Biologically active phenanthrenes from four Juncus species native to Hungary

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.

Publication History

Article published online:
13 December 2021

• References

• 1 Tóth B, Hohmann J, Vasas A. J. Nat. Prod. 2018, 81: 661–678.
• 2 Bús Cs, Tóth B, Stefkó D, Hohmann J, Vasas A. Phytochem. Rev. 2018, 17: 833–851.