title: Redox modulation of curcumin stability: Redox active antioxidants increase chemical stability of curcumin.
abstract: METHODS
  Substantial studies have shown that curcumin, a dietary compound from turmeric, has beneficial effects on many diseases. However, curcumin rapidly degrades at physiological pH, making it difficult to interpret whether the observed actions of curcumin are from curcumin itself or its degradation products. Therefore, it is important to better understand the mechanisms involved in curcumin degradation and the roles of degradation in its biological actions.
  
  
  RESULTS
  Here, we show that a series of redox active antioxidants with diverse chemical structures, including gallic acid, ascorbate (vitamin C), tert-butylhydroquinone (TBHQ), caffeic acid, rosmarinic acid, and Trolox (a water-soluble analog of vitamin E), dramatically increased curcumin stability in phosphate buffer at physiological pH. When treated in basal cell culture medium in MC38 colon cancer cells, curcumin rapidly degraded with a half-life of several minutes and showed a weak antiproliferative effect; co-addition of antioxidants enhanced stability and antiproliferative effect of curcumin. Finally, co-administration of antioxidant significantly increased plasma level of curcumin in animal models.
  
  
  CONCLUSIONS
  Together, these studies strongly suggest that a redox-dependent mechanism plays a critical role in mediating curcumin degradation. In addition, curcumin itself, instead of its degradation products, is largely responsible for the observed biological actions of curcumin.
authors.affiliation: Department of Food Science, University of Massachusetts, Amherst, MA, USA.|Department of Food Science and Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Nimiya
authors.affiliation: Department of Food Science, University of Massachusetts, Amherst, MA, USA.
authors.forename: Weicang
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Food Science, University of Massachusetts, Amherst, MA, USA.
authors.forename: Zheyuan
authors.initials: Z
authors.lastname: Du
authors.affiliation: Department of Food Science, University of Massachusetts, Amherst, MA, USA.
authors.forename: Elvira
authors.initials: E
authors.lastname: Sukamtoh
authors.affiliation: Department of Food Science, University of Massachusetts, Amherst, MA, USA.
authors.forename: Julia
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Department of Food Science, University of Massachusetts, Amherst, MA, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Decker
authors.affiliation: Department of Food Science, University of Massachusetts, Amherst, MA, USA.
authors.forename: Guodong
authors.initials: G
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry* / Q000378:metabolism; D001205:Ascorbic Acid / Q000737:chemistry; D002109:Caffeic Acids / Q000737:chemistry; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002839:Chromans / Q000737:chemistry; D002934:Cinnamates / Q000737:chemistry; D003474:Curcumin / Q000737:chemistry* / Q000378:metabolism / Q000493:pharmacokinetics*; D053630:Depsides / Q000737:chemistry; D004355:Drug Stability; D005707:Gallic Acid / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006873:Hydroquinones / Q000737:chemistry; D008297:Male; D051379:Mice; D010084:Oxidation-Reduction; D000097123:Rosmarinic Acid
chemical_list: D000975:Antioxidants; D001205:Ascorbic Acid; D002109:Caffeic Acids; D002839:Chromans; D002934:Cinnamates; D003474:Curcumin; D053630:Depsides; D005707:Gallic Acid; D006873:Hydroquinones; D000097123:Rosmarinic Acid; C018855:2-tert-butylhydroquinone; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; C040048:caffeic acid
keywords: Antioxidant; Curcumin; Stability