Eupholides A-H, abietane diterpenoids from the roots of Euphorbia fischeriana, and their bioactivities

The roots of Euphorbia fischeriana known as "Langdu" in traditional Chinese medicine have been used for the treatment of tuberculosis in China. Through a bioactive phytochemical investigation of the roots of E. fischeriana, 15 diterpenoids were obtained by various chromatographic techniques. On the basis of wide spectroscopic data, including NMR, UV, IR, HR-ESI-MS, ECD and X-ray crystallography, all of the isolated compounds were elucidated to be ent-abietane diterpenoid analogs, including undescribed eupholides A-H and seven known diterpenoids. In the bioassay for anti-tuberculosis, eupholides F-H moderately inhibited the proliferation of Mycobacterium tuberculosis H37Ra, with the MIC determined to be 50 mu M. Furthermore, eupholides G, ent-11 alpha-hydroxyabieta-8(14), 13(15)-dien-16,12 alpha-olide, and jolkinolide F significantly inhibited the lyase activity of human carboxylesterase 2 (HCE 2), with IC50 values of 7.3, 150, and 34.5 nM, respectively.