title: Effect of dihydrocaffeic acid on UV irradiation of human keratinocyte HaCaT cells.
abstract: Dihydrocaffeic acid, a dietary constituent and a microbial metabolite of flavonoids, is an antioxidant, but few biological effects have been examined. After its production by microflora in the colon, dihydrocaffeic acid is absorbed and found in plasma as a combination of free and metabolized forms. Excess solar UV radiation provokes damage and initiates immune response and inflammation in skin, sometimes leading to cancer. Dihydrocaffeic acid reduced the cytotoxicity and pro-inflammatory cytokine production (interleukin-6 and -8) in HaCaT cells, a keratinocyte model, following UV radiation. The effect of dihydrocaffeic acid may result from a combination of direct radical scavenging of the reactive oxygen species formed or reinforcement of the antioxidant potential of the keratinocytes, as well as a direct interference with the pathway involved in cytokine stimulation. The minimum structure required for such an effect appears to consist of a propionate side chain attached to a catechol moiety, as indicated by the efficacy of caffeic acid, but not of the methyl and glucuronide conjugates of dihydrocaffeic acid. The data obtained suggest that dihydrocaffeic acid is a potential candidate for photo-protection by interfering with the events initiated after UV exposure in keratinocytes.
authors.affiliation: Nestlé Research Centre, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland; School of Biomedical and Molecular Sciences, The University of Surrey, Guildford, Surrey GU2 7XH, UK.
authors.forename: Laure
authors.initials: L
authors.lastname: Poquet
authors.forename: Michael N
authors.initials: MN
authors.lastname: Clifford
authors.forename: Gary
authors.initials: G
authors.lastname: Williamson
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D002109:Caffeic Acids / Q000737:chemistry / Q000494:pharmacology*; D002461:Cell Line, Transformed; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D016209:Interleukin-8 / Q000037:antagonists & inhibitors; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects*; D007770:L-Lactate Dehydrogenase / Q000032:analysis / Q000378:metabolism; D015394:Molecular Structure; D016877:Oxidants / Q000494:pharmacology; D013997:Time Factors; D014466:Ultraviolet Rays; D000093242:Interleukin-6 Inhibitors
chemical_list: D000975:Antioxidants; D002109:Caffeic Acids; D006861:Hydrogen Peroxide; D016209:Interleukin-8; D007770:L-Lactate Dehydrogenase; D016877:Oxidants; D000093242:Interleukin-6 Inhibitors; C040048:caffeic acid