Isolation, structural elucidation, and activities evaluation of proaporphine alkaloids from Thalictrum baicalense

Eight undescribed proaporphine alkaloids, including two with unexpected glucose-proaporphine hybrid skeletons, as well as four known ones, were isolated from Thalictrum baicalense. Their structures were elucidated by the analysis of extensive spectroscopic data, ECD calculations, and X-ray diffraction. All compounds were tested for acetylcholinesterase inhibitory activity and cytotoxicity. Cryprochine B exhibited a certain inhibitory effect against AChE with an IC₅₀ value of 27.35 μM. The binding mode of cryprochine B and AChE was explored by molecular docking. TRP84 residue from AChE was supposed to play an important role in stabilizing the ligand binding with cryprochine B.