From Sea to Skin: Is There a Future for Natural Photoprotectants?

Abstract

In the last few decades, the thinning of the ozone layer due to increased atmospheric pollution has exacerbated the negative effects of excessive exposure to solar ultraviolet radiation (UVR), and skin cancer has become a major public health concern. In order to prevent skin damage, public health advice mainly focuses on the use of sunscreens, along with wearing protective clothing and avoiding sun exposure during peak hours. Sunscreens present on the market are topical formulations that contain a number of different synthetic, organic, and inorganic UVR filters with different absorbance profiles, which, when combined, provide broad UVR spectrum protection. However, increased evidence suggests that some of these compounds cause subtle damage to marine ecosystems. One alternative may be the use of natural products that are produced in a wide range of marine species and are mainly thought to act as a defense against UVR-mediated damage. However, their potential for human photoprotection is largely under-investigated. In this review, attention has been placed on the molecular strategies adopted by marine organisms to counteract UVR-induced negative effects and we provide a broad portrayal of the recent literature concerning marine-derived natural products having potential as natural sunscreens/photoprotectants for human skin. Their chemical structure, UVR absorption properties, and their pleiotropic role as bioactive molecules are discussed. Most studies strongly suggest that these natural products could be promising for use in biocompatible sunscreens and may represent an alternative eco-friendly approach to protect humans against UV-induced skin damage.

Keywords: antioxidants; marine natural products; photoprotection; skin; solar radiation.

Figure 1

Light spectrum penetration at sea.

Figure 2

UVR-induced damage in living organisms. The figure summarizes the main effects caused by UVR occurring at the DNA level in both plant and animal cells and in chloroplasts in photosynthetic cells. CPDs = cyclobutane pyrimidine dimers; 6–4 PP = pyrimidine (6–4) pyrimidone photoproducts; PSII = Photosystem II.

Figure 3

Major UVR-induced damage in humans. The figure summarizes the main direct and ROS-mediated effects caused by UVR in human skin. Abbreviations: AP = activator protein; MMP-1 = matrix metalloproteinase-1.

Figure 4

Mycosporine-like amino acids (MAAs).

Figure 5

Scytonemin.

Figure 6

Marine polyphenols with UVR-protective properties.

Figure 7

Carotenoids.

Figure 8

Marine sulfated polysaccharides.