Efficient Isolation and Structure Analysis of (+)-Ranuncoside, a Unique Tricyclic Spiroacetal Glycoside, from Christmas Rose (Helleborus niger L.)

The use of medicinal herbs as remedies reaches back to the Stone Age, and their importance as a source of drugs has continuously increased since then. Herbal ingredients can serve as active pharmaceuticals themselves or as lead substances for the development of synthetic pharmaceuticals with less toxicity, higher effectiveness or with new properties. To date, only 6% of the ∼600,000 plants on earth have been tested pharmacologically. Among these, the medicinal plant Helleborus niger L. (Christmas rose) is especially promising because its leaves contain ( + )-ranuncoside 1, characterized by a spiroacetal ring system, a motif which is responsible for the biological activity of a multitude of natural products. Structure-activity relationship studies of ( + )-ranuncoside 1 are lacking and no synthesis of 1 has been described yet. Therefore, we developed a protocol for the rapid and efficient isolation of 1 from the leaves of cultivated Christmas rose. Crystals of high purity were obtained that enabled us to study the stereochemistry of 1 by NMR spectroscopy in solution for the first time. The spiro configuration, the absolute stereochemistry, and the geometry of all three rings was then confirmed by x-ray structure analysis. Our data will enable future structure-activity relationship studies to assess the potential of 1 as a lead substance for the development of novel antibiotics and anticancer agents.

Helleborus Niger: Systematics, Ecology, Pollination and Production Technology

The scientific monograph covers the botanical classification of the genus Helleborus L. and the Christmas rose species (Helleborus niger L.), which has undergone numerous changes throughout its botanical history. The Christmas rose is becoming increasingly important in the ornamental plant market. Its characteristic flowering in the coldest months of the year represents a great advantage over many other species of ornamental plants. As the Christmas rose does not require high temperatures to start flowering, its cultivation can be considered affordable and environmentally friendly. The supply of attractive varieties is likely to be one of the key factors that will affect its popularity in the future. The number of genetically improved (bred) varieties is limited on the market, so selective breeding of Christmas rose will become inevitable in the future. The presented results of pollination analyses, related to insect activity, are important for breeding. Observations indicate that the Christmas rose is an entomophilous and a predominantly allogamous species. Knowledge of plant ecology and cultivation technology will also be exceptionally important. In intensive cultivation, the production technology for Christmas roses is still to a large extent incomplete. The monograph includes scientific findings on the ecology and biology of the Christmas rose, its reproductive processes, and the production technology for potted plants. The monograph also presents the results of the study on the effects of beneficial microorganisms (bacteria and endomycorrhizal fungi) on the growth and development of seedlings from in vivo and in vitro environments. The results of the study indicate that biotisation is a useful technology and that inoculation with specific microorganisms has a beneficial effect on growth.

Perspectives of Christmas rose (Helleborus niger L.) genetic improvement

The Christmas rose is becoming a very important ornamental plant on the market. It is relatively new to intensive production technologies. The number of genetically-improved varieties on the market is limited, and many of the old cultivars are no longer available because of slow and economically unfeasible vegetative propagation. In the future, its genetic improvement will probably become inevitable. New cultivars will have to satisfy the specific requirements of the market and producers as well as strict environmental policy. In order to obtain new cultivars it will be necessary to evaluate the existing germplasm and apply an adequate genetic breeding approach. There are seven main possibilities of creating new varieties: the use of natural variation associated with seed germination, population approach based on recurrent selection, individual selection based on specific genetic combinations, the creation of inbred lines and the formation of hybrids, interspecific hybridisation, mutagenesis and genetic engineering. Molecular markers can be very helpful during the breeding process. They can be used in order to study genetic relationships amongst populations, ecotypes, varieties, and hybrids.