Structural Similarity in Natural Products Leading to Sample Misidentification: A Case Study of the Bisbenzylisoquinoline Alkaloids Oxyacanthine and Berbamine

The similar structures of natural compounds and the absence of NMR data for commercial products raise the risk of misidentification. This work reports a case in which purchased samples labeled as "berbamine" from 14 suppliers are oxyacanthine (1). The NMR data of all purchased samples were consistent. The X-ray crystallography characterization of one sample revealed it to be 1. The NMR data of 1 were fully assigned for the first time. Berbamine (2) was isolated from the roots of Berberis sieboldii Miq. The NMR data of 2 were assigned, and its crystal structure was reported for the first time. The authors intend to raise awareness and support the academic/industrial community through a study of this misidentification case.