Sunscreen Properties Research Articles

Adolescent sunscreen use in springtime: a prospective predictive study informed by a belief elicitation investigation

Two studies aimed to understand springtime sunscreen use amongst adolescents and to compare the predictive utility of the theory of planned behavior, descriptive norms, prototype perceptions and planning. In Study 1, a belief elicitation study with N=67 adolescents identified beliefs about, and strategies for, sunscreen use. In Study 2, N=177 adolescents completed measures of direct and belief-based theory of planned behavior measures prototype evaluation and similarity, descriptive norms and planning. Sunscreen use was reported 2months later. In Study 1, sunburn prevention and skin care emerged as the most relevant consequences of sunscreen use. Facilitators were supportive family norms. Sunscreen properties, costs and forgetting were main barriers which were commonly addressed with preparatory actions such as carrying sunscreen. In Study 2, gender, intention and prototype evaluation were predictive of sunscreen use. Positive evaluations of those who use sunscreen were related to lower sunscreen use when controlling for intention, descriptive norm and gender. Belief-based measures were the best predictors of intention. Behavioral, normative and control beliefs are crucial for understanding sunscreen. Future interventions should focus on these beliefs to change intentions.

GC-MS analysis of phytocomponents in the ethanol extract of Polygonum chinense L.

Background:The presence of diverse secondary metabolites has been reported from species of the genus Polygonum. However, there has been not much information available on phytochemical components and biological activity in the whole plant ethanol extract of Polygonum chinense L.Objective:This study was designed to determine the phytocomponents in the whole plant ethanol extract of P. chinense.Materials and Methods:GC-MS analysis of the whole plant ethanol extract of P. chinense was performed using a Perkin-Elmer GC Clarus 500 system comprising an AOC-20i auto-sampler and a gas chromatograph interfaced to a mass spectrometer (GC-MS).Results:This investigation was carried out to determine the possible chemical components from P. chinense by GC-MS. This analysis revealed that the ethanol extract of P. chinense (whole plant) contained mainly a triterpene compound–squalene (47.01%), and a plasticizer compound–1,2-benzenedicarboxylic acid, mono[2-ethylhexyl]ester (40.30%). All identified compounds were, generally, reported as having antimicrobial activity. In addition, the squalene compound also having anti-cancer, anti-oxidant, anti-tumor, chemo-preventive, pesticidal and sun-screen properties, while the plasticizer compound –1,2-benzenedicarboxylic acid, mono[2-ethylhexyl] ester reported to have anti-oxidant and anti-inflammatory properties. No activity was reported in the alcoholic compound-4-hexene-1-ol, 5-methyl-2-(1-methylethanyl)-acetate-(R)-.Conclusions:From the results, it is evident that P. chinense contains various bioactive compounds and is recommended as a plant of phytopharmaceutical importance.

The Preparation and Effect Evaluation of Natural Mineral Skin-Care Cream

In this work, purified and surface-pretreated attapulgite was added to the common recipe of the skin-care cream and the improved cream products, containing clay minerals, were prepared. In order to optimize the moisturizing and sunscreen properties of the cream products, different attapulgite addition was tried and the grinding time of the attapulite was considered. The result shows that, by adding attapulgite clay, the moisturizing and sunscreen properties of the skin-care products can be improved respectively.

