Volume 20, Issue 11

Die Protonenresonanz-Signale von Tetramethylsilan, Benzol und Chloroform wurden in 60 verschiedenen Lösungsmitteln gemessen. Auf die Signalverschiebungen haben fünf Medieneffekte Einfluß: 1. Die magnetische Suszeptibilität, 2. die Van -der - Waalssehe Wechselwirkung, 3. die magnetische Anisotropie, 4. die elektrische Polarisierung und 5. die Wasserstoffbrückenbildung. Die Wasserstoffbrücken-Verschiebung wurde beim Chloroform im Zusammenhang mit der magnetischen Suszeptibilität des Mediums untersucht. Es besteht eine charakteristische Korrelation zwischen Stärke der Wasserstoffbrücke und Orbital-Dipolmoment des Protonenacceptor-Elektronenpaars. Bei dem angewandten Untersuchungsverfahren lassen sich sterische Effekte der Assoziationsbehinderung gut studieren.

NMR-spektroskopisch wurde festgelegt, daß aus 3-Methyl-papaverin unter den Bedingungen der Coralyn-Reaktion das 6′-Aceto-Derivat entsteht. Die Untersuchungen ergaben, daß weder in Benzylisochinolinen und 3.4-Dihydro-benzylisochinolinen noch in den Salzen dieser Verbindungen eine Benzyl-Benzal-Tautomerie vorliegt.

The question of whether the oxygenation pattern of the B-ring of flavonoids is determined at the cinnamic acid stage or at the stage of a C 15 -intermediate remains to be solved. 3.4.2′.4′.6′Penta-hydroxychalcone-2′-glucoside-[β- 14 C] (I) was synthesized and the incorporation of I and of 4.2′.4′.6′ Tetra-hydroxychalcone-2′ glucoside-[β 14 C] (II) into quercetin and cyanidin in buckwheat seedlings was compared in parallel experiments. The percentage incorporation of II into quercetin was about 35 per cent higher than that of I, whereas the incorporation rates and dilution values of both chalcones into cyanidin were about equal. These findings are discussed in the light of earlier results. It is concluded that in the case of asters, buckwheat and red cabbage the 3′-hydroxyl group in ring B is in all probability not introduced until after the formation of a chalcone intermediate. These results are compared with those obtained by other workers with different plants.

Bei der UV-Bestrahlung von Uracil-[5.6- 3 H] bilden sich je nach eingestrahlter Energie dimeres Uracil und Uracil-Wasseranlagerungsprodukt [5.6-Dihydro-6-hydroxyuracil] als radioaktive Photoprodukte. Während bei der Synthese des Wasseranlagerungsproduktes ein beträchtlicher sekundärer Isotopeneffekt wirksam wird, verändert sich die Radioaktivität des dimeren Uracils gegenüber der des Ausgangsuracils kaum. Wird das Wasseranlagerungsprodukt durch Erwärmen zu Uracil zurückgewandelt, so dehydratisiert das Molekül ebenfalls unter Mitwirkung eines Isotopeneffektes. Wird das Uracildimere zu Uracil rückgewandelt, so beobachtet man keinen Isotopeneffekt. Bei der Bestrahlung von Uracil in Tritium-haltigem Wasser werden nur sehr geringe Radioaktivitäten in die Photoprodukte eingebaut. Der Isotopeneffekt beträgt ca. 8. — Durch Synthese der Photoprodukte aus spezifisch an C-5 oder C-6 Tritium-markiertem Uracil bzw. durch Bromierung von 5.6-Tritium-markiertem Uracil bzw. dessen Photoprodukten zu den 5-Brom-Derivaten erhält man Hinweise, daß der Geschwindigkeits-bestimmende Schritt der Wasseraddition an C-6 des Uracils verläuft. Die inversen sekundären Isotopeneffekte betragen für Tritium an C-6 etwa 0,65, für Tritium an C-5 dagegen nur 0,95.

The cytolytic activity of lysolecithin (LL) has been found to be dependent on lysophosphatidespecific enzymes in the cell membrane. The present report deals especially with the analyses of an acyltransferase (LL → lecithin) and of a phospholipase B (LL → glyceryl-phosphoryl-choline) in various cells. It was found that changes in the enzyme activities — as mediated by changes of temperature, of pH, by enzyme inhibitors, or by sensitization of cells with antibody and components of complement — at the same time cause changes of the cytolytic activity of LL. The enhanced LL-cytolysis at reduced temperatures, as well as after addition of p-chloro-mercuri-benzoate (PMB), can accordingly be explained by the inhibition of lysophosphatide-specific enzyme (s) in a way that LL will consequently be of enhanced and/or prolonged action. The PMB-inhibited enzymes can be reactivated by cysteine and concomitantly the extent of LL-cytolysis is reduced. With the aid of C 14 -lysolecithin it was demonstrated that the concentration of ATP and coenzyme A in the cell is of prime influence in the dynamics of LL, which either will be transformed into membrane-fixed lecithin — and thus additionally stabilizing the cell — or will be degraded to glyceryl-phosphoryl-choline. This regulating mechanism would explain the different sensitivity of fresh and aged cells towards LL-lysis. The described experiments were done with erythrocytes. Preliminary experiments suggest that the same mechanism occurs also in nucleated cells and in bacteria. In view of the lysolecithin theory of complement-mediated cytolysis (FISCHER and HAUPT) the relative activity of lysophosphatide-specific enzymes in cell membranes offers a possible explanation for the different sensitivity of many types of cells towards lysis by complement. On the basis of these results, the significance of lysophosphatides as regulators of hemo- and cytodynamics, as postulated in the thirties by BERGENHEM and FAHRAEUS, is again underlined.

