title: Echinacoside and caffeoyl conjugates protect collagen from free radical-induced degradation: a potential use of Echinacea extracts in the prevention of skin photodamage.
abstract: The protective effect of caffeoyl derivatives (echinacoside, chlorogenic acid, chicoric acid, cynarine, and caffeic acid, typical constituents of Echinacea species) on the free radical-induced degradation of Type III collagen has been investigated. The macromolecule was exposed to a flux of oxygen radicals (superoxide anion and hydroxyl radical) generated by the xanthine/xanthine oxidase/Fe2+/EDTA system and its degradation assessed qualitatively by SDS-PAGE and quantitatively as the amount of soluble peptides (according to the 4-hydroxyproline method) released from native collagen after oxidative stress. The SDS-PAGE pattern of native collagen is markedly modified by free radical attack, with formation of a great number of peptide fragments with molecular masses below 97 kDa: in the presence of microM concentrations of echinacoside, there is a complete recovery of the native profile. Collagen degradation was, in fact, dose-dependently inhibited by all the compounds, with the following order of potency: echinacoside approximately chicoric acid > cynarine approximately caffeic acid > chlorogenic acid, with IC50 ranging from 15 to 90 microM. These results indicate that this representative class of polyphenols of Echinacea species protects collagen from free radical damage through a scavenging effect on reactive oxygen species and/or C-, N-, S-centered secondary radicals, and provide an indication for the topical use of extracts from Echinacea species for the prevention/treatment of photodamage of the skin by UVA/UVB radiation, in which oxidative stress plays a crucial role.
authors.affiliation: Istituto Chimico Farmaceutico Tossicologico, Milan, Italy.
authors.forename: R M
authors.initials: RM
authors.lastname: Facino
authors.forename: M
authors.initials: M
authors.lastname: Carini
authors.forename: G
authors.initials: G
authors.lastname: Aldini
authors.forename: L
authors.initials: L
authors.lastname: Saibene
authors.forename: P
authors.initials: P
authors.lastname: Pietta
authors.forename: P
authors.initials: P
authors.lastname: Mauri
mesh_terms: D002109:Caffeic Acids / Q000494:pharmacology*; D003094:Collagen / Q000378:metabolism*; D016166:Free Radical Scavengers / Q000494:pharmacology*; D006027:Glycosides / Q000494:pharmacology*; D006868:Hydrolysis; D017382:Reactive Oxygen Species; D012867:Skin / Q000187:drug effects* / Q000528:radiation effects*; D014466:Ultraviolet Rays; D019820:Xanthine; D014969:Xanthine Oxidase / Q000378:metabolism; D014970:Xanthines / Q000378:metabolism
chemical_list: D002109:Caffeic Acids; D016166:Free Radical Scavengers; D006027:Glycosides; D017382:Reactive Oxygen Species; D014970:Xanthines; D019820:Xanthine; D003094:Collagen; D014969:Xanthine Oxidase; C060297:echinacoside