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Mode of Action of the Thiamine Antagonists Pyrithiamine and Oxythiamine in Rat Brain.

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thin-layer plates, removal of the spots and extraction of the
silica gel with methanol containing 5 % of concentrated
ammonia solution are recommended. After excitation with
the 365 mu Hg line, the intensity of fluorescence of the extract
is determined at 520 m p for DANS-amides and at 530 m p
for phenol- and pyrocatechol-amine derivatives. Reproducibility is 3-5
for concentrations of 2x 10-10 mole/cm3.
Use of Chromatography on Anion-exchangers for
Determination of Low Phosphate Contents
J . Wernet, J . Ebert, and R . Adrinn,
Knapsack bei Koln (Germany)
The usual methods of paper-chromatographic separation and
determination of condensed phosphates require concentrations of 1 to 5 g/l of each phosphate. I n samples of water
or foodstuffs, and in biological chemistry, the phosphate
contents to be determined are usually considerably less than
this. Concentration by evaporation would, inter a h , alter
the form of the phosphates as a result of hydrolysis. Chromatographyon anion-exchangers is suitable for determination
of phosphates in these circumstances. It permits dissolved
ionogenic phosphates to be separated and indications of the
distribution of dissolved, non-ionogenic, inorganic and
organic phosphates to be obtained. Dissolved, ionogenic,
condensed phosphates can be separated and determined in
concentrations down to less than 1 mg of total P205 per
litre. In phosphate-treated drinking water, in river water,
and in effluent water seven forms of phosphate could be
determined in presence of each other: dissolved, nonionogenic, highly condensed, inorganic and organic phosphates - dissolved ionogenic compounds, separated into
mono-, di-, tri-, total > tri- and meta-phosphates - and
highly condensed phosphates.
[VB 923/230 IEI
German version: Angew. Chem. 77, 683 (1965)
Mode of Action of the Thiamine Antagonists
Pyrithiamine and Oxythiamine in Rat Brain
C. J . Giibler, Freiburg/Breisgau (Germany)
Thiamine in the form of its pyrophosphate ester is involved
as coenzyme in the decarboxylation of pyruvate and a-0x0glutarate. Prolonged deficiency of thiamine can lead to
damage of the nerves.
Injection of the thiamine antagonist pyrithiamine into rats
causes polyneuritis and a large decrease in the content of
thiamine in the brain. Injections of oxythiamine d o not
affect the thiamine content. These findings were clarified by
experiments in vitru. Inactive thiamine can be phosphorylated
in brain tissue to give the active pyrophosphate [I 1. The
activating enzyme, thiamine pyrophosphokinase, was concentrated by a factor of 12. Pyrithiamine inhibits this enzyme
I000 times more strongly than oxythiamine (Ki (pyrithiamine) = 1.3,., 10-7; Kj (oxythiamine) = 1.5.1 10-4). Hence
thiamine is not phosphorylated in the presence of pyrithiamine; instead, it is catabolized and excreted.
In contrast to pyrithiamine but like thiamine, oxythiamine is
phosphorylated by thiamine phosphokinase, and the phos-
phate then inhibits the enzymes transketolase and pyruvate
and r-oxoglutarate dehydrogenase.
Experiments with thiamine antagonists labelled with ‘4C and
3 5 s revealed that the oxythiamine injected penetrates into
the brain but in concentrations too low to prevent phosphorylation of the thiamine, and that pyrithiamine suppresses the production of thiamine phosphate in the brain.
[GDCh-Ortsverband Hamburg (Germany).
[VB 934/236 1Ej
April 6th, 19651
German version: Angew. Chem. 77, 684 (1965)
[ I ] L . R . Johnson and C. J. Gubler, Federat. Proc. 24,481 (1965).
The Stereochemistry of Sulfoxides
K . Misluw, Princeton, N.J. (U.S.A.)
Three major problems in sulfoxide stereochemistry are: the
absolute and relative configuration of optically active
sulfoxides, the relation between structure and optical rotatory power of sulfoxides, and the inversion of the sulfoxide
pyramid.
The absolute configuration of menthyl p-iodobenzenesulfinate ( I ) was established by X-ray diffraction [l]. The configurations of menthyl p-toluenesulfinate (2) and of ( I ) were
correlated, utilizing an asymmetric synthesis of the esters
from (-)-menthol and an excess of the corresponding sulfinyl
chloride. Reaction of (2) with a variety of alkyl- and arylmagnesium halides by a n inversion mechanism led to optically activep-lolyl alkyl and aryl sulfoxides of known absolute
configuration. Reaction of diastereomerically enriched menthy1 I-butanesulfinate (which had been prepared by asymmetric synthesis from (-)-menthol and I-butanesulfinyl
chloride) with methylmagnesium bromide led to optically
active methyl n-butyl sulfoxide of known absolute configuration. This constitutes the first preparation of an optically active dialkyl sulfoxide lacking other functionalities.
The optical rotatory dispersions of the abovementioned
sulfoxides were measured and could be conveniently discussed from the viewpoint that the C6HSSO- moiety represents an inherently dissymmetric chromophore whose
chirality determines the signs of the Cotton effects above
200 mp.
Optically active sulfoxides containing aromatic nuclei may
be racemized (a) thermally, by heating at temperatures near
200 “C (depending on the structure), (b) photochemically by
irradiation (at room temperature) in the wavelength region
above 285 mp, and (c) chemically, by the catalytic action of
hydrogen chloride in non-aqueous solvents.
[GDCh-Ortsverband Marburg (Germany),
May 15th, 19651
[VB 938/241 IE]
German version: Angew. Chem. 77, 684 11965)
[ l ] In collaboration with E. Fleischer, University of Chicago.
Erratum
“Inorganic Ring Systems with Silicon and Nitrogen Atoms
as Ring Members” by U.Wnnnngnt, Angew. Chem. internat.
Edit. 4 , 605 (1955).
The last sentence of this lecture summary should begin:
“Compound (6) with R = CH3. . . . .”
SELECTED ABSTRACTS
A table of the masses of molecules and molecular fragments for
help in identifying compounds by high-resolution mass
spectrometry has been compiled by D . D. Tunnicliff, P . A .
Wndsworth, and D . 0 . Schissler. An electronic computer was
used to arrange the sum formulae of all possible combinations
of elements (and their commonest isotopes) into two tables
Angew. Chem. internat. Edit.
VoI. 4 (1965) No. 8
in order of increasing masses. The first table (215781 entries)
gives combinations of the elements C, H, 0, and N up t o
mass numbers of 600, the second (545017 entries) gives
selected combinations of the elements C, H, 0, N, F, CI, Br,
I, S, P, Si, B, Ga, Fe, Sn, and Al up to mass numbers of
400./Analytic.Chemistry37,543(1965)/-Hz. [Rd 31 1/520 IE]
717
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pyrithiamine, mode, oxythiamine, thiamine, action, antagonisms, rat, brain
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