UVA UVB Research Articles

Holistic Photoprotection, Broad Spectrum (UVA-UVB), and Biological Effective Protection Factors (BEPFs) from Baccharis antioquensis Hydrolysates Polyphenols

Overexposure to solar radiation has become an increasingly worrying problem due to the damage to the skin caused by ultraviolet radiation (UVR). In previous studies, the potential of an extract enriched with glycosylated flavonoids from the endemic Colombian high-mountain plant Baccharis antioquensis as a photoprotector and antioxidant was demonstrated. Therefore, in this work we sought to develop a dermocosmetic formulation with broad-spectrum photoprotection from the hydrolysates and purified polyphenols obtained from this species. Hence, the extraction of its polyphenols with different solvents was evaluated, followed by hydrolysis and purification, in addition to the characterization of its main compounds by HPLC-DAD and HPLC-MS, and evaluation of its photoprotective capacity through the measurement of the Sun Protection Factor (SPF), UVA Protection Factor (UVAPF), other Biological Effective Protection Factors (BEPFs), and its safety through the cytotoxicity. In the dry methanolic extract (DME) and purified methanolic extract (PME), flavonoids such as quercetin and kaempferol were found, which demonstrated antiradical capacity, as well as UVA-UVB photoprotection and prevention of harmful biological effects, such as elastosis, photoaging, immunosuppression, DNA damage, among others, which demonstrates the potential of the ingredients in this type of extract to be applied in photoprotection dermocosmetics.

Prevention of Polymorphic Light Eruption Afforded by a Very High Broad-Spectrum Protection Sunscreen Containing Ectoin.

IntroductionPolymorphic light eruption (PLE) is the most common idiopathic, acquired photodermatosis. The pathophysiology of PLE is not yet fully understood but seems to involve immunological mechanisms, UVA-induced oxidative stress, and the subsequent elicitation of a cellular stress response affecting keratinocyte gene expression and skin immune function. In the present study, a high broad-spectrum sunscreen medical device (MD), containing a very high protection complex of UVB and UVA filters and ectoin, was investigated for its ability to protect against UVA-induced PLE.MethodsThe study was carried out as a monocentric, double-blinded, randomized, untreated controlled design. The test MD was applied (2 mg/cm2) on one side of the chest according to a randomization list of 15 patients with a typical history of PLE, and the contralateral area remained untreated. After product application, the test areas were exposed daily to increasing doses of UVA radiation (from 40 to 60 J/cm2) until a PLE reaction was detected or for a maximum of five consecutive days. Evaluations of induced PLE included clinical scoring and chromametry for erythema and pigmentation.ResultsOverall, no positive PLE reaction was observed on the side of the chest treated by the test MD, whereas positive PLE reactions were triggered on the untreated side of 13 subjects. Subjective sensations were very rare on the MD-treated side but were numerous and more severe on the untreated side. Chromametry and clinical visual inspection indicated that the skin color was unchanged on the MD-protected side, whereas high increased values of erythema and pigmentation were observed on the untreated chest side.ConclusionThis MD sunscreen based on a complex of UVA–UVB filters and 1% of ectoin may be effective in preventing UVA-induced PLE. New studies comparing this MD sunscreen versus the same product without ectoin should be conducted.ClinicalTrials.gov identifier: NCT05320315 (retrospectively registered 09/17/2021).Supplementary InformationThe online version contains supplementary material available at 10.1007/s13555-022-00755-5.

