Structural Modification of an Angiogenesis Inhibitor Discovered from Traditional Chinese Medicine and a Structure–Activity Relationship Study

Pseudolaric acid B (PAB), discovered as a promising angiogensis inhibitor, was served as the anticancer drug lead, and a series of its derivatives were synthesized. Among them, some derivatives, such as 13c−13k, exhibited potent inhibition on the HMEC-1 cell proliferation and strong cytotoxic activities against the tested six tumor cell lines. The PAB derivatives 13c−13k also showed significant and specific inhibition on HMEC-1 cell migration in vitro, and only 13d expressed moderate activity against HMEC-1 cell tube formation. The in vitro anticancer tests of the selected natural PAB analogs and the structurally modified PAB derivatives have led to the establishment of a clear structure–activity relationship.