Transdermal penetration of UV filters

A penetration study of 2-ethylhexyl-4-methoxycinnamate (EHMC), 4-methyl benzylidenecamphor (MBC), butyl methoxydibenzoylmethane (BMBM), 2-ethylhexyl-2,4,5-trimethoxycinnamate (EHTMC) and di(2-ethylhexyl)-2,4,5-trimethoxybenzalmalonate (TMB) through baby mouse skin (Mus musculus Linn.) was carried out using a vertical Franz diffusion cell. At 4.4 mg/cm(2) coverage of UV filter on the skin, 2.98 +/- 0.38, 1.15 +/- 0.14 and 0.80 +/- 0.28% of the applied EHMC, MBC and BMBM were detected in the receptor fluid at 24 h after application. Penetrations of UV filter in an ethanolic solution and lotion forms were comparable. EHTMC and TMB showed insignificant penetration across the baby mouse skins. Baby mouse skins kept at 4, -20 and -80 degrees C gave similar EHMC penetration results. Penetrations of EHMC, BMBM, EHTMC and TMB across human epidermis were carried out upon 5 volunteers using the suction blister technique. The results also confirmed the significant penetrations of EHMC and BMBM and the insignificant penetrations of EHTMC and TMB.     

Photoprotective efficacy and photostability of fifteen sunscreen products having the same label SPF subjected to natural sunlight

The first objective of this study is to show how different can be photoprotection by sunscreens with an identical SPF given on the packaging, when subjected to sunlight radiation. The second objective is to highlight the need for global harmonization of photostability testing and UVA protection labelling. Fifteen products with various combinations of UV filters marketed in Europe were assessed based on transmission measurements of 0.75 mg cm?2 layer covered onto polymethylmethacrylate plate roughness 2 μm. Two absolute UV spectroscopic indices (in vitro SPF, UVA-PF), four well-known relative UVA indices: the UVA-PF/SPF ratio and critical wavelength by European Commission (EC); UVA/UVB ratio by Boots Star Rating system; UVA1/UV ratio by FDA Proposed Ruling and one new relative indices the Spectral Uniformity Index (SUI) by Diffey, were compared before and after sunlight exposure with dose about 42 SEDs. The UVA-PF values before exposure proved a high degree of variation among samples. After exposure only five sunscreens observed UVA protection standard by EC and the same products showed compliance with the first UVA rating by Boots system (three stars). According to the UVA1/UV ratio, except for one product, all sunscreens manifested certain UVA protection level (low, medium or high). In compliance with criteria of new rating proposed by Diffey, exactly all fifteen sunscreens gave some UVA rating exhibited as SUI (low, medium or high). These results mean that the different UVA protection indices can exhibit various data and be confusing for consumer. Photostability of each product was assessed with three indices: the area under curve (Auc) Index for the total UV range, and UVB, UVA, UVA2, UVA1 range separately; the residual effectiveness of in vitro SPF and UVA-PF. All fifteen sunscreens were photostable in the UVB region. Seven products exhibited photoinstability in the total UV range (290-400 nm); all of them contained a combination of the ethylhexyl methoxycinnamate (EHMC) and butyl methoxydibenzoylmethane (BMBM) together with other UV filters. Eight products lacked their stability in the UVA1 range (340-400 nm) thus confirmed that photodegradation of some current sunscreens is primarily problem of this region. The most photoinstability showed sunscreens S1 (EHMC, BMBM and phenylbenzimidazole sulphonic acid) and S6 (EHMC, BMBM, phenylbenzimidazole sulphonic acid and ethylhexyl triazone); Auc-UVA1 Index was 0.15 only. Excellent UVA1 photostability showed sunscreen S8 (EHMC, EHT and methylene bis-benzotriazolyl tetramethylbutylphenol); Auc-UVA1 Index was of 1.00. Three sunscreens showed very good UVA1 photostability (Auc-UVA1 Index ranged from 0.98 to 0.93). The fact that these products applied only in the layer of 0.75 mg cm?2 were photostable under the sunlight dose, which corresponds to layer of 2 mg cm?2, is proof of their quality. Comparison of the residual effectiveness of in vitro SPF and UVA-PF values with the Auc-Index showed that methods give a similar ranking of the sunscreens' photostability.     

