AbstractBacopa monnieri (L.) Wettst. (Brahmi) is an Ayurvedic medicinal plant used for centuries as a memory enhancer. Dammarane‐type triterpenoid saponins classified as pseudojujubogenin and jujubogenin glycosides are reported as the active components in this plant. In this study, the monoclonal antibody (MAb) against bacopaside I, a major pseudojujubogenin glycoside found in Brahmi, was produced and characterised. Bacopaside I was conjugated with bovine albumin serum to prepare an immunogen. Hybridomas secreting a monoclonal antibody against bacopaside I was produced by fusing splenocytes from an immunised mouse and SP2/0‐Ag14 myeloma cells. The results showed that the antibodies were raised specifically against pseudojujubonin glycosides. An enzyme‐linked immunosorbant assay (ELISA) using anti‐bacopaside I MAb was performed in the range of 1.95–62.5 ng/mL of bacopaside I, with a limit of detection of 0.5 ng/mL. The method was validated and the practical use of the ELISA for analysing saponin glycosides from Brahmi was demonstrated. Copyright © 2007 John Wiley & Sons, Ltd.