the general name for a group of fat-soluble pigments found in green, yellow, and leafy vegetables, and yellow fruits. they are aliphatic hydrocarbons consisting of a polyisoprene backbone. One of a class of tetraterpenoids (C40), formally derived from the acyclic parent, psi,psi-carotene by hydrogenation, dehydrogenation, cyclization, oxidation, or combination of these processes. This class includes carotenes, xanthophylls and certain compounds that arise from rearrangement of the skeleton of psi,psi-carotene or by loss of part of this structure. Retinoids are excluded. (ChEBI) The term carotene is used for several related unsaturated hydrocarbon substances having the formula C40Hx, which are synthesized by plants but cannot be made by animals. [Wikipedia]