Article

In vitro assessment of the broad-spectrum ultraviolet protection of sunscreen products

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

There are considerable data to suggest that protection from solar ultraviolet (UV) radiation will reduce the risk of acute and chronic skin damage in humans. Whereas the sun protection factor (SPF) provides an index of protection against erythemally effective solar UV, largely confined to the UVB (290-320 nm) and short-wavelength UVA (320-340 nm) region, there is currently no agreed-upon method to measure broad-spectrum protection against long-wavelength UVA (340-400 nm). The objective of these studies was to assess the potential of in vitro UV substrate spectrophotometry and subsequent calculation of the "critical wavelength" value as a measure of broad-spectrum UV protection and as a routine, practical procedure for classification of sunscreen products. The spectral absorption of 59 commercially available sunscreen products and multiple experimental formulas with one or more UV filters was measured. Sunscreen product, 1 mg/cm(2), was applied to a hydrated synthetic collagen substrate, preirradiated with a solar simulator, and then subjected to UV substrate spectrophotometry. Multiple determinations from 5 independent samples per product were used to calculate the critical wavelength value, defined as the wavelength at which the integral of the spectral absorbance curve reached 90% of the integral from 290 to 400 nm. We found that a recognized long-wave UVA active ingredient such as titanium dioxide, zinc oxide, or avobenzone is a necessary but insufficient product requirement for achieving the highest proposed broad-spectrum classification, that is, critical wavelength of 370 nm or more. Although SPF and critical wavelength are largely independent of each other, UVA absorbance must increase commensurate with SPF to maintain the same critical wavelength value. Substrate spectrophotometry and the calculation of critical wavelength can readily account for sunscreen photostability by UV preirradiation. Finally, there is also a strong positive relationship between critical wavelength and a currently available in vivo measure of UVA protection. Determination of critical wavelength by means of UV substrate spectrophotometry provides a rapid, inexpensive, and reliable measure of broad-spectrum protection, which is largely independent of SPF, yet ensures long-wavelength UVA protection commensurate with SPF. The procedure provides a routine, sensitive means of differentiating and classifying sunscreen products and, importantly, obviates the need to subject volunteers to acute exposures of high-dose, nonterrestrial UV, the health risks of which are still poorly understood.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... CW is the wavelength below which 90% of the AUC lies, while UVA/UVB ratio is the ratio between the mean absorbance at UVA wavelength range (320-400 nm) and the mean absorbance at UVB wavelength range (290-320 nm). Both CW and UVA/UVB ratio were calculated to assess the broad spectrum coverage for the selected sunscreen formulations (Diffey, 1994;Diffey et al., 2000). AUC was calculated by the trapezoidal rule to compare between formulations regarding UV absorbance promotion (Kamel et al., 2017). ...
... In fact, SPF is based only on protection against erythema (sunburn) induced principally by UVB (Cole, 2001), so it cannot be considered as an indicator for UVA-induced damage (Haywood et al., 2003). Accordingly, other UV spectroscopic indices, namely; CW and UVA/UVB ratio were assessed for F-Opt containing 6% of TiO 2 and/or ZnO for determination of the broad spectrum coverage (Diffey, 1994;Diffey et al., 2000). ...
... It was previously reported that sunscreens having CW above 370 nm can be considered to have a broad spectrum protection (Diffey et al., 2000). In addition, sunscreens having UVA/UVB ratio > 0.8 are rated to have an excellent broad spectrum protection (Diffey, 1994). ...
Article
All-trans retinoic acid is a natural retinoid and the physiologically active metabolite of vitamin A. The aim of the present study is to develop and optimize a nanostructured lipid carrier formulation to enhance the photostability of all-trans retinoic acid and alleviate its skin photosensitivity. Box–Behnken design was used for optimizing dependent variables such as particle size, zeta potential and viscosity. The total lipid (%), liquid lipid (%) and total surfactant (%) were selected as independent variables. The optimized formulation was characterized by particle size of 151 nm, zeta potential of −31 mV and viscosity of 2064 cps. In vitro photoprotection effect of the optimized formulation containing different types and concentrations of inorganic sunscreens was evaluated employing Transpore® tape assay. Sun protection factor and other spectroscopic indices revealed that 6% titanium dioxide was the best choice to be combined with the optimized formulation. After 6 h of ultraviolet A exposure, the optimized formulation and the optimized formulation combined with 6% titanium dioxide enhanced the photostability of all-trans retinoic acid by about 1.5 and 2 times, respectively, compared to its methanolic solution. In vivo photoprotection effect of the developed formulations was conducted on mice exposed to direct sun light for 4 days. Photographs of the mice's skin, biochemical analysis of the pro-inflammatory cytokines in the skin as well as histopathological examination, depicted that the optimized formulation promoted an obvious alleviation of the all-trans retinoic acid-induced photosensitivity, which was further potentiated by the addition of 6% titanium dioxide, compared to the marketed product.
... This phenomenon, besides overexposure of the skin to the sun, increases various skin disorders in humans such as premature aging and skin cancer (Svobodová et al. 2003; Thomas et al. 2012;Saewan and Jimtaisong 2015). The range of UVR bands that reach the earth include UVB (290-320 nm) and UVA (320-400 nm) (Diffey et al. 2000). The most active and dangerous to the skin is UVB, but since only 4-5% of it reaches the earth, the skin is more likely to be intensely exposed to UVA (Afaq et al. 2002;Hanson et al. 2006). ...
... The absorption spectra of the EF are presented in Fig. 4. The peak within 290-320 nm is related to UVB and the peak within 320-400 nm is associated with UVA (Diffey et al. 2000). In brown algae, the peak in the 400-660 nm range is associated to pigments. ...
... A higher SPF/ UVA-PF ratio indicates that a sample provides more protection against UVA/UVB waves through absorption or reflection (Hojerová et al. 2011). Products with a critical wavelength of > 370 provide the highest UVR protection (Diffey et al. 2000). ...
Article
Full-text available
Phlorotannins are polyphenolic compounds in brown algae and can be used as a natural UV filter in sunscreen formulations. The aim of the present study was to characterize the biological activities of phlorotannins-rich fractions from the brown alga Polycladia myrica and to validate the protective effect as well as stability of cream formulation with phlorotannins against UVR. With respect to antioxidant properties, the ethyl acetate fraction (EF) possessed the highest DPPH radical scavenging (65 ± 0.2%), and the highest antioxidant activity (11.2 ± 0.2 μg ASA mg⁻¹). The EF was active against Gram-positive bacteria with EF effectively reducing UVB-induced cytotoxicity in HaCaT keratinocytes. The cream formulation with 5% EF revealed a high sun protective factor (31.79 ± 4.73), UVA/PF (24.67 ± 4.03), critical wavelength (383.2 ± 0.1 nm), and UVA/UVB ratio (0.98 ± 0.01). The cream formulation was completely homogeneous and had a pH close to human skin pH. The cream was stable in the cooling-heating cycle and the DPPH scavenging activity of the cream was not altered for 30 days of storage at temperatures of 4–40 °C. These findings are promising for the use of brown alga P. myrica extract as a valuable source of sunscreen protective substance for pharmaceutical and cosmetic applications.
... Nonetheless, a combination of organic and inorganic UV filters in topical formulations can display synergistic effects [18]. Although recognized as active long-wavelength UVA ingredients in sunscreen formulations, Diffey et al. [19] have claimed that TiO 2 and ZnO do not meet the requirement to be classified as broadspectrum products for critical wavelengths longer than 370 nm. ...
... The results are typical of those found with various samples. Bottom panel: illumination with 0.2% ZnO for 0, 10, 20, 40 and 60 min before (lanes 1-5) or after (lanes 6-10) adding DMSO; and with 0.0125% sunscreen TiO 2 for 0, 5, 10, 20, 40 and 60 min after adding 200 mM DMSO (lanes [11][12][13][14][15][16] or 340 mM mannitol (lanes [17][18][19][20][21][22]. Reproduced from Ref. [44] with permission under an Elsevier User License converted to the relaxed (R) and linear forms (L) (Fig. 9). ...
... Using an in vitro method, Diffey and coworkers [19] were one of the first groups to assess the broadspectrum UV protection afforded by sunscreen products. They recognized that although the SPF value on sunscreens' labels provided an effective index of protection against erythemally solar UV radiation, largely confined to the UVB wavelengths and to the shorter UVA1 wavelengths (320-340 nm), there was a void as to how broadspectrum protection could be assessed against the longer UVA2 wavelengths (340-400 nm). ...
Article
Sunscreens have now been around for decades to mitigate the Sun’s damaging ultraviolet (UV) radiation which, although essential for the existence of life, is a recognized prime carcinogen. Accordingly, have suncreams achieved their intended purposes towards protection against sunburns, skin photo-ageing and the like? Most importantly, however, have they provided the expected protection against skin cancers that current sunscreen products claim to do? In the last two decades, there have been tens, if not hundreds of studies on sunscreens with respect to skin protection against UVB (280‒320 nm)—traditionally sunscreens with rather low sun protection factors (SPF) were intended to protect against this type of radiation—and UVA (320‒400 nm) radiation; a distinction between SPF and UVA protection factor (UVA-PF) is made. Many of the studies of the last two decades have focused on protection against the more skin-penetrating UVA radiation. This non-exhaustive article reviews some of the important facets of what is currently known about sunscreens with regard (i) to the physical UV filters titanium dioxide (TiO2) and zinc oxide (ZnO) and the mostly photo-unstable chemical UVB/UVA filters (e.g., octinoxate (OMC) and avobenzone (AVO), among others), (ii) to novel chemical sunscreen agents, (iii) to means that minimize the breakdown of chemical filters and improve their stability when exposed to UV sunlight, (iv) to SPF factors, and (v) to a short discussion on non-melanoma skin cancers and melanoma. Importantly, throughout the article we allude to the safety aspects of sunscreens and at the end ask the question: do active ingredients in sunscreen products pose a risk to human health, and what else can be done to enhance protection?Graphic abstractSignificant loss of skin protection from two well-known commercial suncreams when exposed to simulated UV sunlight. Cream I: titanium dioxide, ethylhexyl triazone, avobenzone, and octinoxate; Cream II: octyl salicylate, oxybenzone, avobenzone, and octinoxate.
... Segundo o Guia de Controle de Qualidade de Cosméticos da Agência Nacional de Vigilância Sanitária A determinação do FPS permite avaliar a eficácia fotoprotetora de uma formulação, enquanto a razão UVA/UVB e o comprimento de onda crítico (λ c ) permitem a avaliação da proteção frente à radiação UVA. Quanto maior for a razão UVA/UVB e o comprimento de onda crítico, maior será a proteção UVA que o produto confere (DIFFEY et al., 2000;VELASCO et al., 2008;CERQUEIRA-COUTINHO et al., 2015). ...
... Para um fotoprotetor ser considerado de amplo espectro, deve apresentar λλ c maior que 370 nm. Quando o λλ c estiver entre 340 e 370 nm, o nível de proteção contra a radiação UVA pode ser considerado intermediário (DIFFEY et al., 2000;VELASCO et al., 2011). ...
Article
Ao longo dos últimos anos, as fórmulas cosméticas têm evoluído consideravelmente, tornando os produtos para maquiagem excelentes coadjuvantes para tratar e proteger a pele e seus anexos. Sabe-se que o uso de fotoprotetores de amplo espectro de absorção ultravioleta é essencial na prevenção de neoplasias cutâneas, principalmente de áreas que sofrem exposição diária ao sol, incluindo os lábios. Desta forma, este trabalho tem como objetivo o desenvolvimento de uma formulação de batom de diferentes cores (marrom, vermelho, rosa e roxo), com propriedades que visam não só promover emoliência, hidratação e coloração aos lábios, mas também oferecer proteção contra os raios ultravioletas (UV). Os resultados obtidos indicam que os valores de FPS (Fator de Proteção Solar) das amostras de batons permaneceram na categoria de alta proteção, com capacidade de manter a retenção de água na pele, fácil espalhamento sobre o lábio, dureza condizente com o tipo de produto e baixa possibilidade de deterioração oxidativa. Desta forma, os batons desenvolvidos apresentam características comerciais desejáveis de hidratação, coloração e emoliência, além de alta fotoproteção, podendo atuar na prevenção de câncer labial.
... Subsequently, the absorbance of the photoprotective formulations was determined using the wavelength range of 290-400 nm in triplicate, with seven different points of readings per plate of each sample. The average spectral absorbance values were used to calculate the SPF, critical wavelength and UVB/UVA rate of the formulations [25][26][27][28] by the UV2000 ® software (North Sutton, NH, USA). ...
... According to the literature, the wide variation in the phenolic content of V. vinifera grapes can be attributed to cultivation constraints, such as (a) viticulture conditions, genetic grapevine, maturation stage, edaphoclimatic factors and exposure to fungi; (b) oenology parameters, time and storage temperature of postharvest samples, type and length of maceration, pressing and fermentation; and (c) winemaking extraction process, cultivar, variety, sample type, drying, solvent system, volume, time, milling, temperature, pH value, metal ions, light and oxygen exposure and extraction technologies. It is highly likely that these factors change the chemical and physical characteristics of the coproduct, and thus, their extensive biological activities [26][27][28][29][30][31][32][33][34]. ...
