Determination of ginsenoside Rf and Rg2 from Panax ginseng using enzyme immunoassay

We have developed an enzyme immunoassay (EIA) to quantify trace amounts of ginsenoside Rf (Rf), one of the glycosides of protopanaxatriol from Panax ginseng. A carrier protein of bovine serum albumin (BSA) was coupled to the carbohydrate component of Rf using the periodate oxidation method. Antibodies were raised in rabbits using Rf-BSA conjugate as the immunogen and competitive indirect EIA was used for the determination of Rf. The working range was 0.01-10 ng per assay. The anti-Rf antiserum cross-reacted with ginsenoside Rg2 (105%), which is also a component of Panax ginseng and has a very similar chemical structure to Rf. These results suggest that the anti-Rf antiserum could also be used for the quantitation of ginsenoside Rg2 as well as ginsenoside Rf. In a comparison of EIA and HPLC the linear regression equation and correlation coefficient for the two methods were y(EIA) = 1.31x (HPLC)-11.48 and 0.98, respectively.