Neuroprotective effects of quercetin in animal models of neurodegenerative diseases: A systematic review and meta-analysis.

Neurodegenerative conditions such as Alzheimer's disease and Parkinson's disease are characterized by progressive neuronal loss driven by oxidative stress and inflammation. Quercetin, a dietary flavonoid with established antioxidant and anti-inflammatory properties, has emerged as a potential neuroprotective agent. This study aimed to quantitatively synthesize and evaluate preclinical evidence regarding the impact of quercetin on neurodegenerative biomarkers and cognitive performance. A comprehensive literature search was conducted using PubMed, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL). After strict screening and selection, 19 studies were included. These evaluated the effects of quercetin on: Morris water maze (MWM) performance; inflammatory cytokines - including interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and interleukin-10 (IL-10); the oxidative stress marker malondialdehyde (MDA); antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), and glutathione (GSH); brain-derived neurotrophic factor (BDNF); and acetylcholinesterase (AChE) activity. Subgroup analyses based on quercetin dose (<100 mg kg⁻¹ versus ≥100 mg kg⁻¹) and treatment duration (<28 versus ≥28 days) were performed. Quercetin improved cognitive performance significantly by reducing escape latency and improving performance on memory retention indicators. It decreased pro-inflammatory cytokines (IL-6 and TNF-α), increased IL-10, enhanced antioxidant enzyme activity (CAT, SOD, and GSH), reduced MDA levels, up-regulated BDNF, and inhibited AChE. Subgroup analyses suggested that quercetin exerted stronger effects at lower doses and with longer treatment durations, although not all subgroup differences were statistically significant. Quercetin demonstrated multi-targeted neuroprotective effects in animal models, improving cognition and modulating inflammatory, oxidative, and neurotrophic pathways. These findings support the potential of quercetin as a therapeutic agent for neurodegenerative diseases, warranting further clinical investigation. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.