Cytotoxicity, acute oral toxicity, and skin irritation of 2-ethylhexyl-2,4,5-trimethoxycinnamate and di(2-ethylhexyl)-2,4,5-trimethoxybenzalmalonate

Safety of two new ultraviolet (UV) filters, 2-ethylhexyl-2,4,5-trimethoxycinnamate (E8) and 2-ethylhexyl-2,4,5-trimethoxybenzalmalonate (B8), has been evaluated through the human melanoma cytotoxicity test and seven-day acute oral toxicity studies in rats. At 2.5 mg/mL, both compounds gave similar cell viability to the control. LD50 values for E8 and B8 are more than 5000 and 1000 mg/kg body weight, respectively. No significant difference in body weight and hematological parameters among the 0, 5, 50, 500, and 5000 mg/Kg E8-treated animals could be detected. Pathological examination of rat tissues collected at the end of the study period revealed no significant difference between the control and all E8-administered rats. There was no significant difference in all clinical blood chemistry parameters (aspartate aminotransferase, creatinine, blood urea nitrogen, and cholesterol), except alanine aminotransferase (ALT), between the control and the E8-treated animals. All ALT values were, however, in the normal range of SD rats. E8 showed negative results for the skin irritation study on human volunteers, using patch and photopatch tests. Excitation of respiratory signs of dypsnea in 10, 100, and 1000 mg/Kg B8-treated rats could be observed during 1-24 h. All groups were, however, normal during the second to the seventh day. Hematological parameters of the 0, 10, 100, and 1000 mg/Kg B8-treated animals showed no significant difference. Pathological examination revealed no significant difference between the control and all B8-administered rats. However, significant differences in some clinical blood chemistry parameters and body weights between the control and some B8-treated animals could be detected. All values, however, were in the normal ranges of the SD rats.     

Cytotoxicity,Acute Oral Toxicity,and Skin Irritation of 2-ethylhexyl-2,4,5-trimethoxycinnamate and di(2-ethylhexyl)-2,4,5-trimethoxybenzalmalonate

Safety of two new ultraviolet (UV) filters, 2-ethylhexyl-2,4,5-trimethoxycinnamate (E8) and 2-ethylhexyl-2,4,5-trimethoxybenzalmalonate (B8), has been evaluated through the human melanoma cytotoxicity test and seven-day acute oral toxicity studies in rats. At 2.5 mg/mL, both compounds gave similar cell viability to the control. LD₅₀ values for E8 and B8 are more than 5000 and 1000 mg/kg body weight, respectively. No significant difference in body weight and hematological parameters among the 0, 5, 50, 500, and 5000 mg/Kg E8-treated animals could be detected. Pathological examination of rat tissues collected at the end of the study period revealed no significant difference between the control and all E8-administered rats. There was no significant difference in all clinical blood chemistry parameters (aspartate aminotransferase, creatinine, blood urea nitrogen, and cholesterol), except alanine aminotransferase (ALT), between the control and the E8-treated animals. All ALT values were, however, in the normal range of SD rats. E8 showed negative results for the skin irritation study on human volunteers, using patch and photopatch tests. Excitation of respiratory signs of dypsnea in 10, 100, and 1000 mg/Kg B8-treated rats could be observed during 1–24 h. All groups were, however, normal during the second to the seventh day. Hematological parameters of the 0, 10, 100, and 1000 mg/Kg B8-treated animals showed no significant difference. Pathological examination revealed no significant difference between the control and all B8-administered rats. However, significant differences in some clinical blood chemistry parameters and body weights between the control and some B8-treated animals could be detected. All values, however, were in the normal ranges of the SD rats.     

