Chemical and DNA authentication of taste variants of Gynostemma pentaphyllum herbal tea

Gynostemma pentaphyllum Makino (Gp) was once used as a sweetener in Japan and is now widely consumed as an herbal tea worldwide for lowering cholesterol levels. Two taste variants, bitter and sweet, of Gp exist in the commercial market, but they cannot be differentiated morphologically nor by existing chemical analytical methods. This has been creating a problem in quality control of Gp products. In the present study, using HPLC-DAD and HPLC-ESI-MS analysis, we found that the Gp saponins, not flavonoids, from the sweet and bitter variants have distinctly different profiles. In addition, the two variants share only 69.01% homology in the ribosomal ITS-1 region, suggesting a phylogenic gap between these two variants. The combinations of chemical profiling and phylogenic analysis clearly confirm, for the first time, the distinction between these two taste variants. This information has direct application in the authentication and quality assessment of the various Gynostemma tea products.