carotene


carotene
A class of carotenoids, yellow-red pigments (lipochromes) widely distributed in plants and animals, notably in carrots, and closely related in structure to the xanthophylls and lycopenes and to the open-chain squalene; of particular interest in that they include precursors of the vitamins A (provitamin A carotenoids). Chemically, they consist of 8 isoprene units in a symmetrical chain with the two isoprenes at each end cyclized, forming either α-c. or β-c. (γ-c. has only one end cyclized). The cyclic ends of β-c. are identical β-ionine-like structures; thus, on oxidative fission, β-c. yields 2 molecules of vitamin A. The cyclic ends of α-c. differ: one is an α-ionone, the other a β-ionone; on fission, α-c., like γ-c., yields 1 molecule of vitamin A (a β-ionone derivative).

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car·o·tene 'kar-ə-.tēn n any of several orange or red crystalline hydrocarbon pigments (as C40H56) that occur in the chromoplasts of plants and in the fatty tissues of plant-eating animals and are convertible to vitamin A see BETA-CAROTENE

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n.
a yellow or orange plant pigment - one of the carotenoids - that occurs in four forms: alpha (a), beta (b), gamma (g), and delta (d). The most important form is b-carotene, which is an antioxidant and can be converted in the body to retinol (vitamin A). Foods containing b-carotene (for example, milk and some vegetables) are therefore a source of the vitamin.

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car·o·tene (karґə-tēn) [L. carota carrot] one of four isomeric pigments (α-, β-, γ-, and δ-carotene), having colors from violet to red-yellow to yellow, found in many dark green, leafy, and yellow vegetables, as well as yellow fruits. They are fat-soluble, unsaturated aliphatic hydrocarbons that are converted to vitamin A in animals by an enzyme in the intestinal wall and the liver. β-Carotene is the major precursor (provitamin) of vitamin A in humans, although it is less well absorbed than is retinol. See also retinol equivalent, under equivalent.

Medical dictionary. 2011.

Look at other dictionaries:

  • Carotene — Carotène La coloration des plumes du flamant rose est dû à l accumulation de carotène contenu dans son alimentation. Le carotène est un terpène découvert en 1881 par Wachenroder. C est un pigment de couleur orange, dimère de la vitamine A. Il est …   Wikipédia en Français

  • carotène — [ karɔtɛn ] n. m. • 1924; carottine n. f. 1846; de carotte ♦ Biochim. Pigment caroténoïde, de formule C40H56, précurseur de la vitamine A, trouvé dans des végétaux ou dans certains tissus animaux. Crème bronzante au carotène. ● carotène nom… …   Encyclopédie Universelle

  • carotene — hydrocarbon found in carrots and other plants, 1861, from Ger. carotin, coined 1831 by H.W.F. Wackenroder from L. carota carrot (see CARROT (Cf. carrot)) + German form of chemical suffix INE (Cf. ine) (2), denoting a hydrocarbon …   Etymology dictionary

  • carotene — ► NOUN ▪ an orange or red plant pigment found notably in carrots, important in the formation of vitamin A. DERIVATIVES carotenoid noun. ORIGIN from Latin carota carrot …   English terms dictionary

  • carotene — [kar′ətinkar′ə tēn΄] n. [< L carota, CARROT + ENE] any of several red or orange colored isomeric hydrocarbons, C40H56, found in butter and in carrots and certain other vegetables, and changed into vitamin A in the liver: sometimes called… …   English World dictionary

  • Carotene — The term carotene is used for several related substances having the formula C40H56. Carotene is an orange photosynthetic pigment important for photosynthesis.It is responsible for the orange colour of the carrot and many other fruits and… …   Wikipedia

  • Carotène — La coloration des plumes du flamant rose est dû à l accumulation de carotène contenu dans son alimentation. Le carotène est un terpène découvert en 1881 par Wachenroder. C est un pigment de couleur orange, dimère de la vitamine A. Il est… …   Wikipédia en Français

  • carotene — /kar euh teen /, n. any of three yellow or orange fat soluble pigments having the formula C40H56, found in many plants, esp. carrots, and transformed to vitamin A in the liver; provitamin A. Also, carotin. [1860 65; < LL carot(a) CARROT + ENE] *… …   Universalium

  • carotene — n. a yellow or orange plant pigment – one of the carotenoids – that occurs in four forms: alpha (α), beta (β), gamma (γ), and delta (δ). The most important form is β carotene, which is an antioxidant and can be converted in the body to retinol… …   The new mediacal dictionary

  • carotene — noun Etymology: International Scientific Vocabulary, from Late Latin carota carrot Date: 1861 any of several orange or red crystalline hydrocarbon pigments (as C40H56) that occur in the chromoplasts of plants and in the fatty tissues of plant… …   New Collegiate Dictionary