By: Dana Sackett

The title of this post may produce images of holding up a fish like an umbrella to block the sun but the real meaning comes from natural compounds created by fish that can block harmful ultraviolet (UV) radiation. Recent findings have suggested that it may be possible to reproduce these natural benefits for humans. The substantial loss of the ozone layer and consequent increase in solar UV radiation over the last two decades has provoked concerns on how increased UV rays could affect humans. Thus, this finding comes at an important time, when the need for natural sunscreens is at an all time high.

When scientists first discovered a group of compounds called gadusols in fish eggs, they assumed that they could only be produced by bacteria, algae, plants, and fungi and that when seen in fish, it was the result of the fish eating the gadusol producer, or a symbiotic relationship between the two. They also found that gadusol was a strong antioxidant. Antioxidants prevent oxidative stress, or free-radicals from damaging DNA, and are essential in preserving animal health.

While gadusols were not considered a sunscreen initially they were linked with other compounds that were seen to provide protection from the sun known as MAAs (mycosporine-like amino acids).  For a compound to truly protect from the sun it must not only absorb damaging UV rays but also dissipate the UV rays so that they do not cause oxidative stress.  Thus, MAAs (as the sunscreen) and gadusol (as the antioxidant) were thought to possibly work together to prevent sun damage in marine organisms.

In a surprising study just published a few weeks ago, scientists found that fish can synthesize gadusol themselves and that a similar pathway to create gadusol exists in amphibians, reptiles, and birds, but not mammals. They also showed that gadusol can act like a natural sunscreen, strongly absorbing UV rays as well as acting like an antioxidant. Further, the discovery that there is a pathway for gadusol to be made in vertebrate species has opened the door to engineering yeast to produce this natural sunscreen and antioxidant at a large-scale for people.

One day in the near future, we may be able to produce the beneficial properties of gadusol from yeast, making an easy to consume pill or lotion that can provide the same benefits that fish receive from this compound.  Indeed, gadusol may be a natural alternative to other sunscreens that may not be the best for ourselves or our environment (see Small Things Can Make a Big Difference).

Reference

Arbelo EM, Uez MJ, Bertolotti SG, Churio MS. 2010. Antioxidant activity of gadusol and occurrence in fish roes from Argentine Sea. Food Chemistry 119:586-591.

Bandaranayake WM. 1998. Mycosporines: are they nature’s sunscreens? Natural Product Reports

Brotherton CA, Balskus EP. 2015. Shedding light on sunscreen biosynthesis in zebrafish: zebrafish can synthesize a sunscreen compound called gadusol, which was previously thought to be acquired through the diet. Biochemistry, eLife: DOI: 10.7554/eLife.07961

Osborn AR, Almabruk KH, Holzwarth G, Asamizu S, LaDu J, Kean KM, Karplus PA, Tanguay RL, Bakalinsky AT, Mahmud T. 2015. De novo synthesis of a sunscreen compound in vertebrates. eLife: DOI: 10.7554/eLife.05919

Rastogi RP, Sinha RRP, Singh SP, Hader DP. 2010. Photoprotective compounds from marine organisms. J Ind Microbiol Biotechnol 37:537-558.

Shick JM, Dunlap WC. 2002. Mycosporine like amino acids and related gadusols: Biosynthesis, accumulation, and UV-protective functions in aquatic organisms. Annual Review of Physiology 64:223–262.

http://www.npr.org/sections/health-shots/2015/05/13/404444731/why-would-a-fish-make-its-own-sunscreen

http://time.com/3855406/fish-make-their-own-sunscreen/

http://www.sci-news.com/biology/science-fish-gadusol-sunscreen-02793.html