ABSTRACT
The carotenoids are a group of over 600 natural compounds related by their chemical structure and their biosynthesis from a common biosynthetic precursor. They include carotenes, which have 40 carbon atoms and various numbers of hydrogen atoms, and xanthophylls, derived from the carotenes by the introduction of oxygen atoms (Britton et al. 1998; Goodwin 1976; 1980; 1988; Isler 1971; Sandmann and Misawa 2002). The carotenoids are part of a broader group, the terpenoids, that includes such diverse compounds as menthol, steroids, and rubber.
