Phosphodiesterase 4B (PDE4B) inhibitors and their applications in recent years (2014 to early 2025).

The phosphodiesterase 4B (PDE4B) subtype, a member of the phosphodiesterase (PDE) family, plays a key role in promoting anti-inflammatory and antifibrotic effects by controlling the rate of cyclic adenosine phosphate degradation. To date, inhibitors targeting PDE4B have been widely used in the development of therapeutic agents for pulmonary fibrosis, inflammation, cancer, Alzheimer's disease, adipose tissue dysfunction and chronic liver injury. With the development of techniques such as molecular docking studies, more and more PDE4B inhibitors with different core scaffolds have been discovered, and at least six of these molecular structures have been approved for marketing or entered clinical studies. In this work, we reviewed the PDE4B inhibitors reported in the literature since 2014 and classified the most representative examples with different biological activities according to their structural characteristics. We also made a preliminary analysis of their structure-activity relationship based on the classification results and the conclusions reported in the relevant literature. In addition, we describe the inhibition selectivity of some compounds to PDE4B and PDE4D enzymes, as inhibition of PDE4D is often associated with side effects such as nausea and emesis. We hope that this work will help researchers in the design and optimization of novel PDE4B selective inhibitors and provide a reference for readers who are new to this field.