5-Ethyl-2'-deoxyuridine. Cytotoxicity and DNA incorporation demonstrated with human leukemic cells and PHA-stimulated lymphocytes in vitro

5-Ethyl-2'-deoxyuridine (5EtdUrd) is a biologically active thymidine analogue. The cytotoxicity of 5EtdUrd was investigated with seven established human leukemia cell lines as well as with human peripheral blood PHA-stimulated lymphocytes. All types of leukemia cells were susceptible to the toxicity of 5EtdUrd as assayed with a [U-14C]-L-leucine incorporation system developed for this study. A 50% inhibition of leucine incorporation in 3-day cultures was induced by 1.3-3.8 microM 5EtdUrd with leukemic cells, but the concentration required to induce similar inhibition with PHA-stimulated lymphocytes was approximately was approximately 100-fold. The toxicity of 5EtdUrd seemed to require active DNA synthesis, since the inhibition of leucine incorporation became obvious only after the first 24 hours of culture. The DNA incorporation studies were based on a new isotopically labeled 5EtdUrd derivative, [2-14C]5EtdUrd, synthesized for this study in our laboratory. It was demonstrated for the first time that most of the radioactivity derived from [2-14C]5EtdUrd in DNA was in 5-ethyluracil. 5EtdUrd has a powerful antileukemic potency in vitro. Its effects against human leukemia in vivo remain to be tested.     

Metabolism of [2-14C]thymine and [2-14C]thymidine in germinating black gram (Phaseolus mungo) seeds

The metabolism of [2-14C]thymine and [2-14C]thymidine in the cotyledons and embryonic axes of black gram (Phaseolus mungo) seedlings was investigated. Both [2-14C]thymine and [2-14C]thymidine degraded extensively into [14C]CO2. The rate of release of [14C]CO2 from [2-14C]thymine was much greater than that from [2-14C]thymidine. Radioactivity from both precursors was also observed beta-ureidoisobutyric acid. This indicated that thymine was degraded by the reductive pathway of pyrimidine degradation. Small amounts of [2-14C]thymine and [2-14C]thymidine were salvaged for deoxyribonucleotide and DNA synthesis. The highest incorporation of [2-14C]thymine and [2-14C]thymidine into the DNA fraction was observed in 24 hour-old cotyledons where net DNA synthesis was not observed. These precursors seem to be utilised for DNA synthesis of organelles of the cotyledonary cells, probably mitochondria. In embronic axes, [2-14C]thymine is more effectively salvaged for DNA synthesis than [2-14C]thymine. The incorporation rate increased during the early phase of germination and attained its maximum at 48 h after which it decreased. No thymidine kinase activity was detected in either cotyledons or in the embryonic axes. Thymidine salvage seems to be catalysed by nucleoside phosphotransferase which is present both in the cotyledons and in the embryonic axes. This suggests that, in contrast to other pyrimidine and purine bases and nucleosides, no specific salvage system for thymine and thymidine is present in black gram seedlings.     

Synthesis of 1-(4-methylsulfone-phenyl)-5-(4-fluoro-phenyl)-5-[14C]-1,2,3-triazole and 1-(4-sulfonamide-phenyl)-5-(4-fluoro-phenyl)-5-[14C]-1,2,3-triazole as novel carbon-14 anticonvulsant

Summary Two 1,2,3-triazole anticonvulsants, 1-(4-methylsulfone-phenyl)-5-(4-fluoro-phenyl)-5-[¹⁴C]-1,2,3-triazole and 1-(4-sulfonamide-phenyl)-5-(4-fluoro-phenyl)-5-[¹⁴C]-1,2,3-triazole, both labeled with carbon-14 in the 5-position were prepared from para-fluoro-benzonitrile-[cyano-¹⁴C].     

Synthesis of 5-Hydroxymethyl-8-methyl-3-(3-aryl-[1,2,4]oxadiazol-5-yl)-2H-pyrano[2,3-c]pyridin-2-ones and Their Esters

New 5-hydroxymethyl-8-methyl-3-(3-aryl-[1,2,4]oxadiazol-5-yl)-2H-pyrano-[2,3-c]pyridin-2-ones and their esters were synthesized. The structure of obtained compounds was determined through a complete ¹H NMR analysis.     

Biosynthesis of the antibiotic verrucarin E use of [1-13C]-, [2-13C]-, [1,2-13C]- and [2-13C, 2-2H3]-acetates. Verrucarins and roridins, 37th communication [1]

The origin of the carbon skeleton of verrucarin E (1) from acetate as precursor is confirmed. Incorporation studies with [1,2-¹³C]-acetate have demonstrated that two acetoacetate units couple together as shown in pattern A (Scheme 2) and not as in B . Analysis of the deuterium distribution in both verrucarin E (1) isolated after the incorporation of [2-¹³C,2-²H₃]-acetate and in sodium acetate obtained after Kuhn-Roth oxidation of the metabolite demonstrated that C(7) is derived from the starter unit of one of the acetoacetate moieties. The deuterium exchange in verrucarin E (1) occurring during fermentation was investigated.     

