Cytotoxic aporphine alkaloids from the roots of Thalictrum baicalense Turcz. ex Regel.

Five previously undescribed isoquinoline alkaloids, including one thalifaberine-type aporphine-benzylisoquinoline (ABI) (1), two aporphine-type (2-3), and two oxoaporphine-type alkaloids (4-5), together with fifteen known alkaloids (6-20) were isolated from the roots of Thalictrum baicalense Turcz.ex Regel. Their structures were established on the basis of spectroscopic data and ECD calculations. Cytotoxicity assays revealed that several isolated alkaloids exhibited inhibitory effects against HL-60, HepG2, U937 and HCT116 human cancer cell lines, with IC50 values ranging from 2.41 to over 50 μM. Notably, the undescribed compound 5 exhibited inhibitory activity with an IC50 value of 14.78 ± 1.53 μM against the HL-60 cancer cell lines.