Submitted to: Planta Medica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2004
Publication Date: 10/1/2004
Citation: Crockett, S.L., Douglas, A.W., Scheffler, B.E., Khan, I.A. 2004. Genetic profiling of Hypericum L. (St. John's Wort) species by nuclear ribosomal I.T.S. sequence analysis. Planta Medica. 70:929-935.
Interpretive Summary: The botanical supplement industry has increased dramatically in the past ten years. In order to verify the contents of the products a number of techniques can be used. One of these is genetic profiling, which consists of comparing specific genetic regions of related species to one another. In order to make this comparison the genetic regions must be obtained from the species of interest and then the DNA sequence must be determined. This paper deals with such a determination for one of the most popular dietary supplements, Hypericum perforatum, (commonly known as St. John's Wort) and related species. In addition, the data was used to determine the genetic relationship between the species tested.
Technical Abstract: A PCR-based DNA amplification method was applied to genetically distinguish the popular dietary supplement Hypericum perforatum L. (Common St. John's Wort), which is used to treat mild and moderate depression in North America and Europe, from other related Hypericum species. Nuclear ribosomal gene sequences of the Internal Transcribed Spacer (ITS) region were analyzed for forty-nine taxa of Hypericum native to the Old and New World, representing 11 of the 36 currently recognized taxonomic sections. This study provides a genetic method for authentication of commercial preparations of H. perforatum, as well as an additional technique for differentiation between H. perforatum and related species. These data allowed a preliminary assessment of phylogenetic relationships within the genus, revealing three major strongly supported monophyletic clades, as well as several secondary monophyletic groupings. In addition, using ITS gene sequences, we were able to distinguish H. perforatum from all other species of Hypericum included in this study.