title: Usnea barbata extract prevents ultraviolet-B induced prostaglandin E2 synthesis and COX-2 expression in HaCaT keratinocytes.
abstract: Usnea barbata and its major constituent usnic acid are potent antimicrobial agents. Here, we have investigated anti-inflammatory properties of an U. barbata extract (UBE) containing 4% usnic acid in an ultraviolet-B (UVB) model with HaCaT keratinocytes. UVB irradiation induced PGE(2) production and COX-2 expression in a time and dose-dependent manner. UBE inhibited PGE(2) production at a half-maximal concentration of 60 microg/ml (2.4 microg/ml usnic acid) that did not affect the UVB-induced upregulation of COX-2, suggesting an effect on enzyme activity rather than on protein expression. The inhibition of PGE(2) production by UBE was not due to cytotoxicity. Besides its known antimicrobial properties, UBE displays specific UVB protective effects that might be useful in the topical treatment of UVB-mediated inflammatory skin conditions.
authors.affiliation: Department of Dermatology, University Medical Center Freiburg, Hauptstr. 7, D-79104 Freiburg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Engel
authors.forename: U
authors.initials: U
authors.lastname: Schmidt
authors.forename: J
authors.initials: J
authors.lastname: Reuter
authors.forename: S
authors.initials: S
authors.lastname: Weckesser
authors.forename: B
authors.initials: B
authors.lastname: Simon-Haarhaus
authors.forename: C M
authors.initials: CM
authors.lastname: Schempp
mesh_terms: D002457:Cell Extracts / Q000494:pharmacology; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000096:biosynthesis* / Q000378:metabolism; D015232:Dinoprostone / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects* / Q000528:radiation effects*; D015603:Keratinocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000528:radiation effects; D014466:Ultraviolet Rays; D015854:Up-Regulation / Q000187:drug effects / Q000528:radiation effects; D020949:Usnea / Q000737:chemistry*
chemical_list: D002457:Cell Extracts; D051546:Cyclooxygenase 2; D015232:Dinoprostone