Formulation of a new broad-spectrum UVB + UVA and blue light SPF50+ sunscreen containing Phenylene Bis-Diphenyltriazine (TriAsorB), an innovative sun filter with unique optical properties.

Accumulating evidence from numerous comprehensive studies has demonstrated that blue light, in particular high-energy visible light, can exert a range of harmful effects on skin cells. These forms of radiation are now known to be able to trigger oxidation reactions, DNA damage, erythema and pigmentary changes, and may also be associated with photoaging. Sunscreens protecting the skin from only ultraviolet (UV)-B and UVA rays can therefore no longer be regarded as sufficient to help prevent skin damage from sunlight, and products containing filters that can provide broad-spectrum photoprotection are required. To meet this need, a new sunscreen formulation that provides photoprotection against solar radiation with wavelengths ranging from UV to visible light has been developed, using an innovative organic sun filter with unique optical properties: phenylene bis diphenyltriazine (TriAsorB™). This article outlines the development and characteristics of this innovative filter and describes new key results from studies performed to assess the effectiveness and safety of the filter and the new sunscreen product. The studies conducted so far demonstrate that the filter has a good human and environmental safety profile. In addition, the sunscreen, which contains TriAsorB in combination with three other UV filters to offer broad-spectrum sun protection with a high sun protection factor (SPF50+ ), appears to effectively prevent multiple forms of cellular photodamage, in particular blue light-induced oxidatively generated DNA lesions. Overall, the available data indicate that regular use of the TriAsorB-containing sunscreen could help prevent solar radiation-induced skin damage and the development of signs of premature skin aging, as well as photodermatoses caused or exacerbated by visible light.

Phenylene Bis-Diphenyltriazine (TriAsorB), a new sunfilter protecting the skin against both UVB + UVA and blue light radiations.

Sunlight induces actinic keratosis, skin cancers and photoaging. Photoprotection is thus a major issue in public health to prevent the harmful effects of solar ultraviolet (UV) radiations. Recent data have shown that the visible (VIS) and infrared (IR) radiations can lead to skin damage by oxidative stress, suggesting that a balanced protection across the entire spectrum of sunlight is necessary to prevent cutaneous alterations. In this context, we developed a new generation of sunfilter called Phenylene Bis-Diphenyltriazine or TriAsorB (CAS N°55514-22-2). The aim of the present study was to assess the photoprotective efficacy of TriAsorB from UV to IR light. Spectrophotometric assays were performed to measure absorption and reflectance of TriAsorB in the different spectral ranges of sunlight: UV, VIS including blue light or high energy visible (HEV) and IR. DNA damage was evaluated using reconstructed human epidermis (RHE): 8-hydroxy-2'-deoxyguanosine (8OHdG) in response to HEV exposure, pyrimidine dimers (CPDs) and (6-4) photoproducts following solar-simulated radiation (SSR). TriAsorB is a broad spectrum UVB + UVA filter including long UVA. Interestingly, it also absorbs VIS radiations, especially in the HEV region. These radiations are also reflected. Protection in the IR spectral range is weak. Furthermore, the sunfilter specifically protects the skin against the oxidative lesions 8OHdG induced by HEV and prevents SSR-induced DNA damage. Thus, TriAsorB is an innovative sunfilter that might be used in sun care products for skin photoprotection from UV to VIS radiations. Finally, it prevents sunlight genotoxicity and protected the skin against solar radiations, especially blue light.

Comparison of the DNA damage response in BEAS-2B and A549 cells exposed to titanium dioxide nanoparticles.