Minimal Erythema Dose: Correlation with Fitzpatrick Skin Type and Concordance Between Methods of Erythema Assessment in a Patient Sample in Colombia

Background and objectiveThe minimal erythema dose (MED), an essential measurement in studies of skin photosensitivity, requires establishing MED values for specific populations, given genetic variation. Different ways to assess erythema are also relevant. We aimed to determine MED values in a sample of Colombian patients and correlations between MED and Fitzpatrick skin type. We also studied concordance correlation between MEDs and two alternative ways to assess erythema. Patients and methodsCross-sectional study of 113 individuals in Bogotá, Colombia. We used a solar simulator to measure UV-A radiation and combined UV-A and UV-B (UVA+UVB) radiation, for MED calculation. Narrowband UV-B (NBUVB) radiation was measured in a phototherapy cabin. Erythema was assessed visually and with a Mexameter MX 18 device. ResultsThe median MEDs of UVA+UVB radiation were 22mJ/cm2 for Fitzpatrick skin types I and II, and 33 and 43mJ/cm2, respectively, for skin types III and IV. The MEDs of UV-A radiation were 22, 42, 86, and 100J/cm2 for skin types I, II, III, and IV, respectively. The MEDs of NBUVB radiation were 390, 550, 770, and 885mJ/cm2 for the 4 skin types. The correlation between MEDs and skin types ranged from 0.5 to 0.69. Lin's concordance correlation coefficients between visual and Mexameter assessments of erythema were greater than 0.8 in all cases. ConclusionThis study allowed us to understand MED values for UV-A, UVA+UVB, and NBUVB according to different skin types in the Colombian population. Concordance correlation coefficients between the different methods of erythema assessment were very good. Correlations between MEDs and skin types were moderate to good.

Dosis eritematosa mínima: correlación con el fototipo y método de medición en una muestra de población colombiana

Background and objectiveThe minimal erythema dose (MED), an essential measurement in studies of skin photosensitivity, requires establishing MED values for specific populations, given genetic variation. Different ways to assess erythema are also relevant. We aimed to determine MED values in a sample of Colombian patients and correlations between MED and Fitzpatrick skin type. We also studied concordance correlation between MEDs and two alternative ways to assess erythema. Patients and methodsCross-sectional study of 113 individuals in Bogotá, Colombia. We used a solar simulator to measure UV-A radiation and combined UV-A and UV-B (UVA+UVB) radiation, o se podría suprimir este término porque UVA y UVB son términos conocidos for MED calculation. Narrowband UV-B (NBUVB) radiation was measured in a phototherapy cabin. Erythema was assessed visually and with a Mexameter MX 18 device. ResultsThe median MEDs of UVA+UVB radiation were 22mJ/cm2 for Fitzpatrick skin typesI andII, and 33 and 43mJ/cm2, respectively, for typesIII andIV. The MEDs of UV-A radiation were 22, 42, 86, and 100J/cm2 for typesI, II, III, andIV, respectively. The MEDs of NBUVB light were 390, 550, 770, and 885mJ/cm2 for the 4 skin types. The correlation between MEDs and skin types ranged from 0.5 to 0.69. Lin's concordance correlation coefficients between visual and Mexameter assessments of erythema were greater than 0.8 in all cases. ConclusionThis study allowed us to understand MED values for UV-A, UVA+UVB, and NBUVB according to different skin types in the Colombian population. Concordance correlation coefficients between the different methods of erythema assessment were very good. Correlations between MEDs and skin types were moderate to good.

Cumulative Solar UVA–UVB Exposure Increases Heat Shock Protein (HSP) 72 on Peripheral Blood Cutaneous Lymphocytes Antigen (CLA)+T Lymphocytes in Outdoor Workers

