Structure-activity relationships for 4-anilinoquinoline derivatives as inhibitors of the DNA methyltransferase enzyme DNMT1.

A series of 4-anilinoquinoline derivatives related to the known inhibitor SGI-1027, containing side chains of varying pK(a), were prepared by acid-catalysed coupling of the pre-formed side chains with 4-chloroquinolines. The compounds were evaluated for their ability to reduce the level of DNMT1 protein in HCT116 human colon carcinoma cells by Western blotting. With a very strongly basic N-methylpyridinium side chain, only NHCO-linked compounds were effective, whereas less strongly basic ((diaminomethylene)hydrazono)ethyl or 3-methylpyrimidine-2,4-diamine side chains allowed both NHCO- and CONH-linked compounds to show activity. In contrast, the pK(a) of the quinoline unit had little apparent influence on activity.