Studies on the isolation and structure elucidation of berberine, (−)-β-hydrastine, and jatrorrhizine from goldenseal root (Hydrastis canadensis L.) and Mahonia x media ‘Winter sun’ stem bark

Goldenseal (Hydrastis canadensis L., Ranunculaceae) is a traditional North American herbal medicine with a long history of use to treat various illnesses, primarily as a chemotherapeutic agent for microbial infections. Two of its alkaloid constituents, berberine and (−)-β-hydrastine, have well-defined pharmacological effects. In addition to its presence in goldenseal, berberine (and analogues) are found in other plant families. One such is the barberry family (Berberidaceae), encompassing various medicinal and decorative species, including those of the genus Mahonia (Berberis). This 3-h laboratory practical has been devised to allow undergraduate students to isolate berberine and (−)-β-hydrastine from a commercially available root sample of goldenseal, and both berberine and the closely related alkaloid, jatrorrhizine, from the bark of Mahonia x media ‘Winter sun’. Isolation is carried out on a miniature, sustainable and environmentally friendly scale using flash column chromatography. A gradient mobile phase is utilized for the isolation of (−)-β-hydrastine and berberine from goldenseal. A notable feature of the isolation of berberine and jatrorrhizine from Mahonia is the utilization of silica gel loaded with 10% w/w sodium carbonate. In this way, jatrorrhizine, an acidic alkaloid, is significantly retained while berberine elutes effortlessly from the column. A follow-on spectral assignment workshop is undertaken using 1- and 2-D NMR and IR spectra of the isolated alkaloids. Both formative and summative assessment of student comprehension takes place during the practical, workshop and end-of-semester college examinations. The experiment has been fully validated in the class setting, having been completed by circa 160 third year pharmacy students.