Plants provide vitamins and minerals that help keep humans healthy. But can they do more? Researchers at the University of Arkansas Division of Agriculture think so. Brad Murphy, UA professor of horticulture, is working on two separate projects that hold the potential to greatly enhance the use of plants by people.

In conjunction with Timothy O'Brien of the UAMS Biomedical Biotechnology Center, Murphy is working with a technology that uses plants as “biofactories” to synthesize proteins that can be used in cancer research.

O'Brien has isolated certain proteins that are closely linked to cancer tumor formation. Murphy said the presence of these proteins in the blood could alert doctors to a potential cancer while still in the very early stages. Because they are so closely associated with the tumor, antibodies against these proteins could also be used as a delivery system for anti-cancer medicines. This way, chemotherapy or radiation agents could be targeted directly at the cancer tumor.

Certain of these proteins may also have potential use as vaccines, Murphy said.

Scientists need a way of producing large quantities of these proteins relatively inexpensively. That's where Murphy comes in. By inserting the gene that causes the production of the proteins into the plant species Brassica carinata, he effectively turns the plant into a protein-producing machine. Along with the gene, Murphy inserts a special “promoter” that tells the gene to express itself only in the seeds of the plant.

“Several other biotechnology companies use tobacco plants for this process and allow the gene to express in the leaves,” he explained. “The problem with this method is that leaves don't last very long post-harvest, so you have to extract the proteins within just a few hours of harvesting the plants. Plus, your processing of the proteins is limited to the tobacco growing season.”

Seeds, however, can be harvested, stored for long periods and processed at any time without losing their potency, making this system more efficient and economical, he said.

While Murphy is producing the proteins right now, consumers should be prepared to wait a few years before seeing them used in any commercial cancer treatments, since they will first have to undergo extensive safety testing in order to get FDA approval.

In a related project, Murphy is working with assistant professor Marjorie Fitch-Hilgenberg, UA dietitian in the School of Human Environmental Sciences, to study the effects of plant phytochemicals on people.

“Phytochemicals are naturally occurring substances in plants that have been scientifically proven to have specific health benefits,” Murphy said. “Unlike the proteins and sugars and other substances that are nutritive, these compounds have direct pharmaceutical health benefits.”

Most of these substances, like carotenoids, anthocyanins, and flavonoids, to name just a few, are antioxidants, Murphy said. They have been shown to help protect the body from many different diseases, especially those related to aging.

“In our study, we're determining plasma carotenoid levels in humans and relating that back to their diet,” explained Fitch-Hilgenberg. “In the future, we want to determine if the whole food is more effective at producing a health response or if we can improve the effect by extracting the purified compound and using it alone.”

Murphy's objective in related, research is increasing the production levels of certain phytochemicals through the use of transgenic techniques by increasing the expression of the genes that cause their production. He is also studying the potential for inserting the genes for the production of a certain phytochemical into a plant species that ordinarily wouldn't produce it in measurable quantities.


P.J. Hirschey, University of Arkansas Department of Horticulture, phirsch@uark.edu