Title

 

Authors

D. Impellizzeri

Doctorate School in “Experimental Medicine”
Dept of Clinical and Experimental Medicine and Pharmacology, School of Medicine, University of  Messina, Via C. Valeria – Gazzi – 98100 Messina, Italy

 

Abstract

Olive oil is an integral ingredient of the traditional Mediterranean diet and several studies attribute many of the healthy advantages of this diet to olive oil's unique characteristics [1]. It is well known for its minor components exerting either anti-inflammatory or antioxidant effects. Among the several minor constituents of virgin olive oil, there are vitamins such as α- and γ-tocopherols and β-carotene, phytosterols, pigments, terpenic acids, flavonoids such as luteolin and quercetin, squalene, and phenolic compounds, usually and incorrectly termed polyphenols. The major constituent of the leaves and unprocessed olive drupes of Olea europaea is oleuropein and the majority of polyphenols found in olive oil or table olives are derived from its hydrolysis. Oleuropein has high antioxidant activity in vitro, comparable to a hydrosoluble analogue of tocopherol [2]. Oleuropein scavenges superoxide anions, hydroxyl radicals and inhibits the respiratory burst of neutrophils and hypochlorous acid-derived radicals [3]. In addition to their antioxidant properties, polyphenolic compounds have been shown to exhibit a range of indirect actions that may be beneficial to health, including the inhibition of enzymes involved in the inflammatory process, the inhibition of platelet aggregation and inhibition of the metabolic activation of procarcinogens [4]. Therefore, the phenolic fraction is responsible for the stability and flavor of olive oil and is endowed with ‘‘pharmacological’’ properties as an additional, valuable marker of olive oil quality. In light of the above considerations and of increasing interest in the Mediterranean diet, in the present studies we decided to evaluate the effects of oleuropein aglycone, a hydrolysis product obtained from oleuropein, on the modulation of the acute and chronic inflammatory response (carrageenan induced pleurisy and collagen-induced arthritis CIA, respectively) in animal models. We report here, that oleuropein aglycone (given at 40µg and 100µg/kg i.p. in the pleurisy model 30 min after the challenge with carrageenan, or at 20µg/kg and 40µg/kg every 24 h, starting from day 25 to day 35 in the arthritis model) exerts potent anti-inflammatory effects: inhibition of neutrophil infiltration into the lung and joint tissue, reduction of adhesion molecules expression in the vascular endothelium of inflamed lungs, inhibition of cytokines (TNF-α, IL-1β), and chemokines (MIP-lα and MIP-2) expression, decrease of NO exudate levels and lipid peroxidation in carrageenan-treated mice and also delayed development of clinical indicators, and histological injury) in vivo. Furthermore, oleuropein aglycone reduced the increase in the staining (immunohistochemistry) for nitrotyrosine and poly (ADP-ribose) polymerase in both inflamed tissues, and the expression of inducible nitric-oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in the joints from collagen-treated mice. Thus, oleuropein aglycone reduces the development of acute and chronic inflammation. Therefore, we propose that olive oil and its phenolic constituents such as oleuropein may be useful in the treatment of various inflammatory diseases.
 
1) Menendez et al. (2007)- BMC cancer  vol 7,80.
2) Kremastinos (2008)- Hellenic J Cardiol. vol 49, 295-296.
3)Visioli et al. (1998)-Biochem Biophys Res Commun. vol 247, 60-64.
4) Edgecombe et al. (2000)-J Nutr.vol 130, 2996-3002.