Columbamine is an isoquinoline alkaloid made up of four rings, two of which contain nitrogen. It is related to berberine but without its methylenedioxy group. Columbamine is also called dehydroisocorypalmine. It has usually been isolated and characterised as its chloride salt.

Occurrence

Columbamine has been found in several Berberis species, Coptis chinensis and Jateorhiza palmata.

Biosynthesis

The biosynthesis of columbamine starts with tyrosine and proceeds via (S)-reticuline in a pathway leading to benzylisoquinoline alkaloids. The final step is catalysed by the enzyme tetrahydroberberine oxidase, which oxidises (S)-isocorypalmine:

Metabolism

Columbamine is converted to berberine by the enzyme columbamine oxidase: