Preparation of monoclonal antibody against ginsenoside Rf and its enzyme immunoassay

A rapid and sensitive indirect competitive enzyme immunoassay method has be en developed for quantitating ginsenoside Rf (Rf) in crude total Panax gins eng saponins and in rat plasma using high titer mouse monoclonal antibody ( mAb) raised against a conjugate of Rf and bovine serum albumin (BSA), The i sotype of mAb against Rf was IgG(3) with a kappa chain. The presence of Rf inhibited the binding of the mouse anti-Rf mAb to a Rf-BSA solid phase coat ing antigen. The working range was 0.01-10 ng/assay and detection limits we re 20 pg in various ginseng extract fractions or 34 pg in rat plasma per as say. The anti-Rf mAb cross-reacted with ginsenoside Rg(2) by 57.5%, but not with other ginsenosides, However, this anti-Rf mAb did not cross-react wit h BSA or cellubiose, which is a carbohydrate component of Rf, Using this st andard curve, we could measure the amount of Rf in ginseng total extract, g inseng total saponins, protopanaxadiol saponins, and propanaxatriol saponin s, We could also measure the amount of Rf in rat plasma after the oral admi nistration of Rf and found that Rf reached a maximum level in rat plasma af ter 16 h, These results indicate that the anti-Rf mAb could be useful for t he quantitation of Rf in crude ginseng fractions and in body fluids.