Chapter 49 - The effects of extra-virgin olive oil minority compounds hydroxytyrosol and oleuropein on glioma

Abstract

Tumor development in the central nervous system has been associated not only with oxidative stress but also with a reduced response of antioxidant defense systems due to as the nervous tissue is especially vulnerable to free radical–induced damage. However, free radicals may also kill cancer cells by affecting key steps in cell cycle and promoting apoptosis. Thus administration of exogenous antioxidants has received particular attention due to their potential to modulate oxidative stress and to act as antitumor compounds, both alone or in combination with various anticancer drugs. In this sense, phenolic compounds derived from olives and virgin olive oils have showed anticancer activities both in vitro and in vivo due to their antioxidant properties. Here we summarize the in vivo antitumor properties and the effects of the phenolic compounds oleuropein (OLEU) and hydroxytyrosol (HTX) on oxidative stress biomarkers, on nonenzymatic, and on enzymatic antioxidant defense systems, in the animal model of C6 glioma implanted at the subcutaneous region and in the transplacental N-ethyl-N-nitrosourea-induced glioma. The treatment with HTX, but not with OLEU for both short and long periods and independently of the route of administration, led to the significant inhibition of tumor growth in both animal models of glioma via redox-related mechanisms involving endogenous enzymatic and nonenzymatic antioxidant defense systems.