Diterpenoids from Euphorbia helioscopia and their enhancement of NK cell-mediated killing of NSCLC cells

Fourteen previously undescribed diterpenoids, including an unusual diterpenoid (1) with a 9,10-seco-jatrophane skeleton, ten jatrophane-type diterpenoids (2–11), two lathyrane-type diterpenoids (12, 13), and an abietane-type diterpenoid (14), together with thirty-six known ones (15–50), were isolated from the whole plants of Euphorbia helioscopia L. The structures of the new isolates were characterized by spectroscopic methods, single-crystal X-ray diffraction analysis, and computational prediction of ECD and chemical shifts. Thirty-nine abundant diterpenoids were evaluated for their enhancement of NK cell-mediated killing of NSCLC cells. As a result, compounds 24, 33, and 41 were found to significantly enhance the killing activity of NK cells towards H1299-luci cells and A549-luci cells at the concentration of 2.5 μM.