivery efficiency. Benefit from the advantages of NC-gel, the permeated amounts of rutin on mice in the NC-gel group was more than three times enhancement over that of the coarse drug gel group. Furthermore, the results of pharmacodynamic studies in vivo demonstrated that NC-gel could effectively prevent the skin photoaging and tissue damage induced by UV irradiation. Taken together, these results validated that NC-gel was an ideal carrier for the epidermal application of rutin to obtain excellent anti-photoaging effect, which further might provide a valuable platform for improving the transdermal bioavailability of insoluble drugs.

Pegylated catalase as a potential alternative to treat vitiligo and UV induced skin damage

The metabolic function of catalase (CAT) is to prevent oxidative damage to tissues through the hydrolysis of hydrogen peroxide, which is a strong oxidizing agent. It has been suggested as an alternative to treat skin diseases related to oxidative stress, such as vitiligo. Owing to the instability associated to the protein nature, topical use of CAT is challenging and, in this sense, PEGylation can be an interesting alternative. Here, we conjugated CAT to methoxy-poly(ethylene oxide) (mPEG) of 10, 20 and 40 kDa, by means of a nucleophilic attack of ε-amino groups to an electron-deficient carbonyl group of the reactive PEG, resulting in site specifically PEGylated bioconjugates. PEGylation yields ranged from 31% ± 2% for CAT-PEG40 to 59% ± 4% for CAT-PEG20 and were strongly affected by the reaction pH owing to the protonation/deprotonation state of primary amines of lysine and N-terminal residues. PEGylated conjugates were purified by size-exclusion chromatography (purity > 95%) and characterized by circular dichroism. Irrespectively of MW, PEG did not affected CAT secondary and tertiary structure, but a decrease in specific activity was observed, more pronounced when PEGs of higher MWs were used. However, this loss of activity is compensated by the increased long-term stability, with a gain of >5 times in t_1/2. In vitro antioxidant activity of CAT-PEG20 showed complete elimination of lipid peroxidation at the skin upper layer (stratum corneum) suitable for a topical use to treat vitiligo, as well as other skin conditions related to oxidative stress.

Current developments in the nanomediated delivery of photoprotective phytochemicals

Natural products have been used to protect the skin from harmful UV radiation for decades. Due to the ecotoxicological implications of synthetic sunscreen exposure in aquatic ecosystems, there is a greater need to explore alternative sources of UV filters. Recent research has focused on discovering novel UV absorbing photoprotective molecules from nature. In response to the excessive damage caused by UVB rays, plants induce the production of high concentrations of phytoprotective secondary metabolites and anti-oxidative enzymes. Despite promising UV absorbing and photoprotective properties, plant secondary metabolites have been underutilized in topical delivery due to low solubility and high instability. Numerous phytochemicals have been effectively nanosized, incorporated in formulations, and studied for their sustained effects in photoprotection. The present review outlines recent developments in nanosizing and delivering photoprotective crude plant extract and phytochemicals from a phytochemical perspective. We searched for articles using keywords: "UV damage," "skin photoprotection," "photodamage," and "nano delivery" in varied combinations. We identified and reviewed literature from 43 original research articles exploring nanosized phytochemicals and crude plant extracts with photoprotective activity. Nanosized phytochemicals retained higher amounts of bioactive compounds in the skin and acted as depots for their sustained release. Novel approaches in nanosizing considerably improved the photostability, efficacy, and water resistance of plant secondary metabolites. We further discuss the need for broad-spectrum sunscreen products, potential challenges, and future growth in this area.

Ex vivo penetration analysis and anti-inflammatory efficacy of the association of ferulic acid and UV filters

BACKGROUND

Unprotected chronic exposure to ultraviolet (UV) radiation generates many harmful effects to human skin and sunscreens are essential to health, however, traditional products do not provide enough protection against cutaneous oxidative stress, a process amplified by UV radiation. Therefore, the development of multifunctional photoprotective formulations seems to be a more efficacious approach, since these enable the absorption/reflection of UV radiation and maintain the cutaneous homeostasis.

OBJECTIVES

In the present study, ferulic acid (FA), a well-known antioxidant, has been combined with two UV filters, bemotrizinol and ethylhexyl triazone, and the safety and efficacy of this formulation has been assessed combining ex vivo and in vivo methods.

METHODS

Skin permeation assays were performed by applying the formulation in the volar forearm of participants, after which consecutive samples of the stratum corneum were collected by tape stripping, and the quantification of FA, bemotrizinol and ethylhexyl triazone was performed by high-performance liquid chromatography (HPLC). Also, the FA anti-inflammatory action in combination with the UV filters was probed through a method employing Laser Doppler flowmetry to measure the vasodilatory response to methyl nicotinate topical application.

RESULTS

Skin permeation assay was able to characterize the penetration depth of each substance. It should also be noted that a specific HPLC analytical method was developed in this study to enable the rapid simultaneous quantification of the three substances. Results from Laser Doppler flowmetry showed that the FA was able to mitigate the vasodilatory response.

