Pharmacological mechanisms of fisetin in neurodegenerative disorders: regulation of neuroinflammatory, oxidative, and autophagic pathways.

Neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, and related progressive neurological conditions, are characterized by irreversible neuronal loss, cognitive impairment, and motor dysfunction. Accumulating evidence identifies chronic neuroinflammation as a critical contributor to disease initiation and progression. In particular, activation of the TLR-4/NF-κB signaling cascade in glial cells promotes excessive production of pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6, together with induction of COX-2, iNOS, oxidative stress, and apoptosis, thereby exacerbating neuronal injury. Current pharmacotherapeutic strategies largely provide symptomatic benefit without effectively targeting the underlying pathogenic mechanisms. Fisetin, a naturally occurring flavonoid abundantly present in strawberries, apples, and persimmons, has recently attracted considerable attention owing to its pleiotropic neuroprotective properties. Experimental evidence indicates that fisetin suppresses TLR-4/NF-κB-mediated neuroinflammatory signaling, attenuates microglial activation, and enhances endogenous antioxidant defense through modulation of the Nrf2 pathway. Moreover, fisetin regulates apoptosis-associated mediators, thereby preserving neuronal integrity and survival. Notably, emerging studies demonstrate that fisetin-mediated inhibition of the TLR-4/Akt/mTOR signaling axis promotes autophagy-dependent α-syn clearance and neurogenesis, particularly in Parkinsonian models, highlighting its potential disease-modifying effects. These multifaceted pharmacological actions suggest that fisetin simultaneously targets interconnected inflammatory, oxidative, apoptotic, and proteostatic pathways implicated in neurodegeneration. Despite promising preclinical findings, additional investigations are required to elucidate its effects on inflammasome activation, glial cell crosstalk, pharmacokinetic behavior, and long-term clinical safety. Collectively, fisetin represents a promising multi-target therapeutic candidate for the management of inflammation-associated neurodegenerative disorders.