UV-ABC screens of luteolin derivatives compared to edelweiss extract

Pure luteolin is a remarkably heat (200 °C/6 days) and UV stable UV-A screen, however, native luteolin enriched to 37% in an edelweiss extract lost its UV-A screen properties upon UV irradiation (∼4 MJ m −2). This contrasting behavior led to the examination of a series of purified luteolin derivatives as UV screen candidates. 3′,4′,5,7-Tetralipoyloxyflavones were synthesized from luteolin (3′,4′,5,7-tetrahydroxyflavone) and fatty acid chlorides. These acylated semi-biomolecules show a hypsochromic shift in UV–Vis spectra of about Δ λ A→B = 58 nm and absorbed in the centre of the harmful UV-B band ( λ max = 295 nm). Luteolin was also hydroxyethylated with Br(CH 2) 2OH. This substitution has no effect on the λ max = 330 nm absorption of luteolin (UV-A band). Finally the natural 4′- O-β-glucosyl-3′,5,7-trihydroxyflavone was extracted from edelweiss and used as a purified natural benchmark. Glycosylated and hydroxyethylated luteolin are both UV stable. Fully acylated luteolin derivatives degrade upon UV exposure to a stable UV-C screen with a hypsochroic shift Δ λ B→C = 35 nm. All in all, three molecular structures based on luteolin with sunscreen properties were found, distinguishable in: UV-A, UV-B, and UV-C filters. The natural product based UV-absorbers show promise as alternatives to synthetic molecules and nanoparticles in sunscreen products.

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.

Fluorescence of Sunscreens Adsorbed to Dielectric Nanospheres: Parallels to Optical Behavior on HaCat Cells and Skin

Sunscreens applied to the skin are retained primarily in the stratum corneum, where they adsorb and act as a barrier preventing UV penetration to deeper layers. Photophysical properties of sunscreens have traditionally been studied either in solvents, which are very different from skin, or in skin or complex artificial skin systems, which are difficult to handle. The purpose of this study was to determine whether polystyrene nanospheres could serve as an improvement over solvents for evaluation of the photophysical properties of sunscreens without the presence of autofluorescence from and interactions with specific skin biomolecules. We used HaCat cells and excised skin for this comparative study with nanospheres. Fluorescence spectral properties of common hydrophobic sunscreens octyl salicylate, padimate O (2-ethylhexyl-4-dimethylaminobenzoate) and octyl methoxycinnamate adsorbed to 220 nm polystyrene spheres are similar to those of sunscreens adsorbed to HaCat cells and excised skin. Specifically, similarity in the emission peaks and their approximate positions, excitation peak positions and a measurable reduction in scattering upon sunscreen addition suggest that polystyrene nanospheres constitute a useful system to evaluate the photophysical properties of topical sunscreens and may serve as a model system for high-throughput evaluation of potential sunscreens. An unexpected result of this comparative study was the observation of an increase in a specific skin component emission caused by addition of padimate O.

Use of anionic clays for photoprotection and sunscreen photostability: Hydrotalcites and phenylbenzimidazole sulfonic acid

Abstract Layered double hydroxides of hydrotalcite (HTlc) type have many applications as matrices in pharmaceutical and cosmetic fields when intercalated with active species in anionic form. The aim of this work was to intercalate 2-phenyl-1H-benzimidazole-5-sulfonic acid (Eusolex 232) (EUS) as sunscreen molecule into hydrotalcites in order to obtain the sunscreen stabilization, the reduction of its photodegradation and the elimination of close contact between skin and filter. Hydrotalcites MgAl and ZnAl were used as hosts and the intercalation products obtained were characterized by TG, RX and DSC. They were also submitted to spectrophotometric assays in order to study the matrix influence on sunlight protection and on sunscreen photostability. These experiments showed that both MgAl and ZnAl HTlc intercalation products maintained the sunscreen properties and eusolex photodegradation was reduced. The in vitro EUS release from both formulations was almost negligible when compared with formulations containing free EUS. The EUS intercalation in HTlc and the respective formulations provided advantages in the maintenance of photoprotection efficacy, filter photostabilization and avoidance of a close contact between skin and filter, with consequent elimination of allergy problems and photocross reactions.

Fluorescence of Sunscreens Adsorbed to Dielectric Nanospheres: Parallels to Optical Behavior on HaCat Cells and Skin

