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16 TH INTERNATIONAL SYMPOSIUM ON CAROTENOIDS ed ethanol, it forms predominantly H-aggregates with absorption peak at 390 nm, but J-aggregates coexist in the sample as evidenced by weak absorption band around 510 nm. Excited-state dynamics are significantly changed upon aggregation. Excitation of H-aggregates at 400 nm reveals prolongation of the S 1 lifetime as compared with monomer (38 vs. 24 ps). In addition, contrary to monomers, transient signal of ACOA aggregates does not decay within 100 ps, indicating presence of long-lived species, most likely a triplet state generated by singlet-singlet homofission. ACOA also forms H-aggregates when attached to TiO 2 film. As observed earlier for monomeric ACOA-TiO 2 system in colloidal solution (Pan et al., 2002), excitation of ACOA aggregate on TiO 2 film generates ACOA radical on sub-picosecond time scale due to electron injection from the S 2 state. Contrary to monomeric ACOA, however, the ACOA aggregate also exhibits a slower phase of electron injection that may occur from the S 1 state of the ACOA aggregate. REFERENCES PAN J, BENKÖ G, XU Y, PASCHER T, SUN L, SUNDSTRÖM V, POLÍVKA T. 2002. Photoinduced electron transfer between a carotenoid and TiO2 nanoparticle. J. Am. Chem. Soc. 124: 13949-13957. Exceptional molecular organization of canthaxanthin in lipid membranes Agnieszka Sujak Department of Physics, University of Life Sciences in Lublin, Poland Canthaxanthin (β, β-carotene 4, 4' dione) is a carotenoid pigment widely distributed in nature. It is found in green algae, bacteria, crustaceans, and fish. In the last 30 years it has been a popular E161g food additive and cosmetic colorant due to a very attractive color. There are many reports on undesirable health effects caused mainly by the formation of canthaxanthin crystals in the macula lutea membranes of the retina, called canthaxanthin retinopathy. Our experiments done on model systems indicate an exceptional molecular organization of canthaxanthin in lipid membranes as well as a very strong effect of this carotenoid on the physical properties of the lipid membranes. It has been found that the canthaxanthin localization and orientation in the model lipid membranes depends strongly on its concentration. The mean angle between the dipole transition moment and the axis normal to the plane of the DPPC membrane was determined as 20°- at 0.5 mol% which confirms vertical orientation of the axis connecting opposite keto-groups of the xanthophyll at the 4 and 4' positions and 47°- at 2 mol% of canthaxanthin, which implies the possibility that canthaxanthin incorporated into lipid membranes can be distributed in such a way that its small fraction can be oriented parallel to the plane of the lipid membrane. Strong interactions between canthaxanthin and lipids were found under experimental conditions. For model DPPC lipid membranes and canthaxanthin concentration below 1 mol% significant changes in the membrane properties were observed, in some cases at the pigment concentration as low as 0.05 mol% with respect to lipid. Based on experimental data on phosphatidylcholines several molecular mechanisms of canthaxanthin action can be listed such as strong van der Waals interactions between polyene chain of canthaxanthin and the lipid alkyl chains, modifications of the lipid properties in its polar zone, introduction of a new thermotropic phases upon the incorporation of canthaxanthin, formation of the hydrogen bonds between canthaxanthin keto- groups and the C=O group of lipid or hydrogen bonds between the canthaxanthin polyene chain and water. Two last mechanisms can have a crucial significance in formation of molecular aggregates of canthaxanthin leading to further development of canthaxanthin- induced retinopathy. The cis-carotenoid-membrane interactions SESSION 8 Justyna Widomska 1 , Witold K. Subczynski 2 , Wiesław I. Gruszecki 3 , Kazimierz Strzałka 4 1Department of Biophysics, Medical University of Lublin, Poland, jwidomska@gmail.com 2Department of Biophysics, Medical College of Wisconsin, USA, subczyn@mcw.edu 3Deparment of Biophysics, Institute of Physics, Maria Curie- Skłodowska University, Poland, wieslaw.gruszecki@umcs.pl 4Department of Plant Physiology and Biochemistry, Jagiellonian