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Inhibition of hepatic glucose 6-phosphatase system by the green tea flavanol epigallocatechin gallate.

Csala M, Margittai E, Senesi S, Gamberucci A, Bánhegyi G, Mandl J, Benedetti A

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>

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.

Published 10 April 2007 in FEBS Lett, 581(8): 1693-8.
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