Synthesis and biological activity of substituted xanthines as DPP-IV inhibitors

In order to find more potential DPP-IV inhibitor, a series of xanthine-scaffold analogs of linagliptin, an approved antidiabetes drug, were designed and synthesized for SAR study. All compounds with a concentration of 50 nmol·L^-1 showed the inhibitory activity against DPP-IV enzyme in vitro, and the inhibition rate of compounds 1a, 1d and 1f was over 50%. Virtual docking was also performed to facilitate the SAR analysis of these substituted xanthines.