Pheomelanin Effect on UVB Radiation-Induced  Oxidation/Nitration of L-Tyrosine

Pheomelanin is a natural yellow-reddish sulfur-containing pigment derived from tyrosinase-catalyzed oxidation of tyrosine in presence of cysteine. Generally, the formation of melanin pigments is a protective response against the damaging effects of UV radiation in skin. However, pheomelanin, like other photosensitizing substances, can trigger, following exposure to UV radiation, photochemical reactions capable of modifying and damaging cellular components. The photoproperties of this natural pigment have been studied by analyzing pheomelanin effect on oxidation/nitration of tyrosine induced by UVB radiation at different pH values and in presence of iron ions. Photoproperties of pheomelanin can be modulated by various experimental conditions, ranging from the photoprotection to the triggering of potentially damaging photochemical reactions. The study of the photomodification of l-Tyrosine in the presence of the natural pigment pheomelanin has a special relevance, since this tyrosine oxidation/nitration pathway can potentially occur in vivo in tissues exposed to sunlight and play a role in the mechanisms of tissue damage induced by UV radiation.

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In vivo reprogramming of UV radiation–induced regulatory T-cell migration to inhibit the elicitation of contact hypersensitivity

Journal of Allergy and Clinical Immunology ◽

10.1016/j.jaci.2011.06.005 ◽

2011 ◽

Vol 128 (4) ◽

pp. 826-833 ◽

Cited By ~ 47

Author(s):

Agatha Schwarz ◽

Fatemeh Navid ◽

Tim Sparwasser ◽

Björn E. Clausen ◽

Thomas Schwarz

Keyword(s):

Cell Migration ◽

T Cell ◽

Uv Radiation ◽

Regulatory T Cell ◽

Contact Hypersensitivity ◽

T Cell Migration ◽

Radiation Induced

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Flavonols Protect Against UV Radiation-Induced Thymine Dimer Formation in an Artificial Skin Mimic

Journal of Pharmacy & Pharmaceutical Sciences ◽

10.18433/j34w39 ◽

2015 ◽

Vol 18 (4) ◽

pp. 600 ◽

Cited By ~ 12

Author(s):

Sabia Maini ◽

Brian M. Fahlman ◽

Ed S. Krol

Keyword(s):

Uv Radiation ◽

Artificial Skin ◽

Uvb Radiation ◽

Skin Damage ◽

Dimer Formation ◽

Thymine Dimer ◽

Matrix Metalloproteinase 1 ◽

Pyrimidine Dimers ◽

Limit Of Quantitation ◽

Radiation Induced

Purpose: Exposure of skin to ultraviolet light has been shown to have a number of deleterious effects including photoaging, photoimmunosuppression and photoinduced DNA damage which can lead to the development of skin cancer. In this paper we present a study on the ability of three flavonols to protect EpiDerm™, an artificial skin mimic, against UV-induced damage. Methods: EpiDerm™ samples were treated with flavonol in acetone and exposed to UVA (100 kJ/m2 at 365 nm) and UVB (9000 J/m2 at 310 nm) radiation. Secretion of matrix metalloproteinase-1 (MMP-1) and tumor necrosis factor-α (TNF-a) were determined by ELISA, cyclobutane pyrimidine dimers were quantified using LC-APCI-MS. Results: EpiDerm ™ treated topically with quercetin significantly decreased MMP-1 secretion induced by UVA (100 µM) or UVB (200 µM) and TNF-a secretion was significantly reduced at 100 µM quercetin for both UVA and UVB radiation. In addition, topically applied quercetin was found to be photostable over the duration of the experiment. EpiDerm™ samples were treated topically with quercetin, kaempferol or galangin (52 µM) immediately prior to UVA or UVB exposure, and the cyclobutane thymine dimers (T-T (CPD)) were quantified using an HPLC-APCI MS/MS method. All three flavonols significantly decreased T-T (CPD) formation in UVB irradiated EpiDerm™, however no effect could be observed for the UVA irradiation experiments as thymine dimer formation was below the limit of quantitation. Conclusions: Our results suggest that flavonols can provide protection against UV radiation-induced skin damage through both antioxidant activity and direct photo-absorption. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

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Antioxidant and Anti-inflammatory Effect of Cannabidiol Contributes to the Decreased Lipid Peroxidation of Keratinocytes of Rat Skin Exposed to UV Radiation

Oxidative Medicine and Cellular Longevity ◽

10.1155/2021/6647222 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Anna Jastrząb ◽

Iwona Jarocka-Karpowicz ◽

Agnieszka Markowska ◽

Adam Wroński ◽

Agnieszka Gęgotek ◽

...

Keyword(s):

Lipid Peroxidation ◽

Uv Radiation ◽

Physical Factor ◽

Uvb Radiation ◽

Rat Skin ◽

Metabolic Disturbances ◽

Skin Cells ◽

Anti Inflammatory ◽

Proinflammatory Factors

There is a great need for compounds with antioxidant and anti-inflammatory properties for protection against UV radiation, which is the most prooxidative physical factor that skin cells are exposed to everyday. Therefore, the aim of the study was to evaluate the mechanism of phytocannabinoid-cannabidiol (CBD) action in vivo on lipid metabolism in keratinocytes of rat skin exposed to UVA/UVB radiation. Our results show that CBD protects keratinocytes against the effects of UVA/UVB radiation by reducing lipid peroxidation products: 4-HNE and 8-isoPGF2α. In addition, CBD significantly increases the level of endocannabinoids, such as anandamide, 2-arachidonylglycerol, and palmitoylethanolamide, and the activation of their receptors CB1/2 or TRPV1. The above changes are due to the protective effect of CBD against the UVA/UVB-induced decrease in the level/activity of superoxide dismutase and the components of the thioredoxin and glutathione systems. CBD also increases the in vivo transcriptional activity of Nrf2 and the expression of its Bach1 inhibitor as well as preventing the UVA/UVB-induced increase in the expression of Nrf2 activators p21, p62, p38, and KAP1 and proinflammatory factors such as NFκB and TNFα. By counteracting oxidative stress and changes in lipid structure in keratinocytes, CBD prevents cellular metabolic disturbances, protecting the epidermis against UV damage.

