Complex Benzylisoquinoline and Ipecac Alkaloids
The third major group of alkaloids of this series includes those in which a secoiridoid portion
is incorporated into the molecules. Best known of these are the ipecacuanha alkaloids.
Ipecanuanha alkaloids
Ipecac, from Cephalis ipecacuanha, Rubiaceae, is a mixture of alkaloids derived from tyrosine, via a dopamine intermediate, that have powerful emetic properties. Emetine, the best known of this group of alkaloids, is used as a treatment for amoebic dysentery, but has many side effects. Similar alkaloids are found in a number of other species of Rubiaceae and Alangiaceae.
These alkaloids are similar in biosynthesis to the isoquinoline and benzylisoquinoline types, except that secologanin is used for the aldehyde. They are similar to monoterpene-derived indole alkaloids, except that dopamine is a precursor instead of tryptamine.
The presence of ipecosise, an acetylated derivative of the first proposed intermediate lends credence to the proposed pathway.
Emetine and tubulosine are widely used to treat amoebic dysentery. Emetine also has been used to treat schistosomiasis, leishmaniasis, and malaria. Among the side effects are cardiotoxicity, muscle weakness, and gastrointestinal problems. The alkaloid has a profound reversible effect on DNA synthesis.
Lecture Slides
Plants with Ipecacuanha
Alkaloids
Isoquinoline and benzylisoquinoline alkaloids
© David S. Seigler, Plant Biology 363, Plant Secondary Metabolism, Department of Plant Biology,
265 Morrill Hall, 505 S. Goodwin Ave., University of Illinois, Urbana, Illinois 61801, USA.
217-333-7577. seigler@life.uiuc.edu.
