Epimedium brevicornu flavonoids alleviate neuroinflammation and Alzheimer's disease pathology via immune-related pathways.

BACKGROUND: With global population aging, Alzheimer's disease (AD) has become a critical clinical challenge. This multifactorial neurodegenerative disorder is characterized by amyloid-β aggregation, tau hyperphosphorylation, and neuroinflammation. The lack of effective disease-modifying therapies highlights the urgent need for multi-target strategies. Epimedium brevicornu flavonoids (EF), derived from a traditional medicinal plant used to support cognitive function, exhibit significant neuroprotective potential; however, the underlying mechanisms remain to be fully elucidated. PURPOSE: To investigate the neuroprotective effects and underlying mechanisms of EF against lipopolysaccharide (LPS)-induced neuroinflammation and Alzheimer's disease-related pathology. METHODS: EF were extracted and quantitatively analyzed. Mice were pretreated with EF for 14 days before LPS injection (1.0 mg/kg). Behavioral performance was assessed using the Open field, Y-maze, and Morris water maze tests. EF components in extract, serum, and brain were characterized by UHPLC-QTOF-MS/MS. Network pharmacology and molecular docking were employed to predict active compounds, targets, and signaling pathways. ELISA, Western blot, and immunofluorescence were conducted to evaluate cytokine levels, microglial and astrocytic activation, Aβ42 deposition, tau phosphorylation, and NeuN+ neuronal density. The involvement of PI3K/AKT and cGAS-STING pathways was further validated. In BV2 microglia, NO release and iNOS/Iba1 as well as CD206/Iba1 expression were examined to verify anti-inflammatory effects of EF in vitro. RESULTS: A total of 127 components in EF were identified, among which 45 and 38 were detected in serum and brain, respectively. The key compounds showed favorable target binding (<-6.2 kcal/mol). EF markedly improved cognition performance in LPS-treated mice, suppressed systemic inflammation and neuroinflammation, inhibited glial activation, reduced APP/BACE1/Aβ42 expression and tau phosphorylation, and preserved neuronal integrity. Mechanistically, EF inhibited PI3K/AKT and cGAS-STING signaling pathways in vivo and promoted M2 polarization in BV2 microglia in vitro. CONCLUSION: EF confers neuroprotection against LPS-induced cognitive impairment, a process linked to the modulation of neuroinflammation, Aβ generation, and tau phosphorylation, and associated with PI3K/AKT and cGAS-STING signaling pathways. These findings highlight EF as a promising multi-target candidate for mitigating inflammation-driven AD-relevant pathological features.