Notably, under the assay conditions used in this work, 12 was about ten times more potent against DNMT1 than the positive control SAH (IC 50 = 340 nM). The structural analog 13 had a similar inhibitory activity profile with similar inhibitory potency but higher selectivity towards DNMT1 (IC 50 = 81 nM) over DNMT3A (IC 50 = 14,690 nM), and DNMT3B (IC 50 > 100,000 nM) (Figure and Table ).