ABSTRACT
The commercially most important carotenoids are astaxanthin and b-carotene (structures 22.1 and 22.2, Figure 22.1) (3). Most of the carotenoids on the market is produced by chemical synthesis. A chemical process for the synthesis of lycopene (structure 22.3, Figure 22.1) has recently been established. The industrial use of carotenoids involves their application in nutrient supplementation, for pharmaceutical purposes, as food colorants, and in animal feeds. b-Carotene or other carotenoids with an unsubstituted b-ionone group are essential in human nutrition as a provitamin A. Taken up by the body, they are then metabolized to vitamin A, an integral component of the visual process. Lutein and zeaxanthin (structures 4 and 5, Figure 22.1) are constituents of the yellow eye spot, the macula lutea. There, both carotenoids act as protectants, preventing the retina from photodamage (4). Other carotenoids have a less defined role in human health. Evidence is accumulating that various carotenoids stimulate the immune system and play an important role in the prevention of degenerative diseases and cancer (5).
