Development of new staining technology "eastern blotting" using monoclonal antibody

Ginsenosides contained in Panax species were separated by silica gel TLC blotted to a polyvinylidene difluoride (PVDF) membrane which was dipped in a sodium periodide (NaIO(4)) solution and reacted with protein, preparing a ginsenoside-protein conjugate for binding a ginsenoside on a PVDF membrane. The blotted spots were stained by anti-ginsenoside-Rb1 monoclonal antibody (MAb) and anti-ginsenoside-Rg1MAb, respectively. The newly established immunostaining method, eastern blotting was applied for the determination of ginsenosides possessing protopanaxadiol and/or protopanaxatriol. Double staining of eastern blotting for ginsenosides using anti-ginsenoside-Rb1 MAb and anti-ginsenoside-Rg1 MAb promoted complete identification of ginsenosides in Panax species. This technique has been devised for the chromatographic separation and identification of ginsenosides using polyethersulfone (PES) membrane. It caused an acceptable separation of ginsenoside-Rb1, -Rc and -Rd in various ginseng extracts. Newly developed technique is quite simple and applies for immunoassay system. Ginsenosides separated using a PES membrane were directly treated with a NaIO(4) solution and then reacted with bovine serum albumin (BSA) for making a ginsenoside-protein conjugate. After the blocking, anti-ginsenoside-Rb1 MAb recognized a ginsenoside on a PES membrane and then a sec-ond antibody labeled with enzyme reacted to the first antibody. Finally a substrate was oxidized with the enzyme and de-veloped the staining of ginsenosides. The staining spots of ginsenosides on membrane were quantitatively evaluated by NIH Image indicating at least 62.5 ng of each ginsenoside-Rb1, -Rc and -Rd were detected with clarity. The determination range of three ginsenosides was from 0.125 to 2.0 µg of direct amount on PES membrane.