UVA Photoprotection Research Articles

NLC-Based Sunscreen Formulations with Optimized Proportion of Encapsulated and Free Filters Exhibit Enhanced UVA and UVB Photoprotection.

The topical use of sunscreens is recommended for avoiding the damaging effects of UV radiation. However, improvements are still needed in the existing products to enhance their photoprotection effectiveness and safety. This involves minimizing the use of chemical UV filters while providing enhanced and prolonged photoprotection. This work investigated novel sunscreen formulations and their UV protection effects by encapsulating Uvinul® A, Tinosorb® S, and Uvinul® T150 into nanostructured lipid carriers (NLCs) based on bacuri butter and raspberry seed oil. First, the impact of critical formulation and process parameters on NLCs' particle size was evaluated using a 22 Face Centered Central Composite Design. Then, formulations were evaluated in terms of critical quality factors, in vitro skin permeation, and in vitro and in vivo photoprotection activities. The developed NLCs-containing formulations exhibited appropriate size (122-135 nm), PdI (<0.3), encapsulation efficiency (>90%), and drug content (>80%), which were preserved for at least 90 days under different stability conditions. Moreover, these NLCs-based formulations had equivalent skin permeation to emulsion-based controls, and the addition of NLCs into sunscreen cream bases in the optimum proportion of 20% (w/w) resulted in enhanced UVA and UVB photoprotection levels, despite a 10% reduction in the total filters content. Altogether, these results describe the application of nanoencapsulated organic UV filters in innovative sunscreen formulations to achieve superior photoprotection and cosmeceutical properties.

The Impact of Flavonoid-Loaded Nanoparticles in the UV Protection and Safety Profile of Topical Sunscreens.

Excessive UV radiation exposure is harmful to skin cells since sunburn is accompanied by oxidative burst, leading to a rapid increase in skin cancer. However, the insufficient UV photoprotection of approved sunscreens and the negative impact of their compositions on ecosystems and human health makes the utility of sunscreen a questionable recommendation. Therefore, discovering UV filters with significant antioxidant activity and improved topical performance and photostability is an urgent need. Recently, the use of nanosized natural molecules incorporated in sunscreens has been a scientific hot topic, as it has been suggested that they provide a synergistic effect with synthetic UV filters, improving overall SPF and antioxidant activity, higher retention on the epidermis, and less toxicity. The aim of this review was to verify the usefulness of sunscreens incorporating flavonoid-loaded nanoparticles. A literature review was performed, where original and review articles published in the last 6 years were analyzed. Formulations containing nanosized flavonoids with improved UVA photoprotection and safer toxicological profiles, associated or not with synthetic filters, are promising sunscreens and more clinical investigation must be performed to validate these findings.

Anti-Inflammatory, Antimicrobial, Antioxidant and Photoprotective Investigation of Red Propolis Extract as Sunscreen Formulation in Polawax Cream

Many activities have been described for propolis, including, antiviral, antibacterial, antifungal, anti-inflammatory, immunoregulatory, antioxidant and wound healing properties. Recently, propolis has been highlighted due to its potential application in the pharmaceutical and cosmetic industries, motivating a better understanding of its antioxidant and anti-inflammatory activities. Propolis and its main polyphenolic compounds presented high antioxidant activity, and effectiveness as broad spectrum UVB and UVA photoprotection sunscreens. Through a qualitative phytochemical screening, the ethanolic red propolis extracts (EEPV) (70% at room temperature and 70% at a hot temperature) presented a positive result for flavonoids and terpenoids. It presented an antioxidant activity for reducing 50% of DPPH of 17 and 12 μg/mL for extraction at room temperature and at a hot temperature, respectively. The UPLC-QTOF-MS/MS analysis allowed the annotation of 40 substances for EEPV-Heated and 42 substances for EEPV-Room Temperature. The IC50 results of the ABTS scavenging activity was 4.7 μg/mL for both extractions, at room temperature and at a hot temperature. Additionally, we also evaluated the cytotoxic profile of propolis extracts against macrophage (RAW 264.7 cells) and keratinocytes (HaCaT cells), which showed non-cytotoxic doses in cell viability assays even after a long period of exposure. In addition, propolis extracts showed antibacterial activity for Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis), demonstrating potential biological activity for the creation of formulations aimed at disease control and prevention.

