Figure 2.

PCA and PPA bind to GSH and decrease cellular GSH.A, effects of PCA on intracellular concentration of metabolites involved in the primary metabolic pathway. Intracellular metabolites of PANC-1 cells treated with 59 μm PCA were measured by CE–TOF MS. B–D, intracellular GSH levels. PANC-1 cells were incubated with 59 μm PCA and 88 μm PPA, and intracellular GSH levels and the GSH/GSSG ratio were measured by a GSH/GSSG-Glo assay (B). PANC-1 cells were incubated with various concentrations of PCA and PPA for 2 h (C). Human pancreatic cancer cells were treated with 59 μm PCA or 88 μm PPA for 2 h (D). The data are presented as means ± S.D. of three independent experiments. p values were determined by two-tailed Student's t test. *, p < 0.05; **, p < 0.01; ***, p < 0.001. E, PCA directly binds to GSH. The PCA–GSH conjugate was detected by LC–MS. F, PPA directly binds to GSH. G, formation of the PCA–GSH conjugate in PANC-1 cells. Intracellular metabolites of PANC-1 cells treated with 59 μm PCA were measured by LC–MS. The data are presented as means ± S.D. of three independent experiments. p values were determined by two-tailed Student's t test. **, p < 0.01. H, schematic model to explain the PCA- and PPA-induced decreases in GSH.