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DictionarySeecarotenoidCarotenoids
Carotenoids yellow, orange, or red pigments (cyclic or acyclic isoprenoids) synthesized by bacteria, fungi, and higher plants. Animals do not ordinarily form carotenoids, although they use them to synthesize vitamin A. The carotenoids include carotene and xanthophylls, which are widely found in plants; lyco-pene (C40H56), found in the fruits of the tomato, dog rose, and nightshade; zeaxanthin (C40H56O2), found in corn kernels; vi-olaxanthin and flavoxanthin, found in squashes and gourds; cryptoxanthin (C40H56O), found in papaya; physalin (C72H116−O4), found in the flowers and fruits of Physalis; fucoxanthin (C40H56O6), found in brown algae; crocetin (C20H24O4), found in the stigmata of saffron; and taraxanthin (C40H56O4), found in the flowers of snapdragon and coltsfoot. The relative content of the various carotenoids changes in the course of development of the plant and under the influence of environmental conditions. The concentration of carotenoids is highest in the plastids of the cells. Carotenoids promote the fertilization of plants by stimulating the germination of pollen and the growth of the pollen tubes. They play a part in the absorption of light by plants and in the perception of light by animals. They are also a major factor in the processes of photosynthesis and oxygen transport in plants. The number and position of the double bonds in the molecules of the carotenoids determine their color; over 150 carotenoids (pigments) are known. Carotenoids with a larger number of double bonds absorb in the long-wave part of the spectrum, and their color is bright orange or red. REFERENCESGoodwin, T. SramiteVnaia biokhimiia karotinoidov. Moscow, 1954. (Translated from English.)
Kretovich, V. L. Osnovy biokhimii rastenii, 5th ed. Moscow, 1971.K. E. OVCHAROV carotenoids
ca·rot·e·noids (ka-rot'e-noydz), Generic term for a class of carotenes and their oxygenated derivatives (xanthophylls) consisting of 8 isoprenoid units (thus, tetraterpenes) joined so that the orientation of these units is reversed at the center, placing the two central methyl groups in a 1,6 relationship in contrast to the 1,5 of the others. All carotenoids may be formally derived from the acyclic C40H56 structure known as lycopene, with its long central chain of conjugated double bonds by hydrogenation, dehydrogenation, oxidation, cyclization, or combinations of these. Included as carotenoids are some compounds arising from certain rearrangements or degradations of the carbon skeleton, but not retinol and related C20 compounds. The nine-carbon end groups may be acyclic with 1,2 and 5,6 double bonds or cyclohexanes with a single double bond at 5,6 or 5,4 or cyclopentanes or aryl groups; these are now designated by Greek letter prefixes preceding "carotene" (α and δ, which are used in the trivial names α-carotene and δ-carotene, are not used for that reason). Suffixes (for example, -oic acid, -oate, -al, -one, -ol) indicate certain oxygen-containing groups (for example, acid, ester, aldehyde, ketone, alcohol); all other substitutions appear as prefixes (for example, alkoxy-, epoxy-, hydro-). ). The configuration about all double bonds is trans unless cis and locant numbers appear. The prefix retro- is used to indicate a shift of one position of all single and double bonds; apo- indicates shortening of the molecule. Many carotenoids have anticancer activities.ca·rot·e·noids (kă-rot'ĕ-noydz) Generic term for a class of carotenes and their oxygenated derivatives (xanthophylls).carotenoids A large group of yellow or orange pigments occurring in plants some of which have antioxidant properties. Some of the carotenoids are carotenes.carotenoids a group of yellow/orange pigments found in plants, animals and microorganisms, which includes CAROTENES (orange) and xanthophylls (yellow).CarotenoidsCarotenoids are yellow to deep-red pigments.Mentioned in: Vitamin A Deficiency |