Assessment of the photoprotective potential and toxicity of Antarctic red macroalgae extracts from Curdiea racovitzae and Iridaea cordata for cosmetic use

Botanical and marine extracts have been used in cosmetic products as natural antioxidants or UV-absorbers to reduce the use of organic UV filters. However, despite the high UV exposure of Antarctic macroalgae that induces the production of photoprotective compounds, the use of marine macroalgae extracts for photoprotection has been little explored. Thus our objective was to assess the photoprotective potential and the toxicity of extracts from two red macroalgae Curdiea racovitzae and Iridaea cordata. Chemical characterization was based on the qualitative and quantitative analyses of mycosporine-like amino acids (MAAs) by high performance liquid chromatography coupled to mass spectrometry. Photoprotective properties were assessed by UV spectrophotometry and photostability assay. Antioxidant capacity was studied by DPPH and superoxide radical scavenging assays. UVB and UVA photoprotection was assessed in keratinocytes by cell viability analysis after UVB irradiation and quantification of intracellular reactive oxygen species (ROS) induced by UVA, respectively. Toxicity was estimated by cytotoxicity, phototoxicity and HET-CAM (Hen's egg test-chorioallantoic membrane) assays. Red algae extracts had high concentrations of MAAs, mainly consisted of palythine. The extracts absorbed in the UVB and UVA-II and were photostable. The C. racovitzae extract showed antioxidant activity against superoxide radicals. In addition, the C. racovitzae (1.0 and 0.5 mg/mL) and I. cordata (1.0 mg/mL) extracts had an UVB photoprotection similar to benzophenone-3, which was dependent on the total MAAs concentration. Besides, the C. racovitzae extract decreased ROS generation by 31 and 24% at 100 and 50 μg/mL, respectively. Furthermore, it was more effective in reducing ROS generation than quercetin and Helioguard 365®. Finally, both extracts were considered to be non-cytotoxic, non-phototoxic and non-irritant. Therefore, the C. racovitzae extract is a good candidate to be added to anti-aging and sunscreen formulations in order to protect against oxidative stress and to improve the absorption spectra of UV filters.

Efficacy of a Daily Protective Moisturizer with High UVB and UVA Photoprotection in Decreasing Ultraviolet Damage: Evaluation by Reflectance Confocal Microscopy.

Patients with photodermatoses or actinic keratosis benefit from very high ultraviolet B-ultraviolet A (UVB-UVA) photoprotection. However, poor compliance is an issue that jeopardizes adequate protection, leading to disease recurrence. This study evaluated the efficacy of a daily protective moisturizer with high UVB and UVA photoprotection applied 8 h before irradiation. A monocentric, open-label, prospective, control pilot study was performed including 10 patients. Patients were irradiated with UVB and UVA before and 8 h after topical application of the product. Reflectance confocal microscopy (RCM) assessment was performed 24 h later. Clinical assessment showed a statistically significant increase in minimal erythema dose (MED) after application of the product (p <0.001). Signs of UV damage according to RCM were not observed on photoprotected skin (p <0.05). Skin irradiated 8 h after applying a daily protective moisturizer presented an increase in MED and RCM findings that equal the findings for non-irradiated skin.

Development of sunscreen products containing passion fruit seed extract

Application of sunscreen is the most established method of protecting skin from premature aging and photoaging. In this study, the passion fruit seed extract, enriched with biologically beneficial phenolics, was formulated into sun-protective makeup product. The UVB protection of concealer mousse was found have twofold higher sun protection factor (SPF) than the liquid foundation (15.48 ± 1.60 and 5.88 ± 0.30, respectively). The SPF of concealer mousse as well as the liquid foundation containing 0.1% and 0.3% of the passion fruit seed extract were 18.75 ± 0.28, 18.99 ± 0.71 and 9.32 ± 0.88, 9.77 ± 1.37, respectively. Therefore, the concealers with a similar sun-protective efficacy (p>;0.05) were included for stability test accordingly. The sun-protective efficacy did not significantly shift (p>;0.05) because the 0.1% and 0.3% passion fruit extract concealers had SPF of 18.09 ± 1.48 and 18.60 ± 1.21. The concealers exhibited UVA photoprotection with a boot star rating of 4 and a critical wavelength wider than 370 nm. The safety of 0.1% passion fruit extract concealer mousse was assessed. It did not cause skin irritation when assessed in human volunteers. This sunscreen makeup product provides UVA and UVB protection and is therefore suitable for daily application.

