Fig. 2

Chromatograms of kynurenine pathway metabolites
Tryptophan, B) Kynurenine, C) Kynurenic acid, D) Quinolinic acid, E) Serotonin, F) Glutamine, G) Glutamate. Peak area ratios for the standards and the corresponding analytes are shown on the left and right sides respectively (Peak intensity on the y-axis and retention time on the x-axis of the chromatograms)