Constituents from the Stem Wood of Euphorbia quinquecostata with Phorbol

Abstract

Bioassay-guided fractionation of an EtOAc extract of the stem wood of Euphorbia quinquecostata using a phorbol dibutyrate receptor-binding assay system as a monitor yielded four inhibitory isolates (1-4), inclusive of one new compound, 17-hydroxyingenol 20-hexadecanoate (1), and three previously known compounds, ingenol 20-hexadecanoate (2), ent-16R,17-dihydroxyatisan- 3-one (3), and ent-3â,16R,17-trihydroxyatisane (4). Also isolated from this extract were 10 constituents inactive in this bioassay, namely, 2,2¢-dihydroxy-4,6-dimethoxy-3-methylacetophenone (5), a new structure, and nine known compounds identified as ent-13S-hydroxyatis-16- ene-3,14-dione; 2-hydroxy-4,6-dimethoxyacetophenone (xanthoxylin); 2-hydroxy-4,6-dimethoxy- 3-methylacetophenone; 6-hydroxy-7-methoxycoumarin; lupeol acetate; â-sitosterol; sitosterol â-D-glucopyranoside; 6,7,8-trimethoxycoumarin; and 3,3¢,4¢-tri-O-methyl-4-O-[R-L-rhamnopyranosyl (1¢¢¢f6¢¢)-â-D-glucopyranosyl]ellagic acid. The structures of compounds 1 and 5 were established by chemical and spectroscopic methods.