In vitro photoprotective effects of Marcetia taxifolia ethanolic extract and its potential for sunscreen formulations

The species Marcetia taxifolia (A.St.-Hil.) DC., Melastomataceae, which is endemic of the rupestrian fields of northeastern Brazil, contains a significant amount of flavonoids. In this work, the potential of the ethanolic extract of M. taxifolia as the active principle in a sunscreen photoprotection (UV-A and UV-B) formulation was investigated. The Liquid Chromatography High Performance-Diode Array Detector quantification (quercetin), total flavonoid content, antioxidant activity through 2.2-diphenyl-1- picrylhydrazil method, photoprotective activity against UV-B and UV-A radiation in vitro (spectrophotometric method) and potential for eye irritation using the methodology of the hen egg test-chorioallantoic membrane were performed in the extract. After that, the formulations were prepared using different concentrations of active ethanolic extract (5, 10, 20 and 30%) and the evaluation of the sun protection factor was carried out using the same methodology used for the crude extract. The crude extract showed UV-A photoprotection and low eye irritation in the hen egg test-chorioallantoic membrane test. All formulations containing M. taxifolia extract had ≥ 6 sun protection factor. Its shows the possibility to use this extracts as a sunscreen in pharmaceutical preparations.

Efficacy of a daily protective moisturizer with high UVB and UVA photoprotection in decreasing UV damage after 8 hours in patients with dysplastic nevi syndrome

Efficacy of a daily protective moisturizer with high UVB and UVA photoprotection in decreasing UV damage after 8 hours in patients with dysplastic nevi syndrome

Efficacy of a daily protective moisturizer with high UVB and UVA photoprotection in decreasing UV damage after 8 hours in patients with polymorphic light eruption

Efficacy of a daily protective moisturizer with high UVB and UVA photoprotection in decreasing UV damage after 8 hours in patients with polymorphic light eruption

Propolis as potential cosmeceutical sunscreen agent for its combined photoprotective and antioxidant properties

Propolis, bee glue, and its main polyphenolic components show high antioxidant activity as found measuring their inhibitory action on lipid peroxidation of linoleic acid (LA) in sodium dodecyl sulfate (SDS) micelles. Furthermore, these substances evidence effectiveness as broad spectrum UVB and UVA photoprotection sunscreens, as it results by measurements of sun protection factor (SPF), the universal indicator related primarily to UVB radiations, and of the two parameters giving an indication of the UVA absorbance properties, i.e. UVA/UVB ratio and critical wavelength. The combination of these characteristics moves up propolis and its main polyphenolic components to the class of cosmeceuticals, as possible active ingredient of sunscreen commercial formulations for their protective and preventive properties.

Assessment of the Photoprotection Properties of Sunscreens by Chromatographic Measurement of DNA Damage in Skin Explants

Evaluation of the photoprotection provided by sunscreens is performed either through the induction of erythema and expressed as the sun protection factor (SPF), or by the UVA-mediated persistent pigment darkening (PPD). None of these two endpoints has a link with skin cancer, the most deleterious consequence of excess exposure to solar UV radiation. We thus set up a complementary approach to evaluate the protection provided by sunscreens to the genome of human skin. This is based on the quantification of the thymine cyclobutane dimer (TT-CPD), the main DNA lesion induced by both UVB and UVA radiations. Irradiations were performed ex vivo on human skin explants and the level of TT-CPD in DNA was determined by HPLC associated with tandem mass spectrometry. The technique was first optimized and validated with three standard sunscreens. The study was then extended to the evaluation of a commercial high SPF sunscreen exhibiting efficient UVA photoprotection. The DNA protecting factor was found to reflect the ratio between UVB and UVA photoprotection, although the absolute values of the genomic protection were, as a general trend, lower than either SPF or PPD. These data show the usefulness of the proposed approach for the evaluation of the genoprotection afforded by sunscreens.

How Different Wavelengths of the Ultraviolet Spectrum Contribute to Skin Carcinogenesis: The Role of Cellular Damage Responses

The carcinogenic properties of ultraviolet (UV) light are mediated by its ability to generate DNA damage. Cellular responses to UV-induced DNA damage profoundly modulate the carcinogenic effects of UV exposures, and these responses are wavelength dependent. However, the exact contributions of different wavelengths of UV light to DNA damage, cellular damage responses, mutation, and skin carcinogenesis are incompletely understood. Given that UV-induced apoptosis is a protective cellular response to UV that prevents survival of damaged cells, inhibition of UVB-induced apoptosis by adding UVA, as reported by Ibuki et al. in this issue, may be a mechanism by which UVA augments UVB-mediated mutation and skin cancer formation.

