Renewal of Echinacea and St John's Wort research

May 4 2007

A five-year-old research center dedicated to understanding and improving Echinacea and Hypericum perforatum (St. John's wort) has received $4.4 million in continuation funding from the National Institutes of Health. The renewal is for three years.

The Iowa Center for Research on Botanical Dietary Supplements at Iowa State University was created in 2002 by the NIH Office of Dietary Supplements. In addition to Iowa State, the center includes researchers at the University of Iowa, Yale University and the U.S. Department of Agriculture's North Central Regional Plant Introduction Station in Ames. A total of 27 researchers are involved (including 13 graduate students).

Echinacea and Hypericum are two of the nation's top selling herbal dietary supplements. Before the center was established, however, there were few scientific studies to understand the plants and their effect on human health.

Researchers in the Iowa Center for Research on Botanical Dietary Supplements work with well- defined plant material, identify the chemical profiles and key compounds that contribute to health benefits and define how they work. The center's primary goal is to improve understanding of the characteristics of the selected extracts that contribute to human health benefits and pave the way for optimizing the supplements.

During the past five years, center researchers have gained insight into the antiviral, anti-inflammatory and immune-boosting mechanisms of specific species of Echinacea, and the antiviral and anti-inflammatory activity of different populations of Hypericum, said Diane Birt, director of the center and distinguished professor of food science and human nutrition at Iowa State.

"In studying the nine different species of Echinacea, we found some species work better than others," Birt said. "This suggests that it will be possible to get an improved preparation that will enhance the supplement's benefit to human health."

Researchers also found that lipid-soluble compounds in Echinacea have appreciable anti-inflammatory activity. In Echinacea and Hypericum, water-soluble compounds, such as polyphenols, seem to contribute to the plant material's antiviral activity.

"This suggests that we're not going to find a single compound or even a subset of compounds that are responsible for health benefits," Birt said. "A complex chemical profile is contributing to the health effects, so it's more likely that we're moving toward improving these supplements rather than identifying chemicals for use as drugs. We are moving toward something like a fingerprint of the biologically active chemicals in the species."

In addition, the researchers have identified some specific compounds in Hypericum that provide much greater activity in combination than individually.

The Iowa Center for Research on Botanical Dietary Supplements brings together plant scientists, biochemists, nutritionists, chemists, immunologists, food scientists, virologists, metabolic scientists and statisticians. Center strengths include genomic analysis, broad-based plant metabolic profiling and an ability to integrate complex datasets by using bioinformatics and other statistical tools, Birt said.

"One particular strength we have is our ability to control the genetics and growth conditions of the plant material used in our cellular and animal model studies," Birt said. "Being able to characterize known-source germplasm is a very important resource for our center."

In the renewal, researchers will continue to conduct the anti-viral, anti inflammatory and pain receptor studies to see how components can block inflammation by stimulating the receptor to down regulate it.

"In the next three years, we'll include emphasis on bioavailability," Birt said. "We don't know if the chemicals we've identified are absorbed. We'll also be looking at the mechanism, focusing on cellular, signaling, pathways and receptors."

And they will add a third plant, Prunella. Also known as self heal, Prunella has been used to treat ailments such as inflammatory bowel disease, fever, headache and diarrhea.

"Prunella grows well in Iowa. We have made some extracts and saw very good activity—both antiviral and anti-inflammatory, so it fits well with what we're doing," Birt said.

The nine Iowa State faculty involved are from four colleges (Liberal Arts and Sciences, Agriculture, Human Sciences and Veterinary Medicine.) In addition, two scientists from the USDA Plant Introduction Center, two faculty from Yale and one from the University of Iowa conduct research for the center.