Abstract: In our early screening process, songorine isolated from Aconitum brachypodum diels possessed prominent activity of inhibiting class B G protein-coupled receptors (GPCRs). For further study, a series of ester and carbonyl derivatives were synthesized and their potential inhibitory activities on class B GPCRs were also assayed by the Double Antibody Sandwich ELISA (DAS-ELISA) in vitro. Moreover, the structure-activity relationships (SARs) of songorine derivatives were discussed in detail. In this paper, the story behind this study was described.

Key words: songorine derivatives, G protein-coupled receptors, inhibition, synthesis