Curcumin-glutathione interactions and the role of human glutathione S-transferase P1-1.
Curcumin (diferuloylmethane), a yellow pigment of turmeric with antioxidant properties has been shown to be a cancer preventative in animal studies. It contains two electrophilic alpha, beta-unsaturated carbonyl groups, which can react with nucleophilic compounds such as glutathione (GSH), but formation of the GSH-curcumin conjugates has not previously been demonstrated. In the present studies, we investigated the reactions of curcumin with GSH and the effect of recombinant human glutathione S-transferase(GST)P1-1 on reaction kinetics. Glutathionylated products of curcumin identified by FAB-MS and MALDI-MS included mono- and di-glutathionyl-adducts of curcumin as well as cyclic rearrangement products of GSH adducts of feruloylmethylketone (FMK) and feruloylaldehyde (FAL). The presence of GSTP1-1 significantly accelerated the initial rate of GSH-mediated consumption of curcumin in 10 mM potassium phosphate, pH 7.0, and 1 mM GSH. GSTP1-1 kinetics determined using HPLC indicated substrate inhibition (apparent K(m) for curcumin of 25+/-11 microM, and apparent K(i) for curcumin of 8+/-3 microM). GSTP1-1 was also shown to catalyze the reverse reaction leading to the formation of curcumin from GSH adducts of FMK and FAL.
Awasthi
S
S
Department of Chemistry and Biochemistry, University of Texas at Arlington, 502 Yates Street, PO Box 19065, Arlington, TX 76019-0065, USA. sawasthi@uta.edu
Pandya
U
U
Singhal
S S
SS
Lin
J T
JT
Thiviyanathan
V
V
Seifert
W E
WE
Awasthi
Y C
YC
Ansari
G A
GA
D002851:Chromatography, High Pressure Liquid; D003474:Curcumin / Q000737:chemistry* / Q000378:metabolism; D005470:Fluorometry; D005978:Glutathione / Q000737:chemistry* / Q000378:metabolism; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016339:Spectrometry, Mass, Fast Atom Bombardment; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D007527:Isoenzymes; D011994:Recombinant Proteins; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase; D005978:Glutathione; D003474:Curcumin