We describe the design, synthesis and evaluation of a series of N²,N⁴-diaminoquinazoline analogs as PDE5 inhibitors. Twenty compounds were prepared and these were assessed in terms of their PDE5 and PDE6 activity, ex-vivo vasodilation response, mammalian cytotoxicity and aqueous solubility. Molecular docking was used to determine the binding mode of the series and this was demonstrated to be consistent with the observed SAR. Compound 15 was the most active PDE5 inhibitor (IC₅₀ = 0.072 ± 0.008 µM) and exhibited 4.6-fold selectivity over PDE6. Ex-vivo assessment of 15 and 22 in a rat pulmonary artery vasodilation model demonstrated EC₅₀s of 1.63 ± 0.72 µM and 2.28 ± 0.74 µM respectively.

我们描述了一系列作为PDE5抑制剂的N ²，N ^4-二氨基喹唑啉类似物的设计，合成和评估。制备了二十种化合物，并根据它们的PDE5和PDE6活性，离体血管舒张反应，哺乳动物细胞毒性和水溶性对其进行了评估。分子对接用于确定该系列的结合模式，这被证明与观察到的SAR一致。化合物15是活性最高的PDE5抑制剂（IC ₅₀  = 0.072±0.008 µM），选择性是PDE6的4.6倍。大鼠肺动脉血管舒张模型中离体评估15和22显示EC ₅₀分别为1.63±0.72 µM和2.28±0.74 µM。