Carotenoids

Abstract

A period of descriptive and analytical examination of the carotenoids has now reached a culminating point with the complete synthesis of vitamin A and of representative carotenoid pigments." Thus Endeavour introduces a definitive discussion by Heilbron & Cook (1) on carotenoids and vitamin A. Total synthesis of the common carotenes has been achieved, those of {j-carotene (2) and lycopene (3) being of special interest. The synthesis of an artificial carotenoid free from the limitation of the normal C40 skeleton, yet retaining the cyclohexenyl rings and the isoprenic pattern, a decapreno-,6carotene (Le., with 10 isoprene units), C50H68 (4), gives emphasis to the re mark that a culminating point has been reached, that it is indeed the end of a chapter (1).Two other remarks may be singled out for attention: "that the polyene system as it occurs in the carotenoids remains one of largely unknown po tentialities," and, secondly, that "attention wiII undoubtedly be increasingly directed to the role of these substances in the living cell." It is proposed to elaborate upon these points in this review, with particular emphasis on the biosynthesis of carotenoids.Customary omissions include aspects considered in other chapters, on nu trition, fat-soluble vitamins, and photosynthesis. Carotenoid metabolism in marine invertebrates and the nature of carotenoids found in deep sea muds have already been discussed by Fox (5). Because of a review on the biochem istry of vision next year, the role of carotenoids in the visual purple cycle is also omitted.1 GENERAL Nomenclature.-Carotenoid nomenclature offers difficulties for reasons listed by Zechmeister (6), and sympathy with several of his objections to the report of the Committee on Biochemical N omenc1ature (7) may be expressed. Full discussion of all views is essential, though ultimately compromises or arbitrary decisions are inevitable, and there may indeed be reservations over some of Zechmeister's objections. As he rightly suggests, the pigment C4DH68 should not be termed carotene, but dihydrocarotene. However, we are then confronted with the dilemma of r-carotene, a simple and useful designation for a natural carotenoid hydrocarbon pigment considered by Porter & Lincoln (8) to be an octahydrolycopen�. For simplicity and ease of reference in the immediate future, a useful distinction might be to retain designations such as t-carotene and even If-carotene (9) for naturally oc-I The survey of the literature ' pertaining to this review was completed in De cember. 1951. 473 Annu. Rev. Biochem. 1952.21:473-492. Downloaded from www.annualreviews.org Access provided by University of Washington on 02/05/15. For personal use only. Quick links to online content Further ANNUAL REVIEWS 474 MACKINNEY cUfring hydrocarbons, but not for syntheti� products such as dihydrocaro tene.A second reservation involves unambiguous usage of the prefixes pro and proto-. The Committee may not have followed the most desirable usage with regard to designating precursors, but it can be defended against seri...

OCTAHEDRAL CRYSTALS IN PHYCOMYCES. II

“…Sporangium formation was also delayed and did not appear until the sporangiophore length was about 5 .7 cm . The mycelia, sporangiophores, and sporangia were very pale yellow compared with the bright yellow of the light-grown cultures (Garton et al ., 1951 ;Mackinney, 1952 ;Chichester et al ., 1954 ;Lilly et al ., 1960) .…”

The Protective Anticancer Effect of Natural Lycopene Supercritical CO2 Watermelon Extracts in Adenocarcinoma Lung Cancer Cells

“…Of these, only 20 are detectable both in human blood and cells [ 5 ], represented for 90% by α- and β-carotene, β-cryptoxanthin, lutein, lycopene and zeaxanthin [ 2 ]. The first important review of the effects induced by carotenoids on human health was published in the early 1950s of the last century [ 6 ], reporting the first evidence of these natural compounds in physiological and pathological processes, including lung cancer. Since then, several studies were performed on carotenoids until the publication of the two most well-known large-scale randomized trials on cancer prevention, the CARET [ 7 ] and the ATBC [ 8 ] studies.…”