Nine 9,10-dihydrophenantnes. seven of them described for the fust time, have ken isolated in a further investigation of Juncus t@sus. The structures have been defined on the basis of the spectral properties of the compounds. All the dehydrophenanthrene metabolites present in the plant have been tested for their cytotoxic properties and many of them have been found to have a good in vitro activity. Phenanthrenes represent a rather uncommon class of aromatic metabolites which are presumably formed by oxidative coupling of the aromatic rings of stilbene precursors. In a recent phytochemical investigation of the aquatic plant Juncus ejjhsus L. we have described nine 9,10_dihydrophenanthrenes 1 -9, characterized by a methyl at C-l, an oxygenated function at C-2 and a vinylic group at C-Y. In effect juncusol(1) and effusol(2) have aheady been isolated from the same source2 and juncunol(3) has been reported as the main component of Juncus roemeranius 3. 11 1 R=H R'=Me R'=OHR'=H 2 R=H R'=H R'&IR'=H 3 R=H R '=H R'=Me R3=H 4 R=H R'=OH R'=Me R'=H 5 R=H R'=H R'=OHR'=Me 6 R=H R'=Me R2=H R'c0l-I 7 R=Me R'=Me R2=H R'= OH 8 R=H R'=H R'=OMe R3=Me 9 R=H R '=H R2&10H R3=H
In the light of the potential antitoumoral activity of some of these compounds, evidenced by means of potato discs infected with Agrobacterium rumefaciens 4, Juncus effsus was completely examined and in this paper further nine dehydrophenanthrenes 10 -18 are described together with the results of a screening of the biological activity and the isolation procedures of all the dehydrophenanthrenes from the plant.
Compound 10 was attributed the structure 8-carboxy-2-hydroxy-I-methyl-5-vinyl-9.1O-dihydrophenanthrene. Its HR-EIMS spectrum gave a molecular peak at m/z 280.1119. according to the molecular formula CtsHt603, and its IR spectrum showed the presence of a hydroxyl and a carboxyl function with absorptions at 3350,320O and 1685 cm-t. In the tH-NMR spectrum were evidenced two aromatic AB systems