The pigment in rhubarb has useful chemical properties in terms of blocking tumor cell growth, according to a new US and Chinese study.

A team of scientists from Emory University in Atlanta in the US, other US research institutions, and Peking University in China, has discovered that rhubarb contains a pigment that can inhibit a protein that is essential for tumor growth.

The researchers worked with a concentrated form of this pigment called physcion or parietin, which gives rhubarb stems their red color.

In the lab, the chemical created from this concentrate was added to leukemia cells. The results showed that after 48 hours, 50% of them had died.

The team then worked with another form of physcion that they tested on mice injected with human cancer cells for the needs of this new experiment. Here too, they noted a reduction in cancer cell growth.

The researchers said the pigments blocked a protein called 6PGD, which is involved in tumor cell growth, a process that scientists are familiar with and has been given the name pentose phosphate pathway (PPP). 6PGD is thought to make a key contribution to this process. The scientists said that without 6PGD, cell proliferation and tumor growth is slowed.

To come up with these findings, which were published in the October 19 edition of the journal Nature Cell Biology, the team first tested nearly 2,000 chemicals to see which ones were likely to have an impact on the protein 6PGD and stop tumor growth without attacking other cells.

While these results are encouraging, more research is required. The experiment took place in a lab, and the study's authors concluded that the chemical will now have to be tested on humans to see if efficacy and safety conditions are met.

Past university research has demonstrated that rhubarb, like many red-colored vegetables and fruit, particularly when cooked, is rich in polyphenols, a family of organic molecules known for its anti-cancer proprieties.