Labelled fatty acids. Synthesis and biological behaviour. A review

Fatty acids (FA) are one of the main sources of energy production in mammals and their physiological and biochemical fate has therefore been extensively studied. Recently new attention has been focussed on these compounds because, if labelled with a suitable γ-emitting radionuclide, they may be used to monitor part of the energy producing metabolism in vivo. This paper tries to review how such γ-labelled FA are being made and what the effect of labelling is on the biological behaviour. In principle it would be desirable to use an isotope of one of the elements which naturally occur in FA (C, H, O); but then only 11C may be used, and this restricts its applicability to a few institutes with suitable equipment (a particle accelerator such as a cyclotron, for the production of the nuclide, and a positron emission tomograph for the measurement of the radiation). Moreover only very fast processes can then be studied, because of the 20 min. half life of the isotope. For this reason labelling with radiohalogens (F, Cl, Br, I) and 123m-Te is also considered. (Auth.)