Sunscreens applied to the skin are retained primarily in the stratum corneum, where they adsorb and act as a barrier preventing UV penetration to deeper layers. Photophysical properties of sunscreens have traditionally been studied either in solvents, which are very different from skin, or in skin or complex artificial skin systems, which are difficult to handle. The purpose of this study was to determine whether polystyrene nanospheres could serve as an improvement over solvents for evaluation of the photophysical properties of sunscreens without the presence of autofluorescence from and interactions with specific skin biomolecules. We used HaCat cells and excised skin for this comparative study with nanospheres. Fluorescence spectral properties of common hydrophobic sunscreens octyl salicylate, padimate O (2-ethylhexyl-4-dimethylaminobenzoate) and octyl methoxycinnamate adsorbed to 220 nm polystyrene spheres are similar to those of sunscreens adsorbed to HaCat cells and excised skin. Specifically, similarity in the emission peaks and their approximate positions, excitation peak positions and a measurable reduction in scattering upon sunscreen addition suggest that polystyrene nanospheres constitute a useful system to evaluate the photophysical properties of topical sunscreens and may serve as a model system for high-throughput evaluation of potential sunscreens. An unexpected result of this comparative study was the observation of an increase in a specific skin component emission caused by addition of padimate O.

A New Method to Test the Effectiveness of Sunscreen Ingredients in a Novel Nano-surface Skin Cell Mimic

Photophysical properties of sunscreens are commonly studied in solvent media, which do not mimic the skin, or in complex artificial skin systems, which are difficult to handle. In an earlier study, we showed that polystyrene nanosphere suspensions mimic the mixed polarity environment of skin cell systems. This paper presents a new method to quantify the effectiveness of sunscreens in the polystyrene nanosphere environment. This method utilizes the intrinsic UV-B fluorescence of polystyrene nanospheres. We studied three UV-B sunscreens by this new method and compared their extinction coefficients with observed values in solvent. The values follow the trend observed in solvents, but the ratio of their extinction coefficient in solvent to the value obtained by this new method is 1.3-1.8 instead of 1. This difference might be caused by the mixed polarity or the microgeometry of the nanosphere system. Regardless of the difference in the extinction coefficients, this new system can be used to test hundreds of chemicals for their sunscreening potential in a cost-effective way. One marked advantage of this new method is its ability to test both hydrophobic and hydrophilic sunscreening chemicals in the same environment. This is virtually impossible for current solvent-based models, which require different solvents for hydrophobic and hydrophilic chemicals. The new method also allows the simultaneous evaluation of a host of photophysical properties of sunscreening chemicals.

HIPPOS LEAD THE WAY IN MULTIPURPOSE SUN SCREEN

Flick through a fashion magazine this summer and you'll be bombarded with adverts warning against sunburn. In an era of ozone depletion and heightened awareness of skin cancers, many retailers are earning good PR points by stocking only high-factor sunscreen products; complementing their ranges with a multitude of celebrity-endorsed fake tanning lotions and potions. But with millions of pounds already invested in developing the next generation of sunscreen sprays, industry insiders may be more than a little surprised to hear that hippos, not humans, are leading the way in today's most sophisticated sun protection.A recent study by Yoko Saikawa and his team at Keio University and Kyoto Pharmaceutical University in Japan has revealed that hippos produce their own coolant, antibiotic and sunscreen all in one. Chemical analysis of the pigments responsible for the famous hippo blush has solved the mystery behind the ancient myth that hippos sweat blood.Produced by the glands under the skin, and therefore not strictlya sweat, hot hippos secrete a fluid that acts like sweat in helping to control body temperature. The massive beasts live in central Africa, mainly in the Nile Valley, where they spend most of the year under direct sunlight and searing heat. Their `sweat' is produced as a thick clear fluid but turns red-brown within a few minutes of perspiration. This change in colour creates the famous hippo flush over the face, behind the ears and down the back.Noticing that the animals produce more of this sticky substance when lazing on land than in water, scientists began to wonder if the secretion might have other benefits. Eager to discover more about the colourful liquid, Saikawa's team bravely wiped the brows and backs of two captive hippos to collect samples on gauze swabs. The researchers then extracted the chemicals from the liquid, concentrated and purified them, and ultimately isolated two pigments -one red and one orange. Naming the red pigment `hipposudoric acid' and the orange pigment `norhipposudoric acid', the researchers then set out to test the potential antibiotic and sunscreen properties of the fluid.By trying to grow bacteria in the presence of the pigments, the scientists discovered that the red pigment acts as an effective antibiotic. Male hippos are renowned for their aggressive clashes with rivals, and antibiotic secretions may play an important role in minimising battle-won infections.Satisfied at having solved one mystery, the researchers then turned their attention to the potential sun screening function of the `sweat'. By measuring how much of the sun's spectrum is absorbed by the secreted pigments, Saikawa and colleagues revealed that the fluid blocks a good portion of the ultraviolet and visible spectrum (200-600 nm). The researchers conclude that hippo sweat cools the body and protects against both infection and sunburn. Not bad for an ancient lumbering beast.Having unlocked the secrets of the multipurpose hippo flush, scientists may now focus their attention on discovering how the famous red-brown hue is maintained for hours after secretion. Multipurpose and long lasting - this hippo product appears to have it all.

