A monoclonal antibody-based competitive ELISA for the determination of ruscogenin in Chinese traditional medicines and biological samples

A competitive enzyme-linked immunosorbent assay (ELISA) was developed to determine ruscogenin (RUS) by using the monoclonal antibody (McAb). The monoclonal antibody against RUS, secreted from the established hybridoma cell lines, was identified as being of the IgG(1) isotype. The McAb exhibited high specificity to RUS, showing a very slight cross reactivity with diosgenin (15.7%), and no cross-reactivity to sarsasapogenin, diammonium glycyrrhizinate, oleanolic acid and notoginsenoside R1. The established ELISA, at an IC50 value of 157.55 ng.mL(-1) and a detection limit (IC20) of 20.57 ng.mL(-1), was compared with HPLC analyses, and a good correlation between ELISA and HPLC-ELSD analyses of RUS in the extract of Radix Ophiopogonis was obtained. The experimental data indicated that the ELISA method exhibits more advantages over HPLC-ELSD, such as low detection limit, high specificity, low background, and no requirement for sample pre-treatment, and is more suitable for the determination of natural components in Chinese traditional medicines and in biological samples for pharmacokinetic studies.