For some decades production of titanium dioxide nanoparticle (TiO2-NP) has been increasing at a considerable rate; concerns as to the toxicity of these particles upon inhalation have been raised. Indeed, TiO2-NPs have been shown to induce significant genotoxicity and to adversely affect both major DNA repair mechanisms: base excision repair (BER) and nucleotide excision repair (NER). The aims of the present study were to (i) compare the genotoxicity of TiO2-NPs and their impact on DNA repair processes on A549 alveolar carcinoma and BEAS-2B normal bronchial lung cell lines and (ii) delve deeper into the mechanisms leading to these effects. To achieve these goals, TiO2-NPs effects on cytotoxicity, genotoxicity, DNA repair activity and DNA repair gene expression were investigated in both cell lines upon exposure to 1-100 µg/mL of anatase/rutile, 21 nm TiO2-NPs. Our results show that TiO2-NPs induce comparable cytotoxic and genotoxic responses in BEAS-2B and A549 cells. Functional response to DNA damage is observed in both cell lines and consists of an overall downregulation in DNA repair processes. When evaluating the relative importance of the two DNA repair pathways, we observed a lower impact on BER compared with NER activities, suggesting that repair of oxidatively generated DNA damage is still triggered in these cells. This response becomes measureable at 4 h of exposure in BEAS-2B but only after 48 h of exposure in A549 cells. The delayed response in A549 cells is due to an initial overall and intense downregulation of the genes encoding DNA repair proteins. This overall downregulation correlates with increased methylation of DNA repair gene promoters and downregulation of NRF2 and BRCA1, which may thus be considered as upstream regulators. These results strengthen the evidence that TiO2-NP induces indirect genotoxicity in lung cells, via modulation of DNA repair processes, and shed some light on the mechanisms behind this effect.

Dewar valence isomers, the third type of environmentally relevant DNA photoproducts induced by solar radiation.

UV-induced DNA damage is the main initiating event in solar carcinogenesis. UV radiation is known to induce pyrimidine dimers in DNA, including cyclobutane dimers and (6-4) photoproducts which have been extensively studied. In contrast, much less attention has been paid to Dewar valence isomers, the photoisomerisation product of (6-4) photoproducts. Yet, the available data show that Dewar isomers can be produced by exposure to sunlight and may lead to mutations. Dewars are thus environmentally and biologically relevant. The present review summarizes currently available information on the formation, mutagenic properties and repair of this class of UV-induced DNA damage.

A new hair follicle-derived human epidermal model for the evaluation of sunscreen genoprotection.

Induction of skin cancer is the most deleterious effect of excessive exposure to sunlight. Accurate evaluation of sunscreens to protect the genome is thus of major importance. In particular, the ability of suncare products to prevent the formation of DNA damage should be evaluated more directly since the Sun Protection Factor is only related to erythema induction. For this purpose, we developed an in vitro approach using a recently characterized reconstituted human epidermis (RHE) model engineered from hair follicle. The relevance of this skin substitute in terms of UV-induced genotoxicity was compared to ex vivo explants exposed to solar-simulated radiation (SSR). The yield of bipyrimidine photoproducts, their rate of repair, and the induction of apoptosis were very similar in both types of skin samples. In order to evaluate the protection afforded by sunscreen against DNA damage, bipyrimidine photoproducts were quantified in tissue models following SSR exposure in the presence or absence of a SPF50+ formula. A rather high DNA protection factor of approximately 20 was found in RHE, very similar to that determined for explants. Thus, RHE is a good surrogate to human skin, and also a convenient and useful tool for investigation of the genoprotection of sunscreens.

Radiation-mediated formation of complex damage to DNA: a chemical aspect overview.

During the last three decades, a considerable amount of work has been undertaken to determine the nature, the mechanism of formation and the biological consequences of radiation-induced DNA lesions. Most of the information was obtained via the development of chemical approaches, including theoretical, analytical and organic synthesis methods. Since it is not possible to present all the results obtained in this review article, we will focus on recent data dealing with the formation of complex DNA lesions produced by a single oxidation event, as these lesions may play a significant role in cellular responses to ionizing radiation and also to other sources of oxidative stress. Through the description of specific results, the contribution of different chemical disciplines in the assessment of the structure, the identification of the mechanism of formation and the biological impacts in terms of repair and mutagenicity of these complex radiation-induced DNA lesions will be highlighted.

