MADURAMICIN - RAT-METABOLISM OF A HIGHLY POTENT POLYETHER ANTICOCCIDIAL EXAMINED BY C-13 NMR

Maduramicin is unique among the agriculturally important polyether ionophore antibiotics in that its structure contains a sugar moiety. Exclusively the parent compound (36%) and a single metabolite (64%) are detected in rat liver tissues at 0-day withdrawal after administering carbon-14-labeled maduramicin in feed at 5.2 ppm for 1 week. A single oral dose of 1 mg to 12 rats provided 3 mg of the metabolites in a pure form. Although this material was not the same as the major metabolite found in chicken liver (produced by the O-demethylation of one two methoxy groups not attached to the sugar moiety), mass spectroscopy shows that it is an isomer. Carbon-13 NMR spectroscopy shows that it is an isomer. Carbon-13 NMR spectroscopy shows that it is an isomer of the major chicken metabolite in which O-demethylation occurs selectively at the sugar moiety.