carotene(redirected from Alpha-ring)
Also found in: Dictionary, Thesaurus, Encyclopedia.
a yellow or red pigment found in many dark green, leafy, and yellow vegetables such as collards, turnips, carrots, sweet potatoes, and squash, as well as in yellow fruit, milk, egg yolk, and body fat; it is a chromolipoid hydrocarbon existing in four forms (α-, β-, γ-, and δ-carotene), which can be converted into vitamin A in the body.
A member of 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 symmetric chain with the 2 isoprenes at each end cyclized, forming either α-carotene or β-carotene (γ-carotene has only one end cyclized). The cyclic ends of β-carotene are identical β-ioninelike structures; thus, on oxidative fission, β-carotene yields 2 molecules of vitamin A. The cyclic ends of α-carotene differ in that one is an α-ionone and the other a β-ionone; on fission, α-carotene, like γ-carotene, yields 1 molecule of vitamin A (a β-ionone derivative).
carotene/car·o·tene/ (kar´o-tēn) one of four isomeric pigments (α-, β-, γ-, and δ-carotene), having colors from violet to red-yellow to yellow and occurring in many dark green, leafy, and yellow vegetables and yellow fruits. They are fat-soluble, unsaturated hydrocarbons that can be converted into vitamin A in the body; in humans the β- isomer (β- or beta carotene) is the major precursor of this vitamin.
An orange-yellow to red crystalline pigment, C40H56, found in animal tissue and certain plants, such as carrots and squash. It exists in several isomeric forms and is converted to vitamin A in the liver.
Etymology: L, carota, carrot
a red or orange organic compound found in carrots, sweet potatoes, egg yolk, and leafy vegetables, such as beet greens, spinach, and broccoli. Beta-carotene, the most common form of carotene, is a provitamin and in the body is converted to vitamin A. See also vitamin A.
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; they include precursors of vitamin A (provitamin A carotenoids).
caroteneOne of a group of orange pigments found in carrots and some other vegetables. Beta-carotene (provitamin A) is converted to vitamin A in the liver. This vitamin is needed for normal growth and development of bone and skin, for the development of the fetus and for the proper functioning of the RETINA.
carotenean orange plant pigment of the CAROTENOID group which is usually present in the CHLOROPLASTS, and sometimes occurs in pigment-containing structures called CHROMOPLASTS which are found in yellow/orange leaves, vegetables and fruits. Carotene is also found in green leaves but the colour is masked; the orange colour can be seen in autumn leaves as the chlorophylls break down first. Carotene is necessary for the production of vitamin A in man and has an ABSORPTION SPECTRUM of about 450 nm. Carotene acts as an accessory pigment, passing energy to chlorophyll a for use in LIGHT REACTIONS and protecting chlorophyll from excessive light, and from oxidation by the oxygen produced in PHOTOSYNTHESIS.
n an orange- or red-colored pigment found in plants, which is convertible into vitamin A by the body.
Yellow-red pigments widely distributed in plants and animals, notably in carrots; include precursors of vitamin A.
a yellow or red pigment from carrots, sweet potatoes, milk and body fat, egg yolk, etc.; it is a chromolipoid hydrocarbon existing in several forms. α-, β- and γ-carotene are provitamins which can be converted into vitamin A in the body by all animals except cats. β-carotene is the most important because of a quantitatively greater activity.