Attempt to protect wood using copper(II) complex with 1,7-diphenyl-1,6-heptadiene-3,5-dione, a non-phenolic curcuminoid

For the first time, curcuminoids known for their antioxidant and sunscreen properties were used for photoprotection of lignocellulosics. It was shown that complex between copper(II) and non-substituted curcumin 2, displaying remarkable photostability in ethyl acetate/ethanol solution, is able to photostabilize in some extend α-carbonyl β-O-4 lignin model and more efficiently spruce wood.

A New Model Using Liposomes That Allow to Distinguish Between Absorption and Oxidative Properties of Sunscreens¶

We have developed a new model using liposome-encapsulated fluorescent probes, aiming at assessing both the physical and the biological protection provided by filter molecules such as those incorporated in sunscreens. The fluorescent indicator Indo-1 or 2',7'-dichlorofluorescin (DCFH) was inside the liposomes, in the aqueous inner compartment, whereas the filter molecules octyl methoxycinnamate (OMC), benzophenone-3 (BP3) or avobenzone, widely used in sunscreens, were incorporated into liposome membranes. When liposome suspensions were placed in a fluorometer cuvette exposed to an incident UV beam, the decrease of Indo-1 fluorescence as a function of filter concentration was related to the extinction coefficient of the filters. On the other hand, when liposome suspensions were exposed to moderate UVB doses allowing Indo-1 photobleaching, the remaining intact Indo-1 was linked to the protection provided by filter-containing liposome membranes. Finally, when liposome-encapsulated DCFH was exposed to UVB, the degree of photo-oxidation of the fluorescent probe into 2',7'-dichlorofluorescein accounted for the photoprotection provided by the filter contained in liposome membranes. BP3 was more potent and slightly less efficient than the other two filters in preventing Indo-1 fluorescence; all three filters provided a similar concentration-dependent protection of Indo-1 photobleaching, whereas only OMC was able to prevent the photooxidation of DCFH. The liposome model presented here has the advantage of combining both physical and biological parameters to assess the photoprotection provided by filter molecules, and the lack of photoprotection by two sunscreen molecules having a good filter capacity highlights the need for such a biological parameter when talking about the safety of sunscreens.

A New Model Using Liposomes That Allow to Distinguish Between Absorption and Oxidative Properties of Sunscreens¶

A New Model Using Liposomes That Allow to Distinguish Between Absorption and Oxidative Properties of Sunscreens¶

UV Transmission Measurements of Small Skin Specimens with Special Quartz Cuvettes

Background: The penetration of different wavelengths of UV radiation through human skin is of major importance, especially for the determination of photoprotective properties of sunscreens and UV-protective clothes. Objective: In this study we present a new method for the measurement of UV transmission through small skin specimens. Methods: The transmission measurements were performed by using a UV spectrophotometer with an integrating sphere operating in the wavelength range of 280–390 nm. For the skin samples, special quartz glass cuvettes were developed which allowed measurements for very thin and small skin specimens. Furthermore, the cuvettes prevented dehydration of the specimens and guaranteed, by using an additional diaphragm, that the transmission data were derived solely from the small skin specimen examined. Specimens measuring 8 × 3 mm² with a thickness of 0.3 mm (histometric and sonographic control) were taken from the thighs of 10 subjects via shave biopsy. Results: In the UVA range (315–390 nm) we obtained a mean transmission of 4.6% and for the UVB range (280–315 nm) of 0.9%. No significant (p >0.14) difference of UV transmission was found between the individual skin specimens. Conclusion: This new method seems to be well suitable for UV transmission measurements of small skin specimens. As UVA radiation has a much deeper penetration depth and in in vivo situations dermal hemoglobin could have an effect on UV penetration, the present method is better suitable for the investigation of UVB-induced biological adaptation mechanisms and the impact of topical agents on UVB transmission of the epidermis.

