In vitro assessment of sunscreen photostability: the effect of radiation source, sunscreen application thickness and substrate

The photostabilities of four sunscreen products have been assessed in vitro by applying sunscreen to a substrate and measuring the spectral transmission prior to, and after exposure to a source of ultraviolet (UV) radiation. Results were independent of whether an application thickness of 1 or 2 mg/cm ; 2 was used, and whether the UV source was natural sunlight or a xenon arc solar-simulator. There were significant differences, however, between results obtained on a roughened quartz substrate and those obtained on excised human epidermis. It is unlikely that any substrate will give an exact representation of the in vivo situation and, indeed, both quartz and excised human epidermis have disadvantages associated with their use. However, the ranking of the four products in terms of their photostability was the same for both substrates. This implies that transmission spectroscopy, with either a quartz or a human epidermis substrate, can be used successfully to compare the photostabilities of different sunscreen products.     

Harnessing food‐based bioactive compounds to reduce the effects of ultraviolet radiation: a review exploring the link between food and human health

Appropriate exposure to sun is beneficial to humans and living organisms. However, excessive exposure to ultraviolet (UV) radiation can lead to photoageing, severe health risks and even death. Nowadays, the health risks of excess UV exposure have greatly increased due to the significant changes of global climate and human lifestyle as well as the thinning of the stratospheric ozone (a natural and effective filter for solar UV radiation). Therefore, protecting against UV radiation‐induced damage is a serious challenge. Research needs to address the understanding of the mechanisms underlying the UV‐induced damages and also explore the potential use of natural substances to combat the harm caused by UV radiation. Plant‐based substances have been found to exert significant protective effects against UV radiation. This review explores the most recent hypothesis of natural bioactive compounds (such as flavones, peptides, polysaccharides and terpenoids) as potential protective agents against UV radiation. The similarities and differences in UV photoprotective mechanisms among these different classes of compounds are also discussed.     

J. Cosmet. Sci., 59, 263–289 (July/August 2008)True porosity measurement of hair: A new way to study hair damage mechanisms

The purpose of this study was the development of a microbiological method for the assessment of the ultraviolet (UV) screening effect of sunscreen preparations and determination of their sun protection factor. The method is based on the lethal effect of UV radiation on Escherichia coli and the protective ability of sunscreens. The time of UV exposure required for the reduction of the E. coli viable count by 90% (decimal reduction time, DRT) was used as the photoprotection assessment parameter. The method was tested by assessing the effect of selected experimental variables on the DRT. The suitability of the method as a quality control tool for sunscreen preparations was then checked by assessing the influence of selected formulation variables on the photoprotective effect of a series of o/w emulsion formulations with different compositions. The method proved valid for detecting changes in the photoprotective effect of a market sunscreen product as a result of modifying experimental conditions. It also proved valid for ranking market sunscreen products according to their UV screening effect. Equally important, the method could successfully detect changes in the photoprotective effect of sunscreen test formulations as a function of the concentration and type of the sunscreen agents.     

Research on a natural sunscreen from Chinese herbs

To compare the difference in SPF values between a synthetic sunscreen and a sunscreen derived from Chinese herbs, by using optical and biological methods, we observed the effects of these sunscreens by photochemical reaction, sun protection factor (SPF) values, and UV absorption. The results showed that the synthetic sunscreen was more effective in UV absorption than the sunscreen derived from natural Chinese herbs. When they were tested biologically, it was found that the sunscreen derived from Chinese herbs was able to improve skin tonicity, as well as reduce the itching, photoerythema, squamation, burning, and reddening caused by the excessive UV radiation, while the synthetic sunscreen could not improve these conditions of the skin, and even induced some side-effects in the skin with photoerythema. By comparing the in vivo SPF values of the two types of sunscreen, they were found to be mainly similar. The results indicate that the SPF value was related to both a photo-reaction and a biological reaction. The sunscreen derived from natural Chinese herbs, although having low UV absorption, was able to exhibit the same SPF value as the synthetic sunscreen because of its biological effects.     

