Betulin supplementation reduces oxidative stress in Alzheimer's disease via the activation of KEAP1/NRF2 pathway.

Betulin (BE) is extracted from pentacyclic triterpenoids of many natural plants and has antioxidation activities. However, the neuroprotective effects and underlying mechanism of Betulin in Alzheimer's disease (AD) have remained limited. Integrate SuperPred, SEA, and Targeted Net databases, as well as KEGG pathway enrichment analysis, to predict and analyze BE-related target genes. Male APP/PS1 mice were treated intragastrically with Betulin for 4 weeks, followed by evaluation of cognitive function and pathological changes, and the levels of ROS, HO‑1, SOD2 and GPX4 were detected. Subsequently, molecular docking and molecular dynamics simulations were utilized to investigate the potential interaction between Betulin and KEAP1 protein, and KEAP1 mutant transfection was used to assess the involvement of KEAP1/NRF2 signaling in the antioxidant response to BE. Finally, KEAP1 and NRF2 protein levels were examined in the animal model. Our results showed that KEGG pathway enrichment analysis revealed that Betulin-related target genes were enriched in pathways associated with AD. Moreover, Betulin significantly alleviated cognitive impairment, neuronal damage, Aβ deposits and Tau phosphorylation in the APP/PS1 mice. Moreover, Betulin significantly increased GSH level, while significantly decreased MDA level. Meanwhile, Betulin significantly decreased ROS level, while significantly increased the levels of HO-1, SOD2, and GPX4 in vitro. Notably, molecular docking and molecular dynamics simulations suggested a potential interaction between Betulin and KEAP1, while KEAP1 mutant transfection attenuated the Betulin-induced increase in NRF2 and antioxidant proteins in vitro. Moreover, Betulin treatment was accompanied by decreased KEAP1 and increased NRF2 protein levels in APP/PS1 mice. These findings indicate that Betulin alleviates oxidative stress and modulates KEAP1/NRF2 signaling in AD models.