Constrained ( l-)- S-adenosyl- l-homocysteine (SAH) analogues as DNA methyltransferase inhibitors

Potent SAH analogues with constrained homocysteine units have been designed and synthesized as inhibitors of human DNMT enzymes. The five membered (2 S,4 S)-4-mercaptopyrrolidine-2-carboxylic acid, in 1a, was a good replacement for homocysteine. Optimization of 1a changed the selectivity profile of these inhibitors. Chloro substitution at the 2-position, compound 1b, retained potency against DNMT1 while N 6 alkylation, compound 7a, conserved DNMT3b2 activity. Potent SAH analogues with constrained homocysteine units have been designed and synthesized as inhibitors of human DNMT enzymes. The five membered (2 S,4 S)-4-mercaptopyrrolidine-2-carboxylic acid, in 1a, was a good replacement for homocysteine, while the corresponding six-member counterpart was less active. Further optimization of 1a, changed the selectivity profile of these inhibitors. A Chloro substituent at the 2-position of 1a, compound 1d, retained potency against DNMT1, while N 6 alkylation, compound 7a, conserved DNMT3b2 activity. The concomitant substitutions of 1a at both 2- and N 6 positions reduced activity against both enzymes.