Juncaceae species are rich sources of phenanthrenes. The present study has focused on the isolation and structure determination of biologically active components from Juncus compressus. Eleven compounds (nine phenanthrenes and two flavonoids) have been isolated from the plant by the combination of different chromatographic methods. Two compounds (compressins A (Compound 1) and B (Compound 2)) are novel natural products, while seven phenanthrenes (effusol (Compound 3), effususol (Compound 4), juncusol (Compound 5), 2-hydroxy-1-methyl-4-oxymethylene-5-vinyl-9,10-dihydrophenanthrene (Compound 6), 7-hydroxy-1-methyl-2-methoxy-5-vinyl-9,10-dihydrophenanthrene (Compound 7), effususin A (Compound 8), and dehydroeffusol (Compound 9)), and two flavonoids (apigenin (Compound 10) and luteolin (Compound 11) were isolated for the first time from the plant. Compressin B (Compound 2) is a dimeric phenanthrene, in which two juncusol monomers (Compound 5) are connecting through their C-3 atoms. The structure elucidation of the isolated compounds was carried out using 1D, 2D NMR spectroscopic methods and HR-MS measurements. In vitro investigation of the antiproliferative effect of the phenanthrenes on two cervical (HeLa and SiHa) and an ovarian human tumor cell line (A2780) revealed that compounds have remarkable antiproliferative activity, mainly on the HeLa cell line. Moreover, juncusol (Compound 5) proved to possess significant antiviral activity against the herpes simplex 2 virus (HSV-2).
Keywords: Juncus compressus; anti-HSV-2; antiproliferative; flavonoid; phenanthrene.