Biosynthetic Studies of Protoberberine and Related Alkaloids Using Plant Cell Cultures

The benzylisoquinolines comprise the largest group of alkaloids with about 2000 structures some of which possess valuable medicinal importance (such as codeine or morphine). During the past years the biosynthetic pathway leading to one group of these alkaloids, namely the protoberberines, was elucidated at the enzyme level (refs. 1–2). This progress was only possible by using cell suspension cultures as plant material. These plant cell cultures have the advantage of growing independently of climatical and geographical conditions and in a defined media. In some cases they are able to produce natural products in much higher amounts over shorter time periods than the intact plant (refs. 3–4). The cell cultures used in the investigations of protoberberine biosynthesis had been optimized for a high production of these alkaloids (ref. 5).