title: Isolation and identification of phlorotannins from Ecklonia stolonifera with antioxidant and hepatoprotective properties in tacrine-treated HepG2 cells.
abstract: Four kinds of phlorotannins having antioxidant activity were isolated from the ethyl acetate fraction of Ecklonia stolonifera ethanolic extract. The structures of the phlorotannins were determined on the basis of spectroscopic evidence, including 1D and 2D nuclear magnetic resonance. The isolated phlorotannins showed potential radical-scavenging activities against 2,2-diphenyl-1-picrylhydrazyl and suppressed the intracellular reactive oxygen species in tacrine-treated HepG2 cells. Among them, eckol and 2-phloroeckol showed hepatoprotective activity in tacrine-treated HepG2 cells; however, phlorofucofuroeckol B and 6,6'-bieckol did not show the activity, even though having high antioxidant activity. Both eckol and 2-phloroeckol inhibited the expression of Fas-mediated cell-death proteins, including tBid, caspase-3, and poly(ADP-ribose) polymerase, and suppressed the release of cytochrome c from mitochondria to cytosol in a dose-dependent manner in tacrine-treated HepG2 cells. These results suggest that eckol and 2-phloroeckol are the principal hepatoprotective constituents of the ethyl acetate fraction of E. stolonifera ethanolic extract.
authors.affiliation: Department of Food Science and Nutrition, Pukyong National University, Busan 608-737, South Korea.
authors.forename: Min-Sup
authors.initials: MS
authors.lastname: Lee
authors.forename: Taisun
authors.initials: T
authors.lastname: Shin
authors.forename: Tadanobu
authors.initials: T
authors.lastname: Utsuki
authors.forename: Jae-Sue
authors.initials: JS
authors.lastname: Choi
authors.forename: Dae-Seok
authors.initials: DS
authors.lastname: Byun
authors.forename: Hyeung-Rak
authors.initials: HR
authors.lastname: Kim
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D004147:Dioxins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D056945:Hep G2 Cells; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D000459:Phaeophyceae / Q000737:chemistry*; D020011:Protective Agents / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013619:Tacrine / Q000494:pharmacology; D013634:Tannins / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D004147:Dioxins; D020011:Protective Agents; D017382:Reactive Oxygen Species; D013634:Tannins; D013619:Tacrine; C060311:eckol