New macrocyclic diterpenoids from Euphorbia esula

The structures of two new macrocyclic jatrophane diterpenoid esters from the whole herb of Euphorbia esula, were established as 11,14-epoxy-3beta,5alpha,7beta,8alpha,9alpha,15beta-hexaacetoxy-12-oxo-13alphaH-jatropha-6(17)-ene (1) and 1alpha,3beta-diacetoxy-5alpha,7beta-dibenzoyloxy-9,14-dioxo-11beta,12alpha-epoxy-2alpha,8alpha,15beta-trihydroxy-13betaH-jatropha-6(17)-ene (2) by a combination of 1D- and 2D-NMR techniques as well as UV, IR and mass spectral data. Bioassay evaluation of all isolates against the human tumor cell lines (B16, KB, SMMC and BGC) indicated that ester 2 was cytotoxic to B16 with the IC50 value being 1.81 microg/ml. In addition, the irritant activity assay indicated that both diterpenoids were inactive (ID(24)50 > 100 microg/ear).