title: On the photostability of scytonemin, analogues thereof and their monomeric counterparts.
abstract: As a part of their sun-protective strategy, cyanobacteria produce the natural UV-screener scytonemin. Its accumulation in the extracellular sheaths allows the bacteria to thrive in inhospitable locations highly exposed to solar radiation. Scytonemin is often referred to as photostable and has been reported to be non-fluorescent. Taken together, these properties indicate inherently fast non-radiative relaxation processes. Despite these interesting traits, the photophysics of scytonemin is as yet almost completely unexplored. In this study, we have compared the steady-state photophysics of scytonemin itself and four derivatives thereof. Furthermore, the in vitro photostability of scytonemin was studied in different solvents using a solar simulation system. Scytonemin and the investigated derivatives demonstrated a more rapid photoinduced decay in comparison with two commercial UV-screening agents. The photostability could be modulated by varying the solvent, with the protic solvent ethanol providing the most stabilizing environment.
authors.affiliation: Department of Chemistry and Chemical Engineering/Organic and Physical Chemistry, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden. jerker@chalmers.se.
authors.forename: Andreas
authors.initials: A
authors.lastname: Ekebergh
authors.affiliation: Department of Chemistry and Chemical Engineering/Organic and Physical Chemistry, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden. jerker@chalmers.se.
authors.forename: Peter
authors.initials: P
authors.lastname: Sandin
authors.affiliation: Department of Chemistry and Chemical Engineering/Organic and Physical Chemistry, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden. jerker@chalmers.se.
authors.forename: Jerker
authors.initials: J
authors.lastname: Mårtensson
mesh_terms: D000458:Cyanobacteria / Q000737:chemistry; D007211:Indoles / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D010782:Photolysis; D013473:Sunscreening Agents / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D007211:Indoles; D010636:Phenols; D013473:Sunscreening Agents; C083368:scytonemin