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Isolation and Characterization of Iron Binding Compounds from Turmeric ( Curcuma longa )
Author(s) -
Messner Donald,
Kunakom Brian,
Surrago Christine,
Kowdley Kris
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.773.7
Subject(s) - curcumin , chemistry , curcuma , nitrilotriacetic acid , nuclear chemistry , agarose , metabolite , chelation , biochemistry , stereochemistry , organic chemistry , traditional medicine , medicine
There is significant need for safe and effective iron chelators in the treatment of iron overload disorders. Here we describe a novel method for isolating iron binding compounds from complex extracts and use it to isolate curcumin from the food spice turmeric. A quantifiable assay of curcumin binding to iron was developed and used to investigate effects of other turmeric constituents, physiological metals, and weak iron chelators. The method depends on iron‐nitrilotriacetic acid (NTA)‐agarose. Curcumin binding to this resin was rapid, saturable, and reversible. It was detected when Ga 3+ , but not Ni 2+ or Cu 2+ , was complexed to NTA. All three curcuminoids found in turmeric bound iron‐NTA. Under the conditions used, analysis of saturation binding using a one site model indicated purified curcumin bound to the iron resin with a stoichiometry of 1 and a Kd near 500 μM. Similar results were obtained with standardized turmeric extracts. Binding of 10 μM curcumin to the iron resin was inhibited by 100‐fold excess (1 mM) Cu 2+ or Zn 2+ , but not Ca 2+ , Mg 2+ , or Mn 2+ . Binding of 10 μM curcumin to the iron resin was inhibited by a 100‐fold excess of pharmacological (desferoxamine, EDTA) or physiological (citrate) iron chelators. Inhibition was less effective with silibinin, o‐phenanthroline, or the curcumin metabolite tetrahydrocurcumin. We conclude curcumin can form a 1:1:1 ternary complex with NTA‐iron, and that curcuminoids are the primary iron binding compounds in turmeric. Inhibition of curcumin binding to iron‐NTA‐agarose is a promising assay for iron binding activity in extracts, and the resin can provide a convenient method to isolate the corresponding molecules for further study. Supported by NIH grant AT03448.