Naphthalimide intercalators with chiral amino side chains: Effects of chirality on DNA binding, photodamage and antitumor cytotoxicity

Several novel heterocyclic-fused naphthalimides intercalators with chiral amino side chains were investigated. Their side chains' chiral configuration determines DNA binding activities in the order: S-enantiomers > R-enantiomers. And their DNA photodamaging activities were in good agreement with their DNA binding constants, the S-enantiomers could photocleave circular supercoiled pBR322 DNA more ef.ciently than their R-enantiomers. S-enantiomer B-3 could photodamage DNA at 0.2 mu M and cleave supercoiled plasmid DNA from form I to form II completely at 50 mu M. Almost all of these intercalators showed effective cytoxicities against human lung cancer cells and murine leukemia cells. S-enantiomers showed different antitumor cytotoxicity by comparison with R-enantiomers. This work may provide additional information for the role of amino side chains on intercalators as antitumor agents. (C) 2008 Elsevier Ltd. All rights reserved.