Knowledge structure, latent topics, and emerging trends in quercetin-immunity research from 2006 to 2025: a...

Quercetin is a representative flavonol at the interface of natural-product pharmacology, nutrition, and immune regulation, with reported anti-inflammatory, antioxidant, antiviral, antiallergic, antitumor, and metabolic activities. This systematic mapping review aimed to characterize the publication trajectory, knowledge structure, latent themes, and emerging frontiers of quercetin-immunity research from 2006 to 2025.

English-language original articles and reviews published from January 1, 2006 to December 31, 2025 were retrieved from the Web of Science Core Collection, Scopus, and PubMed. Following harmonized eligibility reassessment, field standardization, and cross-database deduplication, bibliometric analysis, science mapping, keyword co-occurrence, temporal and burst analyses, thematic maturity assessment, citation and co-citation analyses, and latent Dirichlet allocation (LDA) topic modeling were integrated to examine the explicit and latent knowledge structures. Mapping-level risk of bias was qualitatively assessed.

The searches yielded 15,938 raw records, of which 10,619 unique publications were included, comprising 7,754 original articles and 2,865 reviews. Of these, 6,440 publications appeared during 2021-2025, accounting for 60.65% of the dataset and demonstrating rapid growth. The field spanned natural products, pharmacology, molecular biology, nutrition, and immunology, with China, India, and the United States as the leading contributors. Stable mechanistic terms included oxidative stress, inflammation, signal transduction, apoptosis, NF-κB, TNF, IL-6, and IL-1β, indicating a knowledge core centered on inflammatory cytokine networks, redox homeostasis, transcriptional regulation, and cell-fate control. LDA resolved 12 topics spanning inflammatory signaling, systems pharmacology, senescence, oxidative organ injury, tumor immunity, neuroinflammation and ferroptosis, infection and intestinal inflammation, allergy and mast-cell activation, delivery systems, and bioavailability. Recent frontiers included molecular docking, network pharmacology, protein-protein interaction, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology analyses, ferroptosis, macrophage polarization, and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling, indicating a shift toward multi-target, systems-level mechanistic investigation. The mapping-level assessment indicated low-to-moderate residual risk.

Quercetin-immunity research has evolved from broad anti-inflammatory studies into an interdisciplinary field focused on inflammatory signaling, oxidative stress, immune-cell function, disease-specific immunopathology, and systems pharmacology. Future studies should prioritize physiologically attainable exposures, active metabolites, immune-cell specificity, disease-stage effects, multi-omics validation, and clinically relevant dosing.