15-Tritiated synthesis

When specifically labelled compounds are required, direct chemical synthesis may be necessary. The standard techniques of preparative chemistry are used, suitably modified for small-scale work with radioactive materials. The starting material is tritium gas which can be obtained at greater than 98% isotopic abundance. Tritiated water can be made either by catalytic oxidation over palladium or by reduction of a metal oxide ... 

Nevin ST, Toth G, Weltrowska G, Schiller PW, Borsodi A. Synthesis and binding characteristics of tritiated TIPPi T], a highly specific and stable delta opioid antagonist. Life Sci (Pharmacol Lett) 1995 56 PL225-230. 

As of now no details of the synthesis of optically active tritiated compounds produced under microwave-enhanced conditions have been published. Another area of considerable interest would be the study of solvent effects on the hydrogenation of aromatic compounds using noble-metal catalysts as considerable data on the thermal reactions is available [52]. Comparison between the microwave and thermal results could then provide useful information on the role of the solvent, not readily available by other means. 

Synthesis of deuteriated and tritiated echinocandin B and anilinostearamide and the problem of HPLC isotope effects... 

Synthesis of di-tritiated 9-(0)-methano-A6<9a)-prostaglandin /7 methyl esters... 

Kandell and Bernstein published one of the earliest reports to suggest that bile acids also demonstrate DNA-damaging effects in eukaryotic cells. They showed that human foreskin fibroblasts underwent unscheduled DNA synthesis (indicating DNA repair), as measured by tritiated thymidine incorporation when cells were treated with increasing concentrations of sodium deoxycholate or chenodeoxycholate. Utilising mutant Chinese hamster ovary cells deficient in strand rejoining (EM9), the authors were able to demonstrate that the repair of deoxycholate-induced DNA damage was dependent on strand break repair capacity. 

Cell number frequency distribution of nuclear DNA content of cell population, protein content, protein synthesis (e.g., 14C-labeled methionine incorporation), DNA synthesis (e.g., tritiated thymidine incorporation), DNA stains (e.g., Hoechst 33 342 4, 6-diamidino-2-phe-nylindole, DAPI picogreen) mass tracker dyes (e.g., LysoTracker green for lysosomes, MitoTracker deep red for mitochondria, ER-Tracker blue-white DPX for endoplasmic reticulum)... 

The normal cell cycle consists of a definable sequence of evenfs fhaf characferize fhe growfh and division of cells and can be observed by morphological and biochemical means. The cell cycle is depicfed in Fig. 55.1. Two of the four phases of the cell cycle can be studied directly the M-phase, or mitosis, is easily visible using light microscopy because of chromosomal condensation, spindle formation, and cell division. The S-phase is the period of DNA synthesis and is observed by measuring the incorporation of tritiated thymidine into cell nuclei. 

Other Degraded Carotenoids. A new synthesis of the fungal sex hormone ( )-(7 , 9 )-trisporic acid B methyl ester (114) utilized as the key step a Michael-aldol sequence on the /3-keto-ester (115) to yield the highly functionalized cyclo-hexenone (116). The latter underwent Wittig reaction with the phosphonium salt (117) to give (114). After basic alumina-catalysed hydrogen exchange in tritiated... 

Experimental conditions have been found for oxidation of uridine 5 -(a-D-galactopyranosyl pyrophosphate) with D-galactose oxidase.265 The reaction product is the a-D-ga(acto-hexodialdose derivative (55). Analogous treatment of uridine 5 -(acetamido-2-deoxy-a-D-galactopy-ranosyl pyrophosphate), and subsequent reduction of the product with sodium borohydride-t, affords a convenient synthesis of the 6 -tritiated derivative.2656... 

Chloro-orr/2o-toluidine given orally to male mice at a dose of 200 mg/kg bw inhibited testicular DNA synthesis, as measured by tritiated thymidine incorporation (Seiler, 1977). 

Several applications of photoreactive peptides require the presence of a radionuclide to allow specific and sensitive detection of the photo-cross-linked conjugates. In several cases, radioiodination of tyrosyl moieties and radiolabeled Bolton-Hunter reagents have been used. However, the presence of a radiolabel within the benzophenone photophore is desirable, particularly when the objective is to identify the site of photo-insertion of benzophenone. To this end some radiolabeled, benzophenone-based compounds have been developed and used in peptide synthesis, in particular tritiated Phe(4-Bz) (Scheme 24)J2161 [1-14C-carboxy]-4-benzoylbenzoic acid,1221 and 4-benzoyl-(2,3-3H2)-dihydrocinnamic acid.[154l In addition, 4-(4-hydroxybenzoyl)phenylalanine (Scheme 25) has been directly radioiodinated with Na125I and Chloramine-T)151 ... 

Scheme 24 Synthesis of Tritiated lV-(tert-Butoxycarbonyl)-4-benzoylphenylalaninel2161...

By Reduction of Unsaturated Precursors The method of choice for labeling with tritium is the reduction of a suitable unsaturated precursor (containing a double bond, carbonyl group, etc.) with carrier-free tritium gas or tritiated metal hydrides. The major limitation of this method is the availability of a suitable unsaturated precursor of the desired compound. It is essential to carry out the synthesis in a non-hydroxylic solvent (dioxane, ethyl acetate, etc.). Reductions carried out in alcohol or water will lead to almost complete exchange of the tritium gas with the solvent. 

H]GR 168320 was developed as a (stably labelled) tritiated H3 antagonist and evaluated for its in vitro use as a radioligand for the H3 receptor [29], As has been shown for thioperamide, the tritium labels at the 2 and 5 position of the imidazole moiety and at the 4 position of the piperidine moiety are sensitive to exchange with hydrogen from the storage solution. [3H]GR 168320 is labelled at the cyclohexane, by a catalytic reduction with 3H2, no details about the synthesis have been published (scheme 11). [3H]GR 168320 was isolated with a specific activity of 4.8 Ci/mmol. 

The first problem was solved 133) through synthesis (followed by enzymatic degradation) of tritiated citric acid stereospecifically labeled in the pro-R branch, as indicated in Fig. 62. The starting material for this synthesis is the naturally occurring 5-dehydro-... 

Unscheduled DNA Synthesis in Mammalian Cells. The principle of this test is that it measures the repair that follows DNA damage and is thus a reflection of the damage itself. It depends on the autoradiographic measurement of the incorporation of tritiated thymidine into the nuclei of cells previously treated with the test chemical. 

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