Identification and determination butylmethoxydibenzoylmethane in the presence benzophenone-3 and ethylhexylmethoxycinnamate in suncare preparation

The protection of sun radiation is a problem on global level for all living organisms on Earth. The need of people for the overexposure to the UV radiation led human population towards finding novel ways of protection of this kind of radiation, in form of cosmetic preparations applied on the skin. So far, the high values of protection factors of preparations and total block preparations with sun protection factor of 50+ were achieved. Physical and chemical filters which absorb radiation are constituents of these preparations. European Union has set regulations as which substances and in what amounts could be used as UV absorbers. American FDA (Food and Drug Administration) also gave its list of the most frequently used UV absorbers in the sunscreen products, as well as their declared concentrations. The most frequently used concentrations of UV filters in cosmetics is between 0.1% and 10%. Concentrations of UV filters in sunscreen products have to be monitored in order to ensure that they are not less from the declared levels, on which depends the efficacy and safety of the product.
Butyl methoxydibenzoylmethane (BMDM) is used as a UV-A filter in suncare products. Optimized high performance liquid chromatography method for BMDM determination in the presence of other UV filters in suncare preparations is presented in this paper. Determination was performed on C₈ reversed phase using UV detection at 357 nm and isocratic mobile phase of acetonitrile and 0.5% phosphoric acid (70 : 30 v/v). Proposed method has limit of detection of 0.058 μg mL⁻¹, limit of quantification 0.193 μg mL⁻¹ and linearity correlation coefficient of 0.9989. Commercially available products were analysed using the proposed method. All analysed samples complied with EU directives limit of BMDM content to no more than 5%.     

紫菜中类菌胞素氨基酸种类的确定及提取条件优化

类菌胞素氨基酸(MAAs)是小分子、水溶性化合物,具有抗紫外辐射功能。采用紫外光谱和质谱分析,确定了福建产条斑紫菜中所含的MAAs类化合物为Porphyra-334和Shinorine;采用单因素实验和正交实验确定了紫菜中MAAs类化合物的最佳提取工艺条件为:提取液初始pH2.0,提取时间1.5h,提取温度45℃,料液比为1∶8。在最佳提取工艺条件下Porphyra-334和Shinorine的提取率分别为5.124mg/g和3.941mg/g。     

Review of sunscreen and the emergence of non-conventional absorbers and their applications in ultraviolet protection

Protection against ultraviolet (UV) radiation is the major function of sunscreen lotions and UV-protective coatings for vehicles, homes, equipment and clothing. Sunscreen formulations have been optimized to become protective over a broader spectrum of UV radiation and maintain greater photostability. They are comprised of organic and inorganic components that act as chemical and physical UV protectors, respectively. Some of the organic components are limited by their spectrum of protection and photostability. Studies using solid lipid nanoparticles, recently explored organic molecules, inorganic components and antioxidants attempt to further optimize UV protection. In this review, we examine traditional and emerging nanoparticle components and highlight novel ideas in UV protection which may provide pathways for future studies.     

