PDE4B-IN-3 is a potent PDE4B inhibitor with an IC50 of 0.94 μM. PDE4B-IN-3 has anti-inflammatory activities.In Vitro: PDE4B-IN-3 (compound f4) has good inhibitory activity on the production of NO, TNF-α and IL-1β with IC50 values of 20.40 μM, 23.48 μM, and 18.98 μM in RAW264.7 cells. PDE4B-IN-3 could also inhibit the expression of iNOS and COX-2 in RAW264.7 cells.In Vivo: In vivo studies shows that PDE4B-IN-3 (compound f4; 10-30 mg/kg) could improve the degree of foot swelling and knee joint pathology in adjuvant-induced arthritic rats and decrease the levels of serum inflammatory factors TNF-α and IL-1β in a dose-dependent manner.