Figure 1.

Negative ion LC-MS analysis of the reaction of curcumin with GSH, NAc, and βME. Autoxidation reactions of curcumin (50 μM) were supplemented with thiols (1 mM), extracted, and analyzed using LC-MS as described in “Experimental Procedures”. The traces are the extracted ion chromatograms for curcumin, BCP, and the respective thiol adducts of curcumin, dioxygenated curcumin, and methoxyphenol with (A) GSH, (B) NAc, and (C) βME. Elution of two peaks in the traces representing dioxygenated curcumin-thiol adducts was due to a chromatographic artifact. (D-F) LC-MS/MS product ion spectra of the adducts of dioxygenated curcumin with (D) GSH, (E) NAc, and (F) βME obtained by collision-induced dissociation of the peaks marked with an asterisk in the corresponding ion chromatograms. BCP, bicyclopentadione.