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Food Chem Toxicol. 2014 May;67:35-43. doi: 10.1016/j.fct.2014.01.055. Epub 2014 Feb 18.

Biochemical and biological assessment of the inhibitory potency of extracts from vinification byproducts of Vitis vinifera extracts against glycogen phosphorylase.

Author information

1
Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece.
2
Department of Animal Sciences and Aquaculture, Agricultural University of Athens, Iera Odos 75, 11855 Athens, Greece.
3
Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece. Electronic address: ddleonidas@bio.uth.gr.

Abstract

The inhibitory potency of thirteen polyphenolic extracts obtained from vinification byproducts of Greek varieties of Vitis vinifera against glycogen phosphorylase (GP) has been studied by kinetic experiments. GP is an enzyme involved in glucose homeostasis and a molecular target for the discovery of new hypoglycemic agents. Studies have shown that all extracts display significant inhibitory potency for GP in vitro with IC50 values in the range of low μg/mL. X-ray crystallographic analysis of GP crystals soaked with two of these extracts revealed that the most active ingredient is quercetin which binds at novel binding site, distinct from the other known sites of the enzyme. One of the most potent of the studied extracts had also a moderate effect on glycogenolysis in the cellular lever with an IC50 value of 17.35 μg/mL. These results highlight the importance of natural resources in the quest for the discovery of new hypoglycemic agents, while at the same time they can serve as the starting point for their exploitation for antidiabetic usage and the development of novel biofunctional foods.

KEYWORDS:

Bioactive polyphenols; Glycogen metabolism; Glycogen phosphorylase; Type 2 diabetes; Vinification byproducts; X-ray crystallography

PMID:
24556570
DOI:
10.1016/j.fct.2014.01.055
[Indexed for MEDLINE]

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