Pseudohypericin and hypericin in St. John's wort extracts. Breakdown of pseudohypericin

Photodiode array detector-coupled HPLC analysis of extracts of St. John's wort (Hypericum perforatum) reveals two main compounds: pseudohypericin (PH) and hypericin (H) (peaks A and B respectively). When the pH of the extracts is raised, peak A irreversibly disappears whereas peak B does not change. This instability at: high pH means that alkaline conditions should be avoided during extraction and raises a question concerning the bioavailability of pseudohypericin from St. John's wort extract-containing medicinal products designed for oral administration. (C) Academie des sciences/Elsevier, Paris.