Article
Full-text available
Grape pomace retains polyphenols in the peels and in the seeds after winemaking, which is indicative of the high valorization potential of this industrial waste. There is strong evidence that phenolics are robust antioxidants and confer photoprotection; thus, it is rational to apply these active compounds from winemaking waste to sunscreens, in order to increase UV protection. Despite the importance of this class of cosmetics to public health, more efficacious strategies are still needed to overcome the problems caused by the photoinstability of some UV filters. The hydroethanolic extract of Vitis vinifera L. grapes was obtained by percolation and then lyophilized. Six formulations were developed: Type I—cosmetic base and UV filters; Type II—cosmetic base and extract; and Type III—cosmetic base, extract and UV filters. Each formulation was prepared in the pHs 5 and 7. The antioxidant activities of the samples were measured by DPPH• and expressed in Trolox® equivalents (TE), and their photostability and in vitro sun protection factor (SPF) were analyzed by diffuse reflectance spectrophotometry. The anti-radical efficiencies observed in the formulations with grape extract were: (II) 590.12 ± 0.01 μmol TE g−1 at pH 5 and 424.51 ± 0.32 μmol TE g−1 at pH 7; (III) 550.88 ± 0.00 μmol TE g−1 at pH 5 and 429.66 ± 0.10 μmol TE g−1, at pH 7, demonstrating that the UV filters, butylmethoxydibenzoyl methane, ethylhexyl methoxycinnamate and ethylhexyl dimethyl 4-aminobenzoic acid had no influence on this effect. The photoprotective efficacy and the photostability of formulation III containing the extract and UV filters at pH 5 suggested that a synergism between the active molecules provided an 81% increase in SPF. Additionally, this was the only sample that maintained a broad spectrum of protection after irradiation. These results confirmed that the grape pomace extract has multifunctional potential for cosmetic use, mainly in sunscreens, granting them superior performance.
... According to the rating criteria "Boot s star system" recommended by Diffey [33], the better responses obtained for UVA/UVB ratio were verified in formulation E (0.67), which is considered as good protection, followed by formulations H, I, and J with 5% extract (0.65), also considered to provide good protection, and formulation F with 10% of extract (0.59) with moderate pre-irradiation protection (Table 5 and Figure 9). The in vitro UVA-PF method provides a good correlation with clinical results [25]. ...
... solar simulator (Atlas Suntest CPS+, Linsengericht, Hesse, Germany), with a xenon lamp, irradiation dose at 500 Wm −2 and temperature of 35 • C. The measurements were performed in triplicate and the mean transmittance values [%] pre and post irradiation were used to calculate SPF, critical wavelength value (λc), UVA and UVB radiation and UVB/UVA ratio by Labsphere software[24,25,32,33].TheResearch Ethics Committee of the Faculty of Pharmaceutical Sciences of the University of São Paulo approved the clinical trials under the Certificate of Presentation to Ethics Appreciation (CAAE) n • 46383115.0.3001.8021 and following the norms of the Declaration of Helsinki ...
Article
Full-text available
In winemaking, a large amount of grape pomace is produced that is rich in polyphenolics and highly beneficial for human health, as phenols are useful for skin ultraviolet (UV) protection. In this investigation, we evaluated the safety and clinical efficacy of a sunscreen system containing a grape pomace extract from Vitis vinifera L. as a bioactive ingredient. The recovery of phenolics in the waste was performed by percolation. Nine emulsions were developed using a factorial design and two were evaluated clinically: Formulation E, containing only UV filters (butylmethoxydibenzoyl methane, ethylhexyl methoxycinnamate and ethylhexyl dimethyl PABA), and F, with the extract at 10.0% w/w + UV filters. The antioxidant activity was determined by the DPPH assay and the in vitro efficacy was established by sun protection factor (SPF) measurements (Labsphere UV-2000S). Clinical tests were performed to determine safety (human repeated insult patch test) and to confirm efficacy (photoprotective effectiveness in participants). The results showed a synergistic effect between the sunscreen system and the extract on UVB protection and antioxidant activity. Both samples were considered safe. Formulation F was 20.59% more efficient in protecting skin against UVB radiation, taking approximately 21% more time to induce erythema compared to the extract-free sample.
... The commercial sunscreen, which is dispensed directly from the bottle (manufacturer 2, CS3), showed the highest viscosity, while the sunscreen applied through a spray dispenser (manufacturer 3, CS4) The relationship between the shear rate and the shear stress is shown in Fig. 5b. All tested sunscreen formulations exhibited nonlinear behaviour and consequently can be referred to as non-Newtonian fluids [49]. The flow index n classifies the deviation of a system from Newtonian behaviour, which is found for n = 1 (see Eq. (6)) [50]. ...
... ZnO, showed that only 10% of the tested sunscreens had a critical wavelength ≥ 370 nm [49]. This study demonstrates that a simple addition of long wavelength UVA active ingredients does not ensure true broad-spectrum protection, and thus underscores the importance of the obtained results for the homemade sunscreen of TiO2/Bi(OH)3. ...
... SPF of any formulation can be calculated by evaluating its potential in inhibiting erythema (redness due to inflammation) and edema (swelling or inflammation). These skin reactions can be noticed 24 h after exposing skin against UV radiations [10][11][12][13][14][15][16][17]. UVA (315-400 nm) is having longer wavelength, thus it's not efficient in inducing erythema or any other skin reactions whereas UVB (280-315 nm) is required to induce erythema within less period of time. ...
Article
Full-text available
Ba.ckground: Sunscreen formulations primarily offer protection against UV induced damages however nowadays it also maintains skin natural physiological conditions. Current global market is flooded with numerous sunscreen products which offer protection to skin against several UV induced damages. However most of these sunscreen formulations offers narrow spectrum protection against UV and also suffer from stability as well as toxicity related issues. Methods: Present work aims to isolate mycosporine amino acid (Mgy) from green alga namely Ulva fasciata (U. fasciata) and study its sunscreen potential against widely used domestic marketed formulation. Stability evaluations were also performed for almost 90 days. Results: Results demonstrated that the isolated compound, mycosporine glycine (Mgy) preserved physicochemical properties of the product and offered good stability for all formulations throughout the experimental period. Furthermore, Mgy loaded carbopol gel showed better sunscreen protection against marketed formulation in a concentration dependent manner. (7.709). Conclusion: (6.806) Novel Myg loaded gel was proved to demonstrate several quality characteristics that may unlock new prospects for the production of more efficient, safe, and economic skin-care products.
... Topically applied sunscreens can be used to prevent damage to the skin caused by exposure to UV light [102][103][104][105]. Active ingredients in sunscreens, referred as UV filters, act in different ways either by absorbing UV radiation (organic-based compounds) or by scattering and reflecting UV radiation (inorganic molecules) [102,106,107]. Some studies have demonstrated that the combination of the 2 usually results in better UV protection capabilities of the final product [102,108,109]. The efficacy of a sunscreen is measured as the SPF, a term coined by Greiter in 1970 [110], with a higher SPF indicating stronger photoprotective activity [101]. ...
Article
Full-text available
Cosmeceuticals are designed to serve a dual purpose: to provide desired esthetical effects and to treat dermatological conditions. Natural products derived from plants and marine organisms are a novel source of potential cosmeceutical active ingredients for incorporation into new formulations due to consumer demands. Contrary to common perceptions, most regulatory agencies do not view cosmeceuticals as being a separate category from cosmetics; thus, these products are not regulated accordingly, thereby forcing the consumer to rely on the self-regulatory policies of the cosmetics industry. Cosmeceuticals are advertised as having capabilities that include anti-aging, anti-acne, solar-protective, wound healing, and skin whitening. Such traits normally comprise several biological activities. In order to ensure the safety and efficacy of these products, active ingredients employed in the formulations must undergo a series of tests. In this review, in vitro (enzymatic and cellular) and in vivo tests employed to evaluate the potential of new cosmeceutical active ingredients are discussed, and new trends that are being explored by the cosmeceutical industry are described.
... Desired SPF may be achieved by adding more amount of DP25B75 powder or chemical organic agents. The larger the SPF is, the better the light absorption in the ultraviolet light region [37]. This indicates that BB cream with spray-dried DP25B75 composite powder exhibited superior sunscreen protection compared to its pristine h-BN counterpart. ...
Article
Full-text available
In the present study, spherical composite powder was successfully prepared via spray drying process using polymethyl methacrylate (PMMA) and hexagonal boron nitride (h-BN) powders. The pristine and as-prepared composite powders were examined using scanning electron microscopy, a particle size analyzer, oil absorption, and specific surface area analyses. These powders were then mixed with linseed oil to prepare samples for UV-Visible-Near Infrared spectroscopy investigation to determine their light absorption ability. Blank and powder-added blemish balm creams were examined using a sun protection factor tester and a thermal conductivity tester. In addition, transmittances of these creams were also evaluated. The experimental results show that spray-dried spherical composite powder exhibited good oil absorption ability. The blemish balm cream with 10 wt.% spray-dried composite powder not only exhibited superior sunscreen protection ability, but also good thermal conductivity.
... In addition to UV-Vis absorbing agents, recent sunscreens display other properties, such as water resistance, photostability, hydrating agents, sticking lotion to avoid reiterative application, etc. These points are involved in the measurement of the so-called Biological Effective Protection Factors (BEPFs), that are calculated for a determined UV-mediated skin response through transmission measurements according to the Diffey method [31] using the relative action spectrum [32]. BEPFs can be considered as indicators focused on the number of times that a person protected with the agent can be exposed in comparison to an unprotected person (control). ...
Article
Full-text available
Direct sun exposure is one of the most aggressive factors for human skin. Sun radiation contains a range of the electromagnetic spectrum including UV light. In addition to the stratospheric ozone layer filtering the most harmful UVC, human skin contains a photoprotective pigment called melanin to protect from UVB, UVA, and blue visible light. This pigment is a redox UV-absorbing agent and functions as a shield to prevent direct UV action on the DNA of epidermal cells. In addition, melanin indirectly scavenges reactive oxygenated species (ROS) formed during the UV-inducing oxidative stress on the skin. The amounts of melanin in the skin depend on the phototype. In most phenotypes, endogenous melanin is not enough for full protection, especially in the summertime. Thus, photoprotective molecules should be added to commercial sunscreens. These molecules should show UV-absorbing capacity to complement the intrinsic photoprotection of the cutaneous natural pigment. This review deals with (a) the use of exogenous melanin or melanin-related compounds to mimic endogenous melanin and (b) the use of a number of natural compounds from plants and marine organisms that can act as UV filters and ROS scavengers. These agents have antioxidant properties, but this feature usually is associated to skin-lightening action. In contrast, good photoprotectors would be able to enhance natural cutaneous pigmentation. This review examines flavonoids, one of the main groups of these agents, as well as new promising compounds with other chemical structures recently obtained from marine organisms.
... The FDA 2007 standard uses the modified Diffey fraction where the area under the UVA1 absorption curve (340nm to 400nm) is divided into the total absorption region of UVA and UVB (290nm to 400nm). 14,15 Nevertheless, FDA 2011 abolished the modified Diffey fraction for the following reasons: ...
Article
Full-text available
Background: In the past, it was taught that UVA wavelengths (320- 400nm) only plays a major role in skin aging but recently the scientific researches also show that UVA cause cancerous keratinocyte cells in deep layer of the epidermis. Therefore, the protective ability of the product against UVA is important in addition to protection against UVB rays. The UVA protective factor (UVA-PF) is used to evaluate the effectiveness of sunscreen products against UVA rays. This study aims to review and compare all outstanding protocols in the field of UVA-PF measurement and finally the introduction of the best method of measuring UVA-PF based on the further benefits. Materials and methods: Four standards including ISO 24443 (AS/NZS 2604: 2012 recommended approach), CEN 2006, FDA 2007 and FDA 2011 are selected. Results: In order to measure UVA-PF with in vivo method, two standards of CEN 2006 and FDA 2007 recommended persistent pigment darkening (PPD) method. Although the general principle of both is similar, there are some differences in detail. For in vitro measurement of UVA-PF, CEN and FDA 2011 standards use critical wavelengths. FDA 2007 introduces the modified Diffey fraction, and ISO 24443 standard meets the UVA-PF measurement in a manner that is consistent with PPD. Conclusion: Finally, this review discussed the comparison of all in vitro and in vivo UVA-PF measurement standards and provided information in the form of texts and tables to move towards the creation of an integrated standard. Since in vitro methods of UVA-PF measurement are not reproducible due to differences in test conditions, it may be concluded that the in vivo PPD method is a more suitable option.
... P-334 (+ SH), as a natural UVA sunscreen, and M-Ser (OH), as a natural UVB sunscreen, were brought together in the same topical formula as well as separately and SPFs and other Biological Effective Protection Factors (BEPFs) were calculated according to the Diffey method [48]. A reference sunscreen containing butylmethoxydibenzoylmethane (BMDM) and octylmethoxycinnamate (OMC), synthetic UV filters used in photoprotection by Cosmetics Europe [54][55][56], was formulated with the same percentage as that of the MAAs combination sunscreen and used as a control. ...
Article
Full-text available
The safety and stability of synthetic UV-filters and the procedures for evaluating the photoprotective capability of commercial sunscreens are under continuous review. The influence of pH and temperature stressors on the stability of certain Mycosporine-like amino acids (MAAs) isolated at high purity levels was examined. MAAs were highly stable at room temperature during 24 h at pH 4.5–8.5. At 50 °C, MAAs showed instability at pH 10.5 while at 85 °C, progressive disappearances were observed for MAAs through the studied pH range. In alkaline conditions, their degradation was much faster. Mycosporine-serinol and porphyra-334 (+shinorine) were the most stable MAAs under the conditions tested. They were included in four cosmetically stable topical sunscreens, of which the Sun Protection Factor (SPF) and other Biological Effective Protection Factors (BEPFs) were calculated. The formulation containing these MAAs showed similar SPF and UVB-BEPFs values as those of the reference sunscreen, composed of synthetic UV absorbing filters in similar percentages, while UVA-BEPFs values were slightly lower. Current in vitro data strongly suggest that MAAs, as natural and safe UV-absorbing and antioxidant compounds, have high potential for protection against the diverse harmful effects of solar UV radiation. In addition, novel complementary in vitro tests for evaluation of commercial sunscreens efficacy are proposed.