Effect of spectroscopic properties on photostability of tamoxifen citrate polymorphs

The photostability of tamoxifen citrate polymorphs, forms A and B, was investigated by chromatographic and spectroscopic analyses including high-pressure liquid chromatography (HPLC), colorimetry and UV/vis solid-state absorption spectroscopy. On the basis of the results of photostability studies under irradiation by visible light and both UVA (320-400 nm) and a fraction of UVB (290-320 nm) light, form A was chemically unstable, whereas form B was stable against light irradiation. The surface color of pellets prepared with any of these crystal forms turned from white to brown; however, the extent of color change in cross-sections of form A pellet was deeper than that of form B pellet. The maximum peak of UV/vis solid-state absorption spectra of form A was observed at 337 nm within the UVA range and was in longer wavelength regions than form B, which exhibited the strong UV absorption mainly in UVB and UVC region. The results obtained suggested that the photodegradation followed by surface color change of form A crystal was caused by the selective absorption of photoenergy of UVA light irradiated by a xenon lamp.     

Synergistic enhancement of H2O2 production in human epidermoid carcinoma cells by Benzo[a]pyrene and ultraviolet A radiation

Benzo[a]pyrene (BaP) is an ubiquitous environmental pollutant with potential carcinogenecity. It was shown that BaP, upon irradiation by UV A, enhanced the formation of 8-hydroxy-2'-deoxyguanosine in purified DNA and in cultured cells. The purpose of this present study was to determine whether BaP and UV radiation synergistically generate reactive oxygen species (ROS) that consequently result in the oxidation of DNA bases. In this study, the levels of H(2)O(2) were measured as an indicator of ROS in A431 cells and primary human keratinocytes treated with BaP plus UV radiation. Production of H(2)O(2) significantly increased from cells treated with BaP plus UVB or UVA, with the latter having a much greater effect. The responses of A431 cells and primary human keratinocytes to BaP and UVA irradiation were similar in generation of extracellular H(2)O(2). Also, H(2)O(2) production proportionally correlated with UVA and UVB dose, but was independent of time or BaP concentration. Treatment with catalase and general ROS scavengers significantly decreased H(2)O(2) production from cells treated with BaP plus UVA, whereas scavengers of *O2-, *OH, and (1)O(2) had minimal effects. These results demonstrate that BaP synergistically enhances the production of H(2)O(2) from cultured cells by UVA and, to a lesser extent, by UVB, supporting the hypothesis that interaction of BaP and UVA can generate ROS and further substantiate oxidative DNA damage that may lead to carcinogenesis.     

Skin absorption and human exposure estimation of three widely discussed UV filters in sunscreens – In vitro study mimicking real-life consumer habits

Due to health concerns about safety, three UV-filters (Benzophenone-3, BP3, 10%; Ethylhexyl Methoxycinnamate, EHMC, 10%; Butyl Methoxydibenzoylmethane, BMDBM; 5%) were examined in vitro for absorption on full-thickness pig-ear skin, mimicking human in-use conditions. Kinetic profiles confirmed the rapid permeation of BP3; after the first hour of skin (frozen-stored) exposure to 2 mg/cm² (W/O sunscreen; recommended but unrealistic amount), about 0.5% of the applied dose passed into the receptor fluid. The absorption rate of filters was higher from W/O than from O/W emulsions. The fresh/frozen-stored skin permeability coefficient (0.83–0.54) for each UV filter was taken into account. Systemic Exposure Dosage of BP3, EHMC, BMDBM for humans as a consequence of (i) whole-body and (ii) face treatment with 0.5 mg/cm² of W/O sunscreen for 6-h skin exposure followed by washing and subsequent 18-h permeation (a realistic scenario) were estimated to be (i) 4744, 1032 and 1036 μg/kg-bw/day, and (ii) 153, 33 and 34 μg/kg-bw/day, respectively. From Margin of Safety for BP3, EHMC and BMDBM (i) 42, 485 and 192 as well as (ii) 1307; 15,151 and 5882, respectively, only the value of 42 (<100) for BP3 indicated a possible health risk. Escalation of a phobia towards all organic UV filters is undesirable.     

