Cobalt chelate of bleomycin. I. Physicochemical properties and distribution in tumor bearing mice.

Abstract

Co chelate of bleomycin (Co-BLM) was inert to ligand exchange reaction and showed absorption at 450 and 580 nm, which indicated Co is trivalent. Co-BLM accumulated in tumor tissue more than BLM and other BLM metal chelates. In urine of 67Ga-BLM or 111In-BLM injected mice, most of the radioactivity was not bound to BLM. All radioactivity was attributable to BLM bound 57Co in urine of 57Co-BLM injected mice. In tumor tissue homogenate, most of the Co-BLM was present in cell nuclei, while BLM, CoCl2 and other BLM metal chelates distributed in supernatant fractions. Co-BLM may bind to DNA in tumor cells. As a tumor scanning agent Co-BLM is superior to BLM and other BLM metal chelates.