title: Photochemical formation of singlet molecular oxygen ((1)O2) in illuminated 6-methylcoumarin solutions.
abstract: Use of the fragrance 6-methylcoumarin (6-MC) in cosmetic products has declined significantly due to numerous reports of photoallergic contact dermatitis associated with its use. We have determined that 6-MC undergoes direct photolysis with an estimated half-life of 83 minutes when illuminated with mid-latitude U.S., noon-centered, equinox sunlight and a quantum yield for photolysis at 313 nm of phi = 3 x 10(-3). The work presented here also provides evidence that singlet molecular oxygen ((1)O2) is formed in illuminated solutions containing 6-MC. An estimated value of phi = 0.01 is reported for the (1)O2 quantum yield at 313 nm. Formation of (1)O2 is significant because it is known to react with a variety of biomolecules and it is possible that (1)O2 formation is at least partially responsible for reports of 6-MC photoallergenicity and phototoxicity.
authors.affiliation: Department of Health and Safety, Indiana State University, Terre Haute 47809, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Allen
authors.forename: A
authors.initials: A
authors.lastname: Todd
authors.forename: J M
authors.initials: JM
authors.lastname: Allen
mesh_terms: D003374:Coumarins / Q000737:chemistry* / Q000528:radiation effects; D017666:Deuterium Oxide; D005663:Furans / Q000737:chemistry; D007700:Kinetics; D008027:Light; D010100:Oxygen; D010782:Photolysis; D026082:Singlet Oxygen; D012996:Solutions
chemical_list: D003374:Coumarins; D005663:Furans; D012996:Solutions; D026082:Singlet Oxygen; C012986:furfuryl alcohol; C018096:6-methylcoumarin; D017666:Deuterium Oxide; D010100:Oxygen