... UV-B radiation causes skin burns in wavelength regions of 290 -320 nm, some of which can directly damage cellular DNA. Whereas in wavelength regions of 320 -400 nm, UV A radiation can penetrate deeper into the skin layer and sensitively damage DNA through the production of radical oxygen species (ROS) [3]. UV radiation also plays a major role in the photoaging process. ...
Conference Paper
The potential of Andrographis paniculata L. Ness medicinal plant extract as protector of ultraviolet radiation have been analyzed using fluorescence spectrophotometry methods. The Andrographis paniculata L. Ness medicinal plant extract was obtained by maceration process from part of the leaves. The solvent used in maceration process are ethanol as a polar solvent, ethyl acetate as a semi-polar solvent and n-hexane as a nonpolar solvent. The maceration process is carried out for 3, 5, 7 and 9 days at room temperature. The Andrographis paniculata L. Ness medicinal plant extract was characterized using FTIR spectrophotometer and analyzed by fluorescence spectrophotometry methods. The result of FTIR spectra obtained that extract has a molecular bond stretch between molecular stretch OH on 3337.38cm⁻¹ and 3362.46cm⁻¹. Asymmetric strain = CH2 2926.57cm⁻¹ and the asymmetric strain of the -CH group at 2853.29cm⁻¹. The strain of C = C ring at 1454.99 cm⁻¹ and the O-C = O bond at 1375.91cm⁻¹. The optimum extraction results obtained at maceration using ethanol with the excitation fluorescence intensity of 265.72 and the emission of 259.56. The optimum maceration time was obtained at 7 days using ethanol solvent as polar solvent with intensity of excitation fluorescence of 594.73 and emission of 583.34. The results of fluorescence analysis show that the Andrographis paniculata L. Ness medicinal plant extract has potential as a protector of ultraviolet radiation with optimum absorption at 282 nm which is ultraviolet area and re-emitted at 568 nm which is a visible area that is safe and harmless to the skin.
... Overexposure to sunlight causes adverse effects on our skin, being the development of cancer its most harmful effect, melanoma being one of the most prevalent types of cancers diagnosed worldwide IARC 2012, American Cancer, 2016. Ultraviolet (UV) radiation covers the wavelength range of 100 to 400 nm and is divided into UVC (100 to 290 nm), UVB (290 to 320 nm), UVA II (320 to 340 nm) and UVA I (340 to 400 nm) (Diffey et al., 2000). Since UVC rays are absorbed by the ozone layer in the atmosphere, they do not reach the Earth's surface, while5 % of UVB rays and~95% of UVA rays surpass this layer, inevitably reaching human skin at different depths and types of reactions (Lautenschlager et al., 2007;Young, 2009;. ...
Article
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.
... 2-Phenylbenzimidazole-5-sulfonic acid commonly known as "ensulizole" [34] is an effective and recommended sunscreen agent [7,[35][36][37] and it is a part of many commercially available sunscreen products [38]. Therefore, it is essential to study the photophysical properties of this compound in order to have a thorough understanding of its mode of action against absorbed UV radiations. ...
Preprint
Full-text available
Employing natural or artificial sunscreens is essential to protect the skin from ultraviolet radiations that cause premature aging and develop melanoma and other forms of skin cancer. The 2-Phenylbenzimidazole-5-sulfonic acid, commonly known as ensulizole is a water-soluble artificial sunscreen that absorbs mostly UV-B (280 nm − 315 nm) radiations and protects the skin against the harmful effects of these radiations. Steady-state absorption indicates a strong absorption feature at 303 nm and a weak at 316 nm that have been identified as π → π* and n → π* transitions, respectively. The photoluminescence (PL) spectra indicate that the PL of ensulizole is less Stokes-shifted in polar solvents and more Stokes-shifted in non-polar solvents. The average PL lifetime of ensulizole is longer in non-polar solvents as compared to polar solvents and it exhibits the shortest PL lifetime in aqueous medium that signifies its efficiency in water. This suggests in non-polar solvents intersystem crossing is the dominant mode of relaxation of the excited ππ* state. Furthermore, an increase of pH of ensulizole solution decreases the PL intensity and the lifetime. Stern-Volmer equation is employed to evaluate bimolecular quenching rate constant k q that suggests the diffusional dynamic mode of PL quenching is operative.
... 2-Phenylbenzimidazole-5-sulfonic acid commonly known as "ensulizole" [34] is an effective and recommended sunscreen agent [7,[35][36][37] and it is a part of many commercially available sunscreen products [38]. Therefore, it is essential to understand the photophysical properties of ensulizole in order to develop more effective sunscreen products based on this compound. ...
Article
Full-text available
Employing natural or artificial sunscreens is essential to protect the skin from ultraviolet radiations that cause premature aging and develop melanoma and other forms of skin cancer. The 2-Phenylbenzimidazole-5-sulfonic acid, commonly known as ensulizole is a water-soluble artificial sunscreen that absorb UV-B (280 nm − 315 nm) radiations and protects the skin against the harmful effects of these radiations. We have measured steady-state photoluminescence (SSPL) spectra and photoluminescence (PL) kinetics of this compound in various conditions. Steady-state absorption indicates a strong absorption feature at 303 nm and a weak one at 316 nm that have been identified as π → π* and n → π* transitions, respectively. The spectra of PL induced by these absorptions indicate that the PL of ensulizole is less Stokes-shifted in polar solvents and more Stokes-shifted in non-polar solvents. The average PL lifetime of ensulizole is longer in non-polar solvents than in polar solvents and it exhibits the shortest PL lifetime in aqueous medium that maximize its transition efficiency in water. This suggests in non-polar solvents intersystem crossing is the dominant mode of relaxation of the excited ππ* state. Furthermore, an increase of pH of ensulizole solution decreases the PL intensity and the lifetime. Stern-Volmer equation is employed to evaluate bimolecular quenching rate constant kq. The evaluation result suggests the diffusional dynamic mode of PL quenching is operative. Graphical Abstract
... The rate of the achieved adsorption equilibrium is expressed by 1 , small value of 1 and high value of ( − ) are observed in slow adsorption [23]. Azizian has reported that 1 is the combination of the adsorption (ka) and desorption (kd) rate constants in Eq (1) [28]. This equation can be integrated using the initial condition qt = 0 when t = 0, and the resulting equation is represented by Eq. (4): ...
Thesis
Full-text available
L'évolution des techniques de libération contrôlée de principe actifs (PAs) contribue de manière significative à la santé humaine. Dans ce contexte, le développement de nouveaux modèles galéniques représente un véritable défi technologique. L'objectif de cette étude était l'élaboration de complexes organosilicates (OS)-molécules bioactives afin de développer de nouveaux modèles galéniques. Ces organosilicates s'inscrivent dans le cadre du projet breveté de synthèse de particules analogues aux argiles naturelles nommé EBISilc®. En effet, le laboratoire EBInnov® a développé des particules d'OS synthétisées par voie sol-gel avec un rapport préalablement défini d'alkoxysilanes de départ ayant des chaînes latérales lipophiles (L)/hydrophiles (H) avec une catalyse basique, en présence d'ions calcium (Ca2+) et aluminium (Al3+).Dans un premier temps, une étude de preuve de concept a été réalisée sur une des particules d'OS lipophiles (OSL). L'objectif était de déterminer la capacité des OSL à adsorber une molécule hydrophobe modèle, la benzophénone-3 (BZ-3), utilisée comme filtre-UV. Les effets des principaux paramètres expérimentaux sur l’adsorption ont été déterminés en système discontinu (batch) tels que le solvant, le pH, la température, la concentration initiale de BZ-3 et le temps de contact. Une étude comparative de la capacité d'adsorption des OSL a été réalisée en comparaison avec un minéral argileux naturel, la montmorillonite (MMT) et une argile synthétique, la LAPONITE® (Lap). L'équilibre de l'isotherme d'adsorption a été décrit selon les modèles de Langmuir, Freundlich et Temkin ainsi qu’une étude des paramètres thermodynamiques. L'adsorption en surface des adsorbants a été analysée avec des modèles cinétiques empiriques de réaction-adsorption de pseudo-premier ordre (PFO), de pseudo-second ordre (PSO) et d'Elovich. Afin de comprendre le mécanisme de transfert de masse, le modèle de diffusion intraparticulaire de Weber-Morris (WM) et le modèle de diffusion de surface (SDM) ont également été étudiés. Afin d'évaluer la capacité de désorption des adsorbants, une étude comparative des trois adsorbants (OSL, MMT et Lap) complexés à la BZ-3 a été explorée à l'aide de cinq modèles de désorption suivant l'ordre zéro, le premier ordre, le modèle d'Higuchi (H), de Hixson-Crowell (HC) ainsi que le modèle de Korsmeyer-Peppas (KP). La BZ-3 a été libérée à partir des complexes de manière continue et homogène. Pour finir, une étude comparative de l'effet photoprotecteur des trois complexes adsorbant-BZ3 a été mise en application dans des formulations topiques d'écran solaire
... 10 UVA-UVB`ye etkili, fiziksel koruyucu olan çinko oksit, titan dioksit veya kimyasal güneş koruyucu olan parsol 1789 (avobenzone) içeren güneş koruyucular uygundur. [46][47][48][49] SPF minimum 15 faktor olmalıdır. Güneş koruyucu ürünün yeterli miktarda kullanılmaması sonucunda tahmin edilen koruma oranının %50'si sağlanmaktadır. ...
Article
Full-text available
Problems in melasma treatment
... The critical wavelength (CW, λ c ) is calculated from the measured absorbance of a sunscreen across the entire UV spectrum and is intended to provide an objective quantifi- cation of how well a sunscreen reduces exposure to both UVB and UVA wavelengths [45]. Absorbance (A), is the negative of the (base ten) logarithm of transmittance (T): ...
Article
Full-text available
Ultraviolet radiation (UVR) exposure is the most important modifiable risk factor for skin cancer development. Although sunscreen and sun-protective clothing are essential tools to minimize UVR exposure, few studies have compared the two modalities head-to-head. This study evaluates the UV-protective capacity of four modern, sun-protective textiles and two broad-spectrum, organic sunscreens (SPF 30 and 50). Sun Protection Factor (SPF), Ultraviolet Protection Factor (UPF), Critical Wavelength (CW), and % UVA- and % UVB-blocking were measured for each fabric. UPF, CW, % UVA- and % UVB-blocking were measured for each sunscreen at 2 mg/cm2 (recommended areal density) and 1 mg/cm2 (simulating real-world consumer application). The four textiles provided superior UVR protection when compared to the two sunscreens tested. All fabrics blocked erythemogenic UVR better than the sunscreens, as measured by SPF, UPF, and % UVB-blocking. Each fabric was superior to the sunscreens in blocking full-spectrum UVR, as measured by CW and % UVA-blocking. Our data demonstrate the limitations of sunscreen and UV-protective clothing labeling and suggest the combination of SPF or UPF with % UVA-blocking may provide more suitable measures for broad-spectrum protection. While sunscreen remains an important photoprotective modality (especially for sites where clothing is impractical), these data suggest that clothing should be considered the cornerstone of UV protection.
... Importantly, the National Cancer Institute 5 consumer use data for adults aged 18 years or older between the years 2005 and 2015 report that 70.8% of all adults practice one of the three sun protective behaviors identified: (i) seeking shade and avoiding sun during peak hours (ii) wearing protective clothing; and (iii) using sunscreen. Of the three methods, only 33.7% reported applying sunscreens, while 38.4% relied on clothing and 39.1% usually sought shade.Taking into account how products are tested for UV efficacy, the absorption spectrum of the currently approved FDA actives, and how T A B L E 1 Critical wavelength for commonly used UV filters with an attenuation of 370 nm and above3 ...
Article
Full-text available
Oxybenzone (Benzophenone-3) is an emerging human and environmental contaminant used in sunscreens and personal care products to help minimize the damaging effects of ultraviolet radiation. The Center for Disease Control fourth national report on human exposure to environmental chemicals demonstrated that approximately 97% of the people tested have oxybenzone present in their urine, and independent scientists have reported various concentrations in waterways and fish worldwide. Oxybenzone can also react with chlorine, producing hazardous by-products that can concentrate in swimming pools and wastewater treatment plants. Moreover, adverse reactions could very well be increased by the closed loop of ingesting fish contaminated with oxybenzone and/or washing the ingredient off our bodies and having it return in drinking water as treatment plants do not effectively remove the chemical as part of their processing protocols. In humans, oxybenzone has been reported to produce contact and photocontact allergy reactions, implemented as a possible endocrine disruptor and has been linked to Hirschsprung's disease. Environmentally, oxybenzone has been shown to produce a variety of toxic reactions in coral and fish ranging from reef bleaching to mortality. Lastly, with the rise in skin cancer rates and the availability of more effective sunscreen actives such as micronized zinc oxide and titanium dioxide, serious doubts about the relative prevention benefit of personal care products containing oxybenzone must be raised and compared with the potential negative health and environmental effects caused by the accumulation of this and other chemicals in the ecosystem.
