Preliminary Studies Toward Identification of Sources of Protoberberine Alkaloids used as Yellow Dyes in Asian Objects of Historical Interest

摘要

The protoberberines are bright yellow alkaloids that have been used for centuries in Chinese and other traditional medicines and also as dyes for textiles and paper. The most frequently cited source for protoberberine dyes is the Amur cork tree (Phellodendron amurensej. However, many plants contain protoberberines, and, as shown here, the analysis of dyed objects often permits identification of plant types, which sheds light on the resources available to early dyers. In this study, representatives of five genera (Berberis, Coptis, Fibraurea, Mahonia, Phellodendron) of protoberberine-yielding plants were analyzed, all of which have been reported as having been used in Asia as sources of yellow colorants, using high-performance liquid chromatography (HPLC) with diode array and mass spectrometric detection. It is shown that their contents of berberine, palmatine, jatrorrhizine and other protoberberines are distinctive enough to allow them to be distinguished from one another. As a result, analysis of the dyes used in several historical objects allows conclusions to be drawn as to the plant source of the dye. Knowledge of the type of colorant used in an object is important for its conservation because the protoberberine alkaloids, as a class, are both very water-soluble and relatively unstable (among yellow dyes) to light.