Separation of sight-protecting zeaxanthin from Nannochloropsis oculata by using supercritical fluids extraction coupled with elution chromatography

Microalgae is a potent source of carotenoids and is regarded as functional foods consumed by people worldwide. In this study, supercritical fluid extraction coupled with elution chromatography was employed to recover six carotenoids including zeaxanthin from Nannochloropsis oculata and extraction efficiency of zeaxanthin was determined. The amount of the zeaxanthin (400 mg/g) in the elution fraction increased more than twenty folds from that of the SFE extract (13.17 mg/g). The extracts were subsequently subjected to tests of antioxidant capacities in 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) assay, 2-2′-azino-bis (3-ethylbenzo- thiazoline-6-sulfonic acid (ABTS)) assay and adult retinal pigment epithelium-19 (ARPE-19) cells. Experimental results demonstrate that other components than zeaxanthin may play a crucial role in the anti-oxidative ability of the extracts from N. oculata. This work provides a useful method to recover bioactive anti-oxidative zeaxanthin from microalgae of N. oculata by using modified supercritical fluids extraction.

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► We examine co-solvent modified supercritical fluid extractions of zeaxanthin from N. oculata and their bioassay.
► This study demonstrates that the purest zeaxanthin samples may play a crucial role in the anti-oxidative ability.
► We provide useful information in exploring N. ouclata as health supplements materials.