Tritium labeling of simple 7‐membered ring compounds

Abstract

Seven-membered ring compounds, from cylcoheptane to complex ring structures containing heteroatoms, substituents and fused phenyl rings, were labeled with tritium, using activated and adsorbed tritium. The 7-membered ring structures are generally stable towards reactions with tritium, which allows compounds like 1-benzosuberone, 1-am-2-methoxy-1cycloheptene, iminostilbene and clozapine to be labeled to reasonably high specific activities. The best method varies greatly from compound to compound. By optimizing the labeling conditions and use of efficient support exceptionally good results can be obtained. The Pd-on-alumina support gives consistently higher specific activity and less radioimpurity than other supports. Even molecules containing carbon-halogen bond and hydrogen bound to nitrogen can usually be labeled with tritium at stable positions and without dehalogenation.

Determinants of protein modification versus heme alkylation: inactivation of cytochrome P450 1A1 by 1-ethynylpyrene and phenylacetylene

“…7-Ethoxyresorufin and resorufin were from Pierce (Rockford, IL). [3H]1-EP (43 500 cpm/nmol) was synthesized by tritium exchange at the National Tritium Labeling Facility (Berkeley, CA) by Prof. Chin-Tzu Peng (21). The radiolabeled product was shown to be >90% pure by thin-layer chromatography.…”

Recent Developments in Tritium Incorporation for Radiotracer Studies

“…tritium labeling of several groups of substrates, including steroids [34], benzodiazepines [35], polycyclic aromatic hydrocarbons and simple hydrocarbons [36]. Products have been characterized by GC or HPLC analyses, and by 3 H NMR spectroscopy.…”

“…As a further guide to the importance of the radioactive isotopes of hydrogen (tritium, 3 carbon ( 14 C) as biological tracers, it is instructive to conduct a survey of MedLine publications over the period 1964-1999, for the following list of isotopes: 2 H, 3 H, 11 C, 13 C, 14 C, 13 N, 15 N, 16 O, 17 O, 18 O, 18 F, 19 F, 31 P, 32 P, 33 P, and 35 S. More than 200,000 publications are involved in such a survey. Almost 50% of these publications reference tritium, and another 21% involve 14 C, suggesting that almost 70% of published biomedical work involving H, C, N, O, F, P, and S isotopes over the past 36 years has been done with tritium and 14 C.…”