Neuroprotective role of cyanidin in Alzheimer's and Parkinson's disease: current insights and the road ahead.

Neurodegenerative diseases (NDs), including Alzheimer's disease (AD) and Parkinson's disease (PD), are characterized by progressive neuronal loss within the central nervous system, affecting more than 64 million individuals worldwide. Degeneration of cholinergic and dopaminergic neurons leads to cognitive impairment, motor dysfunction, and neuropsychiatric disturbances. Currently available pharmacotherapies provide only symptomatic relief, largely targeting single mechanistic pathways without halting disease progression. Increasing evidence supports the therapeutic potential of plant-derived bioactive compounds owing to their multitargeted pharmacological properties. Among these, cyanidin (CN), a naturally occurring flavonoid, exhibits potent antioxidant, anti-inflammatory, anti-apoptotic, and senolytic activities. CN has been shown to mitigate mitochondrial dysfunction and protect cholinergic and dopaminergic neurons, thereby addressing key pathological features of AD and PD. However, its clinical translation is limited by poor aqueous solubility (log P 2.41), reduced systemic bioavailability, and inadequate brain penetration. Nanotechnology-based novel drug delivery systems (NDDS), including lipid-based, polymeric, and inorganic nanoparticles, offer promising strategies to enhance CN solubility, stability, bioavailability, and blood-brain barrier permeability. This review discusses the pathophysiological mechanisms of AD and PD, the neuroprotective potential of CN, limitations associated with its conventional delivery, and the emerging role of nanoformulations in optimizing brain-targeted therapy.