Acute exposure to solar simulated ultraviolet radiation affects oxidative stress-related biomarkers in skin, liver and blood of hairless mice

The ultraviolet (UV) region of solar radiation is a critical factor in the initiation and development of a number of skin diseases. However, it is not only skin which is directly exposed to solar light that is affected by UV radiation, through low molecular weight mediators, generated upon irradiation, "non-skin" tissues can also be affected. The aim of this study was to examine in detail, the acute effects of UVA and UVB wavebands on hairless mice. Female SKH-1 hairless mice were exposed to a single dose of UVB (200, 800 mJ/cm(2)) or UVA (10, 20 J/cm(2)) using a solar simulator. The effects on haematological parameters, activity and/or expression of antioxidant enzymes, level of glutathione (GSH), markers of oxidative damage (lipid peroxidation and carbonylated proteins) were analysed in erythrocytes, plasma, liver and whole skin homogenates. No macroscopic changes were observed either 4 or 24 h after UVA/UVB exposure. The blood count showed a significant increase in leukocyte number and reduction of platelets 4 h following UVA and UVB irradiation, which disappeared 24 h after irradiation except for the higher UVA dose. Changes in oxidative stress-related parameters, particularly activity of catalase (CAT) and superoxide dismutase (SOD) and level of GSH and lipid peroxidation products, were found in skin, erythrocytes and liver. The expression of several enzymes (CAT, SOD, glutathione transferase (GST), nicotinamide adenine dinucleotide (phosphate) quinone oxidoreductase (NQO1) and hem oxygenase-1 (HO-1)) in skin was affected following UVA and UVB radiation. Increase in carbonylated proteins was found in plasma and skin samples.     

Detection of monohydroxyeicosatetraenoic acids and F2-isoprostanes in microdialysis samples of human UV-irradiated skin by gas chromatography-mass spectrometry

UV irradiation of the human skin leads to induction of oxidative stress and inflammation mediated by reactive oxygen radicals, lipid peroxidation, liberation of arachidonic acid from membrane phospholipids and formation of prostaglandins and leucotrienes. We investigated "lipid mediators", such as F(2)-isoprostanes (8-iso-PGF(2alpha), 9alpha,11alpha-PGF(2alpha)) and monohydroxyeicosatetraenoic acids (HETEs) in the dermal interstitial fluid obtained by a cutaneous microdialysis technique. Defined areas on the volar forearm of 10 healthy volunteers were exposed to UVB irradiation (20-60 mJ/cm(2)). Microdialysis membranes were cutaneously inserted beneath the irradiated area. The probes were perfused with isotonic saline solution, and microdialysate samples were collected at 20-min intervals up to 4-5 h. Oxidized arachidonic acid derivatives (2-, 3-, 5-, 8-12- and 15-HETEs, 8-iso-PGF(2alpha) and 9alpha,11alpha-PGF(2alpha)) could be detected and quantified in microdialysates of normal skin in the picomole (HETEs) and femtomole (isoprostanes) range and after UVB irradiation using sensitive gas chromatography-mass spectrometry/negative ion chemical ionization. UVB irradiation enhanced the levels of 8-iso-PGF(2alpha) after 24 h significantly, whereas the HETE levels were slightly increased within shorter time intervals (3 h after UVB irradiation). Further investigations have to show whether these new findings are relevant to validate therapeutic strategies for topical and systemic UV prevention agents or for monitoring of specific therapeutic strategies in inflammatory skin disorders.     

