Antioxidant Properties of Olive Mill Wastewater Polyphenolic Extracts on Human Endothelial and Vascular Smooth Muscle Cells.

Anna Maria Posadino,Amalia Piscopo,Antonio Piga,Wael M Abdel-Rahman,Annalisa Cossu,Roberta Giordo,Gianfranco Pintus

doi:10.3390/foods10040800

Abstract

This work aims to analyze the chemical and biological evaluation of two extracts obtained by olive mill wastewater (OMW), an olive oil processing byproduct. The exploitation of OMW is becoming an important aspect of development of the sustainable olive oil industry. Here we chemically and biologically evaluated one liquid (L) and one solid (S) extract obtained by liquid–liquid extraction followed by acidic hydrolysis (LLAC). Chemical characterization of the two extracts indicated that S has higher phenol content than L. Hydroxytyrosol and tyrosol were the more abundant phenols in both OMW extracts, with hydroxytyrosol significantly higher in S as compared to L. Both extracts failed to induce cell death when challenged with endothelial cells and vascular smooth muscle cells in cell viability experiments. On the contrary, the higher extract dosages employed significantly affected cell metabolic activity, as indicated by the MTT tests. Their ability to counteract H2O2-induced oxidative stress and cell death was assessed to investigate potential antioxidant activities of the extracts. Fluorescence measurements obtained with the reactive oxygen species (ROS) probe H2DCF-DA indicated strong antioxidant activity of the two OMW extracts in both cell models, as indicated by the inhibition of H2O2-induced ROS generation and the counteraction of the oxidative-induced cell death. Our results indicate LLAC-obtained OMW extracts as a safe and useful source of valuable compounds harboring antioxidant activity.

Highlights

The olive oil industry is a large productive sector globally, and three-quarters of world production takes place in Europe
Olive fruit is rich in phenolic compounds, only 2% of the entire phenolic content transfers into the oil phase, while the rest goes into the olive mill wastewater (OMW), the pomace, the olive oil filtration residue, and olive leaves [5]
In this work, two extracts derived from OMW were assessed for their phenol contents and their potential biological activity on two human vascular cells

Summary

Introduction

The olive oil industry is a large productive sector globally, and three-quarters of world production takes place in Europe. Given the potential environmental impact, active molecule extraction from olive oil byproducts should embrace methodologies that employ green technologies, considering their possible exploitation as food antioxidants or nutraceuticals [7]. The quality of OMW phenolic compounds differs according to several factors, including the olive oil production technological process employed, and for this reason, it is essential to evaluate different OMW technological processes to provide promising bioactive compounds. In this regard, OMW-derived products have been tested for certain biological effects and have showed an interesting bioactivity spectrum [8]. EVOO-containing phenolic compounds have shown In Vivo and In Vitro antioxidant activity, likely due to molecules such as hydroxytyrosol, tyrosol, and secoiridoid derivatives [9,10]

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