[Formation of free radicals during interaction of adriamycin and carminomycin with xanthine oxidase].

Xanthine oxidase reduces carminomycin and adriamycin to the semiquinones which have been detected by ESR technique. The steady state carminomycin semiquinone concentration is some tens times higher than the corresponding value for adriamycin. This effect appears to be a result of carminomycin semiquinone stabilization due to internal hydrogen bonding.