• DOI:10.3390/ijms151018508
• Published online 2014 Oct 14

Barbara Barbaro,^1,† Gabriele Toietta,^2,† Roberta Maggio,¹ Mario Arciello,^1,3 Mirko Tarocchi,⁴ Andrea Galli,⁴ and Clara Balsano^5,* Segura-Carretero Antonio, External Editor

Abstract

The use of the products derived from the olive tree on human health dates back centuries. In several civilizations, the olive tree had and still has a very strong cultural and religious symbolism. Notably, the official seal and emblem of the World Health Organization features the rod of Asclepius over a world map surrounded by olive tree branches, chosen as a symbol of peace and health. Recently, accumulating experimental, clinical and epidemiological data have provided support to the traditional beliefs of the beneficial effect provided by olive derivates. In particular, the polyphenols present in olive leaves, olives, virgin (unrefined) olive oil and olive mill waste are potent antioxidant and radical scavengers with anti-tumor and anti-inflammatory properties. Here, we review the positive impact on human health of oleuropein, the most prevalent polyphenol present in olives. In addition, we provide data collected in our laboratory on the role of oleuropein in counteracting lipid accumulation in a mouse model of non-alcoholic fatty liver disease.

Keywords: olive, oleuropein, Mediterranean diet, polyphenols, antioxidant, anti-inflammatory, anticancer, non-alcoholic fatty liver disease

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1. Introduction

Archeological evidence suggests that Neolithic inhabitants of the Mediterranean basin have collected and consumed olives since the copper age (sixth millennium BC) and that during the third millennium BC, the cultivation of olive trees and oil production were well established in the region. Over the centuries, olive oil has been used as a cosmetic and pharmacological agent [1]. Recently the beneficial effects of virgin olive oil have been ascribed to the content of polyphenols, which exert antioxidant, anti-inflammatory, anti-cancer, antimicrobial, antiviral, anti-atherogenic, hypoglycemic, hepatic-, cardiac- and neuro-protective effects [2,3,4]. Virgin olive oil is consumed unrefined, and humans absorb a large part of the ingested olive oil phenols [5]. Oleuropein, the molecule responsible for unprocessed olives characteristic bitter taste [6], is the most prevalent phenolic component in olive leaves, seed, pulp and peel of unripe olives (up to 14% of the dry weight) (Table 1) [1]; during fruit maturation, oleuropein undergoes hydrolysis, yielding different products, including hydroxytyrosol (2-(3,4-dihydroxyphenyl)ethanol). Olive variety and the process used for making olives edible highly affect oleuropein content in table olives [7]. Similarly, several factors, including the kind of olive fruit, the ripening stage, the oil production and extraction technologies, determine the final content of oleuropein in virgin olive oil [8]. In addition, the difference in the methods used for oleuropein analysis may account for the variability of the reported oleuropein content in several sources (Table 1). In 1959, oleuropein was isolated and its chemical structure defined [9], opening the way to a more precise understanding of the molecular basis of its action.

Reference:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4227229/