title: Inhibition of hepatic glucose 6-phosphatase system by the green tea flavanol epigallocatechin gallate.
abstract: Effect of 5-100 microM epigallocatechin gallate (EGCG) on hepatic glucose 6-phosphatase (G6Pase) system was investigated. EGCG inhibited G6Pase in intact but not in permeabilized rat liver microsomes, suggesting the interference with the transport. However, EGCG did not hinder microsomal glucose 6-phosphate (G6P) uptake. Instead, it increased the accumulation of radioactivity after the addition of [(14)C]G6P, presumably due to a slower release of [(14)C]glucose, the product of luminal hydrolysis. Indeed, EGCG was found to inhibit microsomal glucose efflux. Since G6Pase activity is depressed by glucose in a concentration-dependent manner, we concluded that EGCG inhibits G6Pase through an elevated luminal glucose level.
authors.affiliation: Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Pathobiochemistry Research Group of The Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary. csala@puskin.sote.hu <csala@puskin.sote.hu>
authors.forename: Miklós
authors.initials: M
authors.lastname: Csala
authors.forename: Eva
authors.initials: E
authors.lastname: Margittai
authors.forename: Silvia
authors.initials: S
authors.lastname: Senesi
authors.forename: Alessandra
authors.initials: A
authors.lastname: Gamberucci
authors.forename: Gábor
authors.initials: G
authors.lastname: Bánhegyi
authors.forename: József
authors.initials: J
authors.lastname: Mandl
authors.forename: Angelo
authors.initials: A
authors.lastname: Benedetti
mesh_terms: D000818:Animals; D002392:Catechin / Q000031:analogs & derivatives* / Q000302:isolation & purification / Q000494:pharmacology; D044948:Flavonols / Q000302:isolation & purification / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology; D005952:Glucose-6-Phosphatase / Q000032:analysis / Q000037:antagonists & inhibitors*; D019298:Glucose-6-Phosphate / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology; D051381:Rats; D013662:Tea / Q000737:chemistry*
chemical_list: D044948:Flavonols; D013662:Tea; D019298:Glucose-6-Phosphate; D002392:Catechin; C045651:epigallocatechin gallate; D005952:Glucose-6-Phosphatase; D005947:Glucose