ACTA BIOLOGICA CRACOVIENSIA

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