title: Prasiolin, a new UV-sunscreen compound in the terrestrial green macroalga Prasiola calophylla (Carmichael ex Greville) Kützing (Trebouxiophyceae, Chlorophyta).
abstract: We introduced a novel combination of chromatographic techniques for the purification and analysis of a new UV-sunscreen mycosporine-like amino acid (MAA) in the terrestrial green alga Prasiola calophylla. Prasiola calophylla (Carmichael ex Greville) Kützing (Trebouxiophyceae, Chlorophyta) is a typical member of terrestrial algal communities in temperate Europe, where it regularly experiences various stress conditions including strong diurnal and seasonal fluctuations in ultraviolet radiation (UVR). As a photoprotective mechanism Prasiola species and other related Trebouxiophycean taxa synthesize a mycosporine-like amino acid (MAA) as natural sunscreen whose chemical structure was unknown so far. In the present study a new methodological approach is described for the isolation, purification and structural elucidation of this novel sunscreen in P. calophylla. The new compound exhibits an absorption maximum at 324 nm (in the short ultraviolet-A), a molecular weight of 333 and a molecular extinction coefficient of 12.393 M(-1) cm(-1), and could be identified as N-[5,6 hydroxy-5(hydroxymethyl)-2-methoxy-3-oxo-1-cycohexen-1-yl] glutamic acid using one- and two-dimensional (1)H and (13)C-NMR spectroscopy. As trivial name for this novel MAA we suggest 'prasiolin'. The ecologically essential function of prasiolin for UVR-protection in terrestrial algae of the Trebouxiophyceae is discussed.
authors.affiliation: Institute of Pharmacy, Pharmacognosy, University of Innsbruck, Innrain 80-82/IV, 6020, Innsbruck, Austria.
authors.forename: Anja
authors.initials: A
authors.lastname: Hartmann
authors.affiliation: Institute of Botany, Functional Plant Biology, University of Innsbruck, Sternwartestrasse 15, 6020, Innsbruck, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Holzinger
authors.affiliation: Institute of Pharmacy, Pharmacognosy, University of Innsbruck, Innrain 80-82/IV, 6020, Innsbruck, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Ganzera
authors.affiliation: Institute of Biological Sciences, Applied Ecology and Phycology, University of Rostock, Albert-Einstein-Strasse 3, 18059, Rostock, Germany. ulf.karsten@uni-rostock.de.
authors.forename: Ulf
authors.initials: U
authors.lastname: Karsten
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000302:isolation & purification*; D000460:Chlorophyta / Q000737:chemistry* / Q000528:radiation effects; D002845:Chromatography / Q000379:methods*; D003512:Cyclohexanones / Q000737:chemistry; D018698:Glutamic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D008956:Models, Chemical; D013473:Sunscreening Agents / Q000737:chemistry / Q000302:isolation & purification*; D014466:Ultraviolet Rays
chemical_list: D000596:Amino Acids; D003512:Cyclohexanones; D013473:Sunscreening Agents; C000611946:prasiolin; D018698:Glutamic Acid
keywords: MAA (mycosporine-like amino acid) isolation; MAA purification; Structural elucidation; UV acclimation