大型海藻类菌孢素氨基酸提取工艺及定性检测研究

类菌孢素氨基酸(Mycosporine-like amino acids,MAAs)是一类多功能活性化合物,在大型海藻中广泛存在。以海带、裙带菜、羊栖菜、江蓠、石花菜和海萝为原料,通过一系列单因素和正交实验,建立了此6种大型海藻MAAs的适宜提取工艺,并建立了定性检测方法。结果表明,海带、裙带菜、羊栖菜、江蓠、石花菜和海萝MAAs的适宜提取温度、固液比和甲醇体积分数依次为35、30、30、30、30、25 ℃,1:60、1:60、1:60、1:60、1:60、1:50 g/mL,30%、10%、30%、10%、30%、10%。利用上述工艺条件,制备得到6种大型海藻MAAs提取物,得率分别为(39.0±3.80)%、(20.6±2.20)%、(32.8±2.60)%、(5.41±1.20)%、(9.87±0.80)%、(16.2±1.40)%。在此基础上,250~390 nm波长扫描显示6种大型海藻MAAs提取物均在330 nm附近有吸收,表明它们中存在Porphyra-334。进一步,初次确定了海带、裙带菜、羊栖菜、江蓠、石花菜和海萝中Porphyra-334含量,依次为(1.60±0.69)μg/g、(1.96±0.89)μg/g、(3.97±0.82)μg/g、(41.9±3.41)μg/g、(13.2±2.25)μg/g、(8.89±1.29)μg/g。随后,应用硅胶薄层层析,对上述6种大型海藻MAAs提取物进行检测,建立了大型海藻MAAs检测的一种简便方法,可用于大型海藻MAAs的筛选。     

Evaluation of skin cancer chemoprevention potential of sunscreen agents using the Epstein–Barr virus early antigen activation in vitro assay

In our continuing search for novel cancer chemopreventive compounds of natural and synthetic origin, we have evaluated 14 commonly used ultraviolet (UV) sunscreen agents (designated UV‐1 to UV‐14) for their skin cancer chemoprevention potential. They belong to 8 different chemical categories: aminobenzoate (UV‐5, UV‐7, UV‐8 and UV‐14), benzophenone (UV‐1, UV‐2, UV‐3 and UV‐13), benzotriazole (UV‐10), benzyloxyphenol (UV‐9), cinnamate (UV‐6), quinolone (UV‐4), salicylate (UV‐11) and xanthone (UV‐12). In the in vitro assay employed, the sunscreens were assessed by their inhibition of the Epstein–Barr virus early antigen (EBV‐EA) activation induced by the tumour promoter 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) in human lymphoblastoid Raji cells. All sunscreens tested were found to exhibit anti‐tumour promoting activity: listed in decreasing order, moderate (UV‐11, UV‐2, UV‐7, UV‐12, UV‐3, UV‐9 and UV‐14) to weak (UV‐1, UV‐6, UV‐8, UV‐16, UV‐5, UV‐4 and UV‐10) with octyl salicylate (UV‐11) as the most potent and drometrizole (UV‐10) as the least potent among the compounds evaluated. A plausible relationship between the antioxidant property of sunscreens and their ability to promote anti‐tumour activity was noted. The results call for a comprehensive analysis of skin cancer chemoprevention potential of currently used UV sunscreen agents around the globe to identify those with the best clinical profile.     

Ultraviolet radiation affects emission of ozone-depleting substances by marine macroalgae: results from a laboratory incubation study

The depletion of stratospheric ozone due to the effects of ozone-depleting substances, such as volatile organohalogens, emitted into the atmosphere from industrial and natural sources has increased the amount of ultraviolet radiation reaching the earth's surface. Especially in the subpolar and polar regions, where stratospheric ozone destruction is the highest, individual organisms and whole ecosystems can be affected. In a laboratory study, several species of marine macroalgae occurring in the polar and northern temperate regions were exposed to elevated levels of ultraviolet radiation. Most of the macroalgae released significantly more chloroform, bromoform, dibromomethane, and methyl iodide-all volatile organohalogens. Calculating on the basis of the release of total chlorine, bromine, and iodine revealed that, except for two macroalgae emitting chlorine and one alga emitting iodine, exposure to ultraviolet radiation caused macroalgae to emit significantly more total chlorine, bromine, and iodine. Increasing levels of ultraviolet radiation due to possible further destruction of the stratospheric ozone layer as a result of ongoing global atmospheric warming may thus increase the future importance of marine macroalgae as a source for the global occurrence of reactive halogen-containing compounds.     