Solar UVA–UVB radiation is responsible for development and continuity of life in the earth, but it can endanger human health. Heat shock proteins (HSP) play an essential role in the homeostasis of the living cell when cells exposed to environmental stress. Several investigators had proved increased Hsp72 expression on keratinocytes caused by UVA–UVB exposure, but the effects in peripheral blood Cutaneous Lymphocytes Antigen (CLA)+T lymphocytes, the cells that have a significant role in skin immunity, still have not been proven. To investigate the effect of cumulative solar UVA–UVB exposure on Hsp72 expression on peripheral blood CLA+T lymphocytes in outdoor workers. This cohort study had been conducted involving 70 male subjects consisting of 37 caddies of a golf course and 33 indoor workers (one was drop out) in Surabaya, on July to September, 20–45 years old, skin phototype IV/V. Doses of solar UVA–UVB in first four weeks and eight weeks of the study were measured by Viospor® blue line II dosimeter. Hsp72 expression on the peripheral blood CLA+T lymphocytes were measured at baseline, four weeks, and eight weeks by flow cytometry. The average dose of solar UVA–UVB received over eight weeks by caddies was 12450.5±3948.8 J/m2 whereas that obtained by the indoor workers was 1794.0±1518.5 J/m2 (p = 0.0001). The Cumulative high dose of solar UVA–UVB exposure induced the increased of Hsp72 on peripheral blood CLA+T lymphocytes (p = 0.0001). The Cumulative high dose of solar UVA–UVB exposure in subjects with high outdoor activities increases Hsp72 expression on peripheral blood CLA+T lymphocytes.

First Data on the Effects of Ultraviolet Radiation on Phenolic Compounds in the Model HornwortAnthoceros agrestis

Hornworts are the least species-rich bryophyte lineage, but represent a key group to understand the evolution of plants because, together with the remaining bryophyte lineages (mosses and liverworts), they constitute the earliest diverging land plants. The responses of hornworts to ultraviolet (UV) radiation are unknown, but they may be important to infer how primitive hornworts (and bryophytes in general) coped with UV upon land colonization. In this context, our aim was to show the first data on the effects of UV radiation on the accumulation patterns of phenolic UV-absorbing compounds (UVACs) in the emerging model hornwort Anthoceros agrestis. Thalli of 52 days age were exposed to photosynthetically active radiation (PAR) alone (P regime) and to a combination of PAR UV-A UV-B radiation (PAB regime) for 21 days, using realistic UV doses (equivalent to the natural ambient doses received in summer at mid-latitudes). At the end of the culture period, we measured the bulk levels and individual contents of phenolic UV-absorbing compounds (UVACs), differentiating in both cases the UVACs located in the methanol-soluble (mainly vacuolar) and -insoluble (cell wall-bound) fractions (SUVACs and IUVACs, respectively). Three soluble and one insoluble compounds were identified, among which the soluble rosmarinic and anthocerotonic acids are not present in any other bryophyte lineage. The bulk levels of SUVACs were higher than those of IUVACs, a physiological trait more typical of liverworts than of mosses. None of the variables measured responded significantly to UV exposure, but all of them showed an increasing trend under the PAB regime. Given that UV responsiveness of phenolic compounds depends on the UV levels used and the thallus age (with decreasing responsiveness as age increases), further research using higher UV levels and younger thalli should be conducted to more reliably establish the UV reactiveness of Anthoceros agrestis.

증기폭쇄 방법으로 국내산 대나무줄기에서 추출된 리그닌의 자외선 차단효과

Bamboo trees have high economic values because of rapid growth rate, rich biomass components and good health effects. Among several parts of bamboo tree, bamboo stem contains a considerable amount of cellulose and lignin, and a little amount of minerals, silica, and etc. In this study, domestic bamboos (Phyllostachys bambusoides (1) and Phyllostachys nigra var. henosis (2)) lignins were prepared by steam explosion (temperature 210oC, 2 MPa) and organosolv pretreatment. The results showed that steam explosion lignin (SEL1, SEL2) had a higher yield (12% and 21%). Characteristics of lignin structures were confirmed by FT-IR, and SUP1/SUPH-, SUP13/SUPC-, and 2D HSQC NMR. SEL1 and SEL2 were the typical GHS-type lignins and their bonds units were predominantly β-O-4’linkages. Antioxidant effects were assayed by DPPH and ABTS radical scavenging activity using ascorbic acid as a standard. The antioxidant activity of SEL1 was the best, and IC50 value of 383.89±25.35 μg/mL and 131.78±0.99 μg/mL, respectively. Cytotoxic concentration levels of all lignin samples were 100 μg/mL based on MTT assay. To confirm the UV protection effect of lignin, SEL1 was added to commercial sunscreen (SPF 15) and moisturizing cream (no SPF) respectively. Addition of 10 wt% lignin to commercial sunscreen increased 45% of UV absorbance higher than moisturizing cream after 2 h of UV (UVA+UVB) radiation. The result of lignin addition has shown synergistic effects in UV protection and antioxidant effect.