红景天苷对经紫外线辐射的成纤维细胞中Fas和Bcl-2mRNA表达的影响

目的观察红景天苷对经紫外线A／B（UVA／UVB）辐射的体外培养人皮肤成纤维细胞中Fas和Bcl-2mRNA表达的影响,探讨红景天苷抑制细胞凋亡与凋亡相关细胞因子的关系。方法在体外培养人皮肤成纤维细胞并随机分为正常对照组、红景天苷组、UVB组、UVB＋红景天苷组、UVA组、UVA＋红景天苷组6组,通过反转录聚合酶链反应法检测Fas和Bcl-2的mRNA表达。结果UVB、UVA辐射体外培养的成纤维细胞后,FasmRNA表达增加[（0．45±0．04）,（0．44±0．04）比（0．13±0．03）],Bcl-2mRNA表达减弱[0．17±O．01,0．17±0．03比（0．13±O．03）];加入红景天苷后Fas和Bcl-2的mRNA表达分别降低[（0．17±0．04）比（0．45±0．04）,0．18±0．03比0．44±0．04;（0．31±0．02）比（0．17±0．01）,（0．28±0．04）比（0．17±O．03）]。结论红景天苷对紫外线引起的Fas和Bcl-2的mRNA表达具有抑制作用,延缓UVB、UVA辐射造成的细胞凋亡过程。     

Induction of apoptosis by UV-irradiated chlorinated bisphenol A in Jurkat cells

Chlorinated derivatives of bisphenol A (ClBPAs) have been detected in wastewater from waste paper recycling plants. We previously reported that bisphenol A (BPA) and ClBPAs [3-chlorobisphenol A, 3,3′-dichlorobisphenol A, and 3,3′,5-trichlorobisphenol A] irradiated with ultraviolet (UV) B or UVC (not with UVA) induced inhibition of cell growth, and that 3-hydroxybisphenol A (3-OHBPA) was detected in the photoproducts [Mutou, Y., Ibuki, Y., Terao, Y., Kojima, S., Goto, R., 2006b. Chemical change of chlorinated bisphenol A by ultraviolet irradiation and cytotoxicity of their products on Jurkat cells. Environmental Toxicology and Pharmacology, 21, 283–289]. The formation of hydroxylated BPAs by UV irradiation might contribute to the inhibition of cell growth, but the mechanism of the growth inhibition is not clarified. In this study, we investigated whether BPA and ClBPAs exposed to UVA, UVB, or UVC, and 3-OHBPA could induce the death of Jurkat cells and whether the pattern of cell death was apoptosis. ClBPAs exposed to UVB and UVC induced significant cell death, but those exposed to UVA and BPA did not. The cell death was apoptosis because chromatin condensation and DNA fragmentation were detected. Activation of caspase-3, -8, and -9 and cytochrome c release indicated that ClBPAs exposed to UVB or UVC induced apoptosis via typical apoptotic pathways. In addition, 3-OHBPA induced apoptosis similar to UVB- or UVC-irradiated ClBPA. These results suggested that the photoproducts of ClBPAs generated by UV irradiation, containing 3-OHBPA, contributed to the induction of apoptosis.     

Molecular mechanisms of polypeptide from Chlamys farreri protecting HaCaT cells from apoptosis induced by UVA plus UVB

Aim： To investigate the mechanism of polypeptide from Chlamysfarreri （PCF） protecting HaCaT cells from apoptosis induced by UVA plus UVB in vitro. Methods： An apoptotic model of UV irradiation-induced HaCaT cells was established. The 3-（4,5-dimethyl-2-thiazolyl）-2,5-diphenyl-2H-tetrazolium bromide assay, agarose gel electrophoresis, biochemical methods, and Western blotting were employed in the study. Results： PCF inhibited the UV irradiation-induced apoptosis of HaCaT cells. PCF strongly reduced the intracellular reactive oxygen species level, enhanced activities of superoxide dismutase and glutathione per- oxidase and increased the total anti-oxidative capacity in HaCaT cells following UV irradiation. Furthermore, we found that PCF could inhibit the phosphorylation of c-Jun amino-terminal kinase and the activity of caspase-3 in a concentration- dependent manner. Conclusion： PCF protected HaCaT cells from apoptosis induced by UVA plus UVB, mainly through decreasing the intracellular ROS level and increasing the activities of anti-oxidative enzymes to block the ROS-JNK-caspase-3-apoptosis signaling pathway.     