4种大型红藻类菌胞素氨基酸的提取工艺优化与分离鉴定

类菌胞素氨基酸（Mycosporine-like amino acids,MAAs）广泛存在于大型红藻中,是一类具有良好应用前景的活性物质。本文采用单因素和正交试验,分析了提取温度、时间、次数和料液比对红毛苔、石花菜、菊花江蓠和江蓠中MAAs提取物得率的影响,优化提取MAAs工艺,并对提取物进行了分离鉴定。结果表明,毛苔、石花菜、菊花江蓠和江蓠中MAAs优化提取工艺分别为:45 ℃、3 h、4次、1:25 g/mL;45 ℃、1 h、4次、1:20 g/mL;45 ℃、2 h、3次、1:15 g/mL;40 ℃、1 h、3次、1:20 g/mL。应用上述提取工艺,制备得到4种大型红藻MAAs提取物,提取物得率依次为249.3、197.9、146.4和449.5 mg/g,其在紫外光谱和薄层层析板呈现MAAs紫外吸收特性和颜色反应。同时,采用硅胶柱层析,对红毛苔和江蓠MAAs提取物进行分离,共得到3个组分H1、J1和J2。通过紫外光谱扫描、高效液相色谱和质谱分析,并与已有文献比较,确定了其MAAs组成。H1包括shinorine、palythine和porphyra-334（3种MAA含量为组分H1含量的95.4%）、palythenic acid（4.6%）;J1包括shinorine、palythine和porphyra-334（3种MAA 为组分J1含量的96.3%）、palythenic acid（3.7%）;J2为palythine单体。     

Aqueous photolysis of the organic ultraviolet filter chemical octyl methoxycinnamate

Organic UV filter chemicals are the active ingredients in personal care products designed to protect the skin from UV radiation, and hundreds of tons are estimated to be produced annually. Despite their entrance into the aquatic environment by both direct and indirect routes and their detection in surface waters and fish, little is known about their environmental fate. UV filter chemicals are designed to be photostable, but some undergo transformation upon exposure to UV light. Octyl methoxycinnamate (OMC), a commonly used UV filter chemical, degrades rapidly by direct photolysis; previous studies have focused on its photoisomerization, and a few investigators have reported the formation of cyclodimers. Here, we present the kinetics and quantum efficiency of the direct photolysis of OMC and confirm that dimerization occurs as a result of direct photolysis in aqueous solution. Likely identities of the dimers are offered based on comparison to reported results for other cinnamate derivatives. We have identified additional products of direct photolysis that have not been previously reported and investigated their photostability, as well as the mechanism of product formation. There is also some evidence of indirect photolysis in the presence of dissolved natural organic matter.     

Sunscreens' photochemical behaviour: in vivo evaluation by the stripping method

This study shows the influence of a water-in-oil emulsion and an oil-in-water emulsion on the photochemical behaviour of four sunscreen preparations containing various amounts of three UV filters: octyl methoxycinnamate, butyl methoxydibenzoylmethane, and 4-methylbenzylidene camphor. With the stripping method in vivo, skin-product interactions were evaluated after topical application and ultra-violet exposure. Evaluations were also made under the same operating conditions as in determining sun protection factor in vivo. Results showed that each sunscreen preparation has a particular photochemical behaviour related to filter mixture and emulsion type. When developing a sunscreen preparation the choice of the emulsion type and filters is relevant for achieving optimum efficacy and spectral stability.     

UV absorbance dependent toxicity of acridine to the marine diatom Phaeodactylum tricornutum

