oleuropein and Hyperglycemia

Oleuropein, a component of extra virgin olive oil (EVOO), reduces post-prandial glycemia with a mechanism counteracting oxidative stress-mediated incretin down-regulation. In this study we evaluated if the intake of an oleuropein-enriched chocolate could have positive effects on glycaemia and insulin levels in patients with type 2 diabetes mellitus (T2DM) and healthy subjects (HS).. Twenty-five consecutive T2DM patients and 20 HS were recruited. Participants were randomized to receive 40 g oleuropein-enriched chocolate by EVOO or 40 g control chocolate spread in a cross-over design. Serum glucose, insulin, glucagon-like peptide-1 (GLP1), and dipeptidyl-peptidase-4 (DPP4) were measured before and 2 h after chocolate intake.. In T2DM, the pairwise comparisons showed that intake of oleuropein-enriched chocolate was associated with a significantly less increase of blood glucose compared to control; GLM analysis showed a significant difference for treatments with respect to glucose (p = 0.04), GLP1 (p < 0.001) and DPP-4 activity (p = 0.01). In HS, the pairwise comparisons showed that, after oleuropein-enriched chocolate intake, blood glucose concentration and DPP4 activity did not change; conversely a significant increase was observed for insulin and GLP1. After control chocolate intake, a significant increase for blood glucose, insulin levels and DPP4 activity were observed while GLP1 did not change.. The study shows that using EVOO as source of oleuropein administration of 40 g oleuropein-enriched chocolate is associated with a modest increase or no change of glycemia in T2DM and HS respectively, via an incretin-mediated mechanism.

Topics: Adult; Aged; Biomarkers; Blood Glucose; Chocolate; Cross-Over Studies; Diabetes Mellitus; Diet, Diabetic; Dipeptidyl Peptidase 4; Female; Food, Fortified; Glucagon-Like Peptide 1; Glycemic Control; Humans; Hyperglycemia; Insulin; Iridoid Glucosides; Male; Middle Aged; Olive Oil; Postprandial Period; Rome; Single-Blind Method; Time Factors; Treatment Outcome

Extra virgin olive oil lowers postprandial glycaemia. We investigated if oleuropein, a component of extra virgin olive oil, exerts a similar effect on postprandial glycaemia and the underlying mechanism.. Twenty healthy subjects were randomly allocated in a cross-over design to 20 mg oleuropein or placebo immediately before lunch. Postprandial glycaemia along with blood insulin, dipeptidyl-peptidase-4 (DPP-4) and glucagon-like peptide-1 and oxidative stress, which included soluble NADPH oxidase-derived peptide activity (sNox2-dp), 8-iso-prostaglandin-2α and platelet p47. After 2 h, subjects who assumed oleuropein had significantly lower blood glucose, DPP-4 activity and higher insulin and glucagon-like peptide-1 compared to placebo. Furthermore, sNox2-dp, 8-iso-PGF2α and platelet p47. These findings indicate that oleuropein improves postprandial glycaemic profile via hampering Nox2-derived oxidative stress.

Topics: Adult; Antioxidants; Blood Glucose; Cross-Over Studies; Double-Blind Method; Female; Healthy Volunteers; Humans; Hyperglycemia; Iridoid Glucosides; Iridoids; Male; NADPH Oxidase 2; Olive Oil; Oxidative Stress; Postprandial Period; Treatment Outcome

Oleuropein, a phenolic compound found in abundance in olive leaves, has beneficial effects on various diseases. However, it is unknown whether an oleuropein-rich diet is efficacious against type 2 diabetic phenotypes. In this study, we investigated the effects of the oleuropein-containing supplement OPIACE, whose oleuropein content exceeds 35% (w/w), on the diabetic phenotypes in type 2 diabetes model Tsumura Suzuki Obese Diabetes (TSOD) mouse. TSOD mice were fed OPIACE at 4 weeks of age, i.e., before the TSOD mice exhibited diabetic phenotypes. We revealed that OPIACE attenuated hyperglycemia and impaired glucose tolerance in TSOD mice over the long-term (from 10 to 24 weeks of age) but had no effect on obesity. Furthermore, we demonstrated that OPIACE mildly reduced oxidative stress in TSOD mice by 26.2% and attenuated anxiety-like behavioral abnormality in aged TSOD mice. The results suggest that oleuropein suppresses the progression of type 2 diabetes and diabetes-related behavioral abnormality over the long-term.

Topics: Animals; Blood Glucose; Diabetes Mellitus, Type 2; Diet; Disease Models, Animal; Glucose Tolerance Test; Humans; Hyperglycemia; Iridoid Glucosides; Iridoids; Male; Mice; Mice, Obese

To date, numerous studies have reported on the antidiabetic properties of various plant extracts through inhibition of carbohydrate-hydrolysing enzymes. The objective of this research was to evaluate the inhibitory effect of the hydroxytyrosol and the oleuropein against α-amylase and α-glucosidase. The hydroxytyrosol was purified from olive leaves. The result shows that the hydroxytyrosol had the strongest α-glucosidase inhibitory effect with IC50 values of 150 μM with mild inhibition against α-amylase. The enzyme kinetic studies, using Lineweaver-Burk indicated that, in the presence of the hydroxytyrosol, the Michaelis-Menton constant (Km) remained constant but the maximal velocity (Vmax) decreased, revealing a non-competitive type of inhibition with inhibition constants; Ki for the formation of the inhibitor-enzyme complex and Kis for the formation of the inhibitor-enzyme-substrate complex of 104.3 and 150.1 μM, respectively. On the other hand, oleuropein showedan uncompetitive inhibition. The concentrations used in this work were below cytotoxic levels observed at 400 μM. However, at 600 μM, the hydroxytyrosol significantly decreased viability of the Caco-2 cells (p < 0.05) and in the case of the oleuropein, there's an increase in cell number compared to control (p < 0.05). These results suggest that the hydroxytyrosol and oleuropein are two potential effective α-glucosidase inhibitors for management of postprandial hyperglycemia.

Topics: alpha-Amylases; alpha-Glucosidases; Caco-2 Cells; Cell Survival; Dose-Response Relationship, Drug; Glycoside Hydrolase Inhibitors; Humans; Hyperglycemia; Iridoid Glucosides; Iridoids; Olea; Phenylethyl Alcohol; Phytotherapy; Plant Leaves