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.