The present study seeks quantitative measures for photoenhanced toxicity under natural light regimes by comparing the effects of an aromatic compound under natural and laboratory light. To this purpose, the influence of light irradiance and spectral composition on the extent of photoenhanced toxicity of acridine, a three-ringed azaarene, to the marine diatom Phaeodactylum tricornutum was analyzed. Under laboratory light containing ultraviolet radiation (UV), the 72-h EC50 growth value for acridine was 1.55 microM. Under natural light, a 72-h EC50 value for acridine below the lowest test concentration (0.44 microM) was observed. Under both laboratory and natural light, the toxicity of acridine was equally enhanced by total UV (UV-A and UV-B) and UV-A radiation, while in the absence of UV no enhancement of toxicity was observed. Hence, the UV-A region of light was dominant in the photoenhanced toxicity of acridine to P. tricornutum, in accordance with its absorption spectrum in the UV-A region. Therefore, the total amount of UV radiation absorbed by aqueous acridine was calculated for each separate treatment. The amount of UV absorbed by acridine effectively described the effect of acridine on the growth of P. tricornutum in a dose-response-dependent manner. It is concluded that photoenhanced toxicity of aromatic compounds expressed as a function of the actually absorbed UV may circumvent some of the variability between studies using different concentrations of the phototoxic compounds and light sources. The UV quantity absorbed by these compounds allows a comparison with the absorption characteristics of natural waters and, thus, is a key parameter to determine the role of photoenhanced toxicity in water.     

Reconstructed human epidermis as an efficient tool in the evaluation of the effects of UV irradiation and of the photoprotective capacities of a sunblock

In this study, we used a spectroscopic method, found effective in measuring sunscreen photo-degradation results in terms of a photoabsorption decrease. The traditional approach was to measure variations in well-known parameters such as the absolute in vitro sun protection factor (SPF) or the relative UVA/UVB ratio after a controlled dose of UV radiation. However, these parameters fail to fully reflect the product's photochemical behavior. Variation in the SPF mainly depicts changes in UVB filtration, and variation in the relative parameter UVA/UVB ratio can be subjected to misinterpretation, as is the case for products in which a parallel loss of photoabsorption is observed in the UVA and UVB regions. In our laboratory, we developed a new approach using pure spectroscopic UVA and UVB attenuation factors called UVA attenuation factor and UVB attenuation factor. Attenuation factors are defined here as the inverse of the arithmetic mean of the transmittance data, taken either from the UVB region (290–320 nm, 1 nm steps) or the UVA region (320–400 nm, 1 nm steps). Using these two new spectroscopic indices, the photochemical behavior of a sunscreen formula can be assessed in each UV region. The general procedure consists of applying two UV doses to a film of sunscreen previously spread on a roughened polymethylmethacrylate plate and then measuring the UV transmission versus wavelength before and after the irradiation process. We tested different UV filters in a cosmetic base to demonstrate the efficacy of the method.     

Artificial UV-B and solar radiation reduce in vitro infectivity of the human pathogen Cryptosporidium parvum

The potential for solar ultraviolet (UV) radiation to act as a significant abiotic control of Cryptosporidium parvum oocysts in nature is unknown. Infectivity of C. parvum following exposure to artificial UV-B and natural solar radiation, with and without UV wavelengths, was tested under controlled pH and temperature conditions. Percent infectivity of exposed oocysts was determined by in vitro cell culture. Artificial UV-B exposures of 32 and 66 kJ/m2 significantly decreased oocyst infectivity by an average of 58 and 98%, respectively. Exposure of oocysts to approximately half and full intensity of full solar spectrum (all wavelengths) for a period of less than 1 day (10 h) in mid-summer reduced mean infectivity by an average of 67% and >99.99%, respectively. Exposure of the C. parvum oocysts to UV-shielded solar radiation (>404 nm) in early autumn reduced mean infectivity by 52%, while full spectrum solar radiation (exposure at all wavelengths) reduced mean infectivity by 97%. The data provide strong evidence that exposure to natural solar radiation can significantly reduce C. parvum infectivity. Direct effects of solar radiation on oocysts in nature will depend on the depth distribution of the oocysts, water transparency, mixing conditions, and perhaps other environmental factors such as temperature, pH, and stress.     

Arsenolipids in marine oils and fats: A review of occurrence,chemistry and future research needs

Numerous studies have focused on arsenic in marine organisms, and relatively high natural levels of the element have been reported in marine samples. Despite their seemingly consistent presence in marine oils and fats, there is currently only limited knowledge available on arsenic compounds that exhibit lipid soluble characteristics, the arsenolipids, in contrast to the water-soluble arsenic species. The development of analytical techniques has, however, renewed the interest in these arsenic species and significant novel findings have been published in the last couple of years. The aim of this review is to present current knowledge on the occurrence and chemistry of arsenolipids in marine oils, and to identify future research needs. The occurrence of arsenolipids and their relevance in marine organisms will be discussed, in addition to their relevance for consumers and industry, with respect to feed and food safety and legislative issues. Analytical techniques, including techniques in the early work on arsenolipids in addition to methods employed today, and relevant sample preparation will be discussed.     

Beyond sun protection factor testing

Ultraviolet radiation in sunlight produces a range of acute and chronic adverse effects on the skin including sunburn, photosensitivity rashes, immunosuppression, photoageing and carcinogenesis. Sunscreens aim to provide protection, but standard testing procedures primarily involve assessment of ability to protect against acute erythema, as evidenced by the sun protection factor (SPF). The SPF may correlate poorly with other aspects of protection, particularly since ultraviolet A is weakly erythemogenic compared with ultraviolet B, yet may make a greater contribution to certain other skin effects of sunlight. Nevertheless, there is an increasing tendency for the sunscreen industry to make claims for their products beyond the SPF data. There is a need to develop systems for clinical testing of sunscreens against other endpoints caused by ultraviolet exposure of skin, including immunosuppression and photosensitivity rashes. In particular, there is a largely unrecognized need for testing of sunscreens against the condition known as polymorphic light eruption, a photosensitivity disorder estimated to affect a staggering 10-20% of the population in the northern hemisphere. Ultimately, protection of the skin by sunscreens can only be as effective as their adequacy of application to the skin surface in the everyday setting permits. Optimal sunscreen formulation, and public and patient education in appropriate application technique, both make vital contributions to efficacy of sunscreen protection. This article focuses on the need for extended clinical testing of sunscreens, with particular reference to the photosensitivity disorders, and for improvements in sunscreen formulation and in the adequacy of sunscreen application to the skin surface.     

Nanostructured lipid carriers as novel carrier for sunscreen formulations

Incorporation of sunscreens into lipid carriers with an increased sun protection factor (SPF) has not yet been fully accomplished. In the present paper, the effectiveness of a sunscreen mixture, incorporated into the novel topical delivery systems, i.e. solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), used as ultraviolet (UV) protector enhancers with a distinctly higher loading capacity has been developed and evaluated. SLN and NLC were produced by hot high pressure homogenization technique in lab scale production. Size distribution and storage stability of formulations were investigated by laser diffractometry and photon correlation spectroscopy. Nanoparticles were characterized by their melting and recrystallization behaviour recorded by differential scanning calorimetry. Lipid nanoparticles produced with a solid matrix (SLN and NLC) were established as a UV protection system. The loading capacities for molecular sunscreens reported before now were in the range of 10-15%. It was possible to load NLC with up to 70% with molecular sunscreen, which is appropriate to obtain high SPFs with this novel UV protection system. The developed formulations provide a beneficial alternative to conventional sunscreen formulations. The UV protective efficacy of the lipid particles varied with the nature of lipid and UV wavelength.     

Marine carotenoids: Bioactivities and potential benefits to human health

Among natural pigments, carotenoids play important roles in physiological functions. The characteristics of carotenoids and their effects on human health have been reported for a long time, but most studies have focused on carotenoids from vegetables, fruits, and other parts of higher plants. Few reports are available on carotenoids from marine sources, such as seaweeds, microalgae, and marine animals, which have attracted attention in recent decades. Hundreds of carotenoids have been identified and isolated from marine organisms and their beneficial physiological functions, such as anticancer, antiobesity, antidiabetic, anti-inflammatory, and cardioprotective activities have been reported. The purpose of this review is to discuss the literature on the beneficial bioactivities of some of the most abundant marine carotenoids, including fucoxanthin, astaxanthin, cantaxanthin, peridinin, fucoxanthinol, and halocynthiaxanthin.