UVA photoprotection efficacy and photostability: A comparison of different sunscreen products using in vitro and in vivo methods

UVA photoprotection efficacy and photostability: A comparison of different sunscreen products using in vitro and in vivo methods

Ferulic Acid Stabilizes a Solution of Vitamins C and E and Doubles its Photoprotection of Skin

Ferulic acid is a potent ubiquitous plant antioxidant. Its incorporation into a topical solution of 15%l-ascorbic acid and 1%alpha-tocopherol improved chemical stability of the vitamins (C+E) and doubled photoprotection to solar-simulated irradiation of skin from 4-fold to approximately 8-fold as measured by both erythema and sunburn cell formation. Inhibition of apoptosis was associated with reduced induction of caspase-3 and caspase-7. This antioxidant formulation efficiently reduced thymine dimer formation. This combination of pure natural low molecular weight antioxidants provides meaningful synergistic protection against oxidative stress in skin and should be useful for protection against photoaging and skin cancer.

Clinical Snippets

In acne, inflammatory cells and proinflammatory molecules (Il-1) were present in clinically normal pilosebaceous follicles from uninvolved skin on the back. They were there before the hyperproliferation of follicular cells often thought of as the first event in comedone formation. Jeremy and coworkers (p. 20) postulate that inflammation, with a CD4+ lymphocytic infiltrate, is the initial event in acne. Therapeutic implications include the importance of treating “uninvolved skin” of patients with acne and the role of anti-inflammatory agents in therapy. Thus acne, like psoriasis, may join the ranks of epidermal diseases in which inflammation is a necessary factor in causation. In photographs of late nineteenth-century immigrants from Europe to the US many individuals show apparent hyperpigmentation. Inoue and colleagues (p. 165) show that mice caged at high population density and stressed by restraining them for several hours have increased melanocytes and increased UVB-induced tanning. Corticostatin inhibited the hyperpigmentation. The immigration experiment cannot be repeated, but this group lived with stress and high population density and can thus be considered an historical antecedent for the reported experiments. Sun protective factors (SPF) measure the ability of a sunscreen to protect against sunlight-induced erythema. The pathway from sun exposure to skin cancer is multistepped and usually of long duration. For over a decade the enhancing role of immunosuppression for skin cancers has been demonstrated in experimental models that have corroborated clinicians' extensive observation of increased skin cancers in immunosuppressed patients after organ transplantation. A model for measuring the effect of UVA photoprotection on the immunosuppression of contact hypersensitivity is presented by Poon and coworkers (p. 184). Menon and coworkers (p. 104) report using a Q-switched ruby laser to structurally change the intercellular lipid bilayer in the human stratum corneum and increase percutaneous transport of large molecules. The pressure produced (500 bar) is two orders of magnitude higher than the pressure produced by ultrasound (0.1–5 bar). The rate of increase in pressure by the laser is a billion atmospheres/second. These pressures in the stratum corneum have a response limited to the extracellular bilayer, and they do not affect the bilayer in the intracellular lamellar body. This technique has been shown to increase the transport of insulin and dextran across the stratum corneum. Drug patches with self-contained lasers may be more than a few years off, but don't underestimate technology. In a population-based study from Northern Bavaria, Germany, 37 percent of 3730 workers with occupational dermatitis had an atopic skin diathesis, as reported by Dickel and coworkers (p. 37). The researchers determined Diepgen atopy scores and odds ratios, and attributable risks were calculated for over two dozen occupational categories. Pastry cooks, butchers, florists, health care workers, and dental technicians led the list, while metal processors, unskilled workers, and construction and cement workers had lower odds ratios and attributable risks. The authors conclude that those with atopic skin are more susceptible to irritating substances in the workplace. The high baseline rate of atopy makes counseling challenging. This data-rich paper should be an important source for those instituting preventive measures in many occupational settings.

