Hexahydrobenzophenanthridine alkaloids from Corydalis bungeana Turcz. and their anti-inflammatory activity

[Display omitted] •Five hexahydrobenzophenanthridine alkaloids and 4 known compounds were isolated from Corydalis bungeana Turcz.•Seven tested compounds exhibited significant inhibition of LPS-induced NO production in RAW264.7 cells.•A preliminary structure–activity relationship was discussed. As part of a bioprospecting program aimed at the discovery of anti-inflammatory agents from the Corydalis bungeana Turcz. (C. bungeana), five new hexahydrobenzophenanthridine alkaloids, corycaline A-E (1–5), along with four known alkaloids, were isolated from the whole plant of C. bungeana. Their structures including absolute configurations were elucidated on the basis of extensive spectroscopic analyses and electronic circular dichroism (ECD) calculations. The inhibitory activities of the nine compounds on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 mouse macrophage cells were determined; all tested compounds except 2 and 7 exhibited significant inhibitory effects with IC50 values in the range of 1.00–2.79 μM.