... The samples remained at rest for 20 min prior to recording the transmittance in the wavelength range 250 and 450 nm, at the rate of progression of 1 nm. Measurements were made at 9 different points for each plate [16,17] . ...
Article
Full-text available
The use of sunscreen products is widely promoted by schools, government agencies, and health-related organizations to minimize sunburn and skin damage. In this study, we developed stable solid lipid nanoparticles (SLNs) containing the chemical UV filter octyl methoxycinnamate (OMC). In parallel, we produced similar stable SLNs in which 20% of the OMC content was replaced by the botanical urucum oil. When these SLNs were applied to the skin of human volunteers, no changes in fluorescence lifetimes or redox ratios of the endogenous skin fluorophores were seen, suggesting that the formulations did not induce toxic responses in the skin. Ex vivo (skin diffusion) tests showed no significant penetration. In vitro studies showed that when 20% of the OMC was replaced by urucum oil, there was no reduction in skin protection factor (SPF), suggesting that a decrease in the amount of chemical filter may be a viable alternative for an effective sunscreen, in combination with an antioxidant-rich vegetable oil, such as urucum. There is a strong trend towards increasing safety of sun protection products through reduction in the use of chemical UV filters. This work supports this approach by producing formulations with lower concentrations of OMC, while maintaining the SPF. Further investigations of SPF in vivo are needed to assess the suitability of these formulations for human use.
... It has widely been accepted that protection from ultraviolet radiation (UVR) spectrum reduces the risk of acute and chronic skin damage in humans (Diffey et al. 2000). In addition to preventing sunburn and photoaging, sunscreens exert beneficial effects against skin cancer, and their regular use did not increase mortality (Lindstrom et al. 2019). ...
Article
It is widely accepted that the use of topical sunscreens has medical importance with potential to prevent skin damage by protecting from solar ultraviolet radiation (UVR) effects. Pharmaceutical emulsions require an optimal qualitative and quantitative combination of emollients, emulsifiers and others compounds such as softening agents and, for sunscreens, a combination of chemical and physical UV filters. Herein, we applied the quality by design (QbD) concept to achieve stable and effective compounded sunscreen emulsions. By using the statistical tool of design of experiments, it was possible to identify the influence of emulsifier type (with low and high Hydrophile-Lipophile Balance) and concentrations of emollient and softening agent on the achievement of formulations with suitable organoleptic and physicochemical features. Compounded emulsions with pleasant macroscopic aspects were obtained. Three formulations with physicochemical properties in targeted ranges were selected, namely pH ∼6.0, conductivity >0.0 µS/cm2, spreadability factor ∼1-1.5 g/mm2, viscosity ∼12000 mPa.s and sunscreen protection factor ∼30. Freeze-thaw cycle and accelerated stability study under different storage conditions allowed selecting a stable emulsion that ensured photoprotection in biological assays. The QbD approach was essential to select the best, low-cost compounded sunscreen emulsion, with targeted physicochemical parameters.
... Molecular components of commercially available topical sunscreens, such as titanium dioxide, zinc dioxide, and avobenzone, are effective in blocking or filtering UVA and UVB wavelengths, preventing it from damaging the molecular integrity of the tissue underneath. 17,18 Further animal studies showed similar results. A recent study combining in vitro model of human skin and mouse animal models showed that topical sunscreen application prevent the formation of SCC in animal model. ...
Article
Full-text available
Topical sunscreen is a potential modality to prevent skin cancer development in vulnerable people although few study has evaluated its effectiveness in clinical setting. This study is aimed to review most recently available evidence on the clinical effectiveness of topical sunscreen in preventing skin cancers. We identified literature from online databases including Pubmed and Google Scholar and included population-based study evaluating the effect of sunscreen usage and risk of skin cancers, including melanoma, squamous cell carcinoma (SCC), and basal cell carcinoma (BCC) either as primary objective or as a confounder in multivariate analysis. Data form included articles was harvested and analyzed with thematic analysis. Final analysis included 11 articles. Of these, 6 reported results on melanoma, 4 reported on BCC, and 3 on SCC. Overall, there was conflicting evidence on the effectiveness of topical sunscreen in preventing skin cancer. Available evidence found that topical sunscreen was most effective in preventing melanoma and SCC. However, there was considerable heterogenicity in study design and definition of sunscreen treatment between included articles that may affect the results. There are no consensus among included articles, including among RCTs, on the ideal topical sunscreen regiment to prevent skin cancer. There are conflicting evidence on the clinical effectiveness of topical sunscreen to prevent skin cancer although evidence suggest that it would be effective in preventing melanoma and SCC. More clinical studies should be conducted with special emphasis on ensuring subject apply the sunscreen correctly and consistently.
... The data obtained were then in turn compared with existing literature, which further confirmed the accuracy of the test [29]. There are several advantages in conducting this form of analysis: (1) it measures not only the amplitude but also the width of the product's absorption spectrum, (2) the measurement is not affected by the application thickness of the product, and (3) it can account for both UVA and UVB as a single entity in a continuous electromagnetic spectrum [60]. Finally, in vitro methods of measurement are recommended by the FDA as they have reduced dangers, cost, and time consumption relative to human clinical testing [59]. ...
Article
Full-text available
There are many extrinsic factors that can contribute to the premature aging of the skin. In recent years, the demand for natural cosmetic from the general population has noticeable grow. Therefore, this research aimed to investigate the bioproperties of sky fruit (Swietenia macrophylla) seed extract that could help to inhibit premature skin aging. Firstly, the extract and its fractions were tested on HaCaT cells for their wound healing properties. The presence of sky fruit’s extract and its fractions on scratch wound significantly improved cellular proliferation, migration, and closure of the wound. These effects were distinctly observed following the treatment with S. macrophylla hexane fraction (SMHF) and S. macrophylla water fraction (SMWF). Our continuous research study revealed that SMWF had antioxidant properties, which might be one of the factors contributing to its emerging wound healing properties because antioxidants are known to act as suppressors of the inflammatory pathway and aid the transition towards cell proliferation. In addition, all samples had critical wavelengths that indicated that they were able to absorb the whole UVB range and some parts of the UVA wavelength. This suggested that S. macrophylla might contain potential photoprotective bioactive compounds, which could be developed into anti-UVB photoprotective sunscreens. Thus, this warrants further studies focusing on isolation and identifications of the bioactive compounds responsible for both its photoprotective and wound healing properties. A deeper study on mechanisms of the pathways that were affected by these compounds should be conducted as well to better understand this natural product and develop it into a potential cosmeceutical ingredient.
... to it (in vitro) [9][10][11]. However, there is currently no standard evaluation method for the determination of the efficacy of UVA protection that considers the reduction in skin elasticity, which is the main damaging effect caused by UVB and UVA rays. ...
Article
Full-text available
Regular exposure of facial skin to sunlight promotes wrinkle formation; ultraviolet (UV) radiation causes the skin to harden and lose its elasticity. To study UV damage to the skin in vitro, a short-term in vitro photoaging model is required. Hence, the UV transmittance of excised human skin was measured. Changes in elasticity in the cheeks of humans of different ages were investigated. Moreover, changes in the hardness and elasticity of collagen gels following UV exposure were investigated. UV rays penetrated the upper layer of the dermis and UVA (330 nm) rays penetrated approximately 1.6 times farther than UVB (310 nm) rays. A correlation between age and lower cheek elasticity was observed. Upon exposure to UV rays, collagen gels hardened and their elasticity decreased; UVA rays exhibited a stronger effect than UVB rays. Wavelengths of 300–340 nm caused hardening and reduced elasticity of collagen gels; 330-nm radiation showed the most pronounced effect. These effects were not observed upon exposure to UV wavelengths over 350 nm. Investigating the UV-hardening mechanism of collagen showed increased tyrosine crosslinks (dityrosines) in the in vitro model of photodamage to collagen, suggesting that dityrosine formation contributes to hardening and reduced elasticity of collagen in photoaged skin.
Article
Cosmetic standard poly methyl methacrylate (PMMA) UV evaluation plates, i.e., roughened PMMA plates, are used in the EU and the US for the in vitro evaluation of UV protection abilities of sunscreen, such as in vitro UVA-PF and critical wavelength for the Broad-spectrum approval. In our previous studies, inhomogeneity in the thickness of a pseudo-sunscreen layer applied on a flat quartz plate was observed to alter UV transmission. Thus, the surface roughness of the standard plates should have a significant influence on the in vitro evaluation. In the present study, we have analyzed the surface structures of three cosmetic standard PMMA UV evaluation plates: Helioplates HD6 (Sa = 6 µm) and ISO plates (Ra = 2 and 5 µm). A decamethylcyclopentasiloxane and 2-propanol-mixed solvent solution of acrylsilicone resin was prepared, and the solution was added dropwise onto the plates. After the evaporation of the solvents, the plates were cut and the cross section was analyzed using SEM-EDS. The distribution of silicon atoms at the cross-section suggested that the maximum depth of penetrating of acrylsilicone resin was larger than Ra for all the standard plates, and the surface structure was significantly different for each standard plate. In addition, cracks into which the acrylsilicone resin deeply penetrated were observed on the surface of some plates. Clear-solution-type pseudo-sunscreen samples in which UV absorbers and acrylsilicone resin were dissolved were deposited on the standard roughened PMMA plates. It was observed that the addition of acrylsilicone resin drastically changed the net UV transmission. The degree to which the hollows of the roughened surface were filled with the pseudo-sunscreen samples determined the variation of UV transmittance.
Article
A simple and efficient BF3∙OEt2 mediated methodology for the construction of diverse 2-phenylpyridines bearing benzophenone moieties from readily available 3-formylchromones and phenylacetylenes in wet acetonitrile was developed. The nitrogen source for the pyridine construction was derived from acetonitrile. This one-pot protocol proceeds via [3+2+1] annulation through cascade nucleophilic addition, hydrolysis, Michael-type addition, ring opening, and elimination reactions. The synthesized compounds may have applications as UV filters and exhibit potent antibacterial activities.
Article
Full-text available
Ultraviolet light causes skin cancer. Salicylic acid and other molecular filters absorb damaging radiation but are washed away readily. Conjugation to a collagen mimetic peptide is shown to retain salicylic...
Article
Modified sulfobetaine bearing tertiary amide spacer between the counterions is synthesized and polymerized by reversible addition–fragmentation chain transfer polymerization technique. The tertiary amide spacer influences various characteristics of the zwitterionic polymer. The modified polyzwitterion, PZI, forms coacervates in deionized water. The coacervates are thoroughly characterized by scanning electron microscopy, transmission electron microscopy, and transmittance studies. The ability to form coacervate complexes with functional ingredients has been demonstrated by encapsulating renewable resource actives like ferulic acid. The coacervate complexes have been studied by optical microscopy, transmission electron microscopy, and automated sunscreen sun protection factor analyzer. Synergism is noticed in the coacervate complex. Because of its ability to form self-coacervates, this novel addition to the zwitterionic family is potentially useful for encapsulating many functional ingredients through coacervate complex formation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 135, 46178.
Article
Inorganic oxides such as titanium dioxide (TiO2) and zinc oxide (ZnO) are desired as ultraviolet (UV) filters. Such UV‐filters derived from naturally occurring oxides are promising components for formulating personal care products sustainably. However, UV‐filters based on inorganic oxides pose challenges to formulators and users in terms of strong adherence to skin and high photocatalytic activity. As a means to influence the morphology of such functional oxides, a simple one‐dimensional (1D) ZnO nanorod was synthesized via solvothermal technique assisted by the seed‐growth method. Thus bio‐renewable ferulic acid (FA) was used as a capping and structure‐directing agent to obtain tunable nanostructures such as spheres, sheets, and rods. SEM and TEM analyses revealed the self‐assembled elongated morphology with increased aspect ratio. Based on these as well as other analyses the growth mechanism of zinc oxide functionalized ferulic acid (ZnO@FA) was investigated. ZnO@FA also exhibited broad absorption in the UV−B and A regions, unique antioxidant behavior along with a highly suppressed photocatalytic activity. The ZnO@FA are sustainable, functional materials. These materials are potentially useful in areas such as cosmetics, functional coatings, sensors and solar cells. Tunable ZnO architectures: A simple and benign approach to functionalized ZnO using bio‐derived ferulic acid (ZnO@FA). FA was used as a capping and structure‐directing agent to obtain tunable nanostructures such as spheres, sheets, and rods. ZnO@FA has strong absorption in UV−B and A region and also exhibited antioxidant properties with low photocatalytic activity. The tunable hybrid ZnO@FA nanostructures as a sustainable UV‐filter for personal care applications.
Chapter
During the development of a dermal drug, much efforts tend to be placed on improving its delivery through skin. These efforts are driven by the known risk of not engaging the target, the lack of understanding of skin pharmacokinetics and the risk of using rodent model to predict target engagement. Skin penetration enhancement methods and their limits are therefore reviewed in this chapter. A section is then dedicated to the claims sometimes made about the potential for some vehicles to promote skin retention, with a demonstration that technologies for vehicles with such claims should be investigated with high caution. A discussion then follows about the pros and cons of doing much formulation development before the candidate molecule is selected. The importance of vehicle aesthetics is finally reviewed in the light of its impact of patient adherence to the treatment and overall efficacy. The overall conclusion from this chapter points towards the mistake made often by research projetc team who tend to select the dermal vehicle for its delivery properties at the expenses of its aesthetic properties. This happens as there is always some doubts that not enough drug will be delivered to the target site and therefore, the program team may chose to limit this risk. Unfortunately the gain on the extra delivery are often small compared to the loss on the aesthetics side.
