Metabolic Fate of Curcumin in the Gastrointestinal Tract in Mice

Curcumin (1,7‐bis (4‐hydroxy‐3‐methoxyphenyl)‐1,6‐heptadiene‐3,5‐dione) is a major yellow‐orange pigment found in turmeric, and has been used widely as a food ingredient. Curcumin has been associated with many health benefits, but its health‐promoting potential is limited by its poor bioavailability. This is due to the fact that curcumin is poorly absorbed, and absorbed curcumin is subject to extensive biotransformation. The detailed understanding of biotransformation of curcumin is needed to facilitate the elucidation of its biological significance. This study was aimed to establish the metabolic fate of curcumin in the gastrointestinal (GI) tract. The male CD‐1 mice were fed with curcumin in diet (0.05% w/w) for 5 weeks. The entire GI tract and its content were harvested for LC‐MS analysis. Our results demonstrated that curcumin underwent phase I metabolism in the small intestine to yield two major metabolites, namely hexahydro‐curcumin and octahydro‐curcumin. Curcumin, hexahydro‐curcumin and octahydro‐curcumin were all subject to phase II metabolism that converted them to their corresponding glucuronides and sulfates. The majority of curcumin, hexahydro‐curcumin and octahydro‐curcumin exist as phase II conjugates in the small intestine. However, due to the action of gut microbiota, curcumin, hexahydro‐curcumin and octahydro‐curcumin almost exclusively existed in the non‐conjugated forms in the cecum and colon. Furthermore, our results suggested that gut microbiota could break down curcumin, hexahydro‐curcumin and octahydro‐curcumin to produce different fission products. In summary, our results determined the metabolic fate of curcumin in the GI tract, which can help understand the biological effects of curcumin in the GI tract as well as other related organs. Support or Funding Information This study was partially supported by fund from USDA.