Oxidatively generated DNA lesions as potential biomarkers of in vivo oxidative stress.

During the last three decades there was an increasing interest for developing biomarkers of oxidative stress. Therefore, efforts have been made to develop sensitive methods aimed at measuring cellular levels of oxidatively generated DNA lesions. Initially, most attention had focused on 8-oxo-7,8-dihydro-2'- deoxyguanosine (8-oxodGuo) probably because reliable analytical methods (mostly HPLC coupled to electrochemical detection) were available since mid-eighties to detect that lesion at the cellular level. With the recent development of more versatile analytical (using mass spectrometric detection) and biochemical assays (such as the comet assay) efforts are currently made to measure simultaneously several DNA lesions. The main degradation pathways of the four main pyrimidine (thymine, cytosine) and purine (adenine, guanine) bases mediated by hydroxyl radical (•OH), one-electron oxidants and singlet oxygen (1O2) have been also studied in detail and results indicate that other DNA modification than 8-oxodGuo could represent suitable biomarkers of oxidative stress. In this review article, the main oxidative degradation products of DNA will be presented together with their mechanisms of formation. Then the developed methods aimed at measuring cellular levels of oxidatively generated DNA lesions will be critically reviewed based on their specificity, versatility and sensitivity. Illustration of the powerfulness of the described methods will be demonstrated using quantification of DNA lesions in cells exposed to ionizing radiations. In addition, recent work highlighting the possible formation of complex DNA lesions will be reported and commented regarding the possibility of using such complex damage as potential biomarkers of oxidative stress.

Cytotoxic and genotoxic impact of TiO2 nanoparticles on A549 cells.

Titania nanoparticles are produced by tons, and included in commercial products, raising concerns about their potential impact on human health. This study relates their cytotoxic and genotoxic impact on a cell line representative of human lung, namely A549 alveolar epithelial cells.

Changes in antioxidant status and biochemical parameters after orally cadmium administration in females rats.

The research was conducted to investigate the toxic effects of cadmium chloride (CdCl2), administered during gestation period on female Wistar rats. Pregnant rats received CdCl2 (20 mg/l, orally) from Day 6 to Day 19 of pregnancy. Results showed that Cd treatment induced a decrease in body weight gain. The relative liver weight increased significantly, with a marked decrease of glycogen and total lipids content. The administration of Cd induced hepatotoxicity as indicated by elevations in plasma alanine aminotransferase (ALT), aspartate aminotransferase and lactate dehydrogenase (LDH) activities (p < 0.05). Treatment with CdCl2 caused a significant (p < 0.05) increase in glucose. A significant increase was observed in the level of MDA and 8-oxodGuo tissues in the cadmium-exposed group compared to the control group (p < 0.05). Results showed that cadmium given to dams led to an oxidative stress and DNA damage in tissues of pregnant rats.

A microarray to measure repair of damaged plasmids by cell lysates.

DNA repair mechanisms constitute major defences against agents that cause cancer, degenerative disease and aging. Different repair systems cooperate to maintain the integrity of genetic information. Investigations of DNA repair involvement in human pathology require an efficient tool that takes into account the variety and complexity of repair systems. We have developed a highly sensitive damaged plasmid microarray to quantify cell lysate excision/synthesis (ES) capacities using small amounts of proteins. This microsystem is based on efficient immobilization and conservation on hydrogel coated glass slides of plasmid DNA damaged with a panel of genotoxic agents. Fluorescent signals are generated from incorporation of labelled dNTPs by DNA excision-repair synthesis mechanisms at plasmid sites. Highly precise DNA repair phenotypes i.e. simultaneous quantitative measures of ES capacities toward seven lesions repaired by distinct repair pathways, are obtained. Applied to the characterization of xeroderma pigmentosum (XP) cells at basal level and in response to a low dose of UVB irradiation, the assay showed the multifunctional role of different XP proteins in cell protection against all types of damage. On the other hand, measurement of the ES of peripheral blood mononuclear cells from six donors revealed significant diversity between individuals. Our results illustrate the power of such a parallelized approach with high potential for several applications including the discovery of new cancer biomarkers and the screening of chemical agents modulating DNA repair systems.