Article
Sunscreens have become a mainstream consumer product for protection against the damaging ultraviolet (UV) radiation in sunlight. Before a sunscreen is released to the market, it must undergo a set of safety and efficacy tests established by a government or relevant regulatory authority. Regulatory bodies rely on access to appropriate analytical methods to ensure product compliance. The current sunscreen testing standards, particularly those to evaluate the sunscreen efficacy, are far from ideal from both a regulatory and an ethical perspective. For instance, some tests mandate unwarranted exposure of UV radiation to humans and cannot be reliably replicated. This article aims to provide a comprehensive review of the existing sunscreen testing standards, while providing a critical perspective on associated challenges, demands and opportunities in improving analytical methods for sunscreen testing. This review will provide a roadmap for those interested in sunscreen testing, including manufacturers, regulatory bodies, policy makers and academic researchers.
Article
Seaweeds have been identified as promising sources of bioactive substances for the cosmeceutical industry, especially by their photoprotection capacity. Accordingly, this study aimed to evaluate the photoprotective properties of extracts from macroalgae and one marine lichen. Samples of 22 species of macroalgae and one marine lichen, were collected along the southern Iberian Peninsula. Hydroethanolic extracts were prepared from algal and marine lichen lyophilized biomass. Ultraviolet (UV) and visible absorption spectra, polyphenol content, antioxidant activity, mycosporine-like amino acid content and composition were analyzed. In order to quantify the photoprotection capacity of the extracts against different biological effects, two new indices were used, i.e., effective solar absorption radiation (%ESAR) and extract photoprotection index (EPI), considering the radiation absorbed and transmitted by the extract, respectively. In the ultraviolet spectrum, Porphyra umbilicalis and Pyropia elongata presented the highest absorbance values at 330 nm, while Ulva lactuca showed a prominent peak at 290 nm. In the visible spectrum, a fucoxanthin peak (450 nm) was strongly evident in extracts from the brown algal species, while green algal extracts presented characteristic chlorophyll a and b peaks at 447, 620 and 664 nm. Polyphenol content and antioxidant activity were much higher in Sargassum vulgare, Carpodesmia tamariscifolia, P. umbilicalis and Lichina pygmaea in comparison to the other species. P. umbilicalis and Bangia atropurpurea showed the highest amount of mycosporine-like amino acids. S. vulgare and P. umbilicalis extracts presented the highest values of potential photoprotection against all analyzed biological response according to the different action spectra. S. vulgare and P. umbilicalis showed an increase in %ESAR values associated with an increase in the concentration of their extracts. Considering the analyzed species, our results suggest that S. vulgare and P. umbilicalis could be potential sources of photoprotective extracts. The potential use of these species in cosmeceutical products is discussed.
Article
Sunscreen formulations have been developed to provide an artificial protective barrier against the deleterious effects of overexposure to ultraviolet (UV) radiation in humans. Ultrafast pump-probe spectroscopy techniques have been an invaluable tool in recent years for determining the photochemistry of active ingredients in sunscreen formulations, predominantly UV filters, in both the gas- and solution-phases. These measurements have enabled the elucidation of molecular relaxation pathways and photoprotection mechanisms, which are in turn insightful for assessing a filter's photostability and suitability for sunscreen use. In this review, we discuss the benefits of a bottom-up approach: the progression from the study of UV filters for sunscreens in vacuum, away from the influences of any solvent; in solution, to investigate the relaxation pathways of potential sunscreen filters in closer to real-life conditions, whilst exploring the merits of selective functionalisation to improve their characteristics; and beyond, to current advances that are mimicking the application of sunscreen formulations to the surface of the skin.
Thesis
Full-text available
Mycosporines and mycosporine-like amino acids (MAAs) are UV-absorbing compounds produced by cyanobacteria and other organisms, especially upon exposer to solar ultraviolet radiation (UVR). These compounds are photoprotective and some have additional antioxidant functíons useful to the natural cosmetics market. This study aims to identify MAAs producing cyanobacteria with potential applicatíons in cosmetics. A HPLC DAD MS/HRMS method for the identification of MAAs was developed. Out of the 75 cyanobacteria studied, 27 strains (38%) synthesized MAAs. Oscilatoria sp. CMMA 1600, from homocyte type, produced the greatest diversity of MAAs. 10 different MAAs were identified including a MAA with molecular weight of 316 Da. The chemical structure of mycosporine-glycine-alanine was confirmed by 1D/2D NMR and HRMS analyses. This compound has never been reported from a natural source. In this study, a validated LC-MS/MS quantification method for MAAs is also presented. An easy-to-handle and rapid extraction procedure was developed which uses only water and volatile additives as the extractor solvents. The LC MS/MS method was performed using multiple reaction monitoring in positive mode with a reverse-phase column. The method enabled the accurate determination and quantification of the MAAs porphyra-334, shinorine and mycosporine-glycine-alanine in a 6 minutes running time, with limits of detection < 0.005 μg.mg 1. MAAs induction experiments were performed through UVR exposure. MAAs are constitutively produced by some cyanobacteria and production was further enhanced following UV-irradiance. Other strains start to produce at least one MAA after UV-irradiance. Sphaerospermopsis torques-reginae strain (ITEP 024 and ITEP 026) produced the highest concentration of these photoprotective compounds. S. torques-reginae ITEP 024 strain was further exposed to different radiation compositíons. MAAs were significantly influenced by UVB. In this study, the potential of cyanobacteria as MAA producers, that can be used as photoprotectors in sunscreens, has been demonstrated.
Article
Riassunto I prodotti di protezione solare (PPS) composti da filtri chimici e/o filtri minerali occupano, oggi, un posto importante nella fotoprotezione. Sono stati all’origine di ampie polemiche, alcune delle quali non sono ancora cessate, sulla loro reale efficacia nella prevenzione primaria dei carcinomi cutanei (CC), nonché sui loro potenziali rischi sanitari ed ecologici. I filtri chimici agiscono assorbendo le radiazioni luminose; distinguiamo i filtri UVB puri e i filtri larghi, il cui spettro di assorbimento si estende ai raggi UVA. I filtri minerali diffraggono o riflettono le radiazioni; i due principali sono il biossido di titanio (TiO2) e l’ossido di zinco (ZnO); per contingenze cosmetiche la dimensione delle loro particelle è stata ridotta a nanoparticelle. Un PPS deve rispondere alle qualità di persistenza, sostantività e fotostabilità. Vengono proposti due tipi di metodi per la valutazione dei coefficienti di protezione (CP) dei PPS: metodi in vivo su volontari sani e metodi in vitro, che utilizzano vari substrati e basati sulla spettrometria. Il sun protective factor (SPF) in vivo è il CP UVB universalmente accettato; per il CP UVA, il metodo in vivo del persistent pigment darkening (PPD), anche se non consensuale, rimane ancora oggi il più utilizzato in Europa. La misurazione della lunghezza d’onda critica (Lc) ha un grande interesse nel definire l’entità della protezione negli UVA lunghi più deleteri. I filtri chimici sono una nota causa di reazioni locali; è stato menzionato, negli ultimi anni, un rischio particolare per l’octocrilene. Recentemente, il dibattito si è concentrato principalmente sul rischio di perturbazione endocrina (effetto che imita l’estradiolo dopo somministrazione orale a dosi molto elevate nei ratti), che può essere indotto da alcuni (ma non da altri!) filtri chimici, principalmente il 4-metilbenzilidene canfora e i benzofenoni. Il rischio negli umani sembra irrilevante nelle normali condizioni d’uso dei PPS; il rischio ambientale di alcuni filtri, se dimostrato, sarebbe probabilmente dovuto alla loro presenza in molti altri prodotti, oltre ai PPS. I filtri minerali, spesso esaltati nei bambini, sollevano la questione del rischio di nanoparticelle. In ogni caso, nell’ambito del “Piano d’azione nazionale sulla fertilità” e di una valutazione del rischio delle nanoparticelle, l’Afssaps/ANSM ha fornito le raccomandazioni adeguate relative all’incorporazione di questi filtri, chimici e minerali, nei prodotti cosmetici e all’uso corretto dei PPS. Infine, i dati attuali non suggeriscono che i PPS possano avere un effetto dannoso inibendo gli effetti benefici del sole, in particolare la sintesi di vitamina D. I PPS hanno dimostrato, a condizione di un uso corretto, un’efficacia protettiva contro la maggior parte degli effetti deleteri del sole, purché siano progettati in conformità con le caratteristiche specifiche perfettamente identificate nelle raccomandazioni europee del 2006. In particolare, gli studi epidemiologici dimostrano la loro efficacia nella prevenzione primaria di tutti i CC, siano essi dovuti a esposizioni ambientali o intenzionali, e alcuni PPS di protezione media sono sufficienti a questo scopo. I rischi più che speculativi non devono certamente scoraggiare il loro utilizzo.
Article
Résumé Les produits de protection solaire (PPS) composés de filtres chimiques et/ou de filtres minéraux occupent aujourd’hui une place importante en photoprotection. Ils ont été à l’origine de larges polémiques, dont certaines ne sont pas éteintes, sur leur efficacité réelle en prévention primaire des cancers cutanés (CC), ainsi que sur leurs risques sanitaire et écologique potentiels. Les filtres chimiques agissent en absorbant le rayonnement lumineux ; on distingue les filtres UVB purs et les filtres larges dont le spectre d’absorption s’étend à l’UVA. Les filtres minéraux diffractent ou réfléchissent le rayonnement ; les deux principaux sont le dioxyde de titane (TiO2) et l’oxyde de zinc (ZnO) ; pour des contingences cosmétiques la taille de leurs particules a été réduite aux nanoparticules. Un PPS doit répondre à des qualités de rémanence, de substantivité et de photostabilité. Deux types de méthodes sont proposés pour l’évaluation des coefficients de protection (CP) des PPS : des méthodes in vivo sur volontaires sains, et des méthodes in vitro utilisant des substrats variés et basés sur la spectrométrie. Le sun protective factor (SPF) in vivo est le CP UVB universellement admis ; pour le CP UVA, la méthode in vivo de la persistent pigment darkening (PPD), bien que non consensuelle, reste à ce jour la plus utilisée en Europe. La mesure de la longueur d’onde critique (Lc) a un intérêt majeur pour définir l’étendue de la protection dans les UVA longs les plus délétères. Les filtres chimiques sont connus pour être à l’origine de réactions locales ; un risque particulier pour l’octocrylène a été évoqué ces dernières années. Récemment, le débat s’est surtout centré sur le risque de perturbations endocriniennes (effet mimant l’estradiol après administration orale à très forte dose chez le rat) pouvant être induites par certains (mais pas les autres !) filtres chimiques, essentiellement le 4-méthylbenzylidène camphre et les benzophénones. Le risque humain paraît peu pertinent dans des conditions normales d’usage de PPS ; le risque environnemental de certains filtres, s’il était avéré, relèverait probablement de leur présence dans bien d’autres produits que les PPS. Les filtres minéraux, souvent prônés chez l’enfant, soulèvent la question du risque des nanoparticules. En tout état, dans le cadre du « Plan d’action national sur la fertilité » et d’une évaluation du risque des nanoparticules, l’Afssaps/ANSM a donné les recommandations adéquates concernant l’incorporation de ces filtres, chimiques et minéraux, dans les produits cosmétiques et le bon usage des PPS. Enfin, les données actuelles ne laissent pas à penser que les PPS puissent avoir un effet délétère en inhibant les effets bénéfiques du soleil, en particulier la synthèse de vitamine D. Les PPS ont démontré, sous couvert d’une utilisation correcte, une efficacité protectrice contre la plupart des effets délétères du soleil à condition d’être conçus en respectant le cahier des charges parfaitement identifié dans les recommandations européennes de 2006. En particulier, les études épidémiologiques démontrent leur efficacité dans la prévention primaire de tous les CC qu’il s’agisse des expositions environnementales ou intentionnelles, et des PPS de protection moyenne suffisent pour cela. Les risques plus que spéculatifs ne doivent certainement pas conduire à dissuader de les utiliser.
Article
Ultraviolet radiation (UVR) is a consistent part of the environment that has both beneficial and harmful effects on human health. UVR filters in the form of commercial sunscreens have been widely used to reduce the negative health effects of UVR exposure. Despite their benefit, literature suggests that some filters can penetrate skin and have off-target biological effects. We noted that many organic filters are hydrophobic and contain aromatic rings, making them potential modulators of Aryl hydrocarbon receptor (AhR) signaling. We hypothesized that some filters may be able to act as agonists or antagonists on the AhR. Using a luciferase reporter cell line, we observed that the UVR filter octinoxate potentiated the ability of the known AhR ligand, 6-formylindolo[3,2-b]carbazole (FICZ), to activate the AhR. Co-treatments of keratinocytes with octinoxate and FICZ lead to increased levels of cytochrome P4501A1 (CYP1A1) and P4501B1 (CYP1B1) mRNA transcripts, in an AhR dependent fashion. Mechanistic studies revealed that octinoxate is an inhibitor of CYP1A1 and CYP1B1, with IC50 values at approximately 1 µM and 586 nM, respectively. In vivo topical application of octinoxate and FICZ also elevated CYP1A1 and CYP1B1 mRNA levels in mouse skin. Our results show that octinoxate is able to indirectly modulate AhR signaling by inhibiting CYP1A1 and CYP1B1 enzyme function, which may have important downstream consequences for the metabolism of various compounds and skin integrity. It is important to continue studying the off-target effects of octinoxate and other UVR filters, since they are used on skin on a daily basis world-wide.