Protection against solar ultraviolet radiation

Interest in protection against solar ultraviolet radiation (UVR) among the general public in Australia has been increasing steadily as a result of the `SunSmart' campaigns run by the various state cancer councils. This increasing awareness is due in part to the requirements for occupational protection of outdoor workers and to provision of UVR protection for the recreational market. Behaviour outdoors can significantly affect exposure to solar UVR and use of items of personal protection can provide a substantial reduction in the UVR dose received. The protective properties of sunscreens, sunglasses, hats and clothing against UVR have been the subject of considerable research for some time, and over the last few years interest has extended to the provision of shade structures and the UVR protection provided by various commonly used materials. These materials include shadecloth, plastics, glass, windscreens and applicable tints. Australia has rigorous standards covering protection and UVR, in particular for sunscreens [Standards Australia/Standards New Zealand, Sunscreen products—evaluation and classification, Report No. AS 2604, Sydney/Wellington, 1993.], sunglasses [Standards Australia, Sunglasses and fashion spectacles—nonprescription types, Report No. AS 1067.1, Sydney, 1990.], protective eyewear [Standards Australia/Standards New Zealand, Eye protectors for industrial applications, Report No. AS/NZS 1337, Sydney/Wellington, 1992.] and shadecloth [Standards Australia, Synthetic shadecloth, Report No. AS 4174, Sydney, 1994.]. Compliance with the sunglass standard became mandatory in 1988 and UVR protection provided by sunglasses has increased substantially since then. In July 1996 a standard on `sun protective textiles' [Standards Australia/Standards New Zealand, Sun protective clothing—evaluation and classification, Report No. AS/NZS 4399, Sydney, 1996.] incorporating ultraviolet protection factors (UPFs) and a rating scheme with protection categories, was introduced; this was the first of its kind in the world. Australian Radiation Laboratory (ARL) UPF swing tags with UVR protection advice from the Australian Cancer Society on the reverse side are used to denote the amount of protection against solar UVR provided by clothing. To date in excess of 5 million ARL swing tags have been issued. Work on the various standards is continuing. The maximum allowed `sun protection factor' (SPF) limit for sunscreens may be increased to SPF 30+ in the near future, and additions to the sun protective textiles standard are also planned. This paper discusses measurement methods, results, the rationale used in formulating the Australian Standards and the current state of UVR protection in Australia.

Sun-protective clothing.

Topical sunscreens have been used for many years on exposed areas (i.e., hands, face) to protect the skin from the damaging effects of ultraviolet radiation. Most people do not use sunscreens on their bodies when they are wearing clothes. An average weight cotton T shirt gives only a sun protection factor (SPF) of 7. This is inadequate protection when out of doors. Therefore, clothing with adequate sunscreening properties should be worn. The purpose of this study is to identify the factors in clothing fabrics that contribute to or detract from blocking ultraviolet radiation and to recommend criteria for establishing a standard for sunprotective clothing. The study involves a review of the dermatologic and textile literature to identify various factors in fabrics that contribute to blocking ultraviolet radiation through textiles. For fabrics, the term ultraviolet protection factor (UPF) is used as the measure of ultraviolet radiation penetration through the fabric. The UPF of a fabric depends upon fiber content and weave, fabric colour, finishing processes, and the presence of additives. The performance of a fabric depends upon stretching, shrinkage, hydration, laundering, and wear of the fabric over time. Based upon these criteria the minimum CDA standard UPF for clothing should be 40 to 50+.

