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Inhibition of hepatic neoglucogenesis and glucose‐6‐phosphatase by quercetin 3‐ O ‐ α (2″‐galloyl)rhamnoside isolated from Bauhinia megalandra leaves
Author(s) -
GonzalezMujica Freddy,
Motta Norma,
Estrada Omar,
Perdomo Elsa,
Méndez Jeannette,
Hasegawa Masahisa
Publication year - 2005
Publication title -
phytotherapy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 129
eISSN - 1099-1573
pISSN - 0951-418X
DOI - 10.1002/ptr.1704
Subject(s) - microsome , biochemistry , chemistry , quercetin , phosphatase , enzyme , antioxidant
In intact microsomes, quercetin 3‐ O ‐ α ‐(2″‐galloyl)rhamnoside (QGR) inhibits glucose‐6‐phosphatase (G‐6‐Pase) in a concentration‐dependent manner. QGR increased the G‐6‐Pase K m for glucose‐6‐phosphate without change in the V max . The flavonol did not change the kinetic parameters of disrupted microsomal G‐6‐Pase or intact or disrupted microsomal G‐6‐Pase pyrophosphatase (PPase) activity. This result allowed the conclusion that QGR competitively inhibits the glucose‐6‐phosphate (G‐6‐P) transporter (T1) without affecting the catalytic subunit or the phosphate/pyrophosphate transporter (T2) of the G‐6‐Pase system. QGR strongly inhibits the neoglucogenic capacity of rat liver slices incubated in a Krebs‐Ringer bicarbonate buffer, supplemented with lactate and oleate saturated albumin. The QGR G‐6‐Pase inhibition might explain the decrease in the liver slice neoglucogenic capacity and, in turn, could reduce glucose levels in diabetic patients. Copyright © 2005 John Wiley & Sons, Ltd.