Phytochemical assessment of the effect of stimulated in vitro multiplication on the metabolic profile of in vitro cultured Hypericum richeri and Artemisia alba
In vitro secondary metabolite production requires a fine balance between biomass formation and expression of the biosynthetic capacity of the species. Comparison of the metabolite spectra of the in vitro to ex situ material is a crucial benchmark in this process. HPTLC methods known from similar plant species from the Artemisia and Hypericum genera [1, 2] have been adapted to extracts with varying polarity of different plant parts from ex situ and in vitro samples of Artemisia alba and Hypericum richeri. The main differences and similarities of the secondary metabolite and bioactive constituent profiles between in situ and in vitro produced plant material were assessed.
The results of this study revealed that A. alba can be maintained successfully long-term in medium lacking plant growth regulators (PGR) whereas H. richeri requires cytokinin supplementation in order to stimulate axillary bud multiplication and sustain growth in vitro. It was also established that N6-Benzyladenine (BA) strongly stimulated multiplication index and its individual application led to inhibition of rooting for both species. While the combination of BA and indole-3-butiric acid was found to be favorable for both biomass and polyphenolics stimulation in A. alba, enhanced growth led to the drop of polyphenols and flavonoids in H. richeri. At the same time hypericins were observed in significant levels in vitro. Further research is in progress to clarify the distinctive features of the biochemical and physiological response to PGR treatment as a model system for affecting antioxidant metabolites production in vitro.
Acknowledgments: This work was supported by the Swiss National Science Foundation in the framework of the Bulgarian-Swiss Research Programme (BSRP, grant No. IZEBZ0_142989; DO2 – 1153)
 Proksch P and Wissinger-Gräfenhahn U. Artemisia. In: Blaschek W et al. (Eds.) Hager ROM 2011. Springer Heidelberg
 European Pharmacopoeia 7.7 online edition