Our previous discovery of pyrazolo [1,5-a]pyrimidin-7(4H)-one scaffold-based DPP-4 inhibitors yielded two potent compounds b2 (IC₅₀ = 79 nM) and d1 (IC₅₀ = 49 nM) but characterized by cytotoxicity. Herein, with scaffold hopping and fragment-based drug design strategies, highly potent and selective pyrazolo [1,5-a]pyrimidine DPP-4 inhibitors were found featured by reduced or diminished cytotoxicity. Specifically, c24 (IC₅₀ = 2 nM) exhibits a 25 to 40-fold increase of inhibitory activity respect to those of b2 and d1, respectively, 2-fold from Alogliptin (IC₅₀ = 4 nM), and remarkable selectivity over DPP-8 and DPP-9 (>2000 fold). Further docking studies confirmed that the pyrazolo [1,5-a]pyrimidine core interacts with the S1 pocket whereas its substituted aromatic ring interacts with the sub-S1 pocket. The interactive mode in this case resembles that of Alogliptin and Trelagliptin. Further in vivo IPGTT assays in diabetic mice demonstrated that c24 effectively reduces glucose excursion by 48% at the dose of 10 mg/kg, suggesting that c24 is worthy of further development as a potent anti-diabetes agent.

我们先前发现的吡唑并[1,5 - a ]嘧啶7 （4H） -一种基于支架的DPP-4抑制剂产生了两种有效的化合物b2（IC ₅₀  = 79 nM）和d1（IC ₅₀  = 49 nM），但其特征是通过细胞毒性。在本文中，通过支架跳跃和基于片段的药物设计策略，发现高效或选择性的吡唑并[1,5 - a ]嘧啶DPP-4抑制剂具有降低或减少的细胞毒性的特点。具体而言，c24（IC ₅₀  = 2 nM）的抑制活性是b2和d1的25至40倍分别是Alogliptin的2倍（IC ₅₀  = 4 nM）和对DPP-8和DPP-9的显着选择性（> 2000倍）。进一步的对接研究证实，吡唑并[1,5- a ]嘧啶核与S1袋相互作用，而其取代的芳环与sub-S1袋相互作用。在这种情况下，交互模式类似于阿格列汀和Trelagliptin。在糖尿病小鼠中进一步的体内IPGTT分析表明，c24在10 mg / kg的剂量下可有效减少48％的葡萄糖偏移，这表明c24作为有效的抗糖尿病药值得进一步发展。