A unique collection of St. John’s wort (Hypericum) curated by
Agricultural Research Service (ARS) scientists in Ames, Iowa, is
providing university collaborators with genetically diverse,
well-documented sources of this herb to use in studies examining its
In collaboration with Mark Widrlechner, a horticulturist with the ARS
crop genebank at the North Central Regional Plant Introduction Station
in Ames, scientists from the Center for Research on Botanical Dietary
Supplements (CRBDS) are screening 180 germplasm accessions of St. John’s
wort for biologically active compounds. Some may be worth evaluating
further in clinical trials for their potential to combat viral
infections, reduce inflammation or improve digestive health.
Established in 1948, the ARS Ames crop genebank curates more than
50,000 accessions of ornamental plants, maize, oilseeds, vegetables and
other crops, and provides them to researchers for many applications.
Accessions with medicinal or nutraceutical value include Echinacea
(purple coneflower), Hypericum, Prunella (self-heal)
and Actaea racemosa (black cohosh). ARS horticulturist Luping
Qu curates the collection and Widrlechner coordinates its use for
research at CRBDS, one of six Botanical Research Centers funded by the
National Institutes of Health from 2005-2010.
The Hypericum collection at Ames was started in the 1990s
and today encompasses about 60 species collected from around the world.
This diversity has enabled investigations of genetic, environmental and
developmental factors affecting the quantity and quality of bioactive
compounds, as well as their modes of action.
Of particular interest is how these compounds interact, and whether
those interactions are critical to human health benefits. In a recent
issue of Pharmaceutical Biology, researchers noted that
combinations of four compounds from St. John’s wort (amentoflavone,
chlorogenic acid, pseudohypericin and quercetin) were more effective at
reducing inflammation in mouse macrophage assays than when each was used
Widrlechner’s collaborators include Diane Birt, Kimberly Hammer,
Matthew Hillwig, Jingqiang Wei, George Kraus, Patricia Murphy and Eve
Wurtele at Iowa State University; Jeffrey Neighbors, David Wiemer, Wendy
Maury and Jason Price at the University of Iowa; and Joe-Ann McCoy,
formerly with ARS.
Source : USDA/Agricultural Research Service