title: α-Glucosidase- and α-amylase-inhibitory activities of phlorotannins from Eisenia bicyclis.
abstract: BACKGROUND
  In an effort to develop alternative therapeutic agents, strong inhibitory activity against α-glucosidase and α-amylase was detected in Eisenia bicyclis methanolic extract.
  
  
  RESULTS
  In this study, two phlorotannins were isolated from E. bicyclis and characterised by chromatography and nuclear magnetic resonance. The active substances were identified as fucofuroeckol A (FF) and dioxinodehydroeckol (DD). To the authors' knowledge, this is the first report of the identification of these substances in E. bicyclis. However, to date, no antidiabetic activity of FF and DD has been reported. Both phlorotannins demonstrated significant inhibitory activity against α-glucosidase and α-amylase. FF showed potent antidiabetic activity, with IC(50) values of 131.34 nmol L(-1) against α-glucosidase and 42.91 µmol L(-1) against α-amylase. The corresponding IC(50) values of DD were 93.33 nmol L(-1) and 472.7 µmol L(-1) . Furthermore, kinetic analysis revealed that FF and DD exhibited non-competitive inhibitory activity against α-glucosidase.
  
  
  CONCLUSIONS
  These results suggest that FF and DD may be candidates for the development of an antidiabetic pharmaceutical agent or food additive.
authors.affiliation: Department of Food Science and Technology, Pukyong National University, Busan 608-737, South Korea.
authors.forename: Sung-Hwan
authors.initials: SH
authors.lastname: Eom
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Na-Young
authors.initials: NY
authors.lastname: Yoon
authors.forename: Won-Kyo
authors.initials: WK
authors.lastname: Jung
authors.forename: You-Jin
authors.initials: YJ
authors.lastname: Jeon
authors.forename: Se-Kwon
authors.initials: SK
authors.lastname: Kim
authors.forename: Myung-Suk
authors.initials: MS
authors.lastname: Lee
authors.forename: Young-Mog
authors.initials: YM
authors.lastname: Kim
mesh_terms: D000818:Animals; D001572:Benzofurans / Q000302:isolation & purification / Q000494:pharmacology*; D001688:Biological Products / Q000737:chemistry / Q000494:pharmacology*; D004147:Dioxins / Q000302:isolation & purification / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D065089:Glycoside Hydrolase Inhibitors; D006801:Humans; D007004:Hypoglycemic Agents / Q000302:isolation & purification / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D007700:Kinetics; D009835:Oligochaeta / Q000737:chemistry*; D013634:Tannins / Q000302:isolation & purification / Q000494:pharmacology; D000516:alpha-Amylases / Q000037:antagonists & inhibitors*
chemical_list: D001572:Benzofurans; D001688:Biological Products; D004147:Dioxins; D004791:Enzyme Inhibitors; D065089:Glycoside Hydrolase Inhibitors; D007004:Hypoglycemic Agents; D013634:Tannins; C550453:dioxinodehydroeckol; C064093:phlorofucofuroeckol A; D000516:alpha-Amylases