Urban UV environment in a sub-tropical megacity – A measurement and modelling study

The variations of solar total UV (UVA+UVB) exposure rates in a megacity featured with high-rise buildings during summer months were measured and relevant model predictions were evaluated. The maximum pedestrian-level total solar UV exposure rate was less than the un-obstructed exposure rate at any time, attributing to the prevailing reduction in the diffuse solar radiation due to the obstruction effects of distant buildings. Comparing with the measurements, our coupled model well captured the spatial and temporal variations of the reduction of UV exposure rates. By measurements, large reduction in the solar total UV exposure rate down to 12% of un-obstructed exposure rate due to the building obstruction effects was found, agreeing with our previous simulation results and results from an Australian megacity. On the other hand, building reflection from reflective curtain walls could reach 23% of the un-obstructed solar total UV exposure rate at the ground level. This implied improper building design creating additional harmful effects of solar UV radiation on the environment. The coupled model was also applied to predict the urban UV exposure rates during a tropical-cyclone induced aerosol episode. A well-evaluated urban solar UV model is an important tool for sustainable urban design.

Increased matriptase zymogen activation by UV irradiation protects keratinocyte from cell death

BackgroundOverexposure to ultraviolet (UV) derived from solar light causes skin damage by causing DNA lesions and the generation of reactive oxygen species (ROS) in keratinocytes and other epidermal cells. The type 2 transmembrane serine protease matriptase has characteristics that allow keratinocytes to respond to/recover from, environmental insults to the skin. This response may depend on its roles in epidermal proliferation and early differentiation, and its rapid activation in response to changes in the cellular chemical milieu, including increased oxidative stress. ObjectiveWe investigate the regulation of matriptase activation and its role in the response of the skin to exposure to different parts of the UV spectrum including UVA UVB, and UVR. MethodsThe activation state and distribution of matriptase in ex vivo UV exposed human skin specimens and sun damaged skin samples were analyzed by immunohistochemistry. HaCaT immortalized human keratinocytes were also used to investigate the mechanism of matriptase zymogen activation induced by UV irradiation. Levels of cytosolic ROS were determined by H2DCF assay. Activated matriptase, PARP and caspase 3 cleavage was analyzed by Western blotting, and the apoptotic ratio was measured by Hoechst 33258 staining. ResultsUVB exposure rapidly increased matriptase zymogen activation in the basal keratinocytes of skin samples. Activated matriptase was also detected at much higher levels in both the basal and spinous layer keratinocytes in sun damaged skin with actinic elastosis. UVB and solar light-induced matriptase zymogen activation likely results from UV-induced ROS generation, given that UVR, UVA, and UVB irradiation induced HaCaT human keratinocytes to activate matriptase in a dose- and time-dependent manner, and that this was suppressed by the ROS scavenger N-tert-butyl-α-phenylnitrone and reducing agent dithiothreitol. Matriptase deficient HaCaT keratinocytes were more susceptible to UV-induced apoptosis than control cells, suggesting a protective role for matriptase in UV exposed keratinocytes. ConclusionUV irradiation/ROS induced matriptase proteolysis may have short term protective effects and contribute to the recovery from acute epidermal damage and/or pathology of skin with chronic sun damage.

Reduction of Solar UV Radiation Due to Urban High-Rise Buildings--A Coupled Modelling Study.

