Hypericum brasiliense is a medicinal herb containing several compounds with important pharmacological activity. In this study, we investigated the effects of water stress (waterlogging and drought) and temperature (low and high, constant and alternate) on the content of betulinic acid and phenolic compounds (quercetin, rutin, 1,5-dihydroxyxanthone, isouliginosin B) in this species. In general, the water stress increased the levels of all of the compounds analyzed, particularly some of the phenolic compounds. On the other hand, the responses to alternating temperatures varied according to the compound. The results for plants kept in growth chambers indicated that low light intensity might have influenced the levels of the compounds. There was also a reallocation of carbon, with water-stressed plants showing a reduction in growth while the levels of the compounds increased. In the temperature treatments, such an increase was evident only for the phenolic compounds.

Effect of water and temperature stress on the content of active constituents of Hypericum brasiliense Choisy.

Temperature stress can alter the photosynthetic efficiency and secondary metabolite concentrations in St. John's wort.

We investigated the effects of plant growth regulators [6-benzyladenine (BA), kinetin (Kin), 6-γ,γ-dimethylallylaminopurine (2iP), thidiazuron (TDZ) and α-naphthaleneacetic acid (NAA)], modified Murashige and Skoog (MS) medium containing 10 mM NH4
 + and 5 mM NO3
 − and supplemented with 2iP, BA, Kin and NAA (MSM medium), and two elicitors [jasmonic acid (JA), and salicylic acid (SA)], on plant growth and accumulation of hypericins (hypericin and pseudohypericin) and hyperforin in shoot cultures of Hypericum hirsutum and H. maculatum. Our data suggested that culture of shoots on MS medium supplemented with BA (0.4 mg l−1) or Kin (0.4 mg l−1) enhanced production of hypericins in H. maculatum and hyperforin in H. hirsutum. Hypericins and hyperforin concentrations decreased in both species when TDZ (0.4 mg l−1) was added to the MS medium. Also, TDZ induced hyperhydric malformations and necrosis of regenerated shoots. Cultivation of H. maculatum on MSM medium resulted in approximately twofold increased production of hypericins compared to controls, and the growth of H. hirsutum shoots on the same medium led to a 6.16-fold increase in hyperforin production. Of the two elicitors, SA was more effective in stimulating the accumulation of hypericins. At 50 μM, SA enhanced the production of hypericin (7.98-fold) and pseudohypericin (13.58-fold) in H. hirsutum, and, at 200 μM, enhanced the production of hypericin (2.2-fold) and pseudohypericin (3.94-fold) in H. maculatum.

Effects of plant growth regulators and elicitors on production of secondary metabolites in shoot cultures of Hypericum hirsutum and Hypericum maculatum

Production of adventitious roots and secondary metabolites by Hypericum perforatum L. in a bioreactor

Production of biomass and useful compounds from adventitious roots of high-value added medicinal plants using bioreactor.

In vitro production and chemical characterization of St. John’s wort (Hypericum perforatum L. cv ‘New Stem’)

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.

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

While the interest in medicinal plants continues to grow, there is a lack of basic information with respect to efficient protocols for plant production. Recently, in vitro regeneration protocols have been developed to provide masses of sterile, consistent St. John's wort. The current study assessed the potential for acclimatization of in vitro grown St. John's wort plantlets to a nutrient film technique (NFT) hydroponic system in a controlled environment greenhouse. Quantitative analyses of hypericin, hyperforin and pseudohypericin in flower tissues were used as the parameters to assess the quality of the greenhouse-grown plants. The three bioactive compounds were found to be present in similar or higher amounts than previously reported values for field-grown plants. These data provide evidence that greenhouse hydroponic systems can be effectively used for the efficient production of St. John's wort and other medicinal plants.

An in vitro and hydroponic growing system for hypericin, pseudohypericin, and hyperforin production of St. John's wort (Hypericum perforatum CV new stem).

H.P.V. Rupasinghe

Papers

In vitro production and chemical characterization of St. John’s wort (Hypericum perforatum L. cv ‘New Stem’)

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

An in vitro and hydroponic growing system for hypericin, pseudohypericin, and hyperforin production of St. John's wort (Hypericum perforatum CV new stem).