DNA identification of commercial ginseng samples.

Abstract

An investigation was performed with the objective of developing a DNA-based protocol for the identification of commercial samples of the herbal compound ginseng. There are currently two major herbal products referred to as ginseng. They are Korean or Chinese ginseng (Panax ginseng) and American ginseng (Panax quinquefolius). The market for ginseng in the United States is estimated to be approximately $300 million annually. Current tests for ginseng species identification rely on expert botanical identification of fresh plant/root specimens or on biochemical characterization of active and marker compounds (e.g., ginsenosides). For the determination of the feasibility of ginseng identification by DNA analysis, a strategy based on the direct DNA sequence analysis of the nuclear ribosomal internal transcribed spacer region was developed. Other genetic tests included sequence analysis of the chloroplast ribulose 1,5-bisphosphate carboxylase large subunit gene and DNA fingerprinting by the rapid amplification of polymorphic DNA technique. To confirm the results, each ginseng sample was identified using high-performance liquid chromatography. All methods were successful in distinguishing American from Korean ginseng. In addition, the protocol was improved for the isolation of genomic and plastid DNA from commercial ginseng preparations by incorporating an impact homogenization step into the standard column chromatography purification procedure.