The first organically templated thorium compounds, [C4N2H12]0.5[ThF5] and [C5N2H14][ThF6].0.5H2O

Organically templated thorium compounds were synthesized for the first time under hydrothermal conditions; the piperazine containing compound consists of 2-D layers, while the 2-methylpiperazine phase contains unprecedented 1-D chains of face-sharing ThF9 polyhedra.     

Access to 14C-Ring labelled phenothiazines. Synthesis of 2-chlorophenolhiazine-5a,9-14C

Through the use of a recently reported ring expansion reaction, a new route to phenolhiazines has been developed suitable for the preparation of ring labelled derivatives. As an example, the preparation of 2-chloropheno thiazine-5a,9-¹⁴C ( 1 ) is reported. Condensation of cyclohexanone-2-¹⁴C with 2-amino-4-chlorothiophenol gave the spiro-2,3-dihydro-l, 3-benzothiazole 4 which was protected by acetylation ( 5 ). Treatment of 5 with sulfuryl chloride gave the tetrahydro-phenothiazine olefin mixture 6 and 7 which was directly converted to labelled 1 via treatment with DDQ in refluxing benzene followed by hydrolysis of the acetyl group.     

Application of biosynthetic 13C-enrichment using [1-13C]-, [2-13C]- and [1,2-13C2]-acetate as precursor for 13C NMR spectral assignment of higher plant metabolites. The assignments of some bryonolic acid derivatives

The ¹³C NMR spectra of some derivatives of bryonolic acid (1) (D:C-friedoolean-8-en-3β-ol-29-oic acid) were assigned by means of ¹³C-enrichment, lanthanide-induced shifts (LIS) and comparison of chemical shift data between derivatives. The ¹³C-enriched species of 1, i.e., 1a, 1b and 1c were biosynthesized by Luffa cylindrica (Cucurbitaceae) callus fed with [1-¹³C]-, [2-¹³C]- or [1,2-¹³C₂]-acetate, respectively. Methyl acetylbryonolates 2, 2a, 2b and 2c, methyl bryonolates 3, 3a, 3b and 3c, methyl bryononates 4 and 4a, diacetyl-3β,29-diols (3,29-diacetyl-D:C-friedoolean-8-en-β,29-diol) 5, 5a, 5b and 5c, and 3-acetyl-3β,29-diols 6, 6a and 6b were prepared from 1, 1a, 1b and 1c, and their ¹³C NMR spectra were recorded. The ¹³C concentration of the ¹³C-enriched species was high enough to exhibit the satellite peaks clearly, and the analysed data were very useful for this study. Thus, total assignments for 2, 3, 4, 5 and 6 were established. It was found that conversion of the methoxycarbonyl group at C-29 into an acetoxymethyl group caused complex changes in the chemical shifts of the C, D- and E-ring carbons and those of the methyl carbons linked to these rings.     

Interaction of actinide ions with [NaP5W30O110]14- and [P2W18O62]6-

Stability constants (log b₁₀₁) of Th⁴⁺, UO₂ ²⁺, NpO₂ ⁺ and Am³⁺ with [NaP₅W₃₀O₁₁₀]^14- were determined by solvent extraction (m = 0.1M NaCl) and found to be 6.18±0.07, 3.80±0.06, 2.98±0.04, and 5.85±0.05, respectively. The order of stability constants: Th⁴⁺>Am³⁺>UO₂ ²⁺>NpO₂ ⁺ is due to electrostatic repulsion between the actinyl oxygens and oxygens on the polyoxometalate surface. The order of stability constants for metal complexes with [P₂W₁₈O₆₂]^6- is Th⁴⁺>UO₂ ²⁺>Eu³⁺>NpO₂ ⁺ because the steric repulsion between actinyl oxygens and oxygens on polyoxometalate are less important. Enthalpies of complexation were measured by calorimetric titration of Th⁴⁺, UO₂ ²⁺, Nd³⁺ with [NaP₅W₃₀O₁₁₀]^14- and [P₂W₁₈O₆₂]^6-. The results indicate that the conformation and charge distribution of the microscopic surface structures are important factors in the formation of pseudocolloids.     

Stereocontrolled synthesis of A C14-C20 building block for amphotericin B using a novel [2,3] wittig rearrangement

The C1₄-C₂₀ unit 11 of the polyene macrolide antibiotic amphotericin B (1) was synthesized from L-arabinose in 13 steps. The key step 7 → 10 features diastereocontrol through asymmetric induction in a novel [23] Wittig rearrangement.     

Synthesis of [n]- and [n.n]cyclophanes by using Suzuki-Miyaura coupling

Reaction of the bis-9-BBN adduct of several dienes with 1,3-dibromobenzene via Suzuki coupling leads to a series of [n]metacyclophanes ranging in size from 10 to 17 atom members. In each case, two carbon-carbon bonds are formed in one reaction vessel. However, when the bis-9-BBN adduct of 1,5-hexadiene is coupled with a variety of aryl dihalides, larger [n.n]cyclophanes were formed in preference to the [n]cyclophanes. Four carbon-carbon bonds are formed in this instance. Single-crystal X-ray analyses of these [n.n]cyclophanes reveal interestingly shaped molecules with large cavities.