Feiyang Zheng, Jianlong Zhu, Zisong Xu, Dian Tai, Yanbin Lu, Jue Li, Zhiyuan Dai
The recovery of labile marine bioactives such as fucoxanthin from Sargassum sp. is constrained by oxidative and thermal degradation during processing. Herein, a hydrophobic antioxidant deep eutectic solvent (DES) composed of thymol (Thy) and methyl salicylate (MeSA) was developed for the simultaneous extraction and stabilization of fucoxanthin. Under optimized ultrasound-assisted conditions, the DES afforded 7.59 mg/g fucoxanthin. Untargeted metabolomics showed that the DES extract was enriched in endogenous phenolic antioxidants and contained fewer oxidation-related byproducts, while FT-IR, 1H NMR, and DFT analyses revealed a hydrogen-bonded supramolecular network that stabilized fucoxanthin through hydrogen bonding and dispersion interactions. Accordingly, the DES reduced the photodegradation rate constant from 0.74 to 0.065 h-1 and extended the half-life from 0.94 to 10.64 h. The DES also exhibited cold-chain stability over 40 days and reusability over 10 cycles, supporting the Thy-MeSA DES as a promising green medium for extracting and stabilizing oxidation-sensitive marine carotenoids.