A combination of two plant compounds with medicinal properties – curcumin and silymarin – holds promise in treating colon cancer, a new preliminary study finds.

Curcumin is the active ingredient in the spice turmeric, which is present in spicy curry dishes, and silymarin is a component of milk thistle, which has been used to treat liver disease.

Researchers at St. Louis University in St. Louis, Mo., studied a line of colon cancer cells in a laboratory model. They found treating the cells initially with curcumin, then with silymarin was more effective in fighting cancer than treating the cells with either phytochemical alone, they said.

"The combination of phytochemicals inhibited colon cancer cells from multiplying and spreading. In addition, when the colon cancer cells were pre-exposed to curcumin and then treated with silymarin, the cells underwent a high amount of cell death," says Dr. Uthayashanker Ezekiel, a study author.

Phytochemicals, which are bioactive chemicals found in plants, offer an alternative route to fighting cancer without the toxicity and side effects that chemotherapy can cause, he notes.

This study is the first step in learning if the herbal combination is safe and effective. Scientists next would need to study how these herbs cause the cells to change. They then would need to be studied in animals and finally in humans, he notes of the research, which appears in Journal of  Cancer.