Investigating the effects of Ginkgo biloba leaf extract on cognitive function in Alzheimer's disease

Abstract

Aims: Alzheimer's disease (AD) is a neurodegenerative disorder with limited treatment options. This study aimed to investigate the therapeutic effects of Ginkgo biloba leaf extract (GBE) on AD and explore its potential mechanisms of action.

Methods: Key chemical components of GBE, including quercetin, luteolin, and kaempferol, were identified using network pharmacology methods. Bioinformatics analysis revealed their potential roles in AD through modulation of the PI3K/AKT/NF-κB signaling pathway.

Results: Mouse experiments demonstrated that GBE improved cognitive function, enhanced neuronal morphology, and reduced serum inflammatory factors. Additionally, GBE modulated the expression of relevant proteins and mRNA.

Conclusion: GBE shows promise as a potential treatment for AD. Its beneficial effects on cognitive function, neuronal morphology, and inflammation may be attributed to its modulation of the PI3K/AKT/NF-κB signaling pathway. These findings provide experimental evidence for the application of Ginkgo biloba leaf in AD treatment and highlight its potential mechanisms of action.

Keywords: Alzheimer's disease; Ginkgo biloba leaf extract; PI3K/AKT/NF‐κB signaling pathway; kaempferol; luteolin; quercetin.

FIGURE 1

Screening of candidate genes and chemical components in Ginkgo biloba leaves for alleviating Alzheimer's disease. (A) Schematic diagram of the process for pharmacological network screening of candidate genes and chemical components in Ginkgo biloba leaves for alleviating Alzheimer's disease; (B) PCA principal component analysis plot of GSE37263; (C) Volcano plot based on differential expression analysis results in GSE37263; (D) Venn diagram showing the Alzheimer's disease target genes obtained from the Genecard database, OMIM database, and GEO dataset; (E) Venn diagram showing the target genes of Ginkgo biloba leaf effective chemical components and Alzheimer's disease; (F) network interaction diagram of Ginkgo biloba leaves—effective components—target genes—Alzheimer's disease constructed using Cytoscape software, with Ginkgo biloba leaves and Alzheimer's disease located in the upper right and lower left corners, respectively; common target genes of the disease and drugs are displayed in the middle matrix area, while the effective components of Ginkgo biloba leaves are represented by circles. Node size and color intensity indicate the degree value of the node.

FIGURE 2

Bioinformatics analysis of Alzheimer's disease candidate genes regulated by Gingko leaf extract and its key signaling pathways. (A) Schematic representation of the bioinformatics analysis workflow, illustrating the analytical steps involved in the potential regulation of AD key signaling pathways by Gingko leaf extract. (B–D) GO analysis results of AD candidate genes possibly regulated by Gingko leaf extract, showing the top 10 results for biological processes (BP), cellular components (CC), and molecular functions (MF), with adjusted p‐values. (E) KEGG pathway analysis results of 35 AD candidate genes potentially regulated by Gingko leaf extract, represented by a GOKEGG‐EMAP diagram, with the size of the dots indicating the number of selected genes and the color intensity representing the significance of the enrichment analysis (p‐value). (F) KEGG enriched pathways for gene heatmap analysis (G) protein–protein interaction (PPI) network diagram of the 35 AD candidate genes potentially regulated by Gingko leaf extract, constructed using STRING database data and visualized using Cytoscape software. The font size and background color of the genes in the network diagram represent the degree value. (H) Ranking of degree values in the protein–protein interaction network, highlighting the proteins that may play a crucial role in AD.

FIGURE 3

Effects of Ginkgo biloba leaf extract (GBE) on mouse behavior and neuronal morphology. (A) Comparison of body weight among the different groups of mice before and after experimental intervention. (B, C) Horizontal entries and central grid dwell time of mice in the open field test. (D, E) Escape latency and platform crossings of mice in the Morris water maze test. (F) H&E staining observation and quantitative analysis of the hippocampal region in each group of mice (×20) demonstrate morphological changes of nerve cells and neuron counts. (G) Immunopositive expression of GFAP protein in the hippocampal region of mice in each group. (H) Immunofluorescent staining of GFAP protein in the hippocampal region of mice in each group. *p < 0.05; **p < 0.01; ***p < 0.001; ns indicates no statistical significance (n = 10).

FIGURE 4

The protective effect of GBE on mouse hippocampal neurons and the inhibition of amyloid pathological changes. (A) Dendritic spine morphology and quantity of mouse hippocampal neurons in different groups. (B) Western blot analysis shows the expression levels of p‐Tau and Tau proteins in mouse groups. (C) Expression of amyloid protein in mouse hippocampus of different groups. (D) Expression of TUNEL‐positive cells in the hippocampus of mice in different groups. ***p < 0.001; ns indicates no statistical significance (n = 10).

FIGURE 5

Effects of Gingko biloba leaf extract on the protein and mRNA expression of the PI3K/AKT/NF‐κB signaling pathway. (A) Western blot analysis shows the expression levels of PI3K, p‐PI3K, AKT, p‐AKT, NF‐κB, and p‐NF‐κB proteins in each group of mice. (B) qRT‐PCR analysis shows the expression levels of PI3K, AKT, and NF‐κB mRNA in each group of mice. *p < 0.05; **p < 0.01; ***p < 0.001 (n = 10).

FIGURE 6

Influence of Ginkgo biloba leaf extract on the levels of inflammatory cytokines in mouse serum. (A) Detection of inflammatory factor levels of IL‐1β, TNF‐α, and IL‐6 in the serum of mice in each group using ELISA technique. (B) Detection of inflammatory factor levels of IL‐1β, TNF‐α, and IL‐6 in the brains of mice in each group using ELISA technique. (C) Detection of anti‐inflammatory factor levels of IL‐1ra and IL‐10 in the brains of mice in each group using ELISA technique. ***p < 0.001 (n = 10).