Molecular photoprotection of human keratinocytes in vitro by the naturally occurring mycosporine-like amino acid (MAA) palythine

Summary

Background

Solar ultraviolet radiation (UVR) induces molecular and genetic changes in the skin, which result in skin cancer, photoageing and photosensitivity disorders. The use of sunscreens is advocated to prevent such photodamage, however most formulations contain synthetic UVR filters that are non-biodegradable and can damage fragile marine ecosystems. Mycosporine-like amino acids (MAA) are natural UVR-absorbing compounds that have evolved in marine species for protection against chronic UVR exposure in shallow-water habitats.

Objectives

To determine if palythine, a photostable model MAA, could offer protection against a range of UVR-induced damage biomarkers that are important in skin cancer and photoageing.

Methods

HaCaT human keratinocytes were used to assess the photoprotective potential of palythine using a number of endpoints including cell viability, DNA damage (non-specific, cyclobutane pyrimidine dimers and oxidatively generated damage), gene expression changes (linked to inflammation, photoageing and oxidative stress) and oxidative stress. The anti-oxidant mechanism was investigated using chemical quenching and Nrf2 pathway activation assays.

Results

Palythine offered statistically significant protection (p<0.005) against all endpoints tested even at extremely low concentrations (0.3% w/v). Additionally, palythine was found to be a potent antioxidant, reducing oxidatively generated stress, even when added post exposure.

Conclusions

Palythine is an extremely effective multifunctional photoprotective molecule in vitro that has potential to be developed as a natural and biocompatible alternative to synthetic UVR filters.

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