Previous studies on the indoloquinoline alkaloid, cryptolepine (2), revealed that it has antii- nfective properties among other activities. Using Structure–activity relationship (SAR) techniques, several ring-opened analogs of cryptolepine (3-phenylaminopyridinium and 3- phenylaminoquinolinium derivatives) were designed to improve the potency and lower the cytotoxicity shown by several of the precursor agents. Results indicate that these ring- ...