Curcumin is a bright yellow chemical produced by Curcuma longa plants. It is the principal curcuminoid of turmeric (Curcuma longa), a member of the ginger family, Zingiberaceae. It is sold as an herbal supplement, cosmetics ingredient, food flavoring, and food coloring. Chemically, curcumin is a diarylheptanoid, belonging to the group of curcuminoids, which are natural phenols responsible for turmeric's yellow color. It is a tautomeric compound existing in enolic form in organic solvents and in keto form in water. Curcumin has no confirmed medical use in spite of efforts to find one via both laboratory and clinical research. It is difficult to study because it is both unstable and not bioavailable. It is unlikely to produce useful leads for drug development.