CONCLUSIONS

FA proved to be a valuable resource in a multifunction sunscreen, not only providing an increase in the SPF of sunscreens, previously published, but also decreasing the extent of inflammation.

In vivo SPF from multifunctional sunscreen systems developed with natural compounds-A review

BACKGROUND

The use of sunscreens is mandatory, especially in countries with high ultraviolet (UV) incidence. In consequence, there has been a growing interest in using compounds from natural sources to develop new multifunctional products that protect human skin from the consequences of UV exposition. Even though there are in vitro methods to determine anti-UV efficacy, it is still required to test photoprotection activity on human skin to validate product performance.

AIM AND METHODS

In this review, we summarized all reported clinical studies about sun protection factor (SPF) measurements of sunscreens with natural compounds. We also discussed the probable action mechanism of those actives.

RESULTS

Herein, we provided an overview on recent studies concerning photoprotection activity of compounds from natural sources, for example, rutin, ferulic acid, caffeine, shea butter, and plant extracts, mainly presented in sunscreen systems with efficacy clinically established by SPF.

CONCLUSION

Our review suggested that even when the in vivo SPF evaluation has inherent difficulties, it is essential to assure the real efficacy of sunscreens. Furthermore, the incorporation of natural compounds could enhance the in vivo SPF values of such sunscreens by different mechanisms. Finally, some compounds derived from natural resources with skin benefits could be used as "green"/natural UV filters that provide broad-spectrum sunscreens with further upgrading of the multifunctional dermocosmetic formulation to enhance aesthetics and even skin health.

Antioxidants as stabilizers of UV filters: an example for the UV-B filter octylmethoxycinnamate

Background

Sunlight is one of the main harmful exogenous factors that induce the reactive oxygen species formation. The human skin is the first line of photoprotection against harmful exogenous factors, such as UV radiations. The topical application of sunscreens, containing UV-B filters, is widely used to protect against UV-induced damage. Octylmethoxycinnamate is the world’s most widely used UV-B filter in sunscreens. However, recent studies have demonstrated that this substance is an endocrine disruptor compound and with potential to damage DNA. Thus, the safety of this organic filter is a current concern for human health, and it was urgent to develop new photoprotective strategies. In this sense, due to the potential to neutralize the UV-induced free radicals, the use of antioxidants as UV filter stabilizers presented as a novel promising strategy.

Research

The purpose of this review was to assess the use of antioxidants as stabilizers for UV-B filter octylmethoxycinnamate. For this, we discuss the chemical and physical characteristics of UV-B filter octylmethoxycinnamate, emphasizing the stability, photostability, and reactivity of this UV filter. The use of antioxidants in sunscreens will also be addressed, from a perspective of the main characteristics that allowed their use in sunscreen formulations. Then, the concomitant use of both was described from a historical and physical chemical perspective, always emphasizing the advantages and disadvantages of this association.

Conclusions

The combination of antioxidants with UV-B filter octylmethoxycinnamate in appropriated formulations represents a viable strategy to protect the human skin against UV-induced damage.

Using ordered mesoporous silica SBA-15 to limit cutaneous penetration and transdermal permeation of organic UV filters

Avobenzone (AVO), oxybenzone (OXY), and octyl methoxycinnamate (OMC), are widely used UV filters. The aim of this study was to investigate the effect of incorporation in mesoporous silica (SBA-15) on their cutaneous deposition and permeation. Stick formulations containing "free" and "incorporated" UV filters (SF1 and SF2, respectively) were prepared and characterized with respect to their physicochemical, thermal, and functional properties. Cutaneous delivery experiments using porcine skin with quantification by UHPLC-MS/MS, demonstrated that skin deposition of AVO and OXY after application of SF2 for 6 and 12 h was significantly lower than that from SF1 at each time-point (Student t-test, p < 0.05): e.g. OXY permeation across the skin was 30-, 12- and 1.5-fold lower after 6, 12 and 24 h, respectively, following application of SF2. Cutaneous biodistribution profiles of AVO and OXY to 800 µm evidenced a significant decrease in the amounts in the viable epidermis and dermis. In contrast, deposition of the more lipophilic OMC was not significantly different (p ˃ 0.05). In vitro photoprotective efficacy results demonstrated that adsorption/entrapment of UV filters enhanced the sun protection factor by 94%. In conclusion, SBA-15, an innovative mesoporous material, increased photoprotection by UV filters while reducing their cutaneous penetration and transdermal permeation.

