Oxidative Conversion Mediates Antiproliferative Effects of tert-Butylhydroquinone: Structure and Activity Relationship Study.
Previous studies have shown that tert-butylhydroquinone (TBHQ), a widely used food antioxidant, has cytotoxic effects at high doses; however, the underlying mechanisms are not well understood. Here, we found that the effects of TBHQ on cell proliferation, cell cycle progression, and apoptosis are mainly mediated by its oxidative conversion to a quinone metabolite tert-butylquinone (TBQ). Co-addition of cupric ion (Cu(2+)) caused accelerated oxidative conversion of TBHQ to TBQ and enhanced the biological activities of TBHQ on cell proliferation, cell cycle progression, and apoptosis in MC38 colon cancer cells. In contrast, co-addition of ethylenediaminetetraacetic acid (EDTA) suppressed TBHQ oxidation and inhibited the biological activities of TBHQ in MC38 cells. For example, after 24 h of treatment in basal medium, low-dose TBHQ (1.88-7.5 μM) had little effect on MC38 cell proliferation, while co-addition of 50 μM Cu(2+) caused 30-70% inhibition of cell proliferation; in contrast, treatment with high-dose TBHQ (15 μM) inhibited 50 ± 4% MC38 proliferation, which was abolished by co-addition of 50 μM EDTA. We further showed that TBQ had more potent actions on cell proliferation and associated cellular responses than TBHQ, supporting a critical role of TBQ formation in the biological activities of TBHQ. Finally, a structure and activity relationship study showed that the fast-oxidized para-hydroquinones had potent antiproliferative effects in MC38 cells, while the slow-oxidized para-hydroquinones had weak or little biological activities. Together, these results suggest that the biological activities of TBHQ and other para-hydroquinones are mainly mediated by their oxidative metabolism to generate more biologically active quinone metabolites.
Department of Food Science, and §Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst , Amherst, Massachusetts 01003, United States.
Katherine Z
KZ
Sanidad
Department of Food Science, and §Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst , Amherst, Massachusetts 01003, United States.
Elvira
E
Sukamtoh
Department of Food Science, and §Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst , Amherst, Massachusetts 01003, United States.
Weicang
W
Wang
Department of Food Science, and §Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst , Amherst, Massachusetts 01003, United States.
Zheyuan
Z
Du
Department of Food Science, and §Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst , Amherst, Massachusetts 01003, United States.
Ellie
E
Florio
Department of Food Science, and §Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst , Amherst, Massachusetts 01003, United States.
Lili
L
He
Department of Food Science, and §Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst , Amherst, Massachusetts 01003, United States.
Hang
H
Xiao
Department of Food Science, and §Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst , Amherst, Massachusetts 01003, United States.
Eric A
EA
Decker
Department of Food Science, and §Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst , Amherst, Massachusetts 01003, United States.
Guodong
G
Zhang
D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D003300:Copper / Q000737:chemistry; D006873:Hydroquinones / Q000494:pharmacology*; D010084:Oxidation-Reduction; D013329:Structure-Activity Relationship
D006873:Hydroquinones; D003300:Copper; C018855:2-tert-butylhydroquinone
apoptosis; cell cycle; cell proliferation; tert-butylhydroquinone (TBHQ); tert-butylquinone (TBQ)