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16 TH INTERNATIONAL SYMPOSIUM ON CAROTENOIDS + – Car molecules are being excited, and, as a result, the 1Bu -to-3Ag diabatic electronic mixing and internal conversion become allowed. On the other hand, pump-probe spectroscopy after coherent excitation of the same set of Cars in polar solvent identified three stimulated-emission components (generated by the quantum-beat mechanism) consisting of the long-lived coherent cross term from + – + – the 1Bu + 1Bu or 1Bu + 3Ag diabatic pair and incoherent short- + – – lived 1Bu and 1Bu or 3Ag split incoherent terms. The same type of stimulated-emission components were identified in Cars bound to LH2 complexes, their lifetimes being substantially shortened by the Car-to-BChl singlet-energy transfer. Each diabatic pair and its split components appeared with high intensities in the first com- + – – ponent. The low-energy shifts of the 1Bu (0), 1Bu (0) and 3Ag (0) levels and efficient triplet generation were also found. REFERENCES KOYAMA Y, KAKITANI Y, MIKI T, CHRISTIANA R, NAGAE H. 2010 Excited-State + Dynamics of Overlapped Optically-Allowed 1Bu and Optically- – – Forbidden 1Bu or 3Ag Vibronic Levels of Carotenoids: Possible Roles in the Light-Harvesting Function. Int. J. Mol. Sci. 11: 1888- 1929. Carotenoids and their derivatives prevent cancer by affecting the activity of diverse transcription systems Joseph Levy Department of Clinical Biochemistry, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel The basis for the vivid color of carotenoids and their antioxidant activity is the multiple conjugated double bonds which are characteristic for these plant-derived micronutrients. Moreover, the cleavage of these oxidation-prone double bonds leads to the formation of apocarotenoids. An amazingly large number of different carbonyl-containing oxidation products are expected to be produced as a result of carotenoid oxidation and these can be further metabolized to the corresponding acids and alcohols. Indeed, many, but not all, of these potential products have been detected and identified in edible plants as well as in human and animal plasma and tissues. Some of these compounds were found to be biologically active as anticancer agents. In addition to the inhibition of cancer cell proliferation, several carotenoid metabolites were shown to modulate the activity of various transcription systems. These include the ligand-activated nuclear receptor family, such as the retinoic acid receptor, retinoid X receptor, peroxisome proliferatoractivated receptor and estrogen receptor, as well as other transcription systems which have an important role in cancer, such as the electrophile/antioxidant response element pathway and nuclear factor-κB. Therefore, carotenoid oxidation products can be considered as natural compounds with multifunctional, rather than monofunctional, activity and, thus, can be useful in the prevention of cancer and other degenerative diseases. PLENARY LECTURES Synthesis of highly 13C enriched carotenoids: access to carotenoids enriched with 13C at any position and combination of positions Johan Lugtenburg, Prativa BS Dawadi Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA, Leiden, The Netherlands, lugtenbu@chem.leidenuniv.nl, p.b.s.dawadi@gmail.com (P.B.S.D.) Carotenoids and their metabolites are essential factors for the maintenance of important life processes such as photosynthesis. Animals cannot synthesize carotenoids de novo, they must obtain them via their food. In order to make intensive animal husbandry possible and maintain human and animal health synthetic nature identical carotenoids are presently commercially available at the multi-tonnes scale per year. Synthetically accessible 13C enriched carotenoids are essential to apply isotope sensitive techniques to obtain information at the atomic level without perturbation about the role of carotenoids in photosynthesis, nutrition, vision, animal development, etc. Simple highly 13C enriched C1 , C2 and C3 building blocks are commercially available via 99% 13CO. The synthetic routes for the preparation of the 13C enriched building blocks starting from the commercially available systems are discussed first. Then, how these building blocks are used for the synthesis of the various 13C enriched carotenoids and apocarotenoids are reviewed next. The synthetic schemes that resulted in 13C enriched β-carotene, spheroidene, α-carotene, astaxanthin, (3R,3R')-zeaxanthin and (3R,3R',6R')-lutein are described. The schemes that are reviewed can also be used to synthetically access any carotenoid and apocarotenoid in any 13C isotopically enriched form up to the unitarily enriched form. This paper is written in respectful memory of Dr. Otto Isler, pioneer in the industrial production of synthetic, nature-identical carotenoids. The authors are thankful to the organizations that supplied the financial resources to carry out this work. This paper has been written with great indebtedness to the investigators in the Leiden group and researchers worldwide whose contributions have been essential to the work described in this review. The senior author is grateful for the friendship and support of the members of the carotene club. Carotenoids – mechanisms of photoprotection in the skin Wilhelm Stahl Institute of Biochemistry and Molecular Biology I, University of Duesseldorf, POB 101007, D-40001 Düsseldorf, Germany, wilhelm.stahl@uni-duesseldorf.de The skin is the outer barrier of the organism and protects against external stressors including UV-irradiation. Light-dependent photooxidative processes generate reactive oxygen species (ROS) which damage biologically relevant molecules and cellular structures. UV-light may further interact directly with DNA bases inducing the formation of pyridine dimers. As a result of UV damage cells respond with adaptation to stress and defense signaling. Photoprotection of the skin may be realized at different levels of defense e.g. absorption of light, scavenging of ROS, or modulation of signaling pathways. Carotenoids have a unique structure and are essential for photoprotection in plants and likely suitable for protecting humans. Intervention studies with carotenoid supplements or diets rich in carotenoids have demonstrated that they contribute to endogenous photoprotection ameliorating UV-induced erythema (sunburn). Photoprotection through dietary components such as beta-carotene or lycopene in terms of sun protection factor is 12 ACTA BIOLOGICA CRACOVIENSIA Series Botanica
