Olive Mill Wastewater Polyphenol-Enriched Fractions by Integrated Membrane Process: A Promising Source of Antioxidant, Hypolipidemic and Hypoglycaemic Compounds

Abstract

<jats:p>The valorisation of food wastes is a challenging opportunity for the green, sustainable, and competitive development of industry. The recovery of phenols contributes to the sustainability of olive waste sector, reducing its environmental impact and promoting the development of innovative formulations of interest for pharmaceutical, nutraceutical, and cosmeceutical applications. In this work, olive mill wastewater was treated through a combination of microfiltration (MF), nanofiltration (NF), and reverse osmosis (RO) in a sequential design to produce polyphenol-enriched fractions that have been investigated for their chemical profile using ultra-high-performance liquid chromatography (UHPLC), and their potential antioxidant, hypolipidemic, and hypoglycaemic activities. RO retentate exhibited the highest content of hydroxytyrosol, tyrosol, oleuropein, verbascoside, vanillic acid, and luteolin. In particular, a content of hydroxytyrosol of 1522.2 mg/L, about five times higher than the MF feed, was found. RO retentate was the most active extract in all in vitro tests. Interestingly, this fraction showed a 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS) radicals scavenging activity with an IC50 value of 6.9 μg/mL and a potential inhibition of lipid peroxidation evaluated by the β-carotene bleaching test with IC50 values of 25.1 μg/mL after 30 min of incubation. Moreover, RO retentate inhibited α-amylase and α-glucosidase with IC50 values of 65.3 and 66.2 μg/mL, respectively.</jats:p>

Luteolin abates reproductive toxicity mediated by the oxido-inflammatory response in Doxorubicin-treated rats

“…In vitro and in vivo investigations have shown few ethnopharmaceutical activities, including antioxidative, anti-inflammatory, and anti-neoplastic effects. 23,25,[51][52][53] Therefore, the present study revealed, for the first time, the beneficial health effects of LUT against DOX-induced oxido-inflammatory responses in the reproductive organs of male Wistar albino rats. Rats exposed to DOX exhibited marked (p < 0.05) diminutions in the mean body weight, thus indicating general toxicity and alterations of metabolic functions.…”

Concentration of Bioactive Phenolic Compounds in Olive Mill Wastewater by Direct Contact Membrane Distillation

“…In the previous work, Tundis et al [ 19 ] investigated a combination of pressure-driven membrane operations in a sequential design to produce a polyphenol-enriched fraction from the same OMW sample used in this study. OMW was microfiltered and submitted through NF and RO steps to concentrate phenolic compounds up to volume reduction factors of 4 and 2, respectively.…”

“…This process allowed reducing the suspended solids content from 11.5% to 2.0%. Pre-treated OMW was submitted to a microfiltration process by using a pilot unit equipped with a multichannel ceramic (TiO 2 ) membrane (Ceram Inside, from Tami Industries, nominal pore size of 0.1 μm, and membrane surface area of 0.35 m 2 ), according to the procedure reported by Tundis et al [ 19 ].…”

“…Following our previous study [ 19 ], in which OMW was treated in a sequential design through a combination of microfiltration (MF), nanofiltration (NF), and reverse osmosis (RO) to produce polyphenol-enriched fractions, the present work was undertaken in order to produce a concentrated fraction of phenolic compounds through DCMD of microfiltered OMW. The concentrated fraction was investigated for its chemical profile and bioactivity in order to assess its potential use as antioxidant and anti-obesity formulation.…”

Treatment of Olive Mill Wastewater through Integrated Pressure-Driven Membrane Processes

“…Another integration scheme relied on the direct use of RO instead or in addition to the NF. Tundis et al [ 33 ] showed the recovery and classification of polyphenols by using a MF step on a 0.1 µm TiO 2 membrane followed by a NF step and a RO step based on a membrane typically applied to brackish water. Although a flux decay was observed for all the membrane filtrations, as the aim of the work was about the characterization of the polyphenols in the concentrate, the quality of the final NF and RO permeates was not assessed by the authors.…”