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Carotene
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'''Carotene''' is an
orange (color) 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.
Carotenemia
{{main|Carotenodermia}}
Carotenemia or hypercarotenemia is excess carotene, and unlike excess Vitamin A is non-toxic. Although hypercarotenemia 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 an
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.{{ref|fn1}}.
The two forms
α-carotene
Image:alpha-carotene.png center|α-carotene
β-carotene
Image:beta_carotene.gif
β-carotene can be found in
yellow,
Orange (colour) orange, and
green leafy
fruits and
vegetables. These can be carrots,
spinach,
lettuce,
tomatoes,
sweet potatoes,
broccoli,
cantaloupe,
Orange (fruit) orange, and
squash_(fruit) winter squash. As a
rule of thumb, the greater the intensity of the color of the fruit or vegetable, the more β-carotene it contains.
β-carotene is an
anti-oxidant and 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 (i.e. taken as a pill) is still subject to debate{{ref.html">fat-
soluble.html">solubility|soluble, so a small amount of fat is needed to absorb it into the body.
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 the DSM corporation.
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 (letter) 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''',
References
# {{note|fn1}} [http://content.nejm.org/cgi/content/abstract/334/18/1150 Effects of a Combination of Beta Carotene and Vitamin A on Lung Cancer and Cardiovascular Disease]
# {{note|fn2}} [http://www.cancer.gov/cancertopics/factsheet/Prevention/betacarotene Questions and Answers About Beta Carotene Chemoprevention Trials]
External links
-
Beta-carotene website by Martha Evens, School of Chemistry, University of Bristol
-
Berkeley Wellness Guide to Dietary Supplements
-
Beta-caroten on University of Maryland
-
Carotenoids on Herbal Phytochemistry
Category:Vitamins
Category:Food colorings
Category:Terpenes and terpenoids
Category:Carotenoids
ar:كاروتين
de:Carotine
es:Caroteno
fr:Carotène
lt:Karotinas
mk:Каротин
nl:Caroteen
ja:Β-カロテン
pl:Karoten
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