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Phloroglucinol enhances the repair of UVB radiation-induced DNA damage via promotion of the nucleotide excision repair system in vitro and in vivo

DNA Repair ◽

10.1016/j.dnarep.2015.02.019 ◽

2015 ◽

Vol 28 ◽

pp. 131-138 ◽

Cited By ~ 9

Author(s):

Mei Jing Piao ◽

Mee Jung Ahn ◽

Kyoung Ah Kang ◽

Ki Cheon Kim ◽

Ji Won Cha ◽

...

Keyword(s):

Dna Damage ◽

Nucleotide Excision Repair ◽

Excision Repair ◽

Repair System ◽

Uvb Radiation ◽

Nucleotide Excision ◽

Radiation Induced ◽

Nucleotide Excision Repair System

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Preventive effect of ALA-PDT on UV radiation-induced skin carcinoma ¿C in vivo study in a mouse model

Photodiagnosis and Photodynamic Therapy ◽

10.1016/j.pdpdt.2011.03.097 ◽

2011 ◽

Vol 8 (2) ◽

pp. 151-152

Author(s):

X.L. Wang ◽

T. Lv ◽

H.W. Wang ◽

F. Miao ◽

J.J. Li ◽

...

Keyword(s):

Mouse Model ◽

Uv Radiation ◽

In Vivo Study ◽

Skin Carcinoma ◽

Preventive Effect ◽

Radiation Induced

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Ubiquitination of p53 and p21 is differentially affected by ionizing and UV radiation.

Molecular and Cellular Biology ◽

10.1128/mcb.17.1.355 ◽

1997 ◽

Vol 17 (1) ◽

pp. 355-363 ◽

Cited By ~ 208

Author(s):

C G Maki ◽

P M Howley

Keyword(s):

Gamma Radiation ◽

Uv Radiation ◽

Radiation Effects ◽

P53 Protein ◽

Proteolytic Pathway ◽

Radiation Induced ◽

The Stability ◽

Gamma Irradiated ◽

In Cells

Levels of the tumor suppressor protein p53 are normally quite low due in part to its short half-life. p53 levels increase in cells exposed to DNA-damaging agents, such as radiation, and this increase is thought to be responsible for the radiation-induced G1 cell cycle arrest or delay. The mechanisms by which radiation causes an increase in p53 are currently unknown. The purpose of this study was to compare the effects of gamma and UV radiation on the stability and ubiquitination of p53 in vivo. Ubiquitin-p53 conjugates could be detected in nonirradiated and gamma-irradiated cells but not in cells which were UV treated, despite the fact that both treatments resulted in the stabilization of the p53 protein. These results demonstrate that UV and gamma radiation have different effects on ubiquitinated p53 and suggest that the UV-induced stabilization of p53 results from a loss of p53 ubiquitination. Ubiquitinated forms of p21, an inhibitor of cyclin-dependent kinases, were detected in vivo, demonstrating that p21 is also a target for degradation by the ubiquitin-dependent proteolytic pathway. However, UV and gamma radiation had no effect on the stability or in vivo ubiquitination of p21, indicating that the radiation effects on p53 are specific.

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A revised action spectrum for vitamin D synthesis by suberythemal UV radiation exposure in humans in vivo

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2015867118 ◽

2021 ◽

Vol 118 (40) ◽

pp. e2015867118

Author(s):

Antony R. Young ◽

Kylie A. Morgan ◽

Graham I. Harrison ◽

Karl P. Lawrence ◽

Bibi Petersen ◽

...

Keyword(s):

Vitamin D ◽

Uv Radiation ◽

Ex Vivo ◽

Regression Line ◽

Action Spectrum ◽

Blue Shift ◽

Biologically Active ◽

Uvb Radiation ◽

Action Spectra

Action spectra are important biological weighting functions for risk/benefit analyses of ultraviolet (UV) radiation (UVR) exposure. One important human benefit of exposure to terrestrial solar UVB radiation (∼295 to 315 nm) is the cutaneous synthesis of vitamin D3 that is initiated by the photoconversion of 7-dehydrocholesterol to previtamin D3. An action spectrum for this process that is followed by other nonphotochemical steps to achieve biologically active vitamin D3 has been established from ex vivo data and is widely used, although its validity has been questioned. We tested this action spectrum in vivo by full- or partial-body suberythemal irradiation of 75 healthy young volunteers with five different polychromatic UVR spectra on five serial occasions. Serum 25-hydroxyvitamin D3 [25(OH)D3] levels, as the most accurate measure of vitamin D3 status, were assessed before, during, and after the exposures. These were then used to generate linear dose–response curves that were different for each UVR spectrum. It was established that the previtamin D3 action spectrum was not valid when related to the serum 25(OH)D3 levels, as weighting the UVR doses with this action spectrum did not result in a common regression line unless it was adjusted by a blue shift, with 5 nm giving the best fit. Such a blue shift is in accord with the published in vitro action spectra for vitamin D3 synthesis. Thus, calculations regarding the risk (typically erythema) versus the benefit of exposure to solar UVR based on the ex vivo previtamin D3 action spectrum require revision.

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