Solar UV radiation has both adverse and beneficial effects to human health. Using models (a radiative transfer model coupled to a building shading model), together with satellite and surface measurements, we studied the un-obstructed and obstructed UV environments in a sub-tropical urban environment featured with relatively high pollution (aerosol) loadings and high-rise buildings. Seasonal patterns of the erythemal UV exposure rates were governed by solar zenith angles, seasonal variations of aerosol loadings and cloud effects. The radiative transfer modelling results agreed with measurements of erythemal UV exposure rates and spectral irradiances in UVA and UVB ranges. High-rise buildings and narrow road width (height to width, H/W, ratios up to 15) reduced the modelled total UV (UVA+UVB) radiation and leave 10% of the un-obstructed exposure rate at ground-level at noon. No more than 80% of the un-obstructed exposure rate was received in the open area surrounded by 20-storey buildings. Our modelled reduction of UVB radiation in the urban environment was consistent with similar measurements obtained for Australia. However, our results in more extreme environments (higher H/W ratios) were for the first time reported, with 18% of the un-obstructed exposure rate remained at the ground-level center of the street canyon.

Melanoma Screening in a Hungarian Nuclear Power Plant

The industrial use of the ionizing radiation (IR) particularly stresses the safe work, regular health control is inevitable. Since previous occupational cohorts reported contradictory data on the incidence of melanoma among nuclear industry workers, and in few publications significant increase of it has been described, our clinic was requested by the industry to screen malignant skin tumours among the workers of a power plant. Within a year we have investigated 556 workers, 275 females and 281 males. Out of them 283, majorly males had been officially confirmed as to be employed at hazardous, but strictly controlled environment for an average of 18years (1-32years). To distinguish between IR and environmental UV (UVA+UVB) induced cutaneous malignancies we determined the sun and tanning bed exposure of the workers. One in situ melanoma developed in a woman with type I skin, bullous sunburns in the history, who had worked in safe environment for 26years. Basal cell carcinoma was identified in two men, each of them worked for more than 20years with IR (in hazardous environment). One had type I skin, the other had type II skin. These results didn't differ significantly (chi-squared test; p = 0, 2437 and 1, 0) from the national population data and the results of Euromelanoma screening campaign in Hungary. Our data clearly show, that 1./UV exposure and skin type should be evaluated in occupation cohort studies. 2./The melanoma incidence was not significantly higher among the employees of the power plant than in the general Hungarian population, according to the results of our study, the only Hungarian power plant is safe as far as the skin carcinogenesis is concerned.

Degradation of Japanese Lacquer under Wavelength Sensitivity of Light Radiation

Degradation of Japanese lacquer caused by light irradiation was examined at various wavelengths. By exposing lacquer specimens to a narrow monochromatic light band isolated from dispersed polychromatic light emitted by a Xe lamp source, the wavelength sensitivity characteristics of lacquer degradation could be determined on the basis of radiant energy. Tame-Urushi (brown) lacquer displayed peak degradation maxima at 220 and 315 nm. A broad shoulder peak was also observed in UVA. For Shu-Urushi (cinnabar) lacquer, in addition to peaks in the UVA–UVB range, a large degree of degradation was observed following exposure to light in the visible range. Ao-Urushi (green) lacquer showed similar characteristics, although it was less prone to degradation. Similarly, Shin-Urushi (black) lacquer showed little change in response to light, although UV light caused limited degradation. These results indicate that along with the damage caused by UVA and UVB, visible light in the range 510 - 650 nm may also have a significant degradation effect. Our results provide experimental evidence that Japanese lacquer responds differently to light of various wavelengths and that specific wavelengths, including visible light, can cause significant degradation.

