Fig. 2

OPLS-DA models resulting from UPLC/Q-TOF–MS spectra. A, D represents, respectively, the OPLS-DA two-dimensional graph of the DRE group and the CON group (red dots represent the DRE group and blue dots represent the CON group); B, E represents the permutation test evaluation of OPLS-DA; C, F represent the s-plot of metabolites (red dots show VIP > 1, green dots show VIP ≤ 1); A–C represents the ESI + mode; D–F represent the ESI- mode