Curcumin

Curcumin (/ˈkərkjuːmən/) is a diarylheptanoid. It is the principal curcuminoid of turmeric, which is a member of the ginger family (Zingiberaceae). It was first discovered about two centuries ago when Vogel and Pelletier reported the isolation of a “yellow coloring-matter” from the rhizomes of Curcuma longa (turmeric) and named it curcumin. Turmeric's other two curcuminoids are desmethoxycurcumin and bis-desmethoxycurcumin. The curcuminoids are natural phenols that are responsible for the yellow color of turmeric. Curcumin can exist in several tautomeric forms, including a 1,3-diketo form and two equivalent enol forms. The enol form is more energetically stable in the solid phase and in organic solvents, while in water the 1,3-diketo dominates.

Curcumin can be used for boron quantification in the curcumin method. It reacts with boric acid to form a red-color compound, rosocyanine.

Curcumin is a bright-yellow color and may be used as a food coloring. As a food additive, its E number is E100.