carotene

Carotene is a class of carotenoids that are pure hydrocarbons and pigments synthesized by plants and some microorganisms. The best-known member is beta-carotene; others include alpha-carotene and gamma-carotene. Carotenes are tetraterpenoids with 40 carbon atoms and a long chain of conjugated double bonds, which gives them characteristic orange to yellow colors.

Dietary sources include carrots, sweet potatoes, dark leafy greens, apricots, and mangoes. Carotenes are fat-soluble; their absorption is enhanced by dietary fat and bile salt micelles. In the body, beta-carotene and some related carotenes are provitamin A compounds: enzymes such as BCMO1 convert beta-carotene to retinal, which can be reduced to retinol (vitamin A) or oxidized to retinoic acid.

Functions: Carotenes act as antioxidants, quenching singlet oxygen and scavenging free radicals. Through their vitamin A derivatives, they support vision, growth, immune function, and skin health. Carotenoids contribute to the color of many fruits and vegetables and may influence cellular signaling.

Safety and intake: Dietary intake of carotenes from fruits and vegetables is considered safe and protective against some diseases. Excessive intake can cause carotenemia, a harmless orange discoloration of the skin. High-dose beta-carotene supplements have been associated with increased lung cancer risk in smokers, and are not recommended for cancer prevention in this group.

History and chemistry: The name derives from carrot (Daucus carota). Carotene was first isolated in 1831 by Pelletier and Caventou. Chemically, beta-carotene has formula C40H56 and a long polyene chain, contributing to its instability and light sensitivity.