Reduced benzimidazo[2,1-a]isoquinolines. Synthesis and cytotoxicity studies

6-Butyl-5,6-dihydrobenzimidazo[2,1-a]isoquinoline, 3,9- and 3,10-dimethoxy, and 3,9- and 3,10-dihydroxy analogs, and their quaternary salts were prepd. by a multistep route. Cytotoxicity against 55 cancer cell lines were measured in the National Cancer Institute screen. The quaternary salts of the dimethoxy derivs. were clearly the most active overall, with a mean graph midpoint (MGM) value of 2 μm. The activity of the title compd. was compared to that of dihydroxyindolo[2,1-a]isoquinoline-12-carboxaldehyde derivs.