The synthesis, stability and biological activity of bis-intercalating bis-daunomycin hydrazones

The synthesis of a series of bis-daunomycin hydrazones (5a-g)--all moderately stable at 37 degrees C, pH 6.8, with a half-life of approximately 30 h--is reported. Under a pulse exposure of 2 h they exhibited growth inhibition of mouse L1210 cells, and were 2-3 fold more active than daunomycin. Under continuous exposure growth inhibition conditions with human colon cell lines (HT-29 and HCT-8) they hydrolysed to daunomycin and a partially hydrolysed mono-derivative of daunomycin, and there was no apparent increase in activity over that of the parent anthracycline. Their rate of hydrolysis was observed to increase rapidly with decreasing pH.