Influence of the Developmental Stage on the (Proto)-Hypericin and (Proto)Pseudohypericin Levels of Hypericum Plants from Crete

The contents of (pseudo)hypericin and their immediate precursors were studied in wild populations of various Hypericum species on the island of Crete, Greece. Therefore, the aerial parts of wild grown H. perforatum, H. triquentrifolium, H. empetrifolium and H. perfoliatum shoots were collected throughout the island and the quantitative variations in (proto)hypericin and (proto)-pseudohypericin examined. The plant material was harvested at different stages of the life cycle of the species and the contents in the above-mentioned compounds analyzed discriminating between flowers/fruits and leaves/petioles. HPLC analysis ofhypericin, pseudohypericin and their immediate precursors, protohypericin and protopseudohypericin, revealed great differences in the contents of the compounds in dependence on the developmental stage of the plants. In all examined species the highest concentrations of hypericin were found during blossoming whereas the lowest concentrations were present during ripening of the fruits. H. perforatum and H. triquentrifolium show much higher hypericin levels in flowers/fruits compared to leaves/petioles, whereas the species H. empetrifolium and H. perfoliatum show similar concentrations of total hypericins in both flowers/ fruits and leaves/petioles. In the different species the levels of (proto)hypericin and (proto)pseudohypericin varied, but in almost all samples from flowers/fruits and leaves/petioles the ratio of (proto)hypericin to (proto)pseudohypericin was higher than one. When the total amount of hypericins per entire aerial part of a plant was calculated for all developmental stages, we found that H. perforatum contained the highest amount of hypericin. This in combination with the comparatively high concentration of hypericins in flowers/fruits and in leaves/petioles in this species, as well as the high ratio of (proto)hypericin to (proto)pseudohypericin, especially during the developmental stage of blossoming, encourages us to think about the possibility of cultivating Hypericum perforatum in Crete as a medicinal plant in the future.