Factors affecting growth of cell suspension cultures of hypericum perforatum L. (St. John's wort) and production of hypericin

Use of Hypericum perforatum L., commonly known as St. John's wort, has increased recently due to the pharmaceutical potential of hypericin, found in its leaves. Hypericin has been reported to effect a natural treatment for mild and moderate depression by increasing the concentration of neurotransmitters in the central nervous system. We have developed a novel cell culture system for in vitro growth and production of this species, suggesting a possible technology for large-scale production of hypericin. Leaf explants grown in Murashige and Skoog salts supplemented with 2,4-dichlorophenoxyacetic acid (0.90 μM) and kinetin (0.11 μM) gave maximum percentage callus formation compared to other medium treatments evaluated. Hypericin localization in cell phase and leaves was found to vary, with cell phase accumulating hypericin in special organelles and leaves accumulating it in vacuoles. Light and dark conditions, with cell aggregate size, played important roles in growth and hypericin production in cell suspension cultures.