Phenanthrenes are aromatic plant metabolites derived mainly from stilbenes by oxidative
coupling. Such compounds occur only in few plant families. Phenanthrenes have diverse
structures and they possess different pharmacological activities. Because of their
rare occurrence and specific substituents, they can be served as chemotaxonomic markers
[1]
[2].
The aim of our work was the phytochemical and pharmacological investigation of Juncaceae
species occurring in the Carpathian Basin in order to isolate their phenanthrene constituents.
In the course of this work, four Juncus species (J. atratus, J. ensifolius, J. gerardii, and J. maritimus) were investigated.
The dried and ground plant materials were extracted with methanol. After concentration,
the extracts were dissolved in 50% aqueous methanol, and solvent-solvent partitions
were performed with hexane, chloroform and ethyl acetate. Phenanthrenes are enriched
in the chloroform phase; therefore, these fractions were separated at first by column
chromatography and then further purified by Sephadex LH-20 gel chromatography and
medium pressure liquid chromatography. As final purifications, high-performance liquid
chromatography and preparative thin layer
chromatography were used. The structures of the components were determined by NMR
spectroscopy, and MS measurements. All compounds were tested for antiproliferative
activity in vitro.
Altogether 52 phenanthrenes were identified from the four species, 31 of them are
new natural products. The compounds are methyl-, hydroxyl-, hydroxymethyl-, formyl-,
methoxy-, metoxy-methyl-, acetyl-, acetylene- and vinyl-substituted mono- and diphenanthrenes.
All compounds were determined for the first time from the plants. Most of the isolated
phenanthrenes possessed antiproliferative activity on one or more cancer cell lines.
