EVALUATION OF THE ACTIVITY OF CACTUS PEAR FRUIT EXTRACT AND ITS BIOACTIVE BETALAINS IN AN IN VITRO MODEL OF ENDOTHELIAL ACTIVATION RELEVANT TO ATHEROGENESIS.

Progetto: Research project

Dettagli progetto

Description

Arteriosclerosis is a chronic inflammation-based pathology of large and medium-sized arteries that results in the progressive formation of fibrous plaques. In the early stages of disease, dysfunction and loss of cellular homeostasis of endothelium occur, leading to modification of the pattern of gene expression, cell proliferation and apoptosis. It is largely accepted that oxidized lipoproteins (LDL), transmigrated in the sub-endothelial space, have a major role in the changes leading to the atherosclerotic plaque, both contributing to lipid accumulation in the artery wall, and activating endothelial inflammatory functions. The latter activity has appeared to be due to specific oxidized phospholipids, which may be envisaged as a basis for triggering specific pathways involved the endothelial activation.
A decreased incidence of cardiovascular diseases has been related to high consumption of vegetables, as a source of natural antioxidants and/or redox active phytochemicals capable of limiting LDL oxidation and possibly affecting inflammatory endothelial reaction. In this scenery, besides polyphenol compounds, the redox active betalain pigments, have recently been shown as bioavailable phtochemicals in humans, with anti-inflammatory activities in in vivo and in vitro models.
The proposed study is aimed at evaluating the activity of extracts from fruits of cactus pear (Opuntia ficus indica), and of two betalain pigments, namely betanin and indicaxanthin, purified therefrom in an in vitro model of endothelial activation by LDL oxidized by an in vitro system designed to obtain oxysterol-rich LDL.

Layman's description

Obiettivi
Interaction of oxidized LDL with endothelial cells (EC) has been acknowledged to induce an inflammatory response. This is characterized by an increase of adhesion molecules (ICAM, VCAM, E-Selectins)at the EC surface, which boosts leukocyte chemotaxis, increases endocellular oxidative and nitrosative stress and suppresses endothelial nitric oxide synthase (eNOS) expression (1). In addition, recent data show that oxidized LDL also down-regulates the expression of the endothelial ATP-binding cassette transporter-1 (ABCA1), which may prevent the protective effects of high-density lipoproteins against atherosclerosis (2). After EC modifications the vessel walls are prone to vasoconstriction, leukocyte adherence, platelet activation, vascular inflammation, leading to atheroma formation. We will investigate whether cactus pear fruit extracts, or betalain pigments purified therefrom, could affect signaling pathways elicited in EC by oxidatively-modified-LDL. The results from this study may contribute to consider the fruit of cactus pear as a functional food.
1. Ou HC, Chou FP, Lin TM, Yang CH, Sheu WH. Protective effects of eugenol against oxidized LDL-induced cytotoxicity and adhesion molecule expression in endothelial cells. Food Chem Toxicol. 2006;44:1485-1495.

2. Zhu Y, Liao H, Xie X, et al. Oxidized LDL downregulates ATP-binding cassette transporter-1 in human vascular endothelial cells via inhibiting liver X receptor (LXR). Cardiovasc Res. 2005;68:425-432.

Metodologie

Cactus pear fruit extracts, as well as purified betanin and indicaxanthin, will be tested in a model of endothelial cell dysfunction relevant to atherosclerosis. To this purpose, human umbilical vein endothelial cells (HUVEC), that did or did not undergo pre-incubation with cactus pear fruit extracts or individual purified betalains, will be incubated with MM-LDL, either in the absence or in the presence of either cactus pear fruit extracts or purified betalains.
Fruit extracts and purified betalain pigments will be prepared in our laboratory as reported (1).
Oxidatively-modified LDL will be prepared by oxidizing human LDL in the presence of 1 microM CuSO4 for 24 h, in order to obtain oxysterol-rich oxidized LDL. The latter will be incubated with confluent HUVEC for 24 h.
Three markers of EC dysfunction will be evaluated, i) the expression of the adhesion molecules ICAM-1, VCAM-1, and E-Selectin, ii) the MM-LDL-induced oxidative and nitrosative stress, and iii) the ABCA1 expression. Adhesion molecules and the levels of H2O2, O2-., and ONOO- , will be evaluated by flow cytometry, while western blotting analysis will be used to evaluate eNOS expression. ABCA1 expression will be evaluated by RT-PCR and/or western blotting techniques.
1. Butera D., Tesoriere L., Di Gaudio F., Bongiorno A., Allegra M., Pintaudi AM., Kohen R., Livrea M.A. Antioxidant activities of Sicilian Prickly pear (Opuntia Ficus Indica) fruit extracts and reducing properties of its betalains: betanin and indicaxanthin. J. Agricult. Food Chem. (2002), 50, 6895-6901.
StatoAttivo
Data di inizio/fine effettiva1/1/07 → …

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