Stability of Hypericin and Pseudohypericin in Extract Solutions of Hypericum perforatum and in Standard SolutionsAlexandra Wirz a, Beat Meier b, and Otto Sticher a Department of Applied BioSciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich a, Zürich, and Zeller AG, Herbal Medicinal Products b, Romanshorn (Switzerland) Tests on the stability of hypericin and pseudohypericin in extracts of Hyperici herba and standard solutions were done under different temperature and light conditions monitored by VIS spectroscopy and HPLC-VIS / DAD measurements. All solutions were stable at -20 °C in darkness over the investigated period of 140 days. Higher temperatures, light and the presence of pyridine turned out to accelerate the degradation of pseudo-hypericin, while exposure to light was most aggressive. Hypericin showed higher stability, light being the only factor investigated that decreased the concentration of hypericin. The instability in the presence of light was more pronounced in the extract solution both for hypericin and pseudohypericin. Under all the other storage conditions, the stability of pseudohypericin was better in the extract solutions than in the standard solutions. Cyclopseudohypericin was assumed one of the transformation products of pseudohypericin. Key words Hypericin, stability in solution · Hypericum perforatum L. · Pseudohypericin, stability in solution |
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pharmind 2001, Nr. 4, Seite 410
