procyanidin-b1 and Insulin-Resistance

Phenolic extract in highland barley grain has showed hypoglycemic effect, while little information is available about the active compounds and whether there exist additive or synergistic effect on modulating glucose metabolism.. Procyanidin B1 (PB) and p-coumaric acid (CA) are the active compounds in highland barley grain and show synergistic effect on improving glucose uptake and glycogen synthesis by upregulating glucose transporter (GLUT4) and downregulating 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 exhibits 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 mg kg. PB + CA in highland barley grain synergistically modulate glucose metabolism. These results may provide evidence of whole highland barley grain diet achieve superior effect on restoring IGT than isolated components.

Topics: Animals; Biflavonoids; Catechin; China; Coumaric Acids; Drug Synergism; Glucose; Hep G2 Cells; Hordeum; Humans; Hyperlipidemias; Insulin Receptor Substrate Proteins; Insulin Resistance; Male; Mice; Phosphatidylinositol 3-Kinase; Plant Extracts; Proanthocyanidins; Proto-Oncogene Proteins c-akt; Seeds

Procyanidin oligomers in Cinnamon are thought to be responsible for the biological activity in the treatment of diabetes mellitus (DM). To clarify types of procyanidin oligomers in different Cinnamon species and investigate their different effects, the present study investigated procyanidin oligomers in polyphenolic oligomer-rich extracts of three Cinnamon samples by LC-MS methods, and their hypoglycemic activities were detected in vivo and in vitro. The results showed that two of the three samples from Cinnamomum cassia were rich in B-type procyanidin oligomers, and the other sample was rich in A-type procyanidin oligomers. The Cinnamon extracts were administered at doses of 200 and 300 mg/kg body wt. in high-fat diet-fed and low-dose streptozotocin (STZ)-induced diabetic mice for 14 days. The results showed that blood glucose concentrations were significantly decreased in all Cinnamon extract groups compared with the control group (p<0.05). Administration of the Cinnamon extracts significantly increased the consumption of extracellular glucose in insulin-resistant HepG2 cells and normal HepG2 cells compared with the control group. These results suggest that both A- and B-type procyanidin oligomers in different Cinnamon species have hypoglycemic activities and may improve insulin sensitivity in type 2 DM.

Topics: Animals; Antioxidants; Biflavonoids; Blood Glucose; Catechin; Cinnamomum aromaticum; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Glucose Tolerance Test; Hep G2 Cells; Humans; Hypoglycemic Agents; Insulin; Insulin Resistance; Male; Mice; Phytotherapy; Plant Bark; Plant Extracts; Plants, Medicinal; Proanthocyanidins; Streptozocin