A review on thymoquinone: a promising therapeutic molecule in Alzheimer's

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by memory loss, cognitive decline, amyloid-$\beta$ deposition, tau pathology, oxidative stress, and neuroinflammation. Thymoquinone (TQ), the principal bioactive constituent of Nigella sativa (NS), has emerged as a promising candidate for AD management because of its neuroprotective properties. This review summarizes current evidence on the therapeutic potential of TQ in AD, with emphasis on its antioxidant, anti-inflammatory, anti-amyloid, anti-tau, and cholinergic-modulating actions. Experimental studies indicate that TQ can reduce oxidative damage, suppress NF-$\kappa$B- and TLR-associated inflammatory signaling, limit amyloid-$\beta$ accumulation, modulate tau-related pathology, and improve neuronal survival and cognitive performance in several AD models. The review also discusses delivery strategies to improve the bioavailability and brain targeting of TQ, including nanoformulation-based approaches. Although the available pre-clinical findings support the therapeutic promise of TQ. The well-designed clinical studies are required to establish its efficacy, safety, optimal dosing, and long-term translational value in treating AD.