October 26 (HealthDay News) -- Tomatoes genetically modified to be rich in antioxidants called anthocyanins appeared to extend the life spans of cancer-prone mice, a European study finds.

The modified tomatoes were created by adding two genes (Delila and Rosea1) from the snapdragon flower. The anthocyanins, which belong to the flavonoid class of antioxidants, gave the tomatoes a peculiar purple color.

"The two genes we have isolated are responsible for flower pigmentation and, when introduced in other plants, turned out to be the perfect combination to produce anthocyanins, the same phytochemical found in blueberries," study author Eugenio Butelli, of the FLORA project, said in a news release.

Chemical tests revealed that the "purple tomato has a very high antioxidant activity, almost tripled in comparison to the natural fruit," making it very useful to study the effect of anthocyanins, Butelli said.

The researchers fed a powder obtained from the purple tomatoes to mice that lacked the p53 gene, which helps protect against cancer. These mice had an average life span of 182 days compared to 142 days for p53-deficient mice fed a standard diet.

The findings were published in the Oct. 26 issue of Nature Biotechnology.

The study authors emphasized this is a preliminary study, and much more research needs to be done before there's any possibility of human trials.

SOURCE: Catholic University, news release, Oct. 26, 2008