University, Krakow, Poland, strzalka@mol.uj.edu.pl The heterogeneity of carotenoids is greatly increased by the existence of their geometrical isomers. Carotenoid geometry is a factor that determines their solubility and orientation in the lipid memebrane as well as antioxidant capacities and bioavailability. The polyene-chain double-bonds present in carotenoids can exist in mono-cis, poly-cis, or all-trans configurations; however the vast majority of naturally occurring carotenoids exist in the thermodynamically more stable all-trans conformation rather than in cis configuration. Trans-cis conversion occurs at elevated temperature and/or in the presence of intensive light and triplet sensitizers. The role of the all-trans carotenoids in the modulation of the physical properties of lipid membranes has been a subject of research for the last three decades. Effects of trans-carotenoids on the structural and dynamic properties of lipid bilayers have been studied with application of various techniques, such as differential scanning calorimetry, fluorescence, electron spin resonance and nuclear magnetic resonance spectroscopy, diffractometry, and others. However, the effect of the cis-isomers of carotenoids on the membrane properties is less investigated. Our results indicate that the cis-isomers of xanthophylls, similarly to the trans-isomer adopt a transmembrane orientation and do not show a tendency to organize into high aggregates as trans configuration. Molecules of carotene in form trans and cis are distributed homogeneously without any well-defined orientation within the membrane. The influence of this nonpolar carotenoid on the memebrane properties is negligible and such effects can be related to the low solubility of carotene in the lipid bilayers. Supported by the POL-POSTDOC III grant no. PBZ/MNiSW/07/2006/01 of the Polish Ministry of Higher Education and Science. Structural aspects of antioxidant activity of lutein in models of photoreceptor membranes Anna Wisniewska-Becker1 , Grzegorz Nawrocki1,2 , Mariusz Duda1 , Witold K. Subczynski3 1 Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, ul. Gronostajowa 7, 30-387 Krakow, Poland, anna.m.wisniewska@uj.edu.pl, mariusz.duda@uj.edu.pl 2 Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw, Poland, nawrocki@ifpan.edu.pl 3 Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226 USA, subczyn@mcw.edu It was shown that in membranes containing domains, such as raft-forming mixtures (composed of dioleoylphosphatidylcholine 106 ACTA BIOLOGICA CRACOVIENSIA Series Botanica
MODEL SYSTEMS, COMPUTATIONAL AND IN SILICO STUDIES OF CAROTENOIDS [DOPC], sphingomyelin [ESM], and cholesterol, mixed at a molar ratio of 1:1:1), and in models of photoreceptor outer-segment membranes (containing palmitoyl-docosahexaenoyl-PC [PDHAPC], distearoyl-PC [DSPC], and cholesterol mixed at a molar ratio of 1:1:1), macular xanthophylls, lutein, and zeaxanthin are not distributed uniformly. They are substantially excluded from raft domains rich in saturated lipids and cholesterol and remain ~10 times concentrated in bulk domains, which are enriched in unsaturated lipids (DOPC or PDHAPC) (Wisniewska and Subczynski, 2006; 2006a). The selective accumulation of lutein and zeaxanthin in direct proximity of unsaturated lipids, which are especially susceptible to lipid peroxidation, should be very important as far as the antioxidant activity of these xanthophylls is concerned. Therefore, the protective role of lutein against lipid peroxidation was investigated in raft-forming mixtures and photoreceptor model membranes and compared with their antioxidant activity in homogenous membranes composed of unsaturated lipids. Lipid peroxidation was induced by photosensitized reaction using rose bengal and monitored by an MDA-TBARS test, iodometric assay, and oxygen consumption (using EPR spectroscopy oximetry and the mHCTPO spin label as an oxygen probe). The results show that lutein protects unsaturated lipids more effectively in raft-forming mixtures than in homogenous membranes. This suggests that the selective accumulation of macular xanthophylls in the most vulnerable regions of photoreceptor membranes may play an important role in enhancing their antioxidant properties and their ability to prevent age-related macular diseases (such as age-related macular degeneration [AMD]). Supported by grant EY015526 of the NIH. REFERENCES WISNIEWSKA A and SUBCZYNSKI WK. 2006. Accumulation of macular xanthophylls in unsaturated membrane domains. Free Radic. Biol. Med. 40: 1820-1826. WISNIEWSKA A and SUBCZYNSKI WK. 2006a. Distribution of macular xanthophylls between domains in a model of photoreceptor outer segment membranes. Free Radic. Biol. Med. 41: 257-1265. Vol. 53, suppl. 