Chemopreventive activity of isoquinoline alkaloids from Corydalis plants.

Eighteen isoquinoline alkaloids including protoberberines (1-12), benzophenanthridines (13-16) and an aporphine (17) isolated from plants of Corydalis species (Fumariaceae) were tested for inhibitory effects on Epstein-Barr virus early antigen activation induced by 12-O-tetradecanoylphorbol 13-acetate in Raji cells. In a primary screening test, all of the isoquinoline alkaloids showed inhibitory activity with the IC50 values being in the range of 140-410 mol ratio/32 pmol TPA. The data demonstrate that these isoquinoline alkaloids might be valuable as anti-tumor promoters.