Abstract
Nowadays, increasing interest in olive pomace (OP) valorization aims to improve olive’s industry sustainability. Interestingly, several studies propose a high-value application for OP extracts containing its main phenolic compounds, hydroxytyrosol and oleuropein, as therapy for ocular surface diseases. In this work, the stability and accessibility of OP total phenolic and flavonoid content, main representative compounds, and antioxidant activity were assessed under different pretreatment conditions. Among them, lyophilization and supercritical CO2 extraction were found to increase significantly most responses measured in the produced extracts. Two selected extracts (CONV and OPT3) were obtained by different techniques (conventional and pressurized liquid extraction); Their aqueous solutions were characterized by HPLC-DAD-MS/MS. Additionally, their safety and stability were evaluated according to EMA requirements towards their approval as ophthalmic products: their genotoxic effect on ocular surface cells and their 6-months storage stability at 4 different temperature/moisture conditions (CPMP/ICH/2736/99), together with pure hydroxytyrosol and oleuropein solutions. The concentration of hydroxytyrosol and oleuropein in pure or extract solutions was tracked, and possible degradation products were putatively identified by HPLC-DAD-MS/MS. Hydroxytyrosol and oleuropein had different stability as standard or extract solutions, with oleuropein also showing different degradation profile. All compounds/extracts were safe for ophthalmic use at the concentrations tested.
Highlights
The annual cultivation of olive groves reaches a surface of 10.6 million hectares at a global level
In another study [17], we demonstrated the strong antioxidant and anti-inflammatory activity of two olive pomace (OP)
It was evaluated in terms of richness in total phenolic content (TPC), total flavonoid content (TFC), OL, oleacein (OLC), HT, and tyrosol (TY), as well as extraction yield (EY) and antioxidant activity (AA)
Summary
The annual cultivation of olive groves reaches a surface of 10.6 million hectares at a global level (data 2019). According to FAOSTAT, 72% of the olive oil is produced by the Mediterranean countries of Europe [1]. This fact can be explained by the well-known importance of the Mediterranean diet for human health, with olive oil being its principal fat ingredient [2]. The numerous health benefits of olive oil are mostly related to its antioxidant fatty acids and phenolic compounds [3]. The OP is the main by-product generated and is a mixture of olive fruits after the recovery of olive oil, together with vegetation waters and stones [5]. Its high organic load and phenolic content, along with its phytotoxic properties, make the OP a potential source of soil, water, or air pollution [2,7,8]
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