Determination of new types of DNA lesions in human sperm.

Careful attention has been focused recently on DNA quality in human IVF. Therefore a variety of methods has been developed to evaluate DNA integrity, especially concerning fragmentation. Using liquid chromatography and mass spectrometry (LC/MS/MS) for our best sperm samples, we have established reference values for several oxidative lesions, in order to gain insights into the cause of DNA lesions. Besides 8-oxodeoxyguanosine, we found rather high levels of two ethenonucleosides: 1,N6-ethenoadenosine and 1,N2-ethenoguanosine. These compounds probably arise from a reaction with 4-hydroxy-2-nonenal, the main aldehyde compound released during lipid peroxidation, or after occupational exposure to vinyl chloride. The quantity of chlorinated bases detected is low. All of this decay has to be repaired by the oocytes at the time of fertilization or immediately after. This aspect should not be overlooked in assisted reproductive technology, in order to understand risks and limitations.

Sensitivity to polychromatic UV-radiation of strains of Deinococcus radiodurans differing in their DNA repair capacity.

PURPOSE: To characterize the ultraviolet (UV) sensitivity and establish the UV-induced DNA damage profile of cells of four Deinococcus radiodurans strains. The investigated strains differ in their radiation susceptibility, leading to a classification into a UV-sensitive (UVS78 and 1R1A) and a UV-resistant class (wild type strain R1 and 262). MATERIALS AND METHODS: Deinococcus radiodurans cells were exposed in suspension to monochromatic 254 nm (UV-C) and polychromatic UV radiations; the surviving fraction was determined by assessing the ability of the bacteria to form colonies. The UV-induced DNA lesions were measured quantitatively using an accurate and highly specific assay that involves the combination of high performance liquid chromatography (HPLC) with tandem mass spectrometry detection. RESULTS: Analysis of the DNA photoproducts showed that the TC (6-4) photoproduct and the TT and TC cyclobutane dimers were the major lesions induced by UV-C and UV-(>200 nm)-radiation. The UV-sensitive class was approx. 10 times more susceptible to UV-C and UV-(>200 nm)-radiations than the resistant class. Interestingly, the survival curves of all investigated strains become similar with longer UV wavelengths in the UV-(>315 nm)-radiation range. This observation suggests that the repair mechanisms of the UV-resistant class are not specifically effective for damage produced by UV of the >315 nm range. However, the initial amount of DNA photoproducts produced upon irradiation was found to be the same in resistant and sensitive strains for each wavelength range. CONCLUSION: Compared to mammalian cells, the DNA of Deinococcus radiodurans cells is less susceptible to the photo-induced formation of thymine cyclobutane dimers as inferred from comparative analysis. The ongoing investigations may contribute to a better understanding of the mechanism of DNA photoprotection against the direct effects of UV radiation. This may be of interest in the present context of a possible continuous decrease in the ozone layer thickness.

Age-related sensitivity to lung oxidative stress during ozone exposure.

