Formation of Cyclobutane Pyrimidine Dimers after UVA Exposure (Dark-CPDs) Is Inhibited by an Hydrophilic Extract of Polypodium leucotomos

Abstract

Exposure to sun and especially to ultraviolet radiation (UVR) exerts well known detrimental effects on skin which are implicated in malignancy. UVR induces production of cyclobutane pyrimidine dimers (CPDs), immediately during exposure and even hours after the exposure, these latter being called dark-CPDs, as consequence of the effects of different reactive species that are formed. Fernblock® (FB), an aqueous extract of Polypodium leucotomos, has proven to have photoprotective and antioxidant effects on skin. The aim of our work was to investigate the potential photoprotective effect of FB against dark-CPD formation. Murine melanocytes (B16-F10) were exposed to UVA radiation and the production of dark-CPDs and different reactive oxygen and nitrogen species (ROS and RNS) was measured. Significant dark-CPD formation could be seen at 3h after UVA irradiation, which was inhibited by the pre-treatment of cells with FB. Formation of nitric oxide, superoxide and peroxynitrite was increased after irradiation, consistent with the increased CPD formation. FB successfully reduced the production of these reactive species. Hence, these results show how dark-CPDs are formed in UVA irradiated melanocytes, and that FB acts as a potential antioxidant and ROS scavenger, preventing the DNA damage induced by sun exposure.

Protective Effect of the Hydrophilic Extract of Polypodium leucotomos, Fernblock®, against the Synergistic Action of UVA Radiation and Benzo[a]pyrene Pollutant

“…In addition, based on previous studies, FB is a promising photoprotector, specially preventing oxidative stress and DNA damage [ 39 , 46 ]. Polypodium leucotomos ’ extract has been extensively used, mostly to counteract oxidative stress.…”

“…Additionally, it leads to decreased oxidative damage by enhancing antioxidant cellular mechanisms in skin cells upon exposure to fine pollutant particles (PM 2.5 ) [ 38 ]. Moreover, it can reduce UVB-induced light and dark-CPDs [ 39 ].…”

Probing photoprotection properties of lipophilic chain conjugated thiourea-aryl group molecules to attenuate ultraviolet-A induced cellular and DNA damages

“…UVA is also responsible for the formation of dark CPDs which are formed through chemiexcitation via ROS and RNS. These CPDs are formed long after exposure to UV radiation 68 . Another type of damage induced by UVA is the DNA strand breaks which are formed via intermediates of ROS generated by UV exposure.…”

Uses of Polypodium leucotomos Extract in Oncodermatology

“…Finally, Portillo and his group in 2021 [ 60 ] conducted an in vitro study to demonstrate the efficacy of PLE against UV-induced effects on the skin. The authors used murine melanocytes (B16-F10) and exposed them to UVA radiation in order to produce dark-CPDs.…”