Eco-Friendly Lipid Nanoformulations: Toward Greener Alternatives for Organic Extraction Solvents

Dealing with lipid extraction procedures, the use of organic solvents, i.e. primarily chloroform and methanol, is still very popular, despite of the proved toxicity of these solvents. In the last decades, several contributions reported the possibility of employing more eco-friendly solvents as extraction agents, but the efficacy of chloroform and methanol has not been attained yet, making their substitution one of the big challenges of green chemistry. In this work, we compared four alternative solvent mixtures for the extraction of the lipid component from olive pomace, the exhausted waste of olive oil processing used as resource to build eco-sustainable nanoformulations for agrotechnological applications. Specifically, the mixtures tested were ethyl acetate/ethanol (EtAc/EtOH), ethyl acetate/methanol (EtAc/MeOH), acetonitrile/ethanol (ACN/EtOH), and acetonitrile/methanol (ACN/MeOH) to compare with the standard one. The lipid extracts thus obtained were analyzed by Gas Chromatography-Mass Spectrometry and then employed for the manufacturing of nanoformulations. The obtained lipid nanovectors were then fully characterized by Dynamic Light Scattering and Small Angle X-ray Scattering. The comparison of the collected data shows that among the mixtures tested, EtAc/EtOH and ACN/MeOH resulted to be the most suitable alternatives to the standard method, thus representing a possible different choice that better matches with green chemistry requirements.