Steroidal alkaloid H89712 ameliorates neuroinflammation and memory deficits: Enhancing cerebral oxidative phosphorylation in APP/PS1 mice

AIMS: Alzheimer's disease (AD) poses a major health challenge with limited therapeutic options. This study aimed to investigate the anti-AD potential and underlying mechanism of a novel steroidal alkaloid, H89. MATERIALS AND METHODS: In vitro, Aβ₂₅₋₃₅-exposed HT-22 hippocampal neurons and LPS-stimulated BV2 microglia were used to assess H89 neuroprotection and anti-inflammatory activity. In vivo, 6-month-old APP/PS1 mice were orally administered H89 for 2 months. Spatial memory was assessed by Y-maze (YM) and Morris water maze (MWM). Hippocampal morphology, neuronal apoptosis (TUNEL/NeuN), Aβ deposition (IHC), microglial activation (Iba1), inflammatory cytokines (ELISA), and oxidative phosphorylation (RNA-seq, qRT-PCR, Western blot) were examined. Brain malondialdehyde (MDA), ATP, and cellular ROS were quantified. KEY FINDINGS: H89 (10 and 50 nM) significantly protected HT-22 cells against Aβ₂₅₋₃₅-induced injury and attenuated LPS-induced TNF-α, IL-1β, and IL-6 secretion while elevating IL-10 in BV2 cells. In APP/PS1 mice, H89 increased novel arm exploration in the YM and target quadrant residence in the MWM, indicating improved spatial learning and memory. H89 ameliorated hippocampal neuronal morphology, reduced apoptosis, attenuated Aβ plaques and microglial activation (Iba1), decreased TNF-α, IL-6 and MDA, and elevated IL-10 and cerebral ATP. Transcriptomic and molecular analyses confirmed that H89 upregulated oxidative phosphorylation-related genes and proteins (ATP5E, ATP5J2, NDUFA13, NDUFB3, COX7C, COX11). Cerebral ATP positively correlated with spatial memory but negatively correlated with neuroinflammation and oxidative stress. SIGNIFICANCE: H89 exerts neuroprotective effects by enhancing mitochondrial oxidative phosphorylation and brain energy supply, concurrently suppressing neuroinflammation, oxidative stress, and neuronal apoptosis, suggesting its potential as a therapeutic candidate for AD.