A monoclonal antibody-based indirect competitive enzyme-linked immunosorbent assay to quantify swertiamarin and related compounds inSwertia japonicaMakino

Introduction Swertia japonicaMakino (S. japonica) has a long history of use as a folk medicine, and it is one of the three essential Japanese folk medicines.S.japonicahas been reported to have various biological activities. The biologically active secoiridoid glycoside swertiamarin (SM) has been isolated fromS. japonica. The efficacy of this plant is attributed to SM and related secoiridoid glycosides. To control the quality ofS. japonicafor medicinal use, a method for the determination of SM and other secoiridoid glycosides in the plant is needed. Objective To produce an anti-SM monoclonal antibody (MAb) and develop an indirect competitive enzyme-linked immunosorbent assay (icELISA) forS. japonicastandardisation and quality control. Methodology SM was conjugated to cationised bovine serum albumin (cBSA), and the SM-cBSA conjugate was used to immunise BALB/c mice. Splenocytes from the immunised mice were then fused with SP2/0 myeloma cells to produce hybridoma cells that expressed anti-SM MAb. Results The developed icELISA was sufficiently sensitive and had a quantitative range of 0.78 to 12.5 mu g/mL. Coefficients of variation below 10% indicated good repeatability. Recoveries in a spike and recovery assay ranged from 91.84% to 115.50%, which confirmed that the icELISA was accurate. The SM content measured using the icELISA was in agreement with the results of a high-performance liquid chromatography-ultraviolet (HPLC-UV) assay. Conclusion The icELISA is suitable for the high-throughput analysis of SM and other secoiridoid glycosides inS. japonica. The method is fast, economical, and reliable forS. japonicaquality control.

Automated summary

The study aimed to produce an anti-SM monoclonal antibody (MAb) