iridoids and Arteriosclerosis

Olive tree (Olea europaea L.) leaves have been widely used in traditional remedies in European and Mediterranean countries such as Greece, Spain, Italy, France, Turkey, Israel, Morocco, and Tunisia. They have been used in the human diet as an extract, an herbal tea, and a powder, and they contain many potentially bioactive compounds that may have antioxidant, antihypertensive, antiatherogenic, anti-inflammatory, hypoglycemic, and hypocholesterolemic properties. One of these potentially bioactive compounds is the secoiridoid oleuropein, which can constitute up to 6-9% of dry matter in the leaves. Other bioactive components found in olive leaves include related secoiridoids, flavonoids, and triterpenes. The evidence supporting the potentially beneficial effects of olive leaves on human health are presented in this brief review.

Topics: Anti-Inflammatory Agents; Anticholesteremic Agents; Antihypertensive Agents; Antioxidants; Arteriosclerosis; Biological Availability; Flavonoids; Humans; Hypoglycemic Agents; Iridoid Glucosides; Iridoids; Olea; Phenols; Phytotherapy; Plant Extracts; Plant Leaves; Polyphenols; Pyrans

The aim of the current study was to investigate the antioxidant and cellular activity of the olive oil phenolics oleuropein, tyrosol, hydroxytyrosol, and homovanillic alcohol (which is also a major metabolite of hydroxytyrosol). Well-characterized chemical and biochemical assays were used to assess the antioxidant potential of the compounds. Further experiments investigated their influence in cell culture on cytotoxic effects of hydrogen peroxide and oxidized low-density lipoprotein (LDL), nitric oxide production by activated macrophages, and secretion of chemoattractant and cell adhesion molecules by the endothelium. Inhibitory influences on in vitro platelet aggregation were also measured. The antioxidant assays indicated that homovanillic alcohol was a significantly more potent antioxidant than the other phenolics, both in chemical assays and in prolonging the lag phase of LDL oxidation. Cell culture experiments suggested that the olive oil phenolics induce a significant reduction in the secretion of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 (and a trend towards a reduced secretion of monocyte chemoattractant protein-1), and protect against cytotoxic effects of hydrogen peroxide and oxidized LDL. However, no influence on nitric oxide production or platelet aggregation was evident. The data show that olive oil phenolics have biochemical and cellular actions, which, if also apparent in vivo, could exert cardioprotective effects.

Topics: Antioxidants; Arteriosclerosis; Cell Adhesion Molecules; Cells, Cultured; Chemokine CCL2; Endothelium; Homovanillic Acid; Hydrogen Peroxide; In Vitro Techniques; Intercellular Adhesion Molecule-1; Iridoid Glucosides; Iridoids; Lipoproteins, LDL; Macrophages; Nitric Oxide; Olive Oil; Phenols; Phenylethyl Alcohol; Plant Oils; Platelet Aggregation; Pyrans; Vascular Cell Adhesion Molecule-1

Epidemiology suggests that Mediterranean diets are associated with reduced risk of cardiovascular disease. Because monocyte adhesion to the endothelium is crucial in early atherogenesis, we evaluated whether typical olive oil and red wine polyphenols affect endothelial-leukocyte adhesion molecule expression and monocyte adhesion.. Phytochemicals in olive oil and red wine, including oleuropein, hydroxytyrosol, tyrosol, elenolic acid, and resveratrol, with or without antioxidant activity, were incubated with human umbilical vein endothelial cells for 30 minutes, followed by co-incubation with bacterial lipopolysaccharide or cytokines to trigger adhesion molecule expression. At nutritionally relevant concentrations, only oleuropein, hydroxytyrosol, and resveratrol, possessing a marked antioxidant activity, reduced monocytoid cell adhesion to stimulated endothelium, as well as vascular cell adhesion molecule-1 (VCAM-1) mRNA and protein by Northern analysis and cell surface enzyme immunoassay. Reporter gene assays with deletional VCAM-1 promoter constructs indicated the relevance of nuclear factor-kappaB, activator protein-1, and possibly GATA binding sites in mediating VCAM-1 transcriptional inhibition. The involvement of nuclear factor-kappaB and activator protein-1 was finally demonstrated at electrophoretic mobility shift assays.. Olive oil and red wine antioxidant polyphenols at nutritionally relevant concentrations transcriptionally inhibit endothelial adhesion molecule expression, thus partially explaining atheroprotection from Mediterranean diets.

Topics: Animals; Antioxidants; Arteriosclerosis; Cattle; Cell Adhesion; Cells, Cultured; Diet; Endothelium, Vascular; Flavonoids; Gene Expression Regulation; Humans; Iridoid Glucosides; Iridoids; NF-kappa B; Olive Oil; Phenols; Phenylethyl Alcohol; Plant Oils; Polyphenols; Pyrans; Resveratrol; RNA, Messenger; Stilbenes; Transcription Factor AP-1; Transcription, Genetic; U937 Cells; Vascular Cell Adhesion Molecule-1; Wine