Immunochromatographic assay for the detection of pseudojujubogenin glycosides

AbstractIntroductionBacopa monnieri contains pseudojujubogenin glycosides as pharmacologically active compounds. In order to screen large numbers of plant samples for the presence of pseudojujubogenin glycosides, a rapid and simple assay system is required for application to small quantities of test materials. Immunoassays using monoclonal antibodies could be useful for the determination of small quantities of pseudojujubogenin glycosides in plant extracts.ObjectiveThe objective of this work was to develop a simple method for the detection of pseudojujubogenin glycosides by the immunochromatographic strip test using anti‐bacopaside I monoclonal antibody.MethodologyThe qualitative assay was based on a competitive immunoassay in which the detector reagent consisted of a colloidal gold particle coated with the respective anti‐bacopaside I MAb. The capture reagent was a bacopaside I‐human serum albumin conjugate immobilised onto a test strip membrane.ResultsThe sample containing pseudojujubogenin glycosides and the detection reagent were incubated with the immobilised capture reagent. The glycosides in the sample competed in binding to the limited amount of antibodies in the detection reagent with the immobilised bacopaside I‐HSA conjugates and, hence, positive samples showed no colour in the capture spot zone. The detection limit for the strip test was 125 ng/mL.ConclusionThe assay system was found to be useful as a rapid and simple screening method for the detection of pseudojujubogenin glycosides in plants. Copyright © 2008 John Wiley & Sons, Ltd.