Table 1.

Chemical structures and affinity of compounds with PDE9A

Compounds	R	R′	IC50 (µM)
26			0.721 ± 0.096
27			0.052 ± 0.008
28			0.021 ± 0.005
29			0.696 ± 0.059
30			0.595 ± 0.071
31			0.237 ± 0.055
32			0.308 ± 0.057
33			0.204 ± 0.022
34			7.51 ± 0.88
35			7.47 ± 0.93