�ber eine neue Form der Konjugation von Geninen im tierischen Stoffwechsel

Enzymatic Basis for Epimerization of Cardiotonic Steroids at Carbon 3 in Rat Liver*

“…The two possibilities must also be taken into account for the epimerization of cardioactive steroids in the animal body. In studies on the metabolic transformation of some genins by rat liver, carried out in vivo (Repke, 1962) and in vitro with liver slices (Lauterbach and Repke, 1960) or homogenates (this paper), their 3-keto derivatives were never found. This fact might speak in favor of the first possibility.…”

“…The epimerization of the genins, rather, can be regarded as a process of detoxification because the 3dehydro-and 3-epimetabolites exert biological effects which are much weaker or almost negligible in comparison with the parent compounds (Repke, 1961). The detoxification of the epi-derivatives is then completed by formation of their glucuronides (Lauterbach and Repke, 1960) or sulfates (Herrmann and Repke, 1962). On the whole, the short lifetime of aglycones in the body (Repke, 1962) apparently is due to the rapid processes of epimerization and conjugation as pictured in Figure 2.…”

“…The detoxification of the epi-derivatives is then completed by formation of their glucuronides (Lauterbach and Repke, 1960) or sulfates (Herrmann and Repke, 1962). On the whole, the short lifetime of aglycones in the body (Repke, 1962) apparently is due to the rapid processes of epimerization and conjugation as pictured in Figure 2. Hence, these detoxification processes may explain the extremely transistory nature of biological effects which distinguish genins afrom glycosides.…”