Pflanzenfarbstoffe XXV. Über die Konstitution des Lycopins und Carotins

Karrer, P.; Helfenstein, A.; Wehrli, H.; Wettstein, A.

doi:10.1002/hlca.19300130532

Cited by 156 publications

(31 citation statements)

References 3 publications

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“…Shortly after, Karrer and coworkers (Karrer et al, 1930) proposed a central cleavage mechanism at the 15,15 0 carbon double bond. The biochemical characterization of this enzyme activity was independently described in the laboratories of Dewitt Goodman (Goodman and Huang, 1965) and James Allen Olsen (Olson and Hayaishi, 1965).…”

Section: Intestinal Absorption Of Provitamin a Carotenoidsmentioning

confidence: 98%

Overview of retinoid metabolism and function

2006

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Retinoids (vitamin A) are crucial for most forms of life. In chordates, they have important roles in the developing nervous system and notochord and many other embryonic structures, as well as in maintenance of epithelial surfaces, immune competence, and reproduction. The ability of all-trans retinoic acid to regulate expression of several hundred genes through binding to nuclear transcription factors is believed to mediate most of these functions. The role of all-trans retinoic may extend beyond the regulation of gene transcription because a large number of noncoding RNAs also are regulated by retinoic acid. Additionally, extra-nuclear mechanisms of action of retinoids are also being identified. In organisms ranging from prokaryotes to humans, retinal is covalently linked to G protein-coupled transmembrane receptors called opsins. These receptors function as light-driven ion pumps, mediators of phototaxis, or photosensory pigments. In vertebrates phototransduction is initiated by a photochemical reaction where opsin-bound 11-cis-retinal is isomerized to all-trans-retinal. The photosensitive receptor is restored via the retinoid visual cycle. Multiple genes encoding components of this cycle have been identified and linked to many human retinal diseases. Central aspects of vitamin A absorption, enzymatic oxidation of all-trans retinol to all-trans retinal and all-trans retinoic acid, and esterification of all-trans retinol have been clarified. Furthermore, specific binding proteins are involved in several of these enzymatic processes as well as in delivery of all-trans retinoic acid to nuclear receptors. Thus, substantial progress has been made in our understanding of retinoid metabolism and function. This insight has improved our view of retinoids as critical molecules in vision, normal embryonic development, and in control of cellular growth, differentiation, and death throughout life.

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Section: Intestinal Absorption Of Provitamin a Carotenoidsmentioning

confidence: 98%

Overview of retinoid metabolism and function

2006

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“…In fact, the conversion of β-carotene to vitamin A in the small intestine provided the first evidence that these carotenoids are direct precursors of vitamin A in animals (20). β-Carotene in the diet can be converted to retinaldehyde in the small intestine by cleavage, specifically at its central double bond, catalyzed by β-carotene, 15,15 -dioxygenase (21). The retinaldehyde thus formed can be converted either to retinol by retinaldehyde reductase or to retinoic acid by either retinaldehyde oxidase or retinaldehyde dehydrogenase.…”

Section: Discussionmentioning

confidence: 98%

Mild Whole-Body Heat Stress Alters Retinoid Metabolism in the Rat Small Intestine

et al. 2006

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Mild heat treatment can modulate metabolism and prevent stress-induced alterations in cells and tissues. Retinoids are known to influence cellular metabolism and are essential for growth and differentiation, particularly of epithelial tissue. This study examines the effect of mild heat treatment on retinoid alterations in enterocytes in the rat small intestine. Heat treatment changed the differentiation pattern of enterocytes along the villus-crypt axis, accompanied by increases in retinol, retinaldehyde, and retinoic acid in proliferating crypt cells. Activities of retinoid metabolizing enzymes such as retinaldehyde oxidase and retinaldehyde reductase were also increased. These results suggest that mild heat treatment can alter retinoid metabolism in the small intestine, which might influence epithelial cell proliferation and differentiation.

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“…The chemical structure of the parent carotenoids was deduced from those of its oxidation products. For instance, the number of side-chain methyl groups was first determined by oxidation using potassium permanganate in alkaline solution, thus forming acetic acid [5,6].…”

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confidence: 99%

Carotenoid oxidation products: From villain to saviour?

Carail¹,

Caris-Veyrat²

2006

Pure and Applied Chemistry

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Carotenoid oxidation products have various structures, among which epoxides and apo-or seco-carotenoids are the two main families. Although both these compound types are widely found in the natural world, the sensitivity of carotenoids to oxidation means they can also be an unwanted presence in in vitro assays. On the other hand, carotenoid oxidation products have also provided chemists with useful chemical tools for the structural identification of carotenoids, and in the natural world they are important biological mediators for plants and animals. In vitro, carotenoid oxidation products have been found to exert various effects which are either potentially beneficial or, on the contrary, detrimental to human health. However, to date, few carotenoid oxidation products have been found in humans.In order to isolate and characterize carotenoid oxidation products and identify their mechanism of formation, we set up two chemical oxidation systems. Lycopene was oxidized with potassium permanganate in a biphasic system to produce the fullest possible range of apo-lycopenals and some diapocarotene-dials. Biomimetic chemical systems of a heminic enzyme center were shown to oxidize lycopene and β-carotene into different families of molecules. Analysis by high-performance liquid chromatography coupled with a diode array-UV/vis detector and a mass spectrometry detector (HPLC-DAD-MS) was used to gain insight into the possible mechanisms of formation of the carotenoid oxidation products formed by these biomimetic systems.

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Pflanzenfarbstoffe XXV. Über die Konstitution des Lycopins und Carotins

Cited by 156 publications

References 3 publications

Overview of retinoid metabolism and function

Overview of retinoid metabolism and function

Mild Whole-Body Heat Stress Alters Retinoid Metabolism in the Rat Small Intestine

Carotenoid oxidation products: From villain to saviour?

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