Fig. 2

Identification of the differential metabolomic profiles between the POI and control groups. A Volcano plot visualizing the differentially regulated metabolites in POI compared to the control in positive polarity mode (fold change≥ 2 or ≤ 0.5, p < 0.05). B Volcano plot in negative polarity mode (fold change ≥ 2 or ≤ 0.5, p < 0.05). C Heatmap clustering presenting differentially regulated metabolites in positive polarity mode. D Heatmap clustering presenting differentially regulated metabolites in negative polarity mode. E KEGG pathway analysis for identifying the metabolic pathways associated with the differentially abundant metabolites between the indicated groups in positive polarity mode. F KEGG pathway analysis for negative polarity mode