Fig. 1
(A) PCA scores plot, (B) OPLS-DA scores plot and (C) important features (VIP-plot from OPLS-DA) distinguishing healthy controls and COVID-19 serum samples. Scaling was done to Pareto. R2X = 0.79, R2Y = 0.90, Q2 (cum) = 0.83, CV-ANOVA = 2.12 x 10-32 for OPLS-DA, which was validated through Permutation Test (Figure S2). Important features (VIP > 1) plot shows those buckets that contain metabolites that increase (in red) or decrease (in blue) its content for each group. (D) Significantly enriched metabolic routes by COVID-19 built with serum metabolites with VIP > 1 from OPLS-DA model: 1) Phenylalanine, tyrosine and tryptophan biosynthesis, 2) Phenylalanine metabolism, 3) Glycerolipid metabolism and 4) Arginine and proline metabolism. The more affected metabolic pathways appear with a color gradient, from yellow (less significant) to red (most significant) and satisfy the following criteria: number of matching metabolites in the pathway > 1, false discovery rate (FDR) adjusted p < 0.05 and impact index > 0 (see Table S5).
