Neogenkwanines A–H: daphnane-type diterpenes containing 4,7 or 4,6-ether groups from the flower bud of Daphne genkwa

Neogenkwanines A-H (1-8), eight daphnane-type diterpenes possessing new skeletons with 4,7- or 4,6-ether groups, along with seven known ones (10-16), were isolated from Daphne genkwa. Their structures and absolute configurations were established by analysis of their NMR, X-ray crystallography, CD exciton chirality data and hydrolysis experiments. In addition, an MTT assay was used to examine the growth-inhibitory effects of all the new isolates on HL-60, Hep3B, and U87 cells; compounds 3, 4 and 5 exhibited significant inhibitory effects against Hep3B cell lines with IC50 values of 7.61, 8.16 and 8.35 mu M, respectively.