Figure 4. Ability of curcumin to reduce ferric iron in comparison with a known hydrophilic antioxidant, trolox.

Measurements were made at pH 7.4 in phosphate buffered saline (PBS) using a UV-Vis spectrophotometer to monitor the reduction of ferric ion to ferrous ion at OD₇₀₀ nm. This assay used a 1∶1 mixture of potassium ferricyanide (1%) and PBS containing different concentrations of curcumin (▴) and trolox (♦).