1, 2011 ORAL PRESENTATIONS 17–22 July 2011, Krakow, Poland Importance of stability tests of lycopene in experimental animal feed Kati Fröhlich1,2 , Volker Böhm1 , Mario Lorenz3 , Mandy Fechner3 1Institute of Nutrition, Friedrich Schiller University Jena, Dornburger Str. 25-29, 07743 Jena, Germany, 2Food GmbH Jena Analytik Consulting, Orlaweg 2, 07743 Jena, Germany, 3Charité – Universitätsmedizin, Schumannstr. 20-21, 10117 Berlin, Germany, k.froehlich@food-jena.de, volker.boehm@uni-jena.de, mario.lorenz@charite.de, mandy.fechner@charite.de The EU-funded project "LYCOCARD" (www.lycocard.com) investigated the role of lycopene, tomatoes/tomato products in reducing the risk of cardiovascular diseases. An animal study with NZWrabbits (Charité Berlin, Germany) examined the influence of lycopene on atherogenesis induced by high-cholesterol diet. Lycopene is sensitive to degradation and isomerization. Therefore, an important part of the animal study was to investigate the lycopene stability in lycopene-enriched experimental feed according to diverse processing methods, formulations and storage conditions. These experiments were mandatory to ensure the correct daily dose of lycopene in animal diets. Therefore, storage stability of carotenoids should always be monitored in chow used for animal studies. Lycopene beadlets, provided by DSM Nutritional Products Ltd. (Basel, Switzerland), were used for production of different experimental diets (ssniff Spezialdiäten GmbH, Soest, Germany or Altromin Spezialfutter GmbH & Co. KG, Lage, Germany). To test the stability of lycopene in rabbit chow enriched with lycopene beadlets, lycopene content as well as the isomer pattern were measured in a variety of chows (different processing conditions: e.g. temperature, pressure, added oxygen absorber) over the course of time (8 days, 3 months) under various storage conditions (different temperatures, with and without exposure to light and oxygen) by using C30-HPLC (Fröhlich et al., 2007). In contrast to the high stability of unprocessed lycopene beadlets (6 months at room temperature – no significant change), strong decrease of lycopene contents in chows enriched with beadlets was observed. After 8 days of storage, the lycopene contents were reduced significantly by about half of the basal level. Exposure to light showed no significant effects on lycopene stability. During the long-term stability tests (3 months), reduction of lycopene was significant and depending on the storage temperature. Surprisingly, no significant changes in the isomer ratio (all- E:Z) of lycopene were observed during all storage experiments. Special thanks are given to the diploma students Anne Trautmann and Claudia Nebe (FSU Jena, Germany) for the carotenoid analysis and the EU (LYCOCARD, IP: 2006-016213) for financial support. REFERENCES FRÖHLICH K, CONRAD J, SCHMID A, BREITHAUPT DE, BÖHM V. 2007. Int J Vitam Nutr Res 77: 369-375. 107
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Patronage Mayor of the City of Krak
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Organizing Committee Małgorzata Ba
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Plenary lectures
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Session 1 Nutritional Carotenoids a
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NUTRITIONAL CAROTENOIDS AND THEIR I
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Session 2 Photosynthesis, Photochem
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PHOTOSYNTHESIS, PHOTOCHEMISTRY, AND
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Professor Dr. Hans-Dieter Martin 19
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Page 95: Session 7 Carotenoids and Vision
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Page 111 and 112: Index of Authors Abe K 44 Abramchik
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