Production in vivo of falloff monosomes in mouse liver by sparsomycin

Enhancement of glutathione S-transferase activity in rat liver by repeated administration of propylthiouracil

Treatment of rats with propylthiouracil for one to two weeks caused an increase in glutathione S-transferase (GST) activity of the liver cytosol, but not of the particulate fraction. Increased GST activity was reversed two weeks after discontinuing PTU administration. Activation of the enzyme was inversely proportional to the decrease in leukocytes. Repeated administration of PTU increased the Vmax of the enzyme without affecting the Km value for the substrate 1-chloro-2,4-dinitrobenzene, whereas both the Km and Vmax for glutathione (GSH) were increased by PTU treatment. GSH content and GSH peroxidase activity were not affected by PTU, but this resulted in an increase in glucose 6-phosphate dehydrogenase activity. PTU treatment caused increase in GST activity using 1-chloro-2,4-dinitrobenzene, 1,2-dichloro-4-nitrobenzene, p-nitrobenzyl chloride, and benzalacetone as substrates; enzyme activity towards chlorodinitrobenzene was the highest.

Determination of sparsomycin in plasma and urine of the dog by means of reversed-phase high-performance liquid chromatography and first pharmacokinetic results

Sparsomycin--an antibiotic with marked cytostatic activity--was the subject of a clinical Phase I study in 1964. The structure of sparsomycin was elucidated in 1970 and its first total synthesis was reported in 1981. Here we describe a sensitive high-performance liquid chromatographic method of determination. The detection limit was found to be 10 ng/ml of plasma and 20 ng/ml of urine. With this procedure sparsomycin and isosparsomycin can readily be separated. In addition, we performed a first pharmacokinetic study in the dog and found a half-life time t1/2 beta of 1.1 h. Only 25% of the administered dose could be recovered in the urine as sparsomycin. We consider that by now many prerequisites for further preclinical studies have been achieved, and the results of these studies will determine whether sparsomycin deserves reintroduction into clinical use.