title: Lichens--photophysical studies of potential new sunscreens.
abstract: Fundamental photophysical properties have been obtained for six polyaromatics, calycine, usnic acid, vicanicine, 1-Cl-pannerine and epiphorelic acids I and II, extracted from Antarctic lichens--potential future sunscreens. None of the lichen compounds produced a measurable amount of triplet states and the singlet oxygen quantum yield was also very low ranging from 0.003 to 0.06. However, three exhibited triplet energy levels which may be above that of thymine. The radical cations of calycine and usnic acid were generated via pulse radiolysis and were observed to be quenched by vitamin C, vitamin E and Trolox.
authors.affiliation: Department of Dermatology, Humboldt University, 10117 Berlin, Germany.
authors.forename: Fritz
authors.initials: F
authors.lastname: Boehm
authors.forename: Kristy
authors.initials: K
authors.lastname: Clarke
authors.forename: Ruth
authors.initials: R
authors.lastname: Edge
authors.forename: Ernesto
authors.initials: E
authors.lastname: Fernandez
authors.forename: Suppiah
authors.initials: S
authors.lastname: Navaratnam
authors.forename: Wanda
authors.initials: W
authors.lastname: Quilhot
authors.forename: Fiorenza
authors.initials: F
authors.lastname: Rancan
authors.forename: T George
authors.initials: TG
authors.lastname: Truscott
mesh_terms: D001572:Benzofurans / Q000737:chemistry* / Q000302:isolation & purification / Q000528:radiation effects; D005609:Free Radicals / Q000737:chemistry / Q000528:radiation effects; D008011:Lichens / Q000737:chemistry*; D010782:Photolysis; D011675:Pulse Radiolysis; D011789:Quantum Theory; D026082:Singlet Oxygen / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013473:Sunscreening Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000528:radiation effects
chemical_list: D001572:Benzofurans; D005609:Free Radicals; D013473:Sunscreening Agents; D026082:Singlet Oxygen