Curcumin, but not its degradation products, in combination with silibinin is primarily responsible for the inhibition of colon cancer cell proliferation.

Colorectal cancer (CRC) is the third leading cause of cancer death globally and the most-commonly diagnosed cancer in men and women in the United States. We have previously shown that the phytochemicals curcumin, derived from turmeric, and silibinin from milk thistle exhibit synergistically enhanced anticancer activity against colorectal cancer cells. In the present study, the combination of curcumin, a major component of turmeric, and its degraded products trans-ferulic acid, ferulic aldehyde, and vanillin in combination with silibinin were assessed for their action against cancer cell proliferation. Our results indicate that only curcumin plus silibinin has significant antiproliferative effects on colon cancer cells.