JSCS Vol 68, No. 11
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Oxidative
fragmentations of 5-hydroxy-1-oxo-5a-cholestan-3b-yl acetate
NATALIJA M.
KRSTIC*, MIRA S. BJELAKOVIC*, LJUBINKA B. LORENC*,** and VLADIMIR D.
PAVLOVIC*,**
*Center for Chemistry,
ICTM, P. O. Box 473, 11001 Belgrade and
**Faculty of Chemistry, University of
(Received 22 May 2003)
5-Hydroxy-1-oxo-5a-cholestan-3b-yl
acetate (11) was prepared in 5 steps starting from (E)-3b-acetoxy-5,10-seco-1(10)-cholesten-5-one (6).
Treatment of the 1-oxo-5-hydroxy derivative 11 with lead tetraacetate
(LTA) (under thermal or hypoiodite conditions) or with mercuric oxide/iodine
(HgO/I2) reagent resulted in the oxidative b-fragmentation of the C(5)–C(10) bond affording
1,5-dioxo-5,10-secocholest-10(19)-en-3b-yl
acetate (12), in different yields, depending on the reagent. Also the
stereochemistry of the 1b,6b-cyclization product 13, formed by transannular
cyclization of the 1,5-diketone 12 on silica gel, is discussed in this
work.
Keywords:
5-Hydroxy-1-oxo-5a-cholestan-3b-yl acetate,
1,5-dioxo-5,10-secocholest-10(19)-en-3b-yl
acetate, b-fragmentation,
transannular cyclization.
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A formal synthesis of (+)-muricatacin from
D-xylose
VELIMIR POPSAVIN, SANJA GRABEZ, IVANA KRSTIC, MIRJANA POPSAVIN and DEJAN
DJOKOVIC*
Department of Chemistry,
Faculty of Science, University of Novi Sad, Trg D. Obradovi}a 3, 21000 Novi Sad
and
*Faculty of Chemistry, University of Belgrade, Studentski trg 16, P. O. Box
158, 11001 Belgrade, Serbia and Montenegro
(Received 9 June 2003)
A multistep route towards the aldehydo-lactone 19, the final chiral
precursor in a new stereospecific synthesis of (+)-muricatacin, has been
developed starting from D-xylose. The key step of the synthesis involves an E-selective
Wittig olefination of the lactol 6 with methoxycarbonylmethylidene
triphenylphosphorane, followed by successive catalytic reduction and g-lactonisation processes. Subsequent selective functional groups
interconversions furnished the key six-carbon intermediate 19, which can
be converted into the (+)-muricatacin via a three-step sequence already
described in the chemical literature.
Keywords:
muricatacin, Wittig reaction, g-lactone,
stereospecific synthesis, D-xylose.
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PRELIMINARY COMMUNICATION
A glucan from active dry baker’s yeast
(Saccharomyces cerevisiae): A chemical and enzymatic investigation of the
structure
DRAGANA ZLATKOVIC, DRAGICA JAKOVLJEVIC* , DJORDJE ZEKOVIC** and MIROSLAV M.
VRVIC**,***
Confectionery Industry “Stark”, 11010 Belgrade, Kumodraska 249,
*Department of Chemistry, Institute of Chemistry, Technology and Metallurgy,
11001 Belgrade, Njegoseva 12, P.O. Box 473,
**”Alltech YU” Ltd., 21000 Novi Sad, Kralja Aleksandra 5,
***Faculty of Chemistry, University of Belgrade, Studentski trg 16, P.O. Box
158, 11001 Belgrade, Serbia and Montenegro
(Received 14 April 2003)
The structure of a polysaccharide consisting of
D-glucose isolated from the cell-wall of active dry baker’s yeast (Saccharomyces
cerevisiae) was investigated by using methylation analysis, periodate
oxidation, mass spectrometry, NMR spectroscopy, and enzymic hydrolysis, as a
new approach in determination of structures. The main structural feature of the
polysaccharide deduced on the basis of the obtained results is a linear chain
of (1->3)-linked b-D-glucopyranoses, a
part of which is substituted through the positions O-6. The side units or
groups are either a single D-glucopyranose or (1->3)-b-oligoglucosides,
linked to the main chaing through (1->6)-glucosidic linkages. The low
optical rotation as well as the 13C-NMR and FTIR spectra suggest
that the glycosidic linkages are in the b-D-configuration.
Keywords: active dry baker’s yeast, Saccharomyces cerevisiae,
polysaccharides, glucan, structure, chemical and enzymatic methods.
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Membrane-associated insulin-like growth factor
(IGF) binding structures in placental cells
ROMANA MASNIKOSA, J. ANNA NIKOLIC and OLGICA NEDIC
INEP – Institute for the
Application of Nuclear Energy, Banatska 31 B, 11080 Zemun-Belgrade,
Serbia and Montenegro
(Received 21 February,
revised 20 June 2003)
The biological activities of IGF-I and –II are
mediated mainly by the type 1 IGF receptor (IGF 1R) and controlled by their
interaction with soluble proteins, the IGF binding proteins (IGFBPs). Although
there is a growing body of evidence that some IGFBPs may be cell surface-bound,
published data concerning cell association of IGFBP-1 are scarce and none of
them concern placental cells. The cell membranes used in this study were
isolated from term human placentae. Detergent-solubilized membranes were shown
to contain two types of IGF binding structures that were separated by gel
filtration on a Sephadex G-100 column. Proteins in the first peak were eluted
at V0 (Mr > 100 kD) and they bound IGF-I
with greater specificity and affinity than IGF-II and insulin. Most likely,
they represented the IGF 1R. Small proteins (Mr ~ 45 kD) were
eluted with the membrane proteins in the second maximum. They were able to bind
IGF-I and IGF-II, but not insulin. The identity of these proteins was shown to
be IGFBP-1 on the basis of their reaction with specific anti-IGFBP-1 antibodies.
