BRL-50481 is a novel and selective inhibitor of PDE7 with IC50s of 0.15, 12.1, 62 and 490 μM for PDE7A, PDE7B, PDE4 and PDE3, respectively.

PDE7A:0.15 μM, PDE3:490 μM, PDE7B:12 μM, PDE4:62 μM

BRL-50481 increases the cAMP content (19.1±6.2% of IBMX response at 300 μM) but is considerably less potent. BRL-50481 (30 μM) fails to suppress proliferation by itself but significantly potentiates the effect of rolipram. BRL-50481 (30 μM) has no effect on IL-15-induced proliferation but augments the inhibitory effect of rolipram. Pretreatment (30 min) of human monocytes with BRL-50481 has, by itself, a negligible (~2 to 10%) inhibitory effect on TNFα output at all concentrations tested. BRL-50481 also potentiates the inhibitory effect of PGE2 on LPS-induced TNFα release. BRL-50481 has no significant effect by itself on κB-dependent transcription (5.6±1.9% inhibition at 30 μM) and fails to enhance the effect of rolipram (maximum inhibition, 52.9±2.7%; pIC30 value of 5.33±0.12). BRL-50481 suppresses, in a concentration-dependent manner, LPS-induced TNFα release in monocytes in which PDE7A1 is induced (21.7±1.6% inhibition at 30 μM at the 12-h time point) [2].

MOLT-4 cells in 96-well plates are treated for 30 min with BRL-50481. The cAMP content is then determined by an immuno-specific ELISA. Results are expressed as a percentage of the response affected by 100 μM IBMX[2].