Dracomolphin A-E, new lignans from Dracocephalum moldavica

Eight new lignans, dracomolphin A-E (1-8), together with eight known lignans (9-16) were isolated from the aerial part of Dracocephalum moldavica. The structures of the isolated compounds were established based on NMR and HRESIMS data. Dracomolphin A (1-4) was elucidated as a lignan possessed a 5-membered ketal ring formed between C-8' and C-3, C-4. The two stereogenic centers rendered dracomolphin A as a mixture of two diastereomeric pairs of enantiomers (1-4). All of the four isomers were separated successfully by using chiral HPLC and their stereochemical features were determined by CD spectra. Bioactivity screening revealed that compounds 1-4, 6, 7, 12, 15 and 16 were potential Nrf2 transcriptional activators. Dracomolphin E (8) reduced cell viability of lung cancer NCI-H292 cells associated with apoptosis.