PLENARY LECTURES considerably lower than that achieved with a sunscreen. However, it may contribute to basal protection and thus increase the defense against UV light-mediated damage to skin. The mechanisms underlying this effect are not completely understood but antioxidant activity and/or interference with inflammatory, apoptotic, and adaptive signaling play a role. The solar erythema is an inflammatory reaction to overexposure to UV light and it his been discussed whether carotenoids prevent its formation or suppress a desired physiological reaction. Modulation of signaling may not only be mediated by parent carotenoids. Apocarotenals of lycopene for example address Nrf- 2 dependent pathways triggering the expression of defense systems against oxidants and other electrophiles. Apo-carotenoic acids interfere with retinoic acid-sensitive signaling. Basic research in model systems contributes to the understanding of protective mechanisms, allows to elaborate structureactivity relationship and helps to understand the properties of natural and non-natural carotenoids. Carotenylflavonoids are synthetic hybrids comprising structural elements of elements of both classes. Compared to the parent carotenoids or flavonoids these compounds exhibit improved photoprotective properties and they outperform the individual constituents with respect to antioxidant properties. Isorenieratene and 3,3'-dihydroxyisorenieratene are aromatic carotenoids carrying phenylic and phenolic residues, respectively. Both compounds are efficient antioxidants preventing lipid, protein and DNA oxidation and suppress the expression of UV-sensitive hemeoxygenase-1. In addition to other carotenoids both compounds prevent the formation of thymidine dimers which is likely due to their UV-absorbing properties related to the aromatic elements in their structure. Xanthophyll-membrane interactions at high and low xanthophyll concentrations Witold K. Subczynski1 , Anna Wisniewska-Becker2 , Justyna Widomska 3 1Deparment of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226 USA, subczyn@mcw.edu 2Department of Biophysics, Jagiellonian University, Krakow, Poland, anna.m.wisniewska@uj.edu.pl 3Department of Biophysics, Medical University, Lublin, Poland, jwidomska@gmail.com Vol. 53, suppl. 1, 2011 17–22 July 2011, Krakow, Poland Membrane localization of some portion of carotenoids in bacteria, plants, and animals is commonly accepted. However, the function of carotenoids in membranes is unclear. To understand the basic mechanisms and effects of carotenoids, it is necessary to understand carotenoid-membrane interaction. For systems with a high carotenoid concentration (for example, in bacteria and plants in which the local carotenoid concentration in membranes can reach a few mol%), it is most important to understand how carotenoids affect the physical properties, structure, and dynamics of the membrane. Leading conclusions drawn from previous investigations are that carotenoids (1) shift to lower temperature and broaden the main phase transition of phosphatidylcholine membranes; (2) decrease membrane fluidity and increase the order of alkyl chains; and (3) increase the hydrophobicity of the membrane interior. The effects of carotenoids are strongest for xanthophylls. These results suggest that anchoring carotenoid molecules at opposite membrane surfaces by polar hydroxyl groups is significant to enhance their effects on membrane properties. In animals, the highest concentration of carotenoids is found in the retinas of primates. But even there, the xanthophyll concentration in the lipid-bilayer portion of the membrane is much lower than 1 mol%. For systems with a low carotenoid concentration, it is especially important to understand how the membrane itself – its composition, structure, and lateral organization – affects the organization of carotenoids in the lipid bilayer, including their orientation (transmembrane vs. parallel) and localization (distribution between membrane domains). Macular xanthophylls are not distributed uniformly in membranes containing domains. Xanthophylls are substantially excluded from domains enriched in saturated lipids that contain a high concentration of cholesterol (raft domains), and remain ~10 times more concentrated in domains that contain mainly unsaturated lipids (including highly unsaturated docosahexaenoyl acid) and much smaller amounts of cholesterol. The localization of macular xanthophylls in domains formed from unsaturated lipids is ideal if they are to act as a lipid antioxidant, which is the most accepted mechanism through which lutein and zeaxanthin protect the retina from age-related macular disease. Supported by grant EY015526 of the NIH. REFERENCES SUBCZYNSKI WK, WISNIEWSKA A, WIDOMSKA J. 2010. Archives Biochem. Biophys. 504: 61-66. 13
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CAROTENOIDS IN THE PREVENTION OF CA
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Session 5 Interaction of Carotenoid
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BIOSYNTHESIS, GENETICS, AND METABOL
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Session 7 Carotenoids and Vision
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MODEL SYSTEMS, COMPUTATIONAL AND IN
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Index of Authors Abe K 44 Abramchik
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Szõke E 58 Szolcsány J 58 Szurkow
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ROMEO JT. 1973. A chemotaxonomic st
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