Ultraviolet Radiations: Skin Defense-Damage Mechanism

Abstract

UV-radiations are the invisible part of light spectra having a wavelength between visible rays and X-rays. Based on wavelength, UV rays are subdivided into UV-A (320-400 nm), UV-B (280-320 nm) and UV-C (200-280 nm). Ultraviolet rays can have both harmful and beneficial effects. UV-C has the property of ionization thus acting as a strong mutagen, which can cause immune-mediated disease and cancer in adverse cases. Numbers of genetic factors have been identified in human involved in inducing skin cancer from UV-radiations. Certain heredity diseases have been found susceptible to UV-induced skin cancer. UV radiations activate the cutaneous immune system, which led to an inflammatory response by different mechanisms. The first line of defense mechanism against UV radiation is melanin (an epidermal pigment), and UV absorbing pigment of skin, which dissipate UV radiation as heat. Cell surface death receptor (e.g. Fas) of keratinocytes responds to UV-induced injury and elicits apoptosis to avoid malignant transformation. In addition to the formation of photo-dimers in the genome, UV also can induce mutation by generating ROS and nucleotides are highly susceptible to these free radical injuries. Melanocortin 1 receptor (MC1R) has been known to be implicated in different UV-induced damages such as pigmentation, adaptive tanning, and skin cancer. UV-B induces the formation of pre-vitamin D3 in the epidermal layer of skin. UV-induced tans act as a photoprotection by providing a sun protection factor (SPF) of 3-4 and epidermal hyperplasia. There is a need to prevent the harmful effects and harness the useful effects of UV radiations.

Vitamin D levels and cancer incidence in 217,244 individuals from primary health care in Denmark

“…showed a significantly higher incidence of non‐melanoma skin cancers with higher levels of vitamin D in approximately 12,000 individuals pooled from 3 population based studies carried out in Denmark from 1993 to 2008. Thus, it is likely there is confounding by sun exposure for non‐melanoma skin cancer as these cancers are induced by exposure of the skin to the ultraviolet light from the sun. Furthermore, an inverse association of vitamin D levels with lung cancer was shown by Afzal et al .…”

Riboflavin Plays a Pivotal Role in the UVA-Induced Cytotoxicity of Fibroblasts as a Key Molecule in the Production of H2O2 by UVA Radiation in Collaboration with Amino Acids and Vitamins

“…The UV spectrum is divided into three groups based on the wavelength: ultraviolet C (UVC: 100-280 nm), ultraviolet B (UVB: 280-320 nm), and ultraviolet A (UVA: 320-400 nm) [6]. UVA is further subdivided into UVA2 (320-340 nm) and UVA1 (340-400 nm) [7].…”

Surface modification and biological evaluation of kojic acid/silica nanoparticles as platforms for biomedical systems

“…Pure kojic acid is an unstable molecule that is sensitive to moisture, easily oxidized, and discolored, which may influence its quality. 8,9 In order to ensure the efficiency of kojic acid activity, often its higher concentration should be used, which may result in non-desirable side effects. 10 To overcome these drawbacks, the silica nanoparticle and kojic acid combination are proposed, aiming at obtaining a new way to design a potent and safe product.…”