As immature and aged rats could be more sensitive to ozone (O(3))-linked lung oxidative stress we have attempted to shed more light on age-related susceptibility to O(3) with focusing our interest on lung mitochondrial respiration, reactive oxygen species (ROS) production and lung pro/antioxidant status. For this purpose, we exposed to fresh air or O(3) (500 ppb 12 h per day, for 7 days) 3 week- (immature), 6 month- (adult) and 20 month-old rats (aged). We determined, in lung, H(2)O(2) release by mitochondria, activities of major antioxidant enzymes [superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT)], heat shock protein (HSP(72)) content and 8-oxodG and dG-HNE nDNA contents, as DNA oxidative damage markers. In adult rats we did not observe alteration of pro/antioxidant status. In contrast to adults, immature rats exposed to O(3) higher nDNA 8-oxodG content and HSP(72) and without antioxidant enzymes modification. Aged rats displayed mild uncoupled lung mitochondria, increased SOD and GPx activities, and higher 8-oxodG content after O(3) exposure. Thus, in contrast to adults, immature and aged rats displayed lung oxidative stress after O(3) exposure. Higher sensitivity of immature to O(3) was partly related to ventilatory parameters and to the absence of antioxidant enzyme response. In aged rats, the increase in cytosolic SOD and GPx activities during O(3) exposure was not sufficient to prevent the impairment in mitochondrial function and accumulation in lung 8- oxodG. Finally, we showed that mitochondria seem not to be a major source of ROS under O(3) exposure.

Resveratrol enhances UVA-induced DNA damage in HaCaT human keratinocytes.

Resveratrol, a polyphenolic phytoalexin, is a very effective antioxidant that also exhibits strong antiproliferative and anti-inflammatory properties. Recent studies have provided support for the use of resveratrol in human cancer chemoprevention, in combination with either chemotherapeutic drugs or cytotoxic factors for a most efficient treatment of drug refractory tumor cells. Resveratrol is also widely used in topical preparations, as a chemoprotective compound against development of several cutaneous disorders, including skin cancer. Nevertheless, the combined effect of resveratrol and UVA irradiation on cellular toxicity and DNA damage has never been assessed. The aim of this work was to investigate the effect of resveratrol on cell fate in immortalized human keratinocytes HaCaT cells. The results indicated that resveratrol potentiates the production of significant amounts of 8-oxo-7,8-dihydro-2'-deoxyguanosine in UVA-irradiated genomic DNA. Moreover, the combination of resveratrol with UVA significantly enhances the induction of DNA strand breaks and cell death in HaCaT keratinocytes. The conclusion is a potential hazardous effect of topical application of resveratrol, particularly on regions exposed to sunlight.

UV laser photolysis of DNA: effect of duplex stability on charge-transfer efficiency.

The distribution of the final base damage was determined within isolated DNA exposed to pulses of 266 nm laser light. Studied lesions included oxidation products arising from biphotonic ionization of DNA bases and pyrimidine dimeric photoproducts arising from monophotonic processes. The distribution of the latter class of damage was found to be correlated with the stability of the DNA duplex. The quantum yield for formation of 8-oxo-7,8-dihydroguanine was much higher than that of other oxidized nucleosides arising from the degradation of thymine and adenine. This observation, together with the shape of the intensity dependence curves, provided evidence for the occurrence of charge-transfer processes within DNA. In addition, increase in the ionic strength of the irradiated DNA and stabilization of the DNA duplex were found to induce a drastic decrease in the yield of thymine and adenine oxidation products. Concurrently, an increase in the yield of 8-oxo-7,8-dihydroguanine was observed. This was rationalized in terms of an increase in the overall charge-transfer efficiency. Therefore, it may be concluded that stabilization of the double-helix favors charge-transfer process toward guanine bases.

Direct and indirect effects of UV radiation on DNA and its components.

In this survey, emphasis was placed on the main photoreactions of nucleic acid components, involving both direct and indirect effects. The main UVB- and UVA-induced DNA photoproducts, together with the mechanisms of their formation, are described. Information on the photoproduct distribution within cellular DNA is also provided, taking into account the limitations of the different analytical methods applied to monitor the formation of the DNA damage. Thus, the formation of the main DNA dimeric pyrimidine lesions produced by direct absorption of UVB photons was assessed using a powerful HPLC-tandem mass spectrometry assay. In addition, it was found that UVA photooxidation damage mostly involves the guanine residues of cellular DNA as the result of singlet oxygen generation by still unknown endogenous photosensitizers.

Individual determination of the yield of the main UV-induced dimeric pyrimidine photoproducts in DNA suggests a high mutagenicity of CC photolesions.