The effect of artificial accelerated weathering on the mechanical properties of maxillofacial polymers PDMS and CPE

The effect of UVA–UVB irradiation on the mechanical properties of three different industrial types of polydimethylsiloxane and chlorinated polyethylene samples, used in maxillofacial prostheses, was investigated in this study. Mechanical properties and thermal analysis are commonly used to determine the structural changes and mechanical strength. An aging chamber was used in order to simulate the solar radiation and assess natural aging. Compression and tensile tests were conducted on a Zwick testing machine. Durometer Shore A hardness measurements were carried out in a CV digital Shore A durometer according to ASTM D 2240. Glass transition temperature was evaluated with a differential scanning calorimeter. Simple mathematical models were developed to correlate the measured properties with irradiation time. The effect of UVA–UVB irradiation on compressive behavior affected model parameters. Significant deterioration seems to occur due to irradiation in samples.

Reduction of UVA UVB radiation reflection by application of polyphenol particles on concrete surfaces

The present work evaluated the UVA and UVB radiation reflection of concrete after the application of a surface polyphenol coating. Measurements of the UVA, UVB and visible light reflections of a solution containing dissolved polyphenol at three different concentrations (0·2, 0·4, and 0·8 mg mL−1) were performed. The reduction of reflection achieved after the coating application was compared with the value obtained by a non-coated concrete surface, indicating 58·66% less UVB reflection for an angle of 58°. Scanning electron microscopy (SEM) observations provided information on the presence and distribution of quercetin. The Fourier transform infrared (FT-IR) spectroscopy analyses showed the changes of quercetin after the application to concrete. The results of this study are essential in the designing of concrete coatings aimed at increasing the amount of environmental energy absorption through the reduction of UV radiation reflection by concrete surfaces.

Effects of UV irradiation on calf thymus DNA in aqueous solution. A Raman spectroscopic study

The Raman spectra of calf thymus DNA in aqueous solution before and after irradiation in two UV regions (UVA, 320–340 nm; UVA–UVB, 280–400 nm) were investigated. Damage to the molecular structure in part was found in the DNA solution after UVA–UVB irradiation. The bands near 811 (±7) and 832 (±7) cm−1 appeared in all Raman spectra after UV irradiation. This result indicates that DNA in solution has a mixture of A- and B-form conformations under UV irradiation. In this experiment, all the main characteristic Raman peaks appeared at almost the original position after UVA irradiation, except for some bands corresponding to deoxyribose phosphate. This indicated that serious changes to the molecular structure did not occur in the DNA solution after UVA irradiation. The spatial structures of the DNA main chain backbone and phosphoric acid backbone were almost unchanged, and the bands corresponding to adenine also appeared at almost the original sites after UVA–UVB irradiation. The bands at 949 and 1445 cm−1 corresponding to deoxyribose shifted and were obviously hypochromic, and the bands assigned to thymine showed a large shift and decline after 5 h of UVA–UVB irradiation. Hence the pyrimidine bases and deoxyribose were likely first damaged when the calf thymus DNA in aqueous solution was irradiated by UVA–UVB. Copyright © 2004 John Wiley & Sons, Ltd.

Spectrofluorimetric assay for the photodegradation products of alprazolam

A new spectrofluorimetric assay for the photodegradation products of the ansiolytic drug alprazolam is described. Alprazolam was found to be highly photolabile and special care should be taken to avoid light exposure during alprazolam storage and handling. The photostability of alprazolam was evaluated at pH 2.0, 3.6 and 5.0. The drug was exposed to UVA–UVB radiations, the photodegradation of alprazolam was followed by high-performance liquid chromatographic (HPLC) and the developed spectrofluorimetric assay allowed determination of the photodegradation products at very low concentrations (≥10 −5 M). The photoinstability was found to increase with the pH value decreasing, consequently acidic media should be avoided during the drug-development process.

