Synthesis and potent inhibitory activities of carboxybenzyl-substituted 8-(3-(R)-aminopiperidin-1-yl)-7-(2-chloro/cyanobenzyl)-3-methyl-3,7-dihydro-purine-2,6-diones as dipeptidyl peptidase IV (DPP-IV) inhibitors

Fourteen 3-methyl-3,7-dihydro-purine-2,6-dione derivatives 1–14 bearing carboxybenzyl and 2-chloro/cyanobenzyl groups at the N-1 and N-7 positions, respectively, were synthesized as dipeptidyl peptidase IV (DPP-IV) inhibitors. These compounds were characterized on the basis of NMR (1H and 13C) and ESI MS data. In vitro bioassay indicates that most of these compounds showed moderate to good inhibitory activities against DPP-IV. Among them, compound 13 (IC50 = 36 nM) exhibited comparable activity with a positive control, Sitagliptin (IC50 = 16 nM). In addition, the structure–activity relationship of these compounds is also briefly discussed.

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