Polyphenols Extracted from Olive Mill Wastewater Exert a Strong Antioxidant Effect in Human Neutrophils

Samia Bedouhene

doi:10.4172/2252-5211.1000161

Abstract

Olive mill wastewater (OMW) is produced seasonally by the olive oil-producing countries. A large amount of liquid waste results from olive oil extraction, with a very high organic load which renders it difficult to treat. Wastewater represents also a significant source of polyphenols which can be revalorized and used for medical or agro-alimentary purposes. The extraction of polyphenols will improve the wastewater biodegradation and reduce its phytotoxicity. The objective of this study was to extract polyphenols from OMW and to investigate their effect on reactive oxygen species (ROS) production by human neutrophil. Polyphenols were extracted from OMW by an established technique. Neutrophils, isolated from blood of healthy volunteers, were incubated with increased concentrations of polyphenol extract and ROS production was measured by luminol-amplified chemiluminescence and cytochrome c reduction techniques. Results show that the polyphenol extract from OMW inhibited phorbolmyristate acetate (PMA)-stimulated neutrophil ROS production as measured by the chemiluminescence assay. The polyphenols extract from OMW also inhibited neutrophil superoxide production as measured by the cytochrome c reduction assay; as well as H2O2 production as measured by flow cytometry. Also, the polyphenol extract reacted with pure H2O2 but did not affect superoxide anions production by the xanthine/xanthine oxidase enzymatic system. Our results show that polyphenols extracted from OMW exert a strong antioxidant effect and they could have an anti-inflammatory effect by inhibiting neutrophil ROS production and by scavenging hydrogen peroxide, thus limiting their toxic effects. OMW could be used to extract polyphenols for medicinal applications.

Highlights

The Mediterranean region is the first producer of olive oil in the world
Total polyphenol compounds in olive mill wastewater (OMW) extract was determined by the Folin–Ciocalteu assay according to the method described by Singleton [26]
Using the cytochrome c reduction assay, a specific method to measure extracellular superoxide anions (O2-) production, we found that the polyphenol extract significantly inhibited neutrophil’s O2- production

Summary

Introduction

The Mediterranean region is the first producer of olive oil in the world. Despite the known beneficial properties of olive oil on health, its production generates large amounts of by-products such as olive mill wastewater (OMW) [1], which constitutes an important environmental pollution product. The Mediterranean region accounts for 95% of the global OMW product in the world [2]. Phenolic compounds such as oleuropein, tyrosol, hydroxytyrosol and caffeic acid are abundant in OMW [3,4]. Several in vitro and in vivo studies confirmed that phenolic compounds from olive reduce the effect of oxidative stress associated with pathological disorders including atherosclerosis [7,8], cancer [9,10], inflammatory diseases [11,12,13], neurodegenerative diseases [14], and they have some anti-microbial and anti-viral properties [15,16,17,18]

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