Terpene-Based Natural Deep Eutectic Systems as Efficient Solvents To Recover Astaxanthin from Brown Crab Shell Residues

The potential of natural deep eutectic systems (NADESs) to efficiently extract astaxanthin (AXT) contained in crab shell wastes was evaluated. Different terpene-based mixtures were prepared and characterized. Aiming at maximizing the AXT recovery, we evaluated the effect of operating temperature and time on the extraction performance. As a proof of concept, this paper also highlights the potential of NADESs for AXT extraction from shrimp shells, mussels, and Haematococcus pluvialis. The biological potential of AXT-rich extracts; the AXT standard; and NADESs, their individual components, and equivalent physical mixtures was evaluated, including cytotoxicity, antiproliferative effects on human colorectal cancer cells, and antimicrobial potential against Staphylococcus aureus and Escherichia coli. Results showed that extractions with menthol:myristic acid (8:1) were able to match the AXT yield obtained by a Soxhlet extraction with acetone. Additionally, when using the same NADESs to recover AXT from the other biomasses under study, there was a 3- to 657-fold increase in yields when compared with the Soxhlet extraction. AXT-rich extracts obtained with NADESs showed antiproliferative and antimicrobial potential. This study suggests that NADESs can truly be used as alternative extraction media for the recovery of AXT from waste biomass and that these systems and respective extracts have the potential to be used as ingredients in industrial applications.