Carotene

Carotene is an orange photosynthetic pigment important for photosynthesis. It is responsible for the orange colour of the carrot and many other fruits and vegetables. It contributes to photosynthesis by transmitting the light energy it absorbs to chlorophyll.

Chemically, carotene is a terpene. It is the dimer of retinol (vitamin A) and comes in two primary forms: α and β-carotene. γ, δ and ε-carotene also exist. Carotene can be stored in the liver and converted to vitamin A as needed, thus making it a provitamin.

Carotenaemia

  Carotenaemia or hypercarotenaemia is excess carotene, and unlike excess Vitamin A is non-toxic. Although hypercarotenaemia is not particularly dangerous, it can lead to a yellowing of the skin (carotenodermia). It is most commonly associated with consumption of an abundance of carrots, but it also can be a medical sign of more dangerous conditions. A randomised trial into the use of β-carotene and Vitamin A for prevention of lung cancer had to be stopped early due to the apparent increase in the incidence of lung cancer in those with lung irritation from smoking or asbestos exposure..

The two primary isomers of carotene, α-carotene and β-carotene, differ in the position of double bonds in the cyclic group at the end.

β-carotene is the more common form and can be found in yellow, orange, and green leafy fruits and vegetables. These can be carrots, spinach, lettuce, tomatoes, sweet potatoes, broccoli, cantaloupe, orange, and winter squash. As a rule of thumb, the greater the intensity of the colour of the fruit or vegetable, the more β-carotene it contains.

β-carotene is an anti-oxidant and as such can be useful for curbing the excess of damaging free radicals in the body. However, the usefulness of β-carotene as a dietary supplement (ie. taken as a pill) is still subject to debate. β-carotene is fat-soluble.

Carotenoids

Carotenes are un-oxidized carotenoids. Carotenoids in which some of the double bonds have been oxidized are known as xanthophylls.

Production

Most of the world's synthetic supply comes from a manufacturing complex located in Freeport, Texas and owned by DSM. This site uses Blakeslea trispora in a fermentation process for the production of beta-carotene. In Australia, organic beta carotene is farmed by Aquacarotene Limited from dried marine algae Dunaliella salina grown in harvesting ponds situated in Karratha, Western Australia.

Nomenclature

The two ends of the β-carotene molecule are structurally identical, and are called β-rings. Specifically, the group of nine carbon atoms at each end form a β-ring.

The α-carotene molecule has a β-ring at one end; the other end is called an ε-ring. There are no "α-rings".

These and similar names for the ends of the carotenoid molecules form the basis of a systematic naming scheme, according to which:

  • α-carotene is β,ε-carotene;
  • β-carotene is β,β-carotene;
  • γ-carotene (with one β ring and one uncyclized end that is labelled psi) is β,ψ-carotene;
  • δ-carotene (with one ε ring and one uncyclized end) is ε,ψ-carotene;
  • ε-carotene is ε,ε-carotene,

    • © Medic8 ® All Rights Reserved.