Procyanidin B1 and p-Coumaric Acid from Highland Barley Grain Showed Synergistic Effect on Modulating Glucose METABOLISM via IRS-1/PI3K/Akt pathway.

Abstract

SCOPE\nPhenolic extract in highland barley grain was reported showed hypoglycemic effect, while little information is available about the active compounds and whether there exist additive or synergistic effect on modulating glucose metabolism.\n\n\nMETHODS AND RESULTS\nProcyanidin B1 (PB) and p-coumaric acid (CA) were the active compounds in highland barley grain and showed synergistic effect on improving glucose uptake and glycogen synthesis by up-regulating glucose transporter (GLUT4) and down-regulating glycogen synthase kinase-3β (GSK-3β) protein expression, respectively. The mechanism may be attributed to target insulin receptor (IRβ) and regulate insulin receptor substrate-1 (IRS-1)/phosphatidylinositol 3-kinase (PI3K)/ protein kinase B (Akt) pathway. Furthermore, PB + CA exhibited synergistic effect on restoring glucose intolerance and insulin resistance, and improving hepatic glycogen synthesis in impaired glucose tolerance (IGT) mice. The postprandial blood glucose (PBG), homeostasis model assessment (HOMA)-IR values and serum insulin contents in PB + CA-treated IGT mice with dosage of 300\xa0mg/kg BW were reversed to normal levels. Additionally, PC + CA showed additive effect on inhibiting gluconeogenesis in vitro and in vivo.\n\n\nCONCLUSION\nPB + CA in highland barley grain synergistically modulated glucose metabolism. These results may provide evidence of whole highland barley grain diet achieve superior effect on restoring IGT than isolated components. This article is protected by copyright. All rights reserved.