Bipyrimidine photoproducts induced in DNA by UVB radiation include cyclobutane dimers, (6-4) photoproducts, and their related Dewar valence isomers. Even though these lesions have been extensively studied, their rate of formation within DNA is still not known for each possible bipyrimidine site (TT, TC, CT, and CC). Using a method based on the coupling of liquid chromatography to mass spectrometry, we determined the distribution of the 12 possible bipyrimidine photoproducts within isolated and cellular DNA. TT and TC were found to be the most photoreactive sequences, whereas lower amounts of damage were produced at CT and CC sites. In addition to this quantitative aspect, sequence effects were observed on the relative yield of (6-4) adducts with respect to cyclobutane pyrimidine dimers. Another interesting result is the lack of formation of Dewar valence isomers in detectable amounts within the DNA of cells exposed to low doses of UVB radiation. The photoproduct distribution obtained does not fully correlate with the UV mutation spectrum. A major striking observation deals with the low yield of cytosine-cytosine photoproducts which are likely to be associated with the UV-specific CC to TT tandem mutation.

The role of duck hepatitis B virus and aflatoxin B1 in the induction of oxidative stress in the liver.

The aim of our study was to use the Pekin duck model to investigate the interactions between hepadnaviral infection and aflatoxin B1 (AFB1) exposure including the role of both factors in the induction of oxidative stress in the liver. AFB1 exposure of duck hepatitis B virus (DHBV) infected Pekin ducks induced a significant increase in viral replication associated with an intense biliary ductular cells proliferation. Interestingly, extremely high levels of AFB1-DNA adducts (40-120 pmol AFB1-Fapy/mg DNA) and AFB1-albumin adducts (1,500-3,000 pg AFB1-lys Eq/mg albumin) were detected in duck liver and serum respectively, as compared to other animal species exposed to a similar AFB1 dose. DHBV infection was found to induce a non-significant increase in AFB1-albumin adduct levels in duck serum. During the treatment duration there was no effect on formation of oxidative base damage within DNA and no effect on oxidative lipid peroxidation following either viral infection or AFB1 exposure. In terms of hepatic antioxidant enzymes (catalase, superoxide dismutase (SOD), glutathione peroxidase) a significant increase in SOD activity occurred following AFB1 exposure, but not DHBV infection, but this was observed only after the cessation of treatment, when biliary ductular cells proliferation was reduced.

Analysis of fluoroquinolone-mediated photosensitization of 2'-deoxyguanosine, calf thymus and cellular DNA: determination of type-I, type-II and triplet-triplet energy transfer mechanism contribution.

Fluoroquinolone (FQ) antibacterials are known to exhibit photosensitization properties leading to the formation of oxidative damage to DNA. In addition, photoexcited lomefloxacin (Lome) was recently shown to induce the formation of cyclobutane pyrimidine dimers via triplet-triplet energy transfer. The present study is aimed at gaining further insights into the photosensitization mechanisms of several FQ including enoxacin (Enox), Lome, norfloxacin (Norflo) and ofloxacin (Oflo). This was achieved by monitoring the formation of DNA base degradation products upon UVA-mediated photosensitization of 2'-deoxyguanosine, isolated and cellular DNA. Oflo and Norflo act mainly via a Type-II mechanism whereas Lome and, to a lesser extent, Enox behave more like Type-I photosensitizers. However, the extent of oxidative damage was found to be relatively low. In contrast, it was found that cyclobutane thymine dimers represent the major class of damage induced by Enox, Lome and Norflo within isolated and cellular DNA upon UVA irradiation. This striking observation confirms that FQ are able to promote efficient triplet energy transfer to DNA. The levels of photosensitized formation of strand breaks, alkali-labile sites and oxidative damage to cellular DNA, as measured by the comet assay, were confirmed to be rather low. Therefore, we propose that the phototoxic effects of FQ are mostly accounted for energy transfer mechanism rather than by Type-I or -II photosensitization processes.