Evaluation of solar UV damage to Crepis capillaris by chromosome aberration test

Ultraviolet (UV) radiation comprises only a small portion of the electromagnetic spectrum of solar light, but it exerts a disproportionally greater genotoxic effect on all organisms, including water plants. However, genotoxicity evaluation of solar UV is complicated because of the simultaneous actions of UVB, UVA, and photoreactivating light (PHL). The latter very effectively repairs the main type of DNA lesions, pyrimidine dimers (PD), which are induced specifically only by UV. However, other types of DNA lesions are induced by UV; they are unrepairable by PHL and present a real danger to the plant genome. To evaluate this part of DNA lesions, the frequency of chromosome aberrations (CA) was determined after solar UVB and UVB+UVA irradiation with or without PHL. Meristematic cells of Crepis capillaris were irradiated in special chambers with filters. The 4-year investigation showed that only about half of CA had been repaired with PHL. Both findings of the study, of the part of CA that remained after PHL and of the stronger genotoxicity of UVB+UVA, are discussed.     

A predictive mouse ear-swelling model for investigating topical phototoxicity

Predictive models should be used to determine the phototoxic potential of consumer products intended for topical exposure and outdoor use. To determine the potential of a compound to elicit a phototoxic reaction, a mouse ear-swelling model, which uses a xenon arc ultraviolet (UV) solar simulator as the radiation source, was used. The UV solar simulator delivered UV radiation from 290 to 400 nm (UVB + UVA) or from 320 to 400 nm (UVA) when appropriate filters were used. With this model, the phototoxic potential of nine known phototoxins and three negative test materials was successfully demonstrated. Based on the time of onset of the phototoxic response following test material application and irradiation, both immediate (20–30 min) and delayed-type (48–96 hr) phototoxic responses were demonstrated using this model with anthracene and 8-methoxypsoralen, respectively. The optimal time for irradiation after application of 8-methoxypsoralen to the ears was 30–60 min. Irradiation of ears immediately after treatment with 8-methoxypsoralen or 6 hr after application resulted in little or no phototoxic response. The phototoxic response to 8-methoxypsoralen was dependent upon the UVA dose and, when tested at a constant UVA dose, the response was concentration dependent. To obtain an optimal phototoxic response to 7-methoxycoumarin, both UVB and UVA radiation were required. These results show that the mouse ear-swelling model, which is quantifiable and more objective than models based on subjective evaluation of skin changes, is an excellent model for investigative and predictive phototoxicity testing.     

Environmental levels of ultraviolet light potentiate the toxicity of sulfonamide antibiotics in Daphnia magna

We assessed the phototoxicity of several major sulfonamide antibiotics, i.e., sulfathiazole, sulfamethazine, and sulfamethoxazole, using acute 48 and 96 h Daphnia magna immobilization toxicity test under several indoor and outdoor lighting conditions. The lighting conditions were as follows: (1) fluorescent light only, (2) continuous irradiation with 15 μW/cm² UVB, (3) pulsed irradiation with 90 μW/cm² UVB for 4 h/d, and (4) natural sunlight (outdoors). Laboratory tests showed that phototoxicity resulting from exposure to continuous UVB light generally increased the acute toxicity of the sulfonamides in D. magna by up to 2.3-fold. However, pulsed UVB exposure resulted in a greater increase in phototoxicity. Compared to fluorescent light only (no UVB), pulsed UVB irradiation (96 h) resulted in 12.0-, 5.8-, and 4.4-fold increases in toxicity for sulfamethazine, sulfathiazole, and sulfamethoxazole, respectively. This suggests that the mode of UV irradiation is more important than the dose (UV-intensity × exposure time) for the photo-enhancement of sulfonamide toxicity. Natural sunlight enhanced the toxicity of the sulfonamides to an even greater degree, likely because of the contribution of UVA light. This study suggests that without taking into account the effects of UV irradiation, it is possible to underestimate the actual consequences of phototoxic sulfonamide antibiotics in the aquatic environment.     

