Cyanobacterial metabolites as a source of sunscreens and moisturizers: a comparison with current synthetic compounds

Figures & data

Fig. 1. Structure of butyl methoxydibenzoylmethane, ethylhexylmethoxycinnamate and octocrylene.

Fig. 2. Strategies used by cyanobacteria to counteract damaging UV from the sun.

Table 1. Molecular structure, maximum absorption wavelength and molar extinction coefficient of MAAs from cyanobacteria.

MAAs	λmax (nm)	Ɛ (l mol^–1 cm^–1)	Molecular structure
Mycosporine-glycine	310	28800
Asterina-330	330	43800
Palythinol	332	43500
Mycosporine-2-glycine	334	43800
Shinorine	334	44668
Porphyra-334	334	42300
Palythene	360	50000
Euhalothece-362	362	43800

Fig. 3. Two possible pathways for the biosynthesis of mycosporine-glycine in the cyanobacterium Anabaena variabilis. 4-deoxygadusol can be produced through either the shikimate pathway or the pentose pathway, and is then combined with a glycine molecule to produce mycosporine-glycine. PEP: phosphoenolpyruvate; E4P: erythrose-4-phosphate; DAHP: 2-keto-3-deoxy-D-arabinoheptulosonate-7-phosphate; DHQ: 3-dehydroquinate; 4-dG: 4-deoxygadusol; SP; sedoheptulose-7-phosphate; EV: 2-epi-5-epi-valiolone (re-drawn from Wada et al., 2013).

Fig. 4. Chemical structure of oxidized (A) and reduced (B) scytonemin.

Fig. 5. Proposed biosynthesis pathway of scytonemin (Wada et al., 2013).

Fig. 6. A biofence photobioreactor used for the cultivation of photosynthetic microorganisms at the Centre for Sustainable Aquatic Research, Swansea University.

Wada, N., Sakamoto, T. & Matsugo, S. (2013). Multiple roles of photosynthetic and sunscreen pigments in cyanobacteria focusing on the oxidative stress. Metabolites, 3: 463–483.

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