Chapter
This chapter details the process of claims substantiation, how claims can be generated, supported, and communicated. It looks at the definition of cosmetic claims and what may be required to substantiate them. It builds on an approach to substantiating cosmetic claims developed in the UK by the CTPA in association with the ASA. This includes defining different classes of claims, the level of evidence required to support the classes, and also the quality of evidence that might be anticipated by an advertising regulator or an in market competent authority. Though it is written from a UK/EU market view, the recognition that clearly identified consumer needs, and how these are fulfilled by the final product, form an essential part of claims development making the approach described in this chapter applicable globally. The chapter also raises the challenges presented by advances in understanding of skin physiology, the technology that can be applied to influencing this and how this might be communicated to consumers.
Article
Many current ultraviolet filters present potential hazards both to humans and to the natural environment. As such there is a new impetus to develop, through intimate characterisation, ultraviolet filters for use in cosmeceuticals. Here we report a new class of organic molecules which have a strong absorption band across the ultraviolet-A and -B regions of the electromagnetic spectrum and high photostability. We have performed ultrafast transient electronic absorption spectroscopy and steady-state spectroscopies, alongside computational studies to track and manipulate photoprotection mechanisms. Our results present a potentially new generation of ultraviolet filters for use in commercial formulations
Article
Full-text available
Koralezko uharriak, ur azpiko ekosistemarik dibertsoenetarikoak dira, inguruneko aldaketa txikiei sentikorrak direnak. Hala, urteetan zehar gizakiek eragindako mehatxu lokal zein mundu mailakoek, koralen heriotza eragin dute eta honekin batera, biodibertsitatearen murrizpena. Mehatxu lokalen artean eguzkitako kremak daude, hauen konposatu den oxibentzona barne. Iragazki organiko hau, azalaren babeserako erabiltzeaz gain, azal eta ilearen zaintze-produktuetan, kosmetikarako eta perfumeen konposaketarako erabili izan da. Itsasoan sartzean, krema bertan murgildu eta koraletan metatzen da, hauen zuritzea eta ondoriozko heriotza eraginez. Konposatu honen eragin toxikoak azterturik, ekosistemaren babeserako alternatibak bilatu beharko dira, zink oxidoa edo titanio dioxidoa bezalako iragazki mineralen ezaugarriak baloratuz.
Article
Full-text available
Ferulic acid is a derivative of cinnamic acid showing efficacious anti-oxidant activity. It catalyzes the stable phenoxy radical formation, upon absorption of ultraviolet light, giving the strength to ferulic acid for terminating free radical chain reactions. Ultraviolet rays are one of the most dangerous factors that daily assault the skin, causing excessive generation of reactive oxygen species (ROS), which are regarded to be important contributors to a variety of cutaneous alterations. The skin possesses endogenous antioxidant defense systems, but the excess of ROS leads to an oxidant-antioxidant imbalance. Although ferulic acid is daily introduced in human organism with the diet, its bioavailability after oral administration is poor, particularly in the skin. The aim of this investigation was to evaluate three types of emulsions (W/O/W multiple emulsions and two simple emulsions) as suitable formulations for topical application of the active compound. In vitro studies were performed to investigate the stability and release profiles of these systems. Multiple emulsions showed great stability and the best ability to carry and release ferulic acid. In vivo evaluations highlighted their best capability to treat UV-B-induced erythema. These findings suggested multiple emulsions as an innovative and more efficient vehicle for topical application of ferulic acid.
Article
Full-text available
Guarana (Paullinia cupana) is a native Amazonian fruit and, due to its medicinal properties, stands out as one of the most promising species of Brazilian flora. Known for its invigorating and stimulating action, this species produces phenolic compounds responsible for its biological activities, which are of great interest to the phytocosmetic industry, in the preparation of anti-aging creams, for example. In this study, the antimicrobial, antioxidant, photoprotective and cytotoxic activities of extracts obtained from guarana seeds were evaluated. Guarana seeds were obtained in Maués, Amazonas state, Brazil and, after drying, the seeds were ground in a knife mill. P. cupana seed extracts were obtained by the depletion method using hexane, dichloromethane and ethanol as solvents. Antioxidant activity assays were performed to determine the ability to scavenge the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH•). To assess the sun protection factor (SPF), Mansur’s spectrophotometric method was used. For the analysis of antimicrobial activity, the microplate dilution technique was used against strains of Escherichia coli, Pseudomonas aeruginosa and Candida albicans. To evaluate the toxicity of the extracts, the lethal concentration of 50% of the population of the microcrustacean Artemia salina was determined. The cytotoxic effect of the extracts against human colorectal carcinoma cells (HCT 116) was also evaluated using the Alamar Blue test. The ethanolic extract from guarana seeds showed SPF value of 249.10 and a critical wavelength number (λc) of 383 nm, when evaluated at a concentration of 0.1% (m/m). The ethanolic extract also showed antioxidant activity, and a 50% efficient concentration (EC50) of 647 μg mL-1. The dichloromethane extract was active against E. coli and P. aeruginosa, with a minimum inhibitory concentration (MIC) of 20 mg mL-1 for both bacteria, and a MIC of 2.0 mg mL-1 for the yeast. This extract did not show toxicity against A. salina (LD50> 1 mg mL-1). The ethanolic and hexane extracts, however, presented low toxicity to the microcrustacean. On the other hand, none of the evaluated extracts inhibited the proliferation of HCT116 cells, showing no cytotoxicity. P. cupana seeds have an important therapeutic value due to the presence of substances with antioxidant, antibiotic and photoprotective activities, though with low cytotoxicity, which allows their use as functional additives in phytocosmetics, as well as in the development of possible phytotherapeutic products.
Article
Living organisms tend to evolve various naturally photoprotective mechanisms to avoid photodamage. Among them, polydopamine (PDA) is an effective sunscreen, a mimic of melanin, which is the main functional component of the photoprotective system of human skin. However, the concerns of its dark color, skin penetration and photoprotective efficiency remain yet to be solved. Herein, we have constructed melanin-inspired nanocomposite hydrogels (CS-PDAh-GP-HA) for photoprotection, in which PDA was prepared as hollow nanoparticles (PDAh NPs) and entrapped in a physically cross-linked hydrogel (CS-GP-HA) formed by chitosan (CS) and hyaluronic acid (HA) using β-glycerophosphate (β-GP) as a modulator. The CS-PDAh-GP-HA hydrogels exhibit a shear-thinning flow behavior with an elastic modulus of 300 Pa with the gel-sol transition temperature maintained at about 37 oC simply by adjusting the β-GP content in the hydrogels. The CS-PDAh-GP-HA hydrogels also possess excellent resistance toward skin penetration. The photoprotective performances of CS-PDAh-GP-HA hydrogels were evaluated by the determination of sun protection factor (SPF) and in vitro UVA protection efficacy (UVAPE) along with UV-Vis spectroscopy. Compared with the TiO2 nanoparticles in CS-GP-HA hydrogel, the CS-PDAh-GP-HA hydrogels show stronger shielding ability in both UVA and UVB regions. When protected by the CS-PDAh-GP-HA hydrogels, the cell viability of NIH-3T3 fibroblasts increases to 96% while it was only 14% in the case of non-protecting group. These results suggest that the CS-PDAh-GP-HA hydrogels could efficiently shield the UV irradiation and protect the skin from photodamage. This work introduces PDA-based nanocomposite hydrogels with safe, biocompatible and photoprotective properties, and provides a melanin-mimicking photoprotection system for the application in sunscreens.
Article
Purpose Excessive exposure of skin to solar radiation is associated with greatly increased production of reactive oxygen and nitrogen species (ROS, RNS) resulting in oxidative stress (OS), inflammation, immunosuppression, the production of matrix-metalloproteases, DNA damage and mutations. These events lead to increased incidence of various skin disorders including photoageing and both non-melanoma and melanoma skin cancers. The ultraviolet (UV) part of sunlight, in particular, is responsible for structural and cellular changes across the different layers of the skin. Among other effects, UV photons stimulate oxidative damage to biomolecules via the generation of unstable and highly reactive compounds. In response to oxidative damage, cytoprotective pathways are triggered. One of these is the pathway driven by the nuclear factor erythroid-2 related factor 2 (Nrf2). This transcription factor translocates to the nucleus and drives the expression of numerous genes, among them various detoxifying and antioxidant enzymes. Several studies concerning the effects of UV radiation on Nrf2 activation have been published, but different UV wavelengths, skin cells or tissues and incubation periods were used in the experiments that complicate the evaluation of UV radiation effects. Conclusions This review summarizes the effects of UVB (280–315 nm) and UVA (315–400 nm) radiation on the Nrf2 signalling pathway in dermal fibroblasts and epidermal keratinocytes and melanocytes. The effects of natural compounds (pure compounds or mixtures) on Nrf2 activity and level as well as on Nrf2-driven genes in UV irradiated human skin fibroblasts, keratinocytes and melanocytes are briefly mentioned as well. • Highlights • UVB radiation is a rather poor activator of the Nrf2-driven pathway in fibroblasts • UVA radiation stimulates Nrf2 activation in dermal fibroblasts • Effects of UVA on the Nrf2 pathway in keratinocytes and melanocytes remain unclear • Long-term Nrf2 activation in keratinocytes disturbs their normal differentiation • Pharmacological activation of Nrf2 in skin needs to be performed carefully
Article
A new method was developed for the in vitro sun protection factor (SPF) evaluation of sunscreen samples. A new type of substrate, a hydroxyalkyl cellulose-coated plate, was also prepared specifically for hydrophilic samples. This new substrate was required because hydrophilic samples would be unlikely to wet the surface of the standard cosmetic PMMA UV evaluation plate. A super-hydrophilic quartz plate was prepared by corona-discharge treatment before an aqueous solution of hydroxyalkyl cellulose was spread on it. A flat and uniform hydroxyalkyl cellulose film was subsequently formed through the evaporation of water. Special care was taken to inhibit the generation of spatial non-uniformity. Six hydrophilic sunscreen samples with in vivo SPF values of 56, 55, 52, 25, 15, and 4, were then applied to the prepared hydroxyalkyl cellulose-coated plate, as well as a super-hydrophilic quartz plate and a flat hydrophobic PMMA plate. The thicknesses of the applied layers were determined using a wheel-shaped wet film thickness gauge immediately after the application, and UV transmission was measured using an SPF analyzer. The value of in vitro SPF was calculated from the UV absorbance and the thickness of the layer. For two out of the six samples, PMMA plate could not be available, as the samples were unable to wet the PMMA surface. Relatively small differences were observed between the in vitro SPF values when the super-hydrophilic and hydroxyalkyl cellulose-coated plates were used. Samples exhibiting higher in vivo SPF were also associated with higher in vitro SPF values, although a linear relationship was not observed. In contrast to the super-hydrophilic plate whose half-life of the super-hydrophilicity is only approximately five days, the hydrophilicity of the hydroxyalkyl cellulose-coated plate scarcely varied during six months of storage. Finally, a simplified evaluation method was also proposed. The validity of the method was verified through a ring test where three researchers employed this method in different laboratories at three independent organizations. graphical abstract Fullsize Image
Article
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.
Chapter
Unprotected exposure to solar ultraviolet (UV) radiation leads to profound public health implications. Short-term physical distresses such as episodic sunburns or blistering, shockingly, could snowball into long-term hazards, including skin cancer. In an effort to suppress these damaging effects of UV radiation, photo-protective measures have been put in place, with sunscreens being an integral part of the strategy. Typically, topical sunscreen formulations comprise organic and inorganic ingredients, which act as chemical and physical UV filters, respectively. An ideal sunscreen includes non-toxic active components with pronounced absorption properties in the broadband UV spectrum and enhanced photostability. Some of these components, however, are photo-labile and display a poor aesthetic elegance. The recent introduction of nanotechnology, which involves the design, production and application of materials in nano-dimensions, seems to circumvent many of the shortcomings associated with the traditional micro-sized topical agents as a preventive modality of the sun-damaging activities. Present-day studies also underpin the use of nanomaterials in sunscreen formulations to have significantly improved cosmesis, ease of application while retaining their UV-protective attributes. There are, however, rising concerns over the size-related properties of nanomaterials, which could elicit unintended negative consequences, such as the formation of free radicals and aggravated cellular toxicity. In this chapter, we review the emerging use of nanonutrition and nanoparticles in UV protection, as well as their mechanism of action and safety concerns. We propose several photoprotection recommendations as a presetting framework for future research to meet the functional demands in the cosmetics and wellness industry.
Article
Full-text available
— Albino hairless mice (Skh-hrl) were exposed daily to radiation from a high-power long wavelength UV-A source (wavelengths longer than 340 nm). The irradiations lasted 2 h per day. The daily dose was 220 kJ/m2. Heavy scratching marks were observed in 13 out of 48 animals. However during the experiment 31 of the animals developed tumors of 1 mm or larger before any scratching was observed. The median induction time was 265 days for 1 mm tumors.
Article
Full-text available
Albino hairless mice (Skh-hr1) were exposed daily to radiation from a high-power long wavelength UV-A source (wavelengths longer than 340 nm). The irradiations lasted 2 h per day. The daily dose was 220 kJ/m2. Heavy scratching marks were observed in 13 out of 48 animals. However during the experiment 31 of the animals developed tumors of 1 mm or larger before any scratching was observed. The median induction time was 265 days for 1 mm tumors.