Chemico‐physical and functional properties of inorganic sunscreens in cosmetic products

Synopsis This paper reports preliminary results of a study carried out on liquid crystal emulsions added to three different inorganic sunscreens: ultrafine zinc oxide, ultrafine titanium dioxide (inorganic-treated) and ultrafine titanium dioxide (organic-treated hydrophobically). The aim of the work was to investigate the influence of chemico-physical properties of inorganic sunscreens on the microstructure of cosmetic emulsions. The study was carried out using three different techniques: rheological measurements performed in dynamic conditions, to study the homogeneity of samples and their structural features; dispersion of powders in emulsions by optical microscopy and SEM/EDX analysis; and functionality of emulsions by UV spectroscopy, with adhesive tape as substrate. Results show that the different chemico-physical properties of the micropigments lead to different interactions with emulsion components; these interactions may affect the functionality and microstructure of the whole system, with loss of stability.

In vitro analysis of immunoprotective effects of topical sunscreens

The aim of this study was to evaluate procedures for the assessment of the immunoprotective capacities of topical sunscreens, using cell cultures. The exposure of humans to solar or ultraviolet radiation has been shown to induce numerous changes at the level of the immunoresponsiveness of the skin, which could be described as immune suppression. In this study, a sunscreen containing the commercially available UVB filters octyl triazone, phenylbenzimidazole sulfonic acid and methylbenzylidene camphor, was tested because of its capacity to protect from the immunosuppressive effects of UVB radiation. In contrast to control suncreens with a comparable sun protector factor (SPF), but that did not contain the UVB-filter octyl triazone, the immunoprotective sunscreen protected from two forms of immune suppression as assessed in vitro. Expression of the immune-relevant cellular communication structure intercellular adhesion molecule-1 is decreased on the cell surface of epidermal cells under the influence of UVB. This effect of immune suppression is totally abolished by the immunoprotective capacity of the tested sunscreen, as monitored cytofluorometrically. The mixed-lymphocyte reaction (MLR) was also used to assess the protective capacities of sunscreens against UVB-radiation-induced suppression of the immune response. Again, this UVB-induced suppression of the MLR was prevented by the sunscreen containing octyl triazone. In summary, the results of this study demonstrate the usefulness of the above-mentioned methods for the in vitro evaluation of the immunoprotective properties of topical sunscreens.

Durable Protection Against Long-Wavelength UV-A Radiation and Blue Light-Reply

To the Editor.— Kaye et al 1 described the efficacy of opaque photoprotective agents for protection against UV-A and visible radiation, and Sayre et al 2 elegantly described the optical properties of physical sunscreens. The former report is of special interest, because it appears clinical investigators are now recognizing a point we stressed for many years 3 : A broad UV-A screen will almost certainly be colored. A screen for visible radiation must, by definition, be colored, preferably a pleasing brown. Physical sunscreens suffer from the same defect as many chemical sunscreens: they rub off or are removed by aqueous fluids. Browning agents such as dihydroxyacetone (DHA) form a brown color in the stratum corneum that absorbs blue light with overlap into the adjoining UV-A region. 3 Thus, DHA covers the window of vulnerability left by chemical sunscreens, ie, long-wavelength UV-A radiation and blue light. Furthermore, the chemically bound color produced

Durable Protection Against Long-Wavelength UV-A Radiation and Blue Light

<h3>To the Editor.—</h3> Kaye et al¹described the efficacy of opaque photoprotective agents for protection against UV-A and visible radiation, and Sayre et al²elegantly described the optical properties of physical sunscreens. The former report is of special interest, because it appears clinical investigators are now recognizing a point we stressed for many years³: A broad UV-A screen will almost certainly be colored. A screen for visible radiation must, by definition, be colored, preferably a pleasing brown. Physical sunscreens suffer from the same defect as many chemical sunscreens: they rub off or are removed by aqueous fluids. Browning agents such as dihydroxyacetone (DHA) form a brown color in the stratum corneum that absorbs blue light with overlap into the adjoining UV-A region.³Thus, DHA covers the window of vulnerability left by chemical sunscreens, ie, long-wavelength UV-A radiation and blue light. Furthermore, the chemically bound color produced