Ionic Liquid-Polymer Nanoparticle Hybrid Systems as New Tools to Deliver Poorly Soluble Drugs

The use of functional excipients such as ionic liquids (ILs) and the encapsulation of drugs into nanocarriers are useful strategies to overcome poor drug solubility. The aim of this work was to evaluate the potential of IL-polymer nanoparticle hybrid systems as tools to deliver poorly soluble drugs. These systems were obtained using a methodology previously developed by our group and improved herein to produce IL-polymer nanoparticle hybrid systems. Two different choline-based ILs and poly (lactic-co-glycolic acid) (PLGA) 50:50 or PLGA 75:25 were used to load rutin into the delivery system. The resulting rutin-loaded IL-polymer nanoparticle hybrid systems presented a diameter of 250-300 nm, with a low polydispersity index and a zeta potential of about -40 mV. The drug association efficiency ranged from 51% to 76%, which represents a good achievement considering the poor solubility of rutin. No significant particle aggregation was obtained upon freeze-drying. The presence of the IL in the nanosystem does not affect its sustained release properties, achieving about 85% of rutin released after 72 h. The cytotoxicity studies showed that the delivery system was not toxic to HaCat cells. Our findings may open a new paradigm on the therapy improvement of diseases treated with poorly soluble drugs.

Another Reason for Using Caffeine in Dermocosmetics: Sunscreen Adjuvant

The excessive exposure to ultraviolet (UV) radiation is the main cause of skin cancer, the most commonly diagnosed cancer in the world. In this context, the development of innovative and more effective sunscreens, with bioactive compounds like caffeine, displaying antioxidant and anticancer potential, is required. This research work assessed in vitro and in vivo the efficacy and safety of topical sunscreen formulations containing caffeine as an adjuvant of the UV filters. Sunscreens were prepared with 2.5% w/w caffeine or in the absence of this compound. In order to evaluate the safety of these formulations, stratum corneum hydration, skin barrier and colorimetry were assessed in vivo in healthy subjects before and after skin treatment with the samples. The efficacy of the sunscreens was assessed in vitro, using PMMA plates and a spectrophotometer equipped with an integrating sphere; and in vivo by the determination of the sun protection factor (SPF). None of the formulations caused erythema or impaired the skin barrier function. The in vitro functional characterization showed higher SPF values for the caffeine formulation. The in vivo studies also confirmed the higher SPF value of the formulation combining caffeine with the filters, compared to the caffeine-free sample. This improvement contributed to an increase of, approximately, 25% in the in vivo anti-UVB protection. In conclusion, caffeine was well tolerated by the skin and increased the photoprotective activity, being a new alternative adjuvant in sunscreens formulation.

Safety of a formulation containing chitosan microparticles with chamomile: blind controlled clinical trial

OBJECTIVE

to evaluate the safety of a topical formulation containing chamomile microparticles coated with chitosan in the skin of healthy participants.

METHOD

phase I blind, controlled, non-randomized, single-dose clinical trial with control for skin, base formulation, and formulation with microparticles. The variables analyzed were irritation and hydration by the Wilcoxon and Kruskall-Wallis tests.

RESULTS

the study started with 35 participants with a mean age of 26.3 years. Of these, 30 (85.71%) were female, 29 (82.90%) were white skinned and 32 (91.40%) had no previous pathologies. One participant was removed from the study reporting erythema at the site of application, and four other participants for not attending the last evaluation. In the 30 participants who completed the study, the tested formulation did not cause erythema, peeling, burning, pruritus or pain; there was an improvement in cutaneous hydration in the site of application of the formulation with microparticles. In the evaluation of the barrier function, there was an increase in transepidermal water loss in all sites.

CONCLUSION

the formulation with chamomile microparticles is safe for topical use, not causing irritation and improving skin hydration over four weeks of use. Its effects on barrier function need further investigation. No. RBR-3h78kz in the Brazilian Registry of Clinical Trials (ReBEC).

Ferulic acid photoprotective properties in association with UV filters: multifunctional sunscreen with improved SPF and UVA-PF

Ultraviolet (UV) radiation stimulates several injurious biological effects on cutaneous tissue, causing, for instance, photocarcinogenesis. Sunscreens are topical products designed to protect the skin against these harmful effects and their use must be encouraged. The addition of antioxidants, as ferulic acid (FA), a phenolic compound from the class of the hydroxycinnamic acids, in sunscreens could improve their sun protection factor (SPF) and prevent inflammatory reactions. Here, the clinical safety and efficacy of an association of ethylhexyl triazone and bis-ethylhexyloxyphenol methoxyphenyl triazine (UV filters) with ferulic acid were assessed. Samples had good skin biocompatibility and presented satisfactory safety profile, even in a sun-exposed condition. A synergic effect between the natural polyphenol and the UV filters was evidenced, as well as, FA increased in vivo SPF in 37% and the UVA protection factor (UVA-PF) in 26%. The in vivo data indicated that FA reinforced the broad-spectrum characteristic of the photoprotective formulations. Additionally, according to the results from the ex vivo antioxidant test, it is plausible to recommend adjustments on the ex vivo protocol to explicitly determine the positive effects of topical antioxidant ingredients applied over the skin. These results provided a new perspective for the development of multifunctional bioactive sunscreens using FA as a new platform.