Article
Full-text available
The carcinogenic effect of long-term exposure to UVA (315-400 nm) radiation was examined in Cr:ORL Sencar mice. Daily exposure to FR40T12 PUVA bulbs, filtered with Mylar to eliminate wavelengths below 315 nm, induced skin tumors with 50% probability of tumor development (T50) occurring after 68 weeks of irradiation. Tumors developed primarily on the dorsa of mice and included squamous cell carcinomas, poorly differentiated (spindle cell) tumors, and benign squamous papillomas. By comparison, thrice-weekly exposure of Sencar mice to unfiltered FS40 sunlamps containing both UVB (280-315 nm) and UVA radiation, induced skin tumors with T50 occurring after 23 weeks of irradiation. Tumors developed primarily on the ears and included squamous cell carcinomas and spindle-cell tumors. A small number of spontaneous mammary adenocarcinomas occurred in mice (both irradiated and unirradiated controls) that were older than 50 weeks. This study demonstrates that UVA radiation, which is the major UV waveband in solar radiation, is carcinogenic in a haired mouse strain, although far less carcinogenic than combined UVB/UVA radiation.
Article
Full-text available
A combination of psoralen and ultraviolet A radiation (PUVA) is widely used in the treatment of psoriasis. However, PUVA treatment increases the risk of developing skin cancer in psoriasis patients and induces skin cancer in mice. Since the DNA damage induced by PUVA is quite different from that induced by UV, we investigated whether PUVA-induced mouse skin cancers display carcinogen-specific mutations in the p53 tumor suppressor gene. The results indicated that 10 of 13 (77%) PUVA-induced skin tumors contained missense mutations predominantly at exons 6 and 7. In contrast, tumor-adjacent, PUVA-exposed skin from tumor-bearing animals did not exhibit p53 mutation in exons 4-8. Interestingly, about 40% of all mutations in PUVA-induced skin tumors occurred at 5'-TA sites, and an equal number of mutations occurred at one base flanking 5'TA or 5'-TAT sites. Since PUVA induces DNA cross-links exclusively at these sites and since UV "signature" mutations were rarely detected in PUVA-induced skin cancers, we can conclude that PUVA acts as a carcinogen by inducing unique PUVA signature mutations in p53. This finding may have implications for identifying the etiology of skin cancer in psoriasis patients who have undergone PUVA therapy.
Article
There is now evidence that UVA wavelengths (320-400 nm) in sunlight may contribute to the clinical changes commonly observed in photodamaged skin. We examined the effects of repetitive, suberythemal doses of UVA radiation on human skin in order to identify the epidermal and dermal changes indicative of early tissue injury. For these purpose, two areas of the back of fourteen female volunteers, phototype I to III, 20 to 40-year-old, were exposed three times a week for 13 weeks, to increasing doses of UVA (330-440 nm) resulting in a cumulative dose of 1,200 J/cm2. During the exposure period, biophysical and clinical changes were examined. After the last irradiation, a series of epidermal and dermal parameters were analyzed and quantified by histochemical staining in combination with image analysis on biopsied tissue sections. HVA induced a strong pigmentation with no alteration of microtopography. Skin hydration and elasticity decreased, whereas total skin thickness, assessed by echography, remained unchanged. Histologically, irradiated epidermis revealed an absence of hyperplasia, a significant thickening of the stratum corneum with an increased number of stratum corneum layers, a depletion of Langerhans cells and an increase in the expression of the protective protein, ferritin. No significant alteration was seen using antisera against type IV collagen or laminin, suggesting that the dermal-epidermal junction (DEJ) was largely preserved. In the dermis, enhanced expression of tenascin was seen below the DEJ, but type I procollagen localized at the same site was unaltered. Although we were unable to visualize any change in elastic fiber content using Luna staining, using an immunofluorescence technique we noticed an increased deposition of lysozyme on elastin fibers, confirming the results of Lavker. These findings suggest that chronic suberythemogenic doses of UVA, resulted in morphological and histological skin changes.
Article
Erythemal action spectra have been the subject of experimental and theoretical interest for over 50 years. Despite all of these studies, or perhaps because of the diversification of the published data resulting from them, no one action spectrum has been universally adopted. In response to a request by Division 6 of the Commission on Illumination (CIE) for the formulation of a reference action spectrum for adoption by the CIE, members of Technical Committee 2 propose the following: 1. The reference action spectrum for erythema should be that shown in figure 1 (proposed action spectrum). 2. The data contained in the action spectrum should be used only as spectral weighting factors to indicate the approximate relative erythemal efficacy of a light source (between 250 and 400 nm).
Article
Although the UVB portion of the electromagnetic spectrum (290 to 320 nm) is responsible for most of the harmful effects of sunlight on the skin, wavelengths in the UVA region also contribute to photodamage. A simple and rapid clinical test, the sun protection factor determination, is available to assess the sunburn protective effect of a sunscreen, primarily a UVB effect. However, no practical test has been proposed to measure a sunscreen's UVA protection. We described a method for the calculation of UVA protection in normal subjects. The determination of UVA protection involves three steps: (1) the UV absorbance spectrum of the sunscreen on skin is determined spectrophotometrically; (2) a convolution spectrum is calculated by multiplying the solar spectrum with the Commission Internationale de l'Eclairage UV Hazard Spectrum; and (3) the sunscreen transmission spectrum is then incorporated into the convolution spectrum to obtain the UVA effectiveness ratio, which can be expressed as the UVA protection percentage. Because the UVA protection percentage value is based both on normal erythemic risk and on standard sunlight, the protection for any product can be easily measured. The procedure is simple, and values generated can be reproduced in other laboratories.
Article
—Ultraviolet radiation produces erythema in human skin, and damages the DNA of living cells in skin. Previous work showed that broad-band UV-B (290–320 nm) radiation produced higher levels of cyclobutyl pyrimidine dimers in DNA of individuals with high UV-B sensitivity (low minimal erythema dose) than in subjects of low UV-B sensitivity [Freeman et al. (1986) J. Invest. Dermatol., 86, 34–36]. We examined the relationship between erythema induction and dimer yields in DNA of human skin irradiated in situ with narrow band radiation spanning the wavelength range 275–365 nm. We find that, in general, higher dimer yields are produced per incident photon in volunteers with higher susceptibility to erythema induced by radiation of the same wavelength.
Article
Abstract— Seven commercially available sunscreens were compared by three different methods. Absorbance spectra were measured for each product in isopropanol solution and also on hairless mouse epidermis. In vivo tests were performed on human volunteers using a Xe arc solar simulator. Sun Protection Factors (SPF) were calculated by each method for each product tested and the results compared. By all methods used, the combination of 7% octyl dimethyl para-aminobenzoic acid and 3% oxybenzone provided the most protection from U.V. light. While estimates of the effectiveness of all products were much too high when calculated by the isopropanol solution method, the hairless mouse epidermis technique seems to be an accurate tool for predicting product efficacy in vivo.
Article
A method is described and evaluated for classifying sunscreen products into different broad spectrum categories. The method is based on spectrophotometric analysis of products applied to a suitable substrate and obviates the need for human or animal studies utilizing clinical endpoints which may be of dubious value in relation to protection from sun exposure. The absorbance spectrum obtained by spectrophotometric assay is reduced to a single index by determining that wavelength λc where the area under the spectrum from 290 nm (the approximate lower wavelength limit of terrestrial sunlight) to λc is 90% of the integral of the absorbance spectrum from 290 to 400 nm. A five-point scale is used to classify products as follows:
Article
We examined the chronic effect of long daily suberythemal, fluorescent solar-stimulated radiation (FSSR; ultraviolet B (UVB)+A(UVA)) and UVA alone on female Skh-1 hairless albino mouse skin. Mice were dorsally irradiated 8 h every weekday for 16 weeks with FSSR or UVA, or 32 weeks with UVA alone. Various topical, low concentration, UVB and/or UVA sunscreens were applied before irradiation. Damage was assessed by skin-fold thickness, histology and biochemically by changes in the proportion of type III collagen. All FSSR-exposed mice showed increased skin thickening, elastic fibre hyperplasia, collagen damage and an increased proportion of type III collagen. Application of the UVB sunscreen (2.00%) resulted in marked protection for all nonbiochemical endpoints. There was no obvious advantage of adding 0.75% UVA sunscreen to the UVB sunscreen, but adding 2.00% UVA sunscreen reduced biochemical changes and connective tissue damage. Sixteen weeks of UVA irradiation caused skin thickening and laxity but the histology and biochemistry were indistinguishable from the controls. The mice irradiated with UVA for 32 weeks showed slight elastic fibre hyperplasia and collagen damage histologically, and increased skin thickening and laxity; these changes were unmodified by the 0.75% UVA sunscreen. These mice showed a significant increase in the proportion of type III collagen against which the UVA sunscreen offered protection. Our data suggest that UVA may be important in photoaging and that the use of low sun protection factor UVB+ UVA sunscreens on a day-to-day basis may offer some protection from solar photoaging.
Article
Ultraviolet radiation produces erythema in human skin, and damages the DNA of living cells in skin. Previous work showed that broad-band UV-B (290-320 nm) radiation produced higher levels of cyclobutyl pyrimidine dimers in DNA of individuals with high UV-B sensitivity (low minimal erythema dose) than in subjects of low UV-B sensitivity [Freeman et al. (1986) J. Invest. Dermatol., 86, 34-36]. We examined the relationship between erythema induction and dimer yields in DNA of human skin irradiated in situ with narrow band radiation spanning the wavelength range 275-365 nm. We find that, in general, higher dimer yields are produced per incident photon in volunteers with higher susceptibility to erythema induced by radiation of the same wavelength.
Article
A method is described for screening potentially useful photoprotective agents against UVA radiation by the use of immediate pigment darkening as an end point. Threshold doses of immediate pigment darkening showed a log normal distribution and the response was found to obey dose-reciprocity at irradiance levels below 50 mW/cm2. With this procedure, several marketed sunscreens containing benzophenone-3 as the only UVA absorber were found to have poor UVA protection factors, whereas those containing combinations of benzophenone-3 and butyl methoxydibenzoyl methane or melanin were more effective. There was no correlation between the sun protection factor cited on the label and the calculated immediate pigment darkening-protection factor.
Article
Reciprocity for sunscreen solar protection factors (SPFs) and for delayed erythema was examined using a solar simulator equipped with neutral density filters to vary the beam intensity. Similar SPFs were obtained over a 15-fold intensity difference, using a sunscreen with a low (SPF-4) and a high (SPF-15) protection factor. Reciprocity was also observed for delayed erythema in unprotected skin.
Article
Albino hairless mice (Skh: HR-1) exposed chronically to sub-erythemal doses of UV radiation display physical, visible and histological alterations. Using narrow bandwidth radiation covering the UV radiation spectrum from 280-380 nm, the wavelength dependence of these alterations was determined. The wavelength dependence spectra indicate that for all but one parameter measured (skin sagging), UV-B radiation is considerably more efficient than UV-A radiation in producing changes in the skin. However, in natural sunlight there is considerably more UV-A than UV-B radiation, providing the potential for UV-A to have a larger contribution to skin damage than UV-B. This argues in favor of using broad spectrum photoprotective agents to shield the skin adequately from UV-induced aging. The spectra were also used to develop potential associations among events by determining which events occur at similar wavelengths. There seems to be a correspondence between mouse visible skin wrinking (UV-B event) and two histological events: increase in glycosaminoglycans and alteration in collagen. There was no obvious correspondence among UV-A-induced events.
Article
We have used a specially modified xenon arc solar simulator to examine ultraviolet A (UVA) protection of a research sunscreen formulation. UVA doses were given to sunscreen-protected and unprotected skin with the use of irradiance values of 50 mW/cm2 and 100 mW/cm2. Erythemal responses were evaluated 5.2 +/- 0.9 hours later and again 24.4 +/- 1.8 hours later. The overall mean unprotected UVA minimal erythema dose (MED) was 23.6 joules/cm2 (SD = 4.8) and the mean UVA protection factor (APF) was 3.2 (SD = 0.78). Neither irradiance nor evaluation time significantly affected MED or APF. These preliminary findings indicate that the modified solar simulator permits convenient determination of sunscreen APF. The APF of a sunscreen is analogous to SPF: APF refers to UVA protection, while SPF refers to protection from the entire solar spectrum, predominantly from the effects of UVB.
Article
Because the protection factor of sunscreens concerns only UVB protection, usually nothing is known about the protection offered in the UVA range. Using different methods, we compared six commercially available sunscreens to determine the UVA protection factor and, thus, to select the most appropriate sunscreen. Two clinical methods on human skin (inhibition of UVA-induced tanning with the use of a high-intensity UVA source and inhibition of methoxsalen plus UVA-induced phototoxicity) were compared with a method in animals (inhibition of UVA-induced sunburn cell production in mice treated with methoxsalen) and with two in vitro techniques (solution-dilution and sandwich spectrophotometry). We conclude that all five methods used give a quantitative estimate of UVA protection, but none can be accepted as a standard because the UVA protection factor varies according to the method used and the reading time.
Article
The efficacy of a sunscreen containing an investigational drug, butyl methoxydibenzoylmethane in combination with padimate O against the erythemogenic effect of ultraviolet A (UVA) radiation was evaluated in two double-blind studies involving subjects sensitized with topical 8-methoxypsoralen. UVA radiation was supplied from either a filtered solar simulator (indoors) or filtered sunlight (outdoors). Five formulations were tested: 3% butyl methoxydibenzoylmethane and 7% padimate O, 7% padimate O, 5% octyl salicylate, and 3% oxybenzone, 3% butyl methoxydibenzoylmethane alone, 7% padimate O alone, and vehicle. Sunscreen protection against the erythemogenic effect of UVA radiation was expressed as phototoxic protection factors. The phototoxic protection factor for each sunscreen was derived from a ratio of the minimal phototoxic dose of UVA radiation that produced delayed erythema on sunscreen-protected and unprotected skin. The combination of 3% butyl methoxydibenzoylmethane and 7% padimate O provided significantly greater protection than the other sunscreen formulations, and for each sunscreen the phototoxic protection factors determined indoors and outdoors were comparable.
