A simple and sensitive method for the determination of the biological activity of bleomycin using isolated rat liver nuclei

Abstract

A simple biochemical method for the determination of bleomycin is presented. The assay is based upon a DNA polymerase response to DNA damage caused by bleomycin in an isolated rat liver nuclear system. In the presence of ascorbate, the assay is sufficiently accurate and reproducible to permit measurement of levels of bleomycin between 0.1 and 1.0 μM. The lowest detectable concentration is approximately 7.5 nM (10.5 ng/ml). In contrast to other reported assays, which require deproteinization of serum samples and other pretreatments prior to assay, this technique is directly applicable to small serum samples (20 μl). Since this assay is predicated upon the molecular mechanism of action of bleomycin, it should, therefore, provide a more meaningful and precise measure of biologic antitumor activity than other chemical methods.