Maduramicin [BSA]

The coccidiostat maduramicin has been approved as a feed additive for chickens and turkeys, although it is prohibited for use in laying hens. In the present study, laying hens were divided into three groups and fed for 14days with medicated feed containing maduramicin, at three different concentrations: 50, 100 and 500 mu gkg(-1). Eggs were collected during treatment and for 26days after the end of feeding with medicated feed. Maduramicin residues were found exclusively in egg yolk, with the highest concentration in egg yolk of 459 mu gkg(-1) for the highest dose. The maximum concentration of maduramicin in whole egg was 16.6 mu gkg(-1) for the group receiving feed containing the maximum permitted level of maduramicin in feed (50 mu gkg(-1)). The half-life of elimination of maduramicin, calculated for post-treatment days 1-10, was 6.5days. Twelve days after drug administration, the concentration of the maduramicin in egg yolk for Group 3 (fed with 500 mu gkg(-1) maduramicin) still exceeded 20 mu gkg(-1), while the concentrations for Groups 1 and 2 were 1.2 and 2.7 mu gkg(-1), respectively.

The polyether antibiotic maduramicin and its methyl ester derivative inhibited photophosphorylation and proton uptake in isolated spinach chloroplasts. Both compounds also enhanced basal and phosphorylating electron transport and stimulated Mg2+-dependent ATPase activity, therefore, they behave as uncouplers of photophosphorylation being the methyl ester derivative more potent than the parent compound. On the other hand, maduramicin inhibited germination and radicle elongation of several crop and weed species. In addition, the antibiotic caused phytotoxic injury and fresh weight reduction to 4-to-6 week old seedlings of two weed and two crop species when applied at 10(-4) M by foliar application in the greenhouse.