Article
The erythemal response of normal human skin to UVA and UVB radiation was measured objectively using a reflectance instrument in seven subjects, and a laser Doppler velocimeter in two subjects. UVA radiation was produced using a newly-developed high-intensity UVA lamp. The slope of the log dose-erythemal response curve for UVA at 24 h after irradiation was found not to differ significantly from that for UVB. The time course of UVA erythema was biphasic; erythema was present immediately after irradiation, fell to a minimum at about 4 h and then rose to a broad plateau between 6 and 24 h. The intensity of the early phase was dose-rate dependent, whereas that in the later phase depended on dose only.
Article
The effect of oxygen deprivation upon UVA-, UVB-, and PUVA-induced pigment and erythema responses in normal human skin was examined. Before exposure, varying degrees of hypoxia in the skin of the forearm were achieved by inflating a sphygmomanometer cuff applied to the upper arm. After the transcutaneously measured pO2 had stabilized, sites on the inner forearm were exposed to UVA, UVB, or 8-MOP + UVA radiation, to determine dose thresholds for the induction of erythema and pigmentation at different cuff pressures. Inflation of the cuff to greater than systolic pressure completely inhibited immediate and delayed pigment responses (IPD, DT) to UVA doses greater than 10 times the normal pigmentation threshold dose. UVA-induced delayed erythema responses were partially inhibited by cuff inflation: 2.7 times the minimal erythema dose of UVA was necessary to cause an erythema response when exposure occurred during vascular occlusion. In contrast, erythema and pigment responses to UVB and PUVA were unaltered by cuff pressures exceeding systolic pressure during exposure. Inhibition of UVA-induced erythema and pigment responses by vascular occlusion were reversed by the transcutaneous diffusion of 100% O2. These findings indicate that the cutaneous responses to UVA and UVB occur by separate pathways differing with respect to O2 dependence. Our findings agree with those of other studies which indicate that PUVA-induced phototoxicity and melanogenesis are not O2-dependent.
Article
Topical formulations containing a new chemical entity, the ultraviolet A absorber Parsol 1789 (butyl methoxydibenzoylmethane), were evaluated as agents for protecting human skin against ultraviolet A (UVA) radiation. Healthy subjects were photosensitized to UVA radiation by ingestion of 8-methoxypsoralen (0.6 mg/kg). After 90 minutes, five formulations (vehicle, vehicle + butyl methoxydibenzoylmethane, vehicle + butyl methoxydibenzoylmethane + padimate O, vehicle + padimate O, and a marketed sunscreen containing padimate O, oxybenzone, and octyl salicylate) were applied in a randomized, double-blind manner to areas on the lower part of the back. Thirty minutes later, sites in the five treated areas and in a sixth unprotected area were exposed to graduated doses of UVA radiation. Test sites were evaluated for erythema 48 and 72 hours after UVA exposure, and for melanogenesis approximately 2 weeks later. The combination of butyl methoxydibenzoylmethane + padimate O demonstrated significantly greater protection than the combination of padimate O, oxybenzone, and octyl salicylate.
Article
Photoprotection against ultraviolet A (UVA) by three sunscreens was evaluated in humans, with erythema and pigmentation used as end points in normal skin and in skin sensitized with 8-methoxypsoralen and anthracene. The test sunscreens were Parsol 1789 (2%), Eusolex 8020 (2%), and oxybenzone (3%). UVA was obtained from two filtered xenon-arc sources. UVA protection factors were found to be significantly higher in sensitized skin compared with normal skin. Both Parsol and Eusolex provided better and comparable photoprotection (approximately 3.0) than oxybenzone (approximately 2.0) in sensitized skin, regardless of whether 8-methoxypsoralen or anthracene was used. In normal unsensitized skin, Parsol 1789 and Eusolex 8020 were also comparable and provided slightly better photoprotection (approximately 1.8) than oxybenzone (approximately 1.4) when pigmentation was used as an end point. The three sunscreens, however, were similar in providing photoprotection against UVA-induced erythema. Protection factors obtained in artificially sensitized skin are probably not relevant to normal skin. It is concluded that pigmentation, either immediate or delayed, is a reproducible and useful end point for the routine assessment of photoprotection of normal skin against UVA.
Article
Human cutaneous erythemogenic and melanogenic responses to long-wave (UVA) ultraviolet radiation were investigated using irradiances ranging from 5-50 mW/cm2. Skin surface temperature changes resulting from the different irradiances were also compared. In general, threshold doses for erythema and pigmentation were higher when UVA was administered at the lowest irradiance (5 mW/cm2) than at the highest (50 mW/cm2). Erythema was maximal immediately after exposure to UVA. The most intense responses (erythema with edema, or intense pigmentation) were induced more frequently by the highest irradiance. Components of both the erythema and the pigment response to UVA are therefore irradiance-dependent. The greatest increase in skin surface temperature was observed after exposure to the highest irradiance.
Article
The action spectra for delayed erythema and melanogenesis in Caucasian human skin are determined for wavelengths between 250 and 435 nm. The untanned skin of very fair volunteers was observed after single exposures to a range of fluences of monochromatic radiation. At wavelengths longer than 300 nm the two action spectra are indistinguishable, and at wavelengths shorter than 300 nm, they are of similar shape despite a distinct separation. This suggests a common or similar chromophore for initiation of the vascular and pigmentary responses to UV. A broad minimum in the action spectra occurs near 280 nm, a maximum near 296 nm, and for wavelengths longer than 300 nm, increasingly larger fluences of radiation are required to induce delayed erythema and melanogenesis. Between 304 and 334 nm both action spectra exhibit a rapid decrease of almost three orders of magnitude. In contrast, between 334 and 405 nm the spectra decrease by only one order of magnitude, and there is a suggestion of a small maximum at or near 365 nm. Different chromophores, sites of damage, or response mechanisms may be responsible for induction of delayed erythema at these longer wavelengths. After spectral corrections for the optical effects of the stratum corneum, the shape and magnitude of the action spectra are grossly consistent with a mechanism in which DNA is the primary chromophore initiating the response pathways for wavelengths less than 313 nm. Whatever the actual basis for these action spectra may be, they are of practical significance in predicting skin response to sources of ultraviolet radiation.
Article
Daily exposures to relatively small suberythemogenic fluences of UVA (50-200 kJ/m2) for 8 days resulted in cumulative morphological skin alterations indicative of early tissue injury. Histologically, irradiated skin revealed epidermal hyperplasia, inflammation and deposition of lysozyme along the dermal elastic fiber network. Sunburn cells were also present within the epidermis. These changes were quantified by image analysis and were found to be related to the cumulative UVA fluence. A long UVA waveband (UVAI, 340-400 nm) was as effective as a broad UVA band (320-400 nm), suggesting that these changes are induced by longer UVA wavelengths.
Article
Repetitive exposure of skin to sunlight is known to result in dermatoheliosis, characterized by photoaging and carcinogenesis. It has been demonstrated previously that relatively large amounts of ultraviolet (UV) A can produce photodamage and it is believed that UVB plays a major role in the induction of photodamage and photocarcinogenesis. The study reported here determines the cutaneous effects of minimal erythemal amounts of solar-simulated UV radiation as well as suberythemal and minimal erythemal doses of UVA. Previously non-sunexposed human skin was irradiated twice weekly for 24 weeks. Biopsies were obtained 12, 24 and 36 weeks after the initial irradiation and assessed for both epidermal and dermal alterations. Dermal elastic tissue content was measured via computerized image analysis. All UV treatment regimens produced observable epidermal and dermal changes. These alterations were observed after only 12 weeks of twice-weekly irradiation and were still evident 12 weeks after the final irradiation. Interestingly, UVA irradiation produced a decrease in elastic tissue content whereas solar-simulated UV produced a slight increase. Most notable were the changes produced by the suberythemal dose of UVA. Surprisingly, this relatively low UVA dose produced a reduction in elastic tissue content. The results of this investigation demonstrate that small amounts of UVA or solar-simulated UV are capable of producing cutaneous photodamage. These findings suggest that even suberythemal doses of repetitive UVA may lead to photoaging of the skin and that there is a need for daily broad spectrum UV protection.
Article
The skin is repeatedly exposed to solar UV radiation. Long-term photodamage is a consequence of cumulative UV radiation injury. Hence an examination of the repetitive effects of UV exposure is more likely to yield clues to the early alterations that lead to photoaged skin than a single exposure. We examined the effects of repetitive low-dose UV irradiation on human skin with the aim of identifying UVA-induced effects that may have a different wavelength dependence than acute erythema. Areas on the lower part of the back were each exposed to a suberythemal dose (0.5 minimal erythema dose [MED]) of solar simulated radiation (290 to 400 nm) and of UVA (320 to 400 nm) once daily, 5 days a week, for 28 doses. One site was also treated daily with a sunscreen having a sun protection factor of 22 and then exposed to 11 MEDs of solar simulated radiation for the same duration. Epidermal and dermal changes were analyzed and quantified by histochemical stains in combination with computer-assisted image analysis of tissue sections. At equal 0.5 MED doses, UVA induced greater cumulative changes than solar simulated radiation, as assessed by development of a greater cumulative erythema response in the first week of treatment, the presence of epidermal hyperplasia and stratum corneum thickening, depletion of Langerhans cells, dermal inflammatory infiltrates, and deposition of lysozyme on elastin fibers. These changes were not prevented by the sunscreen. A single short-term dose of UVA did not elicit these changes. These findings suggest that UVA may contribute significantly to long-term actinic damage and that the spectral dependence for cumulative damage does not parallel the action spectrum for acute injury (erythema) in human beings.
Article
The wavelength dependency of carcinogenesis is an important factor in risk assessments pertaining to sources of ultraviolet radiation, the most important of which is the sun. This wavelength dependency cannot be measured directly in humans, but it has been measured in hairless mice, and represented in an action spectrum. An estimate of the action spectrum for humans can be produced by correcting for differences in epidermal transmission between mice and humans. This carcinogenic action spectrum for humans resembles the action spectrum for ultraviolet-induced erythema (sunburn), and results in small adjustments of earlier estimates of the effects of a stratospheric ozone depletion on skin cancer incidences.
Article
The wavelength dependence for immediate pigment darkening (IPD) was investigated by exposing the midback skin of volunteers to a series of incremental fluences of narrow waveband radiation isolated by band-pass filters in the 310-400 nm region. The threshold IPD fluence for each waveband was determined by visual assessment of the skin responses immediately after each exposure. The action spectrum, constructed from the mean threshold fluences, was broad and extended from 320 nm to 400 nm with a peak at around 340 nm. No IPD could be evoked at 310 nm, even after erythemogenic fluences. The spectrum was similar in each of the three skin types investigated (III, IV, V). The broad nature of the action spectrum within the UVA region suggests that IPD may serve as an alternative endpoint for measuring photoprotection against these wavelengths.
Article
The wavelength dependence for UVA-induced cumulative damage was investigated in human skin. Epidermal changes (stratum corneum thickening, viable epidermal thickening sunburn cell production), as well as dermal alterations (lysozyme deposition, inflammation), were used as indices of cumulative photoperturbation. UVA wavelengths between 320 nm and 345 nm were more effective than longer wavelengths (360-400 nm) in inducing viable epidermal thickening. Similarly, the shorter wavelengths (320-345 nm) elicited more sunburn cells, although these differences did not reach statistical significance. All UVA bands were equally effective in inducing the dermal markers. At equal fluences, wavelengths > 400 nm produced no measurable cutaneous alterations. These findings suggest that (i) chronic epidermal and dermal damages have different spectral dependence and (ii) the action spectrum for dermal damage in the UVA is broad, extending up to 400 nm, and is different from the acute erythema spectrum in humans.
Article
The location of DNA photodamage within the epidermis is crucial as basal layer cells are the most likely to have carcinogenic potential. We have determined the action spectra for DNA photodamage in different human epidermal layers in situ. Previously unexposed buttock skin was irradiated with 0.5, 1, 2, and 3 minimal erythema doses of monochromatic UVR at 280, 290, 300, 310, 320, 340, and 360 nm. Punch biopsies were taken immediately after exposure and paraffin sections were prepared for immunoperoxidase staining with a monoclonal antibody against thymine dimers that were quantitated by image analysis. Dimers were measured at two basal layer regions, the mid and the upper living epidermis. The slopes of dose-response curves were used to generate four action spectra, all of which had maxima at 300 nm. Dimer action spectra between 300 and 360 nm were independent of epidermal layer, indicating comparable epidermal transmission at these wavelengths. Furthermore, we observed 300 nm-induced dimers in dermal nuclei; however, there was a marked effect of epidermal layer between 280 and 300 nm, showing relatively poor transmission of 280 and 290 nm to the basal layer. These data indicate that solar UVB (approximately 295-320 nm) is more damaging to basal cells than predicted from transmission data obtained from human epidermis ex vivo. The epidermal dimer action spectra were compared with erythema action spectra determined from the same volunteers and ultraviolet radiation sources. Overall, these spectral comparisons suggest that DNA is a major chromophore for erythema in the 280-340 nm region.