To the best of our knowledge, the existence of IGFBP-1 associated with
human placental cell membranes has not been reported in the literature before.
Colocalisation of IGFBP-1 with IGF 1R in cell membranes could provide efficient
modulation of IGF 1R receptor-ligand interactions.
Keywords: IGF-I, IGF-II, IGF 1R, IGFBP-1, placental cell membranes, gel
filtration.
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Immobilization of periodate oxidized invertase
by adsorption on sepiolite
RADIVOJE M. PRODANOVIC, MILOS B. SIMIC* and ZORAN M. VUJCIC*
Faculty of Chemistry, University of Belgrade, Studentski trg 16, 11001 Belgrade
and
*Center for New Technologies, CNT, Studentski trg 16, 11001 Belgrade, Serbia
and Montenegro
(Received 17 September
2002, revised 4 June 2003)
Periodate oxidized invertase was immobilized by
adsorption on sepiolite. The obtained immobilized enzyme was more resistant to
washing out by concentrated salt solution, and had an eight times higher
half-life at 60ºC than adsorbed native invertase. In packed bed reactor 50 %
conversion of 500 g/dm3 sucrose at 40ºC and a flow rate of 1 bv/h
was achieved. The specific productivity of the immobilized invertase was 0.187
kg/dm3/h.
Keywords: invertase, periodate oxidation, sepiolite, immobilization, sucrose.
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Gas chromatographic retention indices for
N-substituted AMino s-triazines on capillary columns.
Part V. Temperature dependence of the retention index
DUSAN Z. MIJIN, DUSAN G. ANTONOVIC and BRATISLAV Z. JOVANOVIC
Department of Organic Chemistry, Faculty of Technology and Metallurgy,
University of Belgrade,
P. O. Box 3503, 11120 Belgrade, Serbia and Montenegro
(Received 9 June 2003)
The temperature dependence of the retention
index was studied for N-substituted AMino s-triazines on DB-1, DB-5 and
DB-WAX capillary columns within the temperature range 190–230ºC. Two linear
equations with the column temperature and its reciprocal as variables were
studied. The first one shows a slightly better precision for
2,4-bis(alkylAMino)-6-chloro-s-triazines and 2-alkylAMino-4,6-dichloro-s-triazines,
while the second one shows a better precision for 2,4-bis(cycloalkylAMino)-6-chloro-s-triazines.
Keywords: retention indices, s-triazines, temperature dependence.
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Adsorption of inorganic anionic contAMinants on
surfactant modified minerals
ALEKSANDRA VUJAKOVIC, ALEKSANDRA DAKOVIC, JOVAN LEMIC, ANA
RADOSAVLJEVIC-MIHAJLOVIC and
MAGDALENA TOMASEVIC-CANOVIC
Institute for the
Technology of Nuclear and Other Mineral Raw Materials, P. O. Box 390, Franshe d
Epere 86,
11001 Belgrade, Serbia and Montenegro (e-mail: m.tomasevic@itnms.ac.yu)
(Received 20 March,
revised 16 June 2003)
Organo-mineral complexes were obtained by
treatment of aluminosilicate minerals (zeolite, bentonite and diatomaceous
earth) with a primary AMine (oleylAMine) and an alkyl AMmonium salt
(stearyldimethylbenzyl AMmonium chloride). The modification of the zeolite
surface was carried out in two steps. The first step was treatment of the
zeolite with 2 M HCl. This acid treatment of the zeolite increased its affinity
for neutral molecules such as surface-active AMines. The second step of the
modification was the adsorption of oleylAMine on the acid treated zeolite. Four
types of organo-mineral complexes were prepared and their anion adsorption
properties were compared to those of organo-zeolite. The adsorption of
sulphate, bichromate and dihydrogenphosphate anions on the organo-mineral
complexes was investigated. The anion adsorption measurements showed that the
most efficient adsorbent for anion water pollutants was the primary AMine
modified H+-form zeolite.
Keywords: zeolite, bentonite, diatomaceous earth, oleylAMine, adsorption,
anions.
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Synthesis of copper nanorods using
electrochemical methods
XUEGENG YANG*, SHENHAO CHEN*,**, SHIYONG ZHAO*, DEGANG LI* and HOUYI
MA*
*Department of
Chemistry, Chandong University, Jinan 250100, PR China and
**State Key Laboratory for Corrosion and Protection of Metals, Shenyang 110015,
PR China (e-mail: shchen@sdu.edu.cn.)
(Received 28 March 2003)
Copper nanorods were synthesized using
controlled-current electrochemical methods. The surfactants in the electrolyte
served as both a templates and stabilizers during the synthesis procedure. TEM
images show that the products consist mainly of nanosized rod-like structures.
The current density applied during the electrodeposition was found to have an
effect on the shape and yield of the copper nanorods.
Keywords: copper nanorods, electrochemical, template, microemulsion.
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