Nephroprotective mechanism of Kunkui Baoshen decoction in diabetic kidney disease: Targeting the HERC2/NCOA4-mediated autophagy-dependent ferroptosis pathway

Figure 5 Component identification of Kunkui Baoshen decoction and metabolomics analysis. A: Total ion chromatogram of Kunkui Baoshen decoction (KKBS) obtained via liquid chromatography-mass spectrometry/mass spectrometry, showing the compound distribution profile; B: Representative chemical structures of key quality control components identified in KKBS; C: Sample correlation heatmap. Each cell represents the correlation coefficient between two samples. Color intensity indicates the strength of correlation, and hierarchical clustering (dendrograms on the top and side) reflects similarity—samples on the same branch are more similar to each other; D: Principal component analysis plot: Dimensionality reduction was performed to project samples onto principal components 1 and 2. The relative positions of points reflect similarity, and closer points indicate more similar metabolic profiles. Analysis of similarities was used to assess between-group differences. The R value (range: -1 to 1) indicates effect size, with values closer to 1 suggesting strong inter-group separation; the P value tests for significance; E: Partial least squares discriminant analysis score plot demonstrating group separation based on metabolite profiles. Component 1 and component 2 represent the major explanatory variables; F: Partial least squares discriminant analysis permutation test to evaluate the model’s statistical reliability. The X-axis shows model accuracy, and the Y-axis shows the number of random permutations. Red bars = Q² values; blue bars = R²Y values. P value = (number of permutations outperforming the original model)/(total permutations). A P < 0.05 indicates model validity; G: Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Bar graph showing the number of KKBS-related metabolites mapped to different KEGG pathways. The Y-axis shows KEGG subcategories, and the X-axis shows the number of mapped compounds. Pathways are grouped into seven categories: Metabolism, genetic information processing, environmental information processing, cellular processes, organismal systems, human diseases, and drug development, with distinct colors representing each category. TIC: Total ion chromatogram; PLS-DA: Partial least squares discriminant analysis; PCA: Principal component analysis; TFA: Total fatty acids; PC1: Component 1; PC2: Component 2; KKBS: Kunkui Baoshen decoction; KEGG: Kyoto Encyclopedia of Genes and Genomes.