Introduction
Zeaxanthin (C40H56O2) is the principal pigment obtained from
yellow corn or from the marigold flower; it is involved in many
important physiological functions of the human body. Dietary
xanthophylls such as lutein and zeaxanthin play important roles
against age-related macular degeneration (AMD) and other agerelated
eye disease (AED) [1–3]. Lutein and zeaxanthin have been
found to accumulate in high concentrations within the human
retina [4]. Photo-protective mechanisms are important to prevent
harmful reactions in plants (marigold) and algae (Nannochloropsis
oculata). Harmful reactions are induced by an excess of photons
absorbed from sunlight irradiation. Carotenoids have been suggested
as key molecules in these photo-protective mechanisms. For
example, beta-carotene can act as an effective quencher of singlet
oxygen in the photo-system II reaction center [5]. Another exam
xanthophylls, especially zeaxanthin, is involved in the process
of non-photochemical energy dissipation [6–10]. Algae or marigold
containing zeaxanthin can be cultivated in the environment mentioned
above. However, traditional organic solvent extraction of
these thermal labile and light sensitive carotenoids from natural
material is not so efficient due to low recovery of the carotenoid by
total vaporization of the solvent at high boiling point. Co-solvent
modified supercritical carbon dioxide (SC-CO2) extraction of lipids
and carotenoids from microalgae; ultrasound water extraction of
vitamins B from SC-CO2 defatted rice bran; and SC-CO2 extraction
of cinnamic acid derivatives from propolis were recently investigated
[11–13]. These supercritical fluids extraction showed that
the SC-CO2 is a green solvent in recovering valuable compounds
from natural materials.