Lip Sun Protection Factor of a Lipstick Sunscreen

Background and Objective: There is a well-documented need for effective human UVA and UVB photoprotection. Since there are important anatomical variations, the sun protection factor (SPF) of a lipstick sunscreen was measured on the anatomical site intended for use. Methods: The SPF tests were performed according to Federal US and European COLIPA guidelines. Prior to performing a test on the lip, the minimal erythemal dose (MED) of the unprotected back skin was determined. Subsequently, the sunscreen SPF was measured on the anatomical target site (lip). The evaluator was blinded with respect to scoring the SPF of each sunscreen treatment. Individual test sites were assigned to one of the following treatment conditions: (1) no treatment (MED of unprotected skin); (2) test formulation; (3) reference standard. Results: The MED on unprotected back skin was found to be 25% lower than on unprotected lip skin. The SPF of the lipstick sunscreen was measured 2 units lower than the SPF determined in the classical way on the back skin. Conclusion: It was hypothesized that the higher MED of the lower lip compared with back skin was due to the adaptation of this tissue to the continuous exposure to UV radiation.

Determination of UVA protection factors using the persistent pigment darkening (PPD) as the end point. (Part 1). Calibration of the method.

The accuracy and reliability of any method to assess the UVA protection effectiveness of sunscreens needs to be demonstrated. The aim of the present study was to calibrate the effectiveness of a biological end point (Persistent Pigment Darkening, PPD) to assess UVA photoprotection, Persistent Pigment Darkening was selected as the end point because its action spectrum extends across the UVA. A broad UVA source was chosen to challenge all UVA wavelengths. Attenuation of UVA was performed with neutral density filters (equally absorbing at all wavelengths). Human subjects were tested with a series of UVA beams attenuated by the neutral density filters. The UVA protection effectiveness of a standard sunscreen was also tested with four panels of volunteers to assess the reproducibility of the method. The attenuation factors of the neutral density filters were found to correspond to the UVA protection factors arrived at with PPD as the end point. The repetitive tests showed a good internal consistency of the method. The calibration procedure proposed shows threshold PPD, used as an end point in a UVA-PF test method, to be a reliable endogenous dosimeter for UVA radiation that enters the skin.

40] Photoprotection of skin against ultraviolet a damage

Publisher Summary Changes in lifestyle and the development of leisure activities and holiday habits have led to an increase in daily exposure of the skin to ultraviolet (UV) light, affecting an ever larger section of the population. At the same time, sun protective products have undergone improvements in their ability to protect skin against sunburn as reflected by continuous increases in sun protection factors (SPF). Though there is a plethora of end points related to UVB damage, most of them being directly or indirectly linked to DNA damage, there are only few specific UVA-related phenomena in the skin that can be quantified. In the field of photoprotection, considerable progress was made in the investigation of UVA damage when potent filter substances with maximum absorption in the range of longer than 320 nm became available. It became clear that some subchronic to chronic skin disorders are mainly because of UVA exposure (polymorphous light eruption being a typical and frequent example). This chapter discusses those methods of quantification of the impact of UV light on the skin, which are sufficiently discriminative to distinguish between mere UVB and complete UVB + UVA photoprotection and that are of use in the assessment of the efficacy of photoprotection.

A Review of Sunscreen Safety and Efficacy

The use of sunscreen products has been advocated by many health care practitioners as a means to reduce skin damage produced by ultraviolet radiation (UVR) from sunlight. There is a need to better understand the efficacy and safety of sunscreen products given this ongoing campaign encouraging their use. The approach used to establish sunscreen efficacy, sun protection factor (SPF), is a useful assessment of primarily UVB (290-320 nm) filters. The SPF test, however, does not adequately assess the complete photoprotective profile of sunscreens specifically against long wavelength UVAI (340-400 nm). Moreover, to date, there is no singular, agreed upon method for evaluating UVA efficacy despite the immediate and seemingly urgent consumer need to develop sunscreen products that provide broad-spectrum UVB and UVA photoprotection. With regard to the safety of UVB and UVA filters, the current list of commonly used organic and inorganic sunscreens has favorable toxicological profiles based on acute, subchronic and chronic animal or human studies. Further, in most studies, sunscreens have been shown to prevent the damaging effects of UVR exposure. Thus, based on this review of currently available data, it is concluded that sunscreen ingredients or products do not pose a human health concern. Further, the regular use of appropriate broad-spectrum sunscreen products could have a significant and favorable impact on public health as part of an overall strategy to reduce UVR exposure.

Measurements of UVA photoprotection

Measurements of UVA photoprotection