Microencapsulation of a cyclodextrin complex of the UV filter, butyl methoxydibenzoylmethane: in vivo skin penetration studies

Lipid microparticles loaded with the complex between hydroxypropyl-β-cyclodextrin (HP-β-CD) and the sunscreen agent, butyl methoxydibenzoylmethane (BMDBM) were evaluated for their effect on the UV filter percutaneous penetration. The microparticles were prepared by the melt emulsification technique using tristearin as lipidic material and hydrogenate phosphatidylcholine as the surfactant. Human skin penetration was investigated in vivo by the tape stripping technique, a minimal invasive procedure based on the progressive removal of the upper cutaneous layers (stratum corneum) with adhesive tape strips. The amount of sunscreen fixed to each strip was determined by HPLC after solvent extraction. The recovery of the UV filter from spiked adhesive tapes was >94.4% and the precision of the method was better than 7.6% relative standard deviation. Non-encapsulated BMDBM, its complex with HP-β-CD, the lipid microparticles loaded with the sunscreen alone or the BMDBM/HP-β-CD complex were introduced into oil-in-water emulsions and applied to human volunteers. Compared to the cream with the non-encapsulated sunscreen agent (percentage of the applied dose penetrated, 9.7%±2.5), the amount of BMDBM diffusing into the stratum corneum was increased by the formulations containing the BMDBM/HP-β-CD complex (17.1%±3.2 of the applied dose) or the microparticles loaded with BMDBM only (15.1%±2.7 of the applied dose). On the contrary, a significant decrease in the level of UV filter penetrated into the stratum corneum was achieved by the cream containing the microencapsulated BMDBM/HP-β-CD complex (percentage of the applied dose penetrated, 6.0%±1.5). The reduced BMDBM percutaneous penetration attained by the latter system should enhance the UV filter efficacy and limit potential toxicological risks.     

Porcine skin as a model system for studies of ultraviolet a effects in human skin

The range of diagnostic and therapeutic applications of ultraviolet A (UVA) radiation has been continuously expanding. UVA radiation is a well-known mutagenic factor capable of damaging both cells and tissues. At the same time there is a very limited information on long-term consequences of irradiating the skin with different doses of UVA and long-wavelength ultraviolet B (UVB) radiation used in therapies of skin disorders. It was demonstrated that for UVA doses of 0.1 to 1000 mJ/cm2 the sensitivity of the porcine skin to the UVA-induced breaking of nuclear DNA is similar to that of the human skin. Results indicate that porcine skin may serve as a model system for population studies of the deleterious effects of UVA irradiation of the skin cells.     

Protective effects of quercetin on ultraviolet A light-induced oxidative stress in the blood of rat

