Team:Tartu TUIT/Description

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DESCRIPTION

Toxicity of modern sunscreen

UV-rays cause sunburns, photoaging, photosensitivity, age spots and skin cancer[1]. These risks can be significantly reduced by use of sunscreen.

There are two types of sunscreen available — organic and inorganic. The former contains chemical filters such as Oxybenzone and Octinoxate, which absorb UV radiation by starting a chemical reaction, and the latter contains physical sun blockers such as zinc oxide and titanium dioxide, which scatter UVA and UVB rays, thus reflecting it away from your skin[2].

These UV-absorbents have the following effects on marine life:

1. Oxybenzone and octinoxate cause bleaching (the loss of endosymbionts) by promoting viral infections[3], DNA damage, resulting in reproductive diseases, and endocrine disruption[4].
2. Nanoparticles of titanium dioxide and zinc oxide exert harmful ecotoxicological effects such as bleaching, inhibition of algal growth and increase the lipid peroxidation of the cell membrane, resulting in the deformation of the membrane structure[5] [6].

Every year up to 14,000 tons of sunscreen is being washed into the oceans and seas, resulting in a dramatic increase of the toxicity level and causing a variety of pathologies to corals[4].

Mycosporine-Like Amino Acids(MAA)

Considering all these negative effects on the environment our team decided to look for safer options. Possible alternatives to current synthetic UV filters are Mycosporine-Like Amino Acids(MAA). MAAs are small, water-soluble, colorless molecules[7] produced by a variety of marine organisms, including cyanobacteria, fungi, microalgae, and macroalgae[8]. Nowadays, more than 30 different types of MAAs have been identified[9]. The structure of MAAs consists of cyclohexanone or cyclohexenimine chromophore attached with the nitrogen substituent of an amino acid or amino alcohol[10].

Two types of MAAs, Shinorine and Porphyra-334 (Figure 1), which are originally isolated from red algae Porphyra umbilicalis have relatively high UV-absorption from 310 to 365 nm which covers UV-A and UV-B wavelengths[11]. While both of them are good UV-sunscreening compounds, Porphyra-334 also has anti-aging effects[12] and even works as an antioxidant[13]. Altogether, these compounds can be not only very useful ingredients in sunscreens and other creams but also harmless for marine life as they are protection mechanism of microorganisms[14].

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  Figure 1.1.
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  Figure 1.2.

The only way of industrial production of MAAs nowadays is to extract them from red algae. This process takes time for the reason that algae are harvested from the wild and have long life cycle. It is also expensive because of the specific conditions (water temperature, nutrients) that these organisms need for growth. Specific lighting conditions are also required for optimal MAA production and therefore the concentration of these compounds is different from harvest to harvest[15] [16].

To date, Helioguard 365 is the first commercially produced natural sunscreen which incorporates MAAs as UV-absorbents, protects skin from photo-aging and helps to prevent the appearance of lines and wrinkles[17].

MAA production

Our team was inspired by the scientists from the University of Florida, who used Synechcystis sp. PCC6803 as a host for the heterologous production of Shinorine. Shinorine gene cluster was taken from filamentous cyanobacterium Fischerella sp PCC9339. By optimizing gene expression the yield of Shinorine was made comparable to a commercially used Shinorine producer.

The research has shown that it is possible to effectively produce MAAs in the laboratory with the aid of synthetic biology. This approach is cheaper and faster than farming[18].

To obtain two natural UV-screening compounds, Shinorine and Porphyra 334, Tartu TUIT team is going to use 8 genes(in total): MysA, MysB, MysC, MysD and amir4256, amir4257, amir4258, amir4259. The idea of our project is to insert gene sequences from 2 different organisms, cyanobacterium Nostoc punctiforme and actinobacterium Actinosynnema mirum respectively.

Shinorine and Porphyra 334 are synthesized via four-step enzymatic process:

1. The intermediate of the pentose phosphate pathway, sedoheptulose-7-phosphate, is converted into dimethyl 4-deoxygadusol (DDG) by mysA/amir4259.
2. DDG is then converted to 4-deoxygadusol (4-DG) by O-methytransferase (O-MT) enoded by mysB/amir4258.
3. The ATP-grasp family protein encoded by mysC/amir4257 catalyzes the addition of glycine to 4-DG to form mycosporine-glycine.
4. A non-ribosomal peptide synthetase (NRPS) homolog encoded by mysD/amir4256 catalyzes the last reaction, in which serine and threonine are added to mycosporine-glycine forming Shinorine and Porphyra-334 respectively[19] [20] [21].

Figure 2 Pathway

Yeast and yeast extract

Our team has decided to synthesize MAAs in S. cerevisiae, since yeast cultures have some important advantages. First of all, it is easier to obtain high cell densities with an optimal protein production rate and to control growth and translation by changing the media[22] [23]. Moreover, integrated DNA is more stable in yeast than in prokaryotes.

Our idea is to produce MAA enriched yeast extract.This approach makes it possible to skip the purification step.

There are several reasons why we think that yeast extract is a good component for our sunscreen:

1. It does not cause irritation[23].
2. It is proven to be a good antioxidant due to the presence of beta-glucan[24].
3. It can moisturize, nourish and is able to activate both, collagen production in the skin and cell regeneration.[25].

These properties will make the sunscreen healing, so it not only protects the skin but also helps to fight the consequences of sunburns.

Therefore, we believe that this combination will be advantageous and will make our product multifunctional.

References:

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