Transcription‐Inhibition and Antitumor Activities of N‐Alkylated Tetraazacyclododecanes

A series of alkyl-substituted tetraazacyclododecane congeners were synthesized, and their antitumor activities towards human HeLa cells as well as their effect on the in vitro transcription with T7 RNA polymerase were investigated. A structure-activity-relationship (SAR) study identified the most-active congeners as those with medium alkyl-chain lengths. Three compounds, 5-7, were found to exhibit significant biological activities, with IC50 values towards HeLa cells in the low-micromolar range.