Redox modulation of curcumin stability: redox active antioxidants increase chemical stability and biological activity of curcumin

Abstract

Substantial human and pre‐clinical studies have shown that curcumin, a dietary compound from turmeric, has beneficial effects on many human diseases. However, curcumin rapidly degrades at physiological pH, making it difficult to interpret the biological activities of curcumin and develop curcumin‐based therapeutics. Here we show that a series of redox active antioxidants with diverse chemical structures, including gallic acid, ascorbate (vitamin C), tert‐butylhydroquinone (TBHQ), caffeic acid, rosmarinic acid, and Trolox (a water‐soluble analog of vitamin E), dramatically increased curcumin stability in aqueous buffer and enhanced biological activity of curcumin in colon cancer cells. In addition, co‐administration of antioxidant significantly increased circulating level of curcumin in animal models. Together, these studies strongly suggest that a redox‐dependent mechanism plays a critical role in mediating curcumin degradation, and co‐administration of antioxidants could be a practical strategy to increase the chemical stability and biological activity of curcumin.