NeuproGemp, a Polyphenol-Rich Botanical Formula, Ameliorates Alzheimer's-like Pathology in APP/PS1 Mice via Inhibition of Human Glutaminyl Cyclase

Tien Sheng Tseng^1*Chia-Ching Liaw²Young-Ji Shiao²Ya-I Huang²Yu-Hsiu Cheng²Wang-Chuan Chen³Keng-Chang Tsai^2*

• ¹National Chung Hsing University Institute of Molecular Biology, Taichung City, Taiwan
• ²National Research Institute of Chinese Medicine, Taipei City, Taiwan
• ³E-Da Hospital, Yanchao District, Taiwan

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline and amyloid-β (Aβ) accumulation. Increasing evidence suggests that dietary bioactive compounds may modulate neurodegenerative processes. Here, we evaluated the neuroprotective potential of NeuproGemp, a traditional Chinese functional food formula composed of Gastrodia elata, Paeoniae Radix Rubra, and the immunomodulatory protein GMI from Ganoderma microsporum, in APP/PS1 transgenic mice. Oral supplementation (300 mg/kg/day, 6–8 weeks) significantly improved ethological behaviors, including a ~150% enhancement in burrowing performance (150 ± 25 g vs. 60 ± 40 g in controls), and reduced escape latency in the Morris water maze (Day 4: p < 0.05; Day 6: p < 0.01). Histological analyses demonstrated attenuated plaque-associated gliosis, with microglial/astroglial clusters reduced from 95 ± 22 to 55 ± 11 per section (p < 0.01), alongside increased hippocampal neurogenesis (DCX+ cells: 49 vs. 18 cells/mm, p < 0.001). ELISA revealed reductions of ~30% in soluble Aβ₁₋₄₂ and ~50% in pyroglutamate-modified Aβ₃₋₄₂ (pE-Aβ₃₋₄₂). High-performance liquid chromatography identified pentagalloylglucose (PGG) as the principal polyphenolic constituent of Paeoniae Radix Rubra, which exhibited potent human glutaminyl cyclase (hQC) inhibition (IC₅₀ = 0.09 μM; KD = 63.7 nM). Molecular modeling and dynamics simulations further supported stable binding interactions of PGG and tannic acid with hQC. Collectively, these findings indicate that NeuproGemp, enriched in neuroactive polyphenols, exerts multi-targeted modulation of amyloidogenic pathways and represents a promising botanical intervention for mitigating AD-related neuropathology.