Target isolation of cytotoxic diterpenoid esters and orthoesters from Daphne tangutica maxim based on molecular networking

Guiding by LC-MS/MS analysis and the GNPS Molecular Networking, five undescribed daphnane diterpenoids, tanguticanines A-E, and eleven known analogues were discovered from the whole plants of Daphne tangutica Maxim. Their structures and absolute configurations were determined via extensive NMR spectroscopic analysis, ECD calculations, and X-ray diffraction crystallography. Tanguticanine E (5) exhibited promising cytotoxicity against the HepG2 cell line with an IC50 value of 9.93 ± 0.10 μM. Further flow cytometry experiment was performed to detect cell apoptosis, and the results indicated that cytotoxic diterpenoids (tanguticanines B, D and E, altadaphnan C, gniditrin, hirsein A and simplexin) exert their effects through induction of apoptosis.