Structure‐Guided Optimization of PDE9A Inhibitors Tackling Neuroinflammation: A Combined Computational and In Vitro Study

Oxidative stress and inflammation are key players in central nervous system (CNS) diseases and in neurodegeneration. In this field, the search for novel targets and therapeutic tools is wide open. In this study, the identification of potential inhibitors of phosphodiesterase 9 (PDE9), a target of growing interest in CNS diseases, was done by using a rational virtual screening approach that employed ligand- and structure-based methodologies. Furthermore, a novel method to evaluate PDE9A activity based on high-performance liquid chromatography (HPLC) was developed to address the need for a time- and cost-effective assay to evaluate inhibitors. One of the candidates identified by virtual screening demonstrated potent enzymatic inhibition, and subsequent in vitro tests proved its significant PDE9A-dependent anti-neuroinflammatory effects as it acted on pro-inflammatory mediators such as COX-2, IL-1β, TNFα, and IL-6. The results of this multidisciplinary study underscore the potential of developing PDE9A inhibitors to modulate cyclic guanosine monophosphate (cGMP) signaling pathways implicated in neuroinflammation and also potentially in synaptic plasticity and cognitive functions, paving the way for novel PDE9A-targeting inhibitors addressing neurodegenerative diseases.