Xanthophyll fucoxanthin

Fucoxanthin, lutein, neoxanthin, violaxanthin, and zeaxanthin are the most common xanthophylls on our planet. They are found in the photosynthetic machinery of algae (fucoxanthin) and higher plants (Figure 7.1). Interestingly, lutein and zeaxanthin have also been found in the retina of humans and some primates (Khachik et al., 1997 Landrum and Bone, 2001). It is likely that these carotenoids possess some universal photophysical properties essential for both photosynthesis and vision (Britton, 1995). 

Structure of various terpenoid piant pigments (a) fucoxanthin, (b) (i-carotene, and (c) xanthophyll. OAc = acetate. 

Figure 9.38 Chemical structures of select carotenoids can be divided into two groups the carotenes (e.g., /3-carotene) which are hydrocarbons and the xanthophylls (e.g., violaxanthin, fucoxanthin) which are molecules that contain at least one oxygen atom.

The main pigments of Phaeocystis antarctica were chlorophyll a, chlorophyll c + 2, fucoxanthins, diadinoxanthin and diatoxanthin. The ratio of the photoprotective xanthophyll pigments diadi-no- and diatoxanthin to chlorophyll a was 0.229 in... 

In order to define the carotenoid structures necessary for LHCII assembly and stabilization, a number of different carotenoids have been used in reconstitution assays with only one carotenoid component present. Not only the xanthophyll cycle carotenoids zeaxanthin and antheraxanthin turned out to promote reconstitution but also heterologous carotenoids as diverse structurally as astaxanthin, okenone, and fucoxanthin. In general, a hydroxyl group in position 3 of at least one of the cyclohexane ring seems to be important for complex formation (D. Phillip, S. Hobe, A. Young, and H. Paulsen, unpublished). Similarly, the major LHCII from... 

It should be emphasised that carotenoids and xanthophylls are a vast family of materials and three of the most naturally abundant are fucoxanthin, violaxanthln and neoxanthin (ref. 4) although they are not... 

Several other naturally occurring carotenoids that are not considered significant in the human diet have shown potential as cancer chemopreventive agents. These inclnde neoxanthin, fucoxanthin, phytoflnene, ( -carotene, phytoene, crocetin, capsanthin, peridinin, and astaxanthin. The xanthophyll astaxanthin is a powerful antioxidant and has great potential for reducing human disease processes related to oxidative damage." Therefore, it warrants a more detailed discussion as follows. 

In natural materials, the concentration of C. is usually in the order of 0.02-0.1% of the dry mass. The C. content of the eye ring of the pheasant Narcissus majalis is extremely high, being 16%, or about times that in carrots. An estimated ICf metric tonnes of C. are produced per year by living organisms, the most abundant being fucoxanthin, lutein, violaxan-thin and neoxanthin, followed by p-carotene, zeaxanthin, lycopene, capsanthin and bixin. More than 90 % of the C. in a plant is found in the leaves, usually as a mixture of 20 0% carotenes (containing more than 70 % p-carotene) and 60-80 % xanthophylls like lutein, violaxanthin, cryptoxanthin and zeaxanthin. 

Fig. 114. Layer cellulose, impregnated with triglyceride solvent methanol-acetone-water (74 + 20 + 6), saturated with triglyceride. Applied in non-impregnated part 1 extract of Fucus serratus (brown seaweed) 2 extract of Chara fragilis (stonewort). Substances a jS-carotene b isomer of chlorophyll a c chlorophyll a d chlorophyll b e lutein / and g (in 1) unknown xanthophylls / (in 2) lutein epoxide g (in 2) viol-axanthin h fucoxanthin i neoxanthin [3d, 37]...

The xanthophylls and carotenes of plants are examined conveniently after removal of the chlorophylls by saponification with alkali. For this saponification, add 10 ml of 30% potassium hydroxide in methanol to the centrifuged acetone or methanol extract in the separatory funnel. After 30 min with occasional swirling, add 40 ml of cold petroleum ether (20-40°C)-diethyl ether (1 1) plus 100 ml of 10% aqueous sodium chloride solution. Wash the resultant upper golden-yellow layer with water and take to dryness as above. Prepare the sample solution by dissolving the residue in 1 ml of petroleum ether (60-110°C)-diethyl ether (1 1). This saponification procedure should not be employed with plant extracts containing xanthophylls that are decomposed by alkalies, as are fucoxanthin from diatoms and brown algae and peridinin from dinoflagellates. 

Like all the photosynthetic organisms of the brown lineage, diatoms contain fucoxanthin and two other specific xanthophylls of the class diatoxanthin and diadinoxanthin (Liaaen-Jensen, 1976, 1978 Matsuno and Hirao, 1989). 

Fucoxanthin is always in the majority, and the content of diadinoxanthin is generally higher than that of diatoxanthin some minor xanthophylls have also been reported (Matsuno and Hirao, 1989). 

Two xanthophylls are present in all green algae anther-axanthin (zeaxanthin monoepoxide) and neoxanthin, which is related to fucoxanthin. 

Apart from lutein, zeaxanthin and fucoxanthin, the red algae possess only one specific xanthophyll, taraxanthin, which carries an epoxide on cycle /3 of lutein (epoxy-5,6-lutein). 

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