Japonins A-D, cyathane diterpenoids with neurite outgrowth-promoting activity isolated from Onychium japonicum using NMR and MS/MS-based molecular networking.

Guided by MS/MS-based molecular networking strategy, four new cyathane diterpenoids japonin A-D (1-4), together with the known analogues (5 and 6), have been isolated from aerial parts of Onychium japonicum. The structures of the new compounds were elucidated through a combination of NMR and MS experiments. Through single-crystal X-ray diffraction analysis, and comparison of experimental and calculated computational electronic circular dichroism (ECD) spectra, the absolute configurations of compounds 1-4 were determined. The new compound 1 showed promoting effects on the differentiation of PC12 at a concentration of 40 µM.