Diterpenoids from the aerial parts of Euphorbia antiquorum and their efficacy on nitric oxide inhibition.

Eight previously undescribed diterpenoids of different types were isolated from ethyl acetate extract of the aerial parts of Euphorbia antiquorum L., along with fifteen known diterpenoids. Their structures and configurations were determined by 1D and 2D NMR, MS, and electronic circular dichroism (ECD). Additionally, the absolute configuration of ent-12-oxo-2,3-secobeyer-15-en-2,3-dioic acid-3-methyl ester was confirmed through single-crystal X-ray diffraction. Efficacy of the compounds on lipopolysaccharide (LPS)-stimulated nitric oxide (NO) production in murine macrophage J774.A1 cells was evaluated. ent-15-Acetoxylabda-8(17),13E-diene-3-one, ent-15-oxolabda-8(17),13E-diene-3-one and rhizophorin B was significantly suppressed NO production with IC values of 11.7, 12.5 and 16.1 μM, respectively.