Berberine (BBR)

Berberine is a quaternary ammonium salt from the protoberberine group of isoquinoline alkaloids. Berberine is strongly yellow colored, which is why in earlier times Berberis species were used to dye wool, leather and wood. Wool is still today dyed with berberine in northern India. Under ultraviolet light, berberine shows a strong yellow fluorescence, so it is used in histology for staining heparin in mast cells. The alkaloid berberine has a tetracyclic skeleton derived from a benzyltetrahydroisoquinoline system with the incorporation of an extra carbon atom provided by S-adenosyl methionine (SAM) via an N-methyl group. Formation of the berberine bridge is readily rationalized as an oxidative process in which the N-methyl group is oxidized to an iminium ion, and a cyclization to the aromatic ring occurs by virtue of the phenolic group.