BACKGROUND: Alzheimer's disease (AD) is increasingly recognized as a multisystem disorder shaped not only by central neurodegeneration but also by peripheral metabolic and immune dysregulation. Growing evidence highlights the gut microbiota and its metabolites as key modulators of amyloid accumulation, tau phosphorylation, neuroinflammation, and microglial dysfunction.
PURPOSE: This review aims to synthesize current advances on how plant-derived bioactive compounds modulate AD pathophysiology through microbiota-dependent metabolic and neuroimmune mechanisms, and to establish a systems-level framework linking botanical interventions to gut microbiota remodeling and metabolite signaling.
METHODS: A comprehensive literature survey was conducted using PubMed, Web of Science, ScienceDirect, and Google Scholar, covering publications from 2010 to 2026. Studies investigating gut microbiota, microbial metabolites, and plant-derived bioactive compounds in AD-related metabolic, immune, and neurodegenerative pathways were systematically reviewed and integrated.
RESULTS: Plant-derived bioactive compounds, including phytochemicals, polysaccharides, and multi-herb formulations, interact extensively with the gut microbiota, undergoing microbial biotransformation to yield more active metabolites while simultaneously reshaping microbial community structure and metabolite profiles. These bidirectional interactions position the microbiota as a central mediator of plant-derived therapeutic activity. We summarize current evidence on how plant-derived compounds influence AD pathophysiology through microbiota-dependent metabolic and neuroimmune pathways. Major microbial metabolites, including short-chain fatty acids (SCFAs), trimethylamine N-oxide (TMAO), bile acids (BAs), and indole derivatives, are discussed, together with their regulatory roles in signaling networks such as nuclear factor κB (NF-κB), phosphatidylinositol 3-kinase/Akt (PI3K/Akt), cAMP response element-binding protein/brain-derived neurotrophic factor (CREB/BDNF), and triggering receptor expressed on myeloid cells 2 (TREM2)-associated microglial states. We further summarize evidence for synergistic strategies combining plant bioactives with probiotics and highlight advances in microbial biotransformation, precision metabolite modulation, and engineered microbial systems. Finally, future directions integrating multi-omics, personalized microbiota-guided interventions, and synthetic biology are outlined to support the development of targeted, mechanism-based therapies.
CONCLUSION: By framing AD through a gut microbiota-centered perspective, this review provides a unified mechanistic foundation for the development of next-generation interventions based on plant-derived compounds and microbiota regulation.
