Cinchonidine, a Natural Quinoline Alkaloid, Attenuates Ischemic Neurovascular Injury Through Blood–Brain Barrier Preservation

Background/Objectives: Ischemic stroke remains a major global health challenge, yet therapeutic options are severely restricted by narrow treatment windows and the risk of hemorrhagic transformation. Natural small molecules represent a valuable reservoir for discovering novel neuroprotective leads with favorable safety profiles. Cinchonidine, a natural quinoline alkaloid, has shown anti-inflammatory and cytoprotective properties, but its potential in treating ischemic stroke is largely unexplored. This study aimed to evaluate the neurovascular protective effects and hemostatic safety of cinchonidine in preclinical stroke models. Methods: We evaluated cinchonidine using a mouse model of middle cerebral artery occlusion (MCAO) and in vitro oxygen–glucose deprivation (OGD) models in cerebral endothelial cells (CECs) and Neuro2A cells. Infarct volume, brain edema, and neurological recovery were assessed. Blood–brain barrier (BBB) integrity was measured via Evans blue extravasation. Mechanistic markers, including microglial activation, pro-inflammatory mediators (iNOS, COX-2), and apoptosis-related signaling, were examined. Additionally, cinchonidine’s effect on platelet aggregation was also tested. Results: Cinchonidine significantly reduced infarct volume and brain edema while improving neurological functional recovery. It effectively preserved BBB integrity and enhanced cell viability under OGD conditions. Furthermore, cinchonidine suppressed microglial activation and decreased the expression of pro-inflammatory mediators. These protective effects were associated with the modulation of apoptotic signaling pathways. These protective effects were accompanied by reduced p53-associated stress signaling in endothelial cells and ischemic brain tissue. Importantly, cinchonidine did not significantly interfere with platelet aggregation, suggesting a potentially favorable hemostatic profile. Conclusions: Cinchonidine attenuates ischemic brain injury and is associated with endothelial protection, preservation of BBB integrity, and modulation of inflammatory and apoptotic responses. As a natural lead compound that does not compromise hemostasis, cinchonidine represents a promising lead compound for further development as a neurovascular protective strategy in ischemic stroke.