Reduction of copper(II)-bleomycin: a model for in vivo drug activity.
The effect of aliphatic thiols, including glutathione, cysteine, and dithiothreitol, on the anaerobic reduction of Cu(II)-bleomycin was examined. At neutral pH, cysteine is more efficient in reducing Cu(II)-bleomycin than either dithiothreitol or glutathione, while at alkaline pH the rate of reduction with all three reagents increases substantially. A kinetic treatment suggests that 2 equiv of thiol is required for each mole of Cu(II)-bleomycin reduced. Material balance studies verify this stoichiometry. If anaerobic reduction of Cu(II)-bleomycin is carried out in the presence of Fe(II), iron is chelated by the drug. This metal-drug complex is capable of degrading DNA when O2 is introduced. The extent of DNA degradation, as measured by the release of malondialdehyde-like chromogens from the DNA, is directly dependent on the amount of Cu(II)-bleomycin reduced.
D000818:Animals; D001761:Bleomycin / Q000378:metabolism* / Q000494:pharmacology / Q000031:analogs & derivatives; D002417:Cattle; D003545:Cysteine / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D005978:Glutathione / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008954:Models, Biological; D010084:Oxidation-Reduction
C023502:copper bleomycin; C023503:iron bleomycin; D001761:Bleomycin; D004247:DNA; D005978:Glutathione; D003545:Cysteine; D004229:Dithiothreitol