The intestinal absorption of cyanocobalamin and aquocobalamin was measured in human beings after the oral application of 50, 100, 200 and 500 μg doses with a whole body retention test using a 4 π large volume radioactivity detector with organic scintillator. Cyanocobalamin and aquocobalamin are absorbed in man to the same degree after physiological oral doses (0.1 — 1 μg) as after unphysiologically high oral doses (50 — 500 μg). The absorption rate decreases from 4.2% (after 50 μg) to 1.2% (after 500 μg) with increasing oral dose. The daily oral uptake of 200 μg in a single dose or 50 μg twice as cyanocobalamin or aquocobalamin covers the whole body vitamin B 12 requirement of 2.55 μg vitamin B 12 /day for man. Although cyanocobalamin and aquocobalamin are artifical products not existing in nature they are easily converted within the human body into the C 5 ′-deoxyadenosyl — or coenzyme — derivative of vitamin B 12 which is the original storage and bioactive form of vitamin B 12 in mammals. Cyanocobalamin and aquocobalamin are of equal value in the prophylactic and therapeutic application of vitamin B 12 in medicine.

The intestinal absorption of pure 60 Co-cyanocobalamin was measured in human beings in the dose range between 0.10 and 100,000 µg with the radio-vitamin B 12 -absorption-whole body retentiontest. The 60 Co-vitamin B 12 -whole body-retention was measured within the 200 cm long 4 п detector geometry of a large volume radioactivity detector with liquid organic scintillator. The estimated intestinal 60 Co-vitamin B 12 absorption in man can be described for the whole dose range (0.10 —100,000 µg) by two equations which contain expressions for the intrinsic factordependent vitamin B 12 absorption and the diffusion absorption of vitamin B 12 [see equations (1) and (2) ]. It is evident from these equations that intrinsic factor-dependent vitamin B 12 -absorption is limited to 1.5 µg B 12 /dose whereas the diffusion absorption of vitamin B 12 approaches but never exceeds 0.90% of the oral dose. The diffusion absorption rate can be used together with the vitamin B 12 -whole body turnover rate (~ 2.6 µg/day) as an experimental basis for an efficient oral vitamin B 12 -therapy with high doses.

Mit Hilfe von zwei unabhängigen physikalischen Methoden wird der O 2 -Druck beim Umschlag des Stoffwechsels gemessen. Er beträgt etwa 130 mm Wasser. Wenn dieser niedrige O 2 -Druck auf die Zellen, während sie wachsen, einwirkt, schlägt der embryonale Stoffwechsel in Krebsstoffwechsel um.

The synthesis and the properties of three cytostatic amino acid esters of 9.10-phenanthrahydroquinone are described. These substances, 9.10-Bis-glycyloxy-phenanthrene-bis-hydrobromide, 2-Nitro-9.10-bis-glycyloxy-phenanthrene-bis-hydrobromide and 2-Glycylamino-9.10-bis-glycyloxy-phen-anthrene-tris-hydrobromide are soluble in water.

Isolated chloroplasts and chloroplast-fragments of different structural state characterized by electron microscopy were irradiated with X-rays. The resistance of Hill- activity and phosphorylation coupled with ferricyanide is strongly dependent on the structural state of chloroplasts and thylakoids influenced by isolation media or by treatment with hypotonic media or digitonin. Whole chloroplasts are more resistant than free membrane systems without stroma and envelop. If free membrane systems were suspended in media of low salinity (broken chloroplasts) the rate of oxygen evolution and of phosphorylation decreases with a factor of 3.8 or 3.0 respectively after irradiation. Hill- reaction and phosphorylation are suppressed successively by washing the particles in hypotonic media or by treatment with digitonin. However, the sensitivity of oxygen evolution against X-rays remains constant in the washed particles whereas the rate of ATP-formation further decreases. As demonstrated by dose effect curves low intensities of X-rays activated the Hill- activity for all fractions. The results are discussed in relation to the integrity of chloroplasts and the state of membrane (thylakoids) as carrier for the systems of Hill - reaction and phosphorylation.

14 C-markierte C 3 -Verbindungen. wie Glycerin, Glycerinaldehyd, Glycerinsäure und Pyruvat werden vorwiegend in den Pyridinring der von Mycobacterium tuberculosis Stamm BCG gebildeten Nicotinsäure eingebaut. Entsprechende Abbauversuche ergeben, daß Glycerin bevorzugt in die C-Atome 4, 5 und 6 der Nicotinsäure inkorporiert wird. Danach erfolgt in diesem Organismus die Biosynthese der Nicotinsäure aus Asparaginsäure und einem C 3 -Körper wie Glycerin.

Nach massenspektroskopischen, NMR- und IR-Untersuchungen sowie dem Abbau erweist sich Planasäure als Dimethyläther-perlatolinsäure (I).