carotene

(carotin) Any of a class of orange, red, or yellow pigments all of which are hydrocarbons containing eight *isoprene subunits and hence have the formula C₄₀H₅₆. The most commonly occurring carotenes are α- and β-carotene (see also vitamin A ). Another carotene, lycopene, gives tomato fruits their red colour. Carotenes are accessory pigments in most photosynthetic cells, contributing to the process of gathering light energy. However they are relatively inefficient as light absorbers and are thought to have a second function of protecting the other photosynthetic pigments from photooxidation by ultraviolet light. *Xanthophylls are oxygenated carotenes. See carotenoids.