Elevated carbon supply altered hypericin and hyperforin contents of St. John's wort (Hypericum perforatum L. cv `New Stem') grown in bioreactors

St. John's wort (Hypericum perforatum L.) is a traditional medicinal plant mainly used for the treatment of neurological disorders and depression. Recent investigation revealed that St John's wort can be grown efficiently in large-scale sterile bioreactors. The current investigation was carried out to assess the potential for increasing the concentration of medicinally important biomolecules (hypericin, pseudohypericin and hyperforin) by exposure to elevated levels of CO2 and/or sucrose in a balloon type bubble bioreactor system (BB-bioreactor). The biomass (fresh and dry mass) decreased with increasing sucrose concentration in the culture medium in both CO2 enriched (1500–1800 μmol mol−1) and non-enriched conditions. The results of chemical analyses indicated that the supply of excess carbon either as sucrose or CO2 did not increase the hypericin and pseudohypericin content of the tissues. However, hyperforin content was increased in plantlets grown at 45 g l−1 sucrose under CO2 non-enriched conditions. These findings provide evidence that the synthesis of the bioactive molecule in St. John's wort is likely dependent on several factors in addition to available nutrition and atmospheric conditions and indicate an alternate mechanism for regulation of the synthesis of hypericin/pseudohypericin and hyperforin.