The oxidative effects of ultraviolet A (UVA) light (320-400 nm) and the antioxidant effects of quercetin were examined in rat blood. For this purpose, rats were divided into three groups: control, ultraviolet (UV) and ultraviolet + quercetin (UV + Q). The UV and UV + Q groups were irradiated for 4 h a day with UVA light (1.25 mW cm(2)) during periods of 3, 6 and 9 days. Quercetin (50 mg kg(-1) body wt.) was administered intraperitoneally in the UV + Q group rats before irradiation periods. Blood was taken 3, 6 and 9 days post-treatment. Plasma malondialdehyde (MDA) levels significantly increased after 9 days of daily exposure to UVA. Whole blood glutathione (GSH) levels significantly declined after 3-9 days of irradiation. Glutathione peroxidase activity on days 6 and 9 and glutathione reductase activities on days 3, 6 and 9 post-irradiation were diminished significantly. Superoxide dismutase and catalase activities decreased significantly 3-9 days post-irradiation. The administration of quercetin before the 9-day period of irradiation significantly reduced the increase in plasma MDA value. Whole blood GSH levels significantly decreased with the administration of quercetin on all days. Quercetin significantly increased antioxidant enzymes diminished by UVA irradiation. Exposure of rats to UVA light leads to oxidative stress, reflected by increased MDA and reduced antioxidant enzyme levels. The administration of quercetin appears to be a useful approach to reduce the damage produced by UVA radiation.     

Photoprotection by tocopherol submicron emulsion against UV-mediated damage in HaCaT cells

alpha-Tocopherol is a lipophilic vitamin E that shows antioxidative, antiaging and antiphotodamage activity. Nanometer biotechnology is more widely used in the entrainment system of drug carriers and the development for new pharmaceutical preparations. Ultraviolet irradiation to human skin in the long term can result in photoaging and photocarcinogenesis. The purpose of this study was to observe the biological features of tocopherol submicron emulsion (vitE SME) and to clarify the roles of vitE SME on UVB-induced photodamage in HaCaT keratinocytes (KC). VitE SME was prepared by high-pressure homogenization and microemulsion technique. HaCaT KC was incubated in the culture medium supplied with 1/200 and 1/400 of VitE SME prior to different dosages of UVB irradiation. The vitamin E amount in the culture medium was measured by high-performance liquid chromatography (HPLC). Cell growth and cellular viability was detected by MTT assay. The amount of vitamin E remaining in the culture medium significantly decreased during the first 8 h, and less than 10% can be detected by the terminal experiment (24 h). No cytotoxicity effect of tocopherol NM on HaCat KC was observed. In contrast to the control group, the cellular viability of VitE SME-treated group increased 44.22% by 24 h. Compared with irradiated groups without VitE SME, cell proliferation decreased by 17.77% and 40.42% when the HaCaT KC was irradiated with 30 mJ/cm(2) and 90 mJ/cm(2) UVB irradiation, respectively. VitE SME has no toxicity to cell culture system and is characterized by stable release and penetration. Pre-incubation with VitE SME can partly reduce UV-induced cell damage, and the photoprotective efficiency to UVB irradiation also shows time dependence.     

Evaluation of the photostability of different UV filter combinations in a sunscreen

Development of photostable sunscreens is extremely important to preserve the UV protective capacity and to prevent the reactive intermediates of photounstable filter substances behaving as photo-oxidants when coming into direct contact with the skin. Thus, the objective of this study was to evaluate the photostability of four different UV filter combinations in a sunscreen by using HPLC analysis and spectrophotometry. The formulations that were investigated included four different UV filter combinations often used in SPF 15 sunscreens. The UV filter combinations were: octyl methoxycinnamate (OMC), benzophenone-3 (BP-3) and octyl salicylate (OS) (formulation 1); OMC, avobenzone (AVB) and 4-methylbenzilidene camphor (MBC) (formulation 2); OMC, BP-3 and octocrylene (OC) (formulation 3); OMC, AVB and OC (formulation 4). In the photostability studies, 40 mg of each formulation were spread onto a glass plate and left to dry before exposure to different UVA/UVB irradiation. Exposed samples were then immersed in isopropanol and the dried film dissolved ultrasonically. The filter components in the resulting solution were quantified by HPLC analysis with detection at 325 nm and by spectrophotometry. In this study, the four UV filter combinations showed different photostability profiles and the best one was formulation 3 (OMC, BP-3 and OC), followed by formulations 4, 1 and 2. In addition, OC improved the photostability of OMC, AVB and BP-3.