The active ingredient of Ginkgo biloba extract (quercetin) improved H2O2-induced microglia injury by activating NQO1-PI3K/Akt/mTOR signaling.

Activated microglia are considered to be closely related to brain senescence and the pathogenesis of neurodegenerative diseases. Ginkgo biloba extract (GBE) is widely used to treat cognitive impairment and Alzheimer's disease (AD). This study aims to investigate the active ingredients of GBE and the underlying molecular mechanisms. The active ingredients of GBE in AD treatment were first analyzed by network pharmacology, culminating in the identification of the key ingredient, quercetin, and its targeted protein, NQO1. GO function enriched the oxidative stress pathway, while KEGG enriched the PI3K/Akt/mTOR pathway. Quercetin binding to NQO1 was verified by molecular docking and DARTS analysis. Cytotoxicity assay revealed no significant toxicity of GBE (0-1 mg/mL) and quercetin (0-0.4 μM) over 48 h. Subsequently, we constructed the microglial injury model by H₂O₂-induced HMC3 and BV2 cell lines. GBE and quercetin suppressed the senescence characteristics in H₂O₂-induced microglia. Further investigation revealed that the expression of NQO1 was downregulated in the injury model, and treatment with GBE and quercetin facilitated the protein expression of NQO1. In addition, silencing NQO1 reduced the promoting effect of quercetin on microglia viability and phosphorylation levels of PI3K, Akt, and mTOR. At the same time, it significantly increased the levels of p53, p21, p16 and β-galactosidase (SA-β-gal). Collectively, GBE mitigated H₂O₂-induced microglial injury, which activated the PI3K/Akt/mTOR pathway through the quercetin/NQO1 axis. These findings highlight quercetin/NQO1 signaling as a possible therapeutic target for senescence-related neurodegeneration.