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. 2019 Dec 9;5:150. doi: 10.1038/s41420-019-0234-y

Fig. 2. Curcumin binds iron.

Fig. 2

a Test of the removal of curcumin from solution by Fe-NTA resin. Increasing amounts of curcumin were incubated with Fe-NTA-agarose (black circles) or without (open circles). The free curcumin remaining in solution after removal of the resin was determined by absorbance at 435 nm against a calibration range. The experiments have been repeated more 12 times and the eman values are given in ±SD (but are so small that they are not vosibles on the figure drawing). b Inhibition of curcumin binding to iron. Curcumin (20 μM) was incubated alone (no NTA resin), with iron resin (Fe-NTA agarose), or with iron resin preincubated with excess deferoxamine (250 μM), excess vitamin E (1 mM), excess EGTA (2 mM) or excess EDTA (2 mM). Unbound curcumin was determined as for a. The means ± S.E. are presented from at least five independent determinations. c Absorbance spectrum of Huh-7 cells treated with 20 μM curcumin for 6 h with (in red) or without (in blue) 100 μM Fe-NTA loading for 24 h. d Fluorescence emission spectra of Huh-7 cells treated with 20 μM curcumin for 6 h (same conditions as in c). e Microspectrofluorimetry of Huh-7 cells treated with 20 μM curcumin for 6 h with recording of the curcumin emission fluorescence (same conditions as in d). f Effect of Fe-NTA (10 and 100 μM addition) on the fluorescence recording of a curcumin solution (20 μM) at 535 nm in a cuvette with excitation at 435 nm.