Photoprotection from Ultraviolet and Visible Radiation Induced Damage to the Skin

Student thesis: Doctoral ThesisDoctor of Philosophy


Solar radiation has numerous effects on the skin. Some are beneficial,
however the majority are negative and contribute to development of skin cancer.
Most studies have focused on ultra violet radiation (UVR ~290-400nm), however
there is growing evidence to suggest that visible light (400- 700nm) also causes
skin damage. The main way of preventing solar damage is with the use of
sunscreens, however these absorb in the UVR region with poor protection in the
UVA/visible boundary waveband. There is growing evidence to suggest that
synthetic UVR filters damage fragile marine environments, causing bleaching of
corals and hormonal changes in fish. There is also evidence that some filters may
damage human health, acting as exogenous oestrogens and inducing oxidative
The aim of this thesis was to assess biomarkers of skin damage with a range
of in vitro and in vivo endpoints: DNA photodamage, inflammation/
immunoregulation, photoageing, oxidative stress and pigmentation. The focus
was on broadband solar simulated UVR and its boundary with visible radiation
(385-405nm). It was determined whether current sunscreen formulations
provided adequate protection in this region, and if the addition of a new
synthetic filter, could improve photoprotection. Furthermore, the ability of
naturally occurring marine UVR filters, mycosporine-like amino acids (MAAs)
was assessed, with a view to the development of a new generation of
biocompatible alternatives to eco-toxic synthetic UVR filters.
The results demonstrate that there is substantial damage in the UVR/visible
boundary region for all biomarkers tested, and sunscreens using currently
available filters do not provide sufficient protection; however the addition of the
new filter significantly improved the protection offered. The MAA provided
significant protection against all endpoints induced by solar simulated UVR.
Furthermore, it demonstrated anti-oxidant capacity when added post UVR
exposure. These results demonstrate that further investigation into the effects of
visible radiation on the skin is required and the importance of improving
sunscreens from an efficacy and environmental standpoint.
Date of Award2017
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorAntony Young (Supervisor) & Paul Long (Supervisor)

Cite this