103 | Valorization of olive mill wastewaters for the recovery of polyphenols with reducing, radical scavenging and anti-inflammatory activities

Francesco Longo¹, Luisa Tesoriere¹, Claudio Luparello¹, Ignazio Restivo¹, Federica Bellistrì¹, Serena Indelicato¹, David Bongiorno¹, Rosi De Luca¹, Giulia Abruscato¹, Antonio Fabbrizio², Salvatore Terrani³, Mirella Vazzana¹, Vincenzo Arizza¹, Manuela Mauro¹ | ¹Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Italy; ²Department of Theoretical and Applied Sciences DiSTA, University e Campus, Novedrate [CIO], Italy; ³The Wave Innovation Group, Verona, Italy.

Abstract

Olive oil production represents a key sector of the Italian agri-food economy, while simultaneously generating residues and by-products with a high environmental impact. Among these, olive mill wastewaters (OMW), consisting of the aqueous fraction of olives and the wash and processing waters, represent the primary management challenge due to the large volumes produced and their high organic load. OMW is rich in a wide range of hydrophilic biophenols, mainly belonging to the classes of phenolic alcohols, phenolic acids, secoiridoids, and flavonoids. Since OMW is currently disposed of primarily through controlled land spreading on agricultural soils, these compounds, characterized by a high bioactive potential, are the main contributors to its pollutant impact on soil, surface water, and groundwater. As a part of the SCORELINE project, which focuses on valorizing by-products of olive oil and wine production for applications in human health, this study was conducted with the aim of recovering bioactive polyphenols from OMW for potential pharmaceutical use. By optimizing the protocol described by Azzam and Hazaimeh (2021) (1), a polyphenol-enriched OMW extract (OMW-PE) was obtained and subsequently characterized by UPLC-MS analysis, which enabled the identification of nine phenolic compounds. Among these, hydroxytyrosol was found to be the compound present at the highest concentration. Furthermore, OMW-PE showed a high total polyphenol content, as determined by the Folin-Ciocalteu test, along with an effective ferric ion reduction capacity in the FRAP test and significant free radical scavenging activity in both the DPPH and ABTS tests. The activity of OMW-PE was evaluated on RAW 264.7, a mouse macrophage cell line, and on SW 982, a human synovial cell line, which are useful in vitro tools used to study inflammation in osteoarthritis. In both cell lines, OMW-PE was cytocompatible over a wide range of concentrations and showed significant anti-inflammatory activity, as evidenced by the reduction of nitric oxide production in inflamed cells. Overall, these results highlight OMW as a valuable source of bioactive polyphenols and support the potential use of extracts derived from OMW for pharmaceutical applications, particularly for the treatment of inflammatory diseases such as osteoarthritis.
Dr. Giulia Abruscato is supported by Fondazione Umberto Veronesi.