Studies on the photostability and in vitro phototoxicity of Labetalol

The purpose of this study was to obtain information on the photochemical and phototoxic properties of Labetalol, a beta-blocker drug. Preliminary information on the drug photoreactivity was achieved using a flow system with a photochemical reactor on-line with a diode array detection system. Photophysical and photochemical investigations on the drug were performed in aqueous solutions at different pH values using spectrophotometric and fluorimetric methods; the photodegradation quantum yield was found to be 2.7×10 −3 at pH 5.8 and 1.5×10 −2 at pH 11.5. Forced photodegradation of labetalol solutions under exposure to UVA–UVB radiations (xenon arc lamp) was monitored by reversed-phase liquid chromatography. The main photodegradation products were isolated and characterized by NMR and mass spectrometry; labetalol was found to give 3-amino-1-phenylbutane and salicylamide-4-carboxaldehyde as the main photoproducts. Preliminary phototoxic testings on human keratinocyte cultures were performed evaluating the viability of the cells by the neutral-red uptake assay; mutagenic and photomutagenicity tests were also carried out based on Salmonella typhimurium strains. As a result, labetalol was found to be photolabile,mainly in alkaline medium, but evidences of significant phototoxic and photomutagenic effects by the drug were not observed.

Photodegradation studies on Atenolol by liquid chromatography

The photostability of the β-blocker drug Atenolol was evaluated at pH 9, 7.4 and 4.0. The drug was exposed to UVA–UVB radiations and the photoproducts were detected by reversed phase LC methods. The photodegradation was found to increase with the pH value decreasing. The major photodegradation product at pH 7.4 was identified as 2-(4-hydroxyphenyl)acetamide. The LC method developed for routine analyses (column: C-18 Alltima; mobile phase: TEA acetate (pH 4; 0.01 M)–acetonitrile 96:4) was found to be suitable for the stability — indicating determination of Atenolol in pharmaceutical dosage forms.

Synthesis, in vitro percutaneous absorption and phototoxicity of new benzylidene derivatives of 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-one as potential UV sunscreens

A series of 5-(alkoxyphenylmethylene)-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-ones ( 1a–i) were prepared to evaluate their potential cosmetic application as UV sunscreens. All new synthesised compounds were studied for their UV absorption and the relative sunscreening action was determined by sunscreen index values obtained from the UV spectra: compound 1c showed its maximum absorption in the UVB region, compounds 1a and 1d showed their maximum absorption in the UVA–UVB immediate zone, the others in the UVA sunscreen area. Since an ideal sunscreen should show a high extent of substantivity without penetrating the skin, on the basis of UV spectral data, four of them ( 1a, 1d, 1f, 1h) were evaluated as regards their in vitro percutaneous absorption. Subsequently, the two less absorbed compounds, 1f and 1h, were also assayed for their potential in vitro phototoxicity, by photohemolysis and lipid peroxidation tests. The skin permeation and the phototoxicity data of the studied compounds were compared to the data of 3-(4-methylbenzyliden)bornanone ( 2), a commercially available UV filter having a chemical structure similar to the new derivatives. Compounds 1f and 1h were less absorbed than compound ( 2) and showed a photoinduced lytic activity which is comparable to that displayed by the marketed compound.

The effects of chronic sunscreen use on the histologic changes of dermatoheliosis

Background: Sunscreen application to the skin of hairless mice is effective in reversing the histologic changes associated with photoaging (solar elastosis, epidermal thickening, collagen depletion, glycosaminoglycan deposition). These reparative processes have not been studied in human beings. Objective: The aim of this study was to evaluate histologically the effects of daily application of a UVA UVB sunscreen versus placebo. Methods: We examined 46 patients who were given either sunscreen or vehicle and asked to apply it daily for 24 months. Punch biopsy specimens were obtained from preauricular skin at 0, 12 and 24 months. Each specimen was examined for epidermal thickening and organization and dermal inflammatory infiltrate by light microscopy. Computer-generated analysis of tissue sections was used to evaluate solar elastosis. Results: A significant difference in solar elastosis was found between the treatment groups; however, the other features remained largely unchanged. Conclusion: The dermal changes of photoaging may be affected differently than epidermal changes when UV radiation exposure is diminished. UVA and UVB may contribute diversely to these cutaneous changes. Computer-generated evaluation of dermatoheliosis may be more accurate than visual inspection.