Photosensitization of the Sunscreen Octyl p-Dimethylaminobenzoate by UVA in Human Melanocytes but not in Keratinocytes¶

  title={Photosensitization of the Sunscreen Octyl p-Dimethylaminobenzoate by UVA in Human Melanocytes but not in Keratinocytes¶},
  author={C Xu and Ad{\`e}le Green and Alfio V. Parisi and Peter G. Parsons},
  booktitle={Photochemistry and photobiology},
Abstract Sunscreens penetrate human epidermis and modify the biology of proliferating cells. This study addressed the question whether the UV response of cultured human cells is affected by direct treatment with nontoxic levels of sunscreens. Cell survival following exposure to UVC or unfiltered UVB was not altered by preincubation with 25 μg/mL of octyl p-dimethylaminobenzoate (o-PABA), 2-ethylhexyl p-methoxycinnamate (EHMC) or oxybenzone. However, UVA or UVB filtered to reproduce the solar UV… 
The sunscreen agent 2-phenylbenzimidazole-5-sulfonic acid photosensitizes the formation of oxidized guanines in cellulo after UV-A or UV-B exposure.
It is found that PBSA provided good protection against CPD formation after UV-B exposure, however, PBSA also photosensitized oxidized guanines on UV-A andUV-B irradiation.
Determination of Wavelength‐Specific UV Protection Factors of Sunscreens in Intact Skin by EPR Measurement of UV‐Induced Reactive Melanin Radical
A novel electron paramagnetic resonance assay that uses the photogeneration of reactive melanin radical as a measure of UV light penetration to melanocytes in situ in skin to determine the monochromatic protection factors of research and commercial sunscreens.
Changes in cell morphology, apoptosis and p21 expression in tissue engineered epidermis are evaluated to increase the understanding of the mechanisms behind the potential protective effects of milk phospholipids against UV-induced photodamage.
Sunscreen Penetration of Human Skin and Related Keratinocyte Toxicity after Topical Application
The human viable epidermal levels of sunscreens are too low to cause any significant toxicity to the underlying human keratinocytes, as indicated by changes in cell morphology and proliferation.
UV-B induced keratinocyte apoptosis is blocked by 2-selenium-bridged beta-cyclodextrin, a GPX mimic.
  • Y. Mu, Shaowu Lv, G. Luo
  • Biology
    Journal of photochemistry and photobiology. B, Biology
  • 2003
Molecular mechanisms of inhibition of photocarcinogenesis by silymarin, a phytochemical from milk thistle (Silybum marianum L. Gaertn.) (Review).
It is suggested that silymarin may favorably supplement sunscreen protection, and may be useful for skin diseases associated with solar UV radiation-induced inflammation, oxidative stress and immunomodulatory effects.
Silymarin and skin cancer prevention: anti-inflammatory, antioxidant and immunomodulatory effects (Review).
  • S. Katiyar
  • Biology, Chemistry
    International journal of oncology
  • 2005
Silymarin is a promising chemopreventive and pharmacologically safe agent which can be exploited or tested against skin cancer in human system and may favorably supplement sunscreen protection and provide additional anti-photocarcinogenic protection.
Pharmacognosy Can natural products improve skin photoprotection?
The paradoxical effect of chemical UV filters and the influence of phytochemicals in in vitro and in vivo tests of photoprotection are discussed.
Can natural products improve skin photoprotection?
Abstract Due to increased UV radiation on the Earth’s surface, caused by depletion of the stratospheric ozone, people have become more susceptible to different types of skin damage, such as erythema,
Titanium dioxide-montmorillonite nanocomposite as photoprotective agent against ultraviolet B radiation-induced mutagenesis in Saccharomyces cerevisiae: a potential candidate for safer sunscreens.
An interesting TiO2 -MMT NC endowed with antimutagenic activity that can be associated to organic sunscreen molecule (ODP) and still maintain its positive effect, whereas its respective PM is unable to grant antimUTagenic protection against UVB.


Cell Cycle Delay, Mitochondrial Stress and Uptake of Hydrophobic Cations Induced by Sunscreens in Cultured Human Cells
The results established conditions for studying the action of sunscreens on cultured human cells and determined thatMelanocytes and fibroblasts tended to be more resistant than tumor cell lines (melanoma, cervical carcinoma) and mitochondrial dysfunction was significantly more sensitive to growth inhibition by EHMC and PABA.
Sunscreens, skin photobiology, and skin cancer: the need for UVA protection and evaluation of efficacy.
  • F. Gasparro
  • Biology
    Environmental health perspectives
  • 2000
In this review, the basic aspects of sunscreens and skin photobiology are reviewed briefly and in vivo and in vitro methods proposed for the evaluation of candidate sunscreen formulations of UVA protective ability are reviewed.
Differential susceptibility of epidermal keratinocytes and neuroblastoma cells to cytotoxicity of ultraviolet-B light irradiation prevented by the oxygen radical-scavenger ascorbate-2-phosphate but not by ascorbate.
Human or mouse epidermal keratinocytes NHEK or Pam212 was less susceptible to ultraviolet (UV)-B irradiation than mouse neuroblastoma NAs1 cells in culture, undergoing apoptosis-like cell death as
Scavenging effect of benzophenones on the oxidative stress of skeletal muscle cells.
Characterization of DNA Damage Inflicted by Free Radicals from a Mutagenic Sunscreen Ingredient and Its Location Using an in vitro Genetic Reversion Assay
Using a genetic reversion assay that depends on regenerating P‐galactosidase activity in photodamaged plas‐mids, it is found that GC base pairs are particularly susceptible to attack by Padimate‐O.
Redox regulation and oxidant activation of heme oxygenase-1.
It is observed that heme is released from microsomal heme-containing proteins by UVA and other oxidants and that activation of HO-1 expression by U VA correlates with levels of heme release, and heme oxygenase levels are constitutively high in keratinocytes.
Differences in Sensitivity to UVC, UVB and UVA Radiation of a Multidrug‐Resistant Cell Line Overexpressing P‐Glycoprotein
Although cell viability was not significantly altered, Pgp function was impaired after UVA treatment, suggesting that this glycoprotein may be a physical target for oxidative damage, and that other factors may be responsible for the UVA resistance.
Contact and photocontact sensitivity to sunscreens
Clinicians should consider contact and photocontact allergy, especially in patients with photodermatoses and photo‐aggravated dermatoses and they should perform photopatch testing, and patients must be warned to avoid products containing the (photo)allergen.