• α-Lipoic acid


The principal physiological function of lipoic acid appears to be its action as coenzyme in the oxidative decarboxylation of α-oxo acids. In order to find out whether lipoic acid is essential to higher organisms, structurally modified lipoic acids were prepared as potential antagonists. Only 4-oxalipoamide promotes the growth of S. faecalis 8043; the other substances tested are inactive or else inhibit growth. In experiments to determine the substrate specificity of lipoamide oxidoreductase and its inhibition by structurally modified lipoic acids, no strong inhibitors were discovered. –; Ring strain, spectra, and ring cleavage of compounds containing the 1, 2-dithiolane ring are discussed in relation to the biological function and the reactivity of lipoic acid.