To measure the herb's potency,
Gibson, along with Cornell University Department of Plant Pathology graduate
student Tara Sirvent, have developed a new method of analyzing the hypericin
compounds. This method is faster than current methods of analysis that are
insufficient or laborious to perform.
Gibson says their method takes just 15 minutes to separate hypericin from
pseudohypericin, a related compound, in crude extracts using high-performance
liquid chromatography (HPLC). She says that other methods require much longer
times and more complex mixtures for adequate separation.
"Our HPLC method permits the fast quantitative analysis of hypericins
in crude acetone or methanol samples," says Gibson. She and Sirvent also
studied the photoconversion of protohypericinsthe precursor
compoundsas well as the stability of hypericin and pseudohypericins as a
function of light, time, and storage conditions.
According to Gibson, "Since hypericins are typically used as the
measure of extract potency and since market pricing for this herbal product has
switched from a yield basis to a price based on specific product ingredients,
producers may receive $2,000 to $3,000 more per acre if their crops have higher
Gibson's lab is currently completing a survey of wild-collected H.
perforatum samples from the Pacific Northwest. The survey's purpose is to
ascertain the range of variation that might be due to environmental influences.
Canel is using genetic fingerprinting to screen plants at the seed level.
His goal is to identify genetic markers capable of differentiating between
closely related Hypericum species.
"Unlike phytochemical profiles and morphological features, DNA sequence
normally remains unaltered during the development of the plant and under
various environmental conditions," he says. Genetic fingerprinting can be
used at any stage of the herbal manufacturing process, but it is especially
suited to the seedling level.
Canel believes this research will lead to a seed-certification program for
cultivated H. perforatum that requires applying genetic techniques. His
work on young leaves of H. perforatum is a model for locating genetic
markers that can be used to find the best sources of compounds in other herbal
products manufactured from cultivated plants.
Genetically certified plant material and products made from them can be
expected to have a higher market value than uncertified material or material
certified by other means. Certification of St. John's-wort at the seed level
would not only establish the authenticity and purity of the starting material,
but would also document its source and provide information about seed viability
and germination rates.
Canel is developing a fingerprinting kit based on the genetic differences he
has observed. He hopes to make it available for commercial use soon.
According to Gibson, since hypericin is a supplement, it doesn't have Food
and Drug Administration approval. However, it is currently being evaluated in
the first long-term, controlled clinical trials directed by the National
Institutes of Health.
Gibson was recently notified that her research proposal on using plant cell
biotechnology to produce hypericin and hyperforinanother hypericum
compound also linked to antidepressive effectshas been awarded funding
from USDA's Foreign Agricultural Service.By
Hank Becker, Agricultural
Research Service Information Staff.
This research is part of New Uses, Quality, and Marketability of Plant
and Animal Products, an ARS National Program (#306) described on the World Wide
Web at http://www.nps.ars.usda.gov/programs/cppvs.htm.
Donna M. Gibson is in the USDA-ARS
Plant Protection Research Unit, U.S.
Plant, Soil, and Nutrition Research Laboratory, Tower Rd., Ithaca, NY
14853; phone (607) 255-2359, fax (607) 255-1132.
Camilo Canel is in the USDA-ARS
Products Utilization Research Unit, P.O. Box 8048, University of
Mississippi, Oxford, MS 38677-8048; phone (662) 915-7965, fax (662) 915-1035.