Abstract:
Two new compounds, an ent-isopimarane-type diterpene, 3R,12R-dihydroxy-ent-8(14),15-isopimaradien-
18-al (1), and a dihydrobenzo[b]furan neolignan, (-)-trans-9-acetyl-4,9¢-di-O-methyl-3¢-de-O-methyldehydrodiconiferyl
alcohol (2), along with five known compounds, 7,7¢-dihydroxy-6,8¢-bicoumarin (bicoumol)
(3), 3,4-dimethoxycinnamaldehyde (4), 6-hydroxy-7-methoxycoumarin (isoscopoletin), N-butylaniline, and
vanillin, have been isolated from an ethyl acetate-soluble extract of the stem wood of Euphorbia
quinquecostata. The structures of compounds 1 and 2 were elucidated on the basis of spectroscopic data
interpretation, and single-crystal X-ray diffraction analysis was used to confirm the structure and relative
stereochemistry of 1. The absolute configuration of 1 was established by a convenient Mosher ester
procedure in which the sample was treated with MTPA chlorides in deuterated pyridine directly in NMR
tubes. All isolates were evaluated for the induction of quinone reductase in Hepa1c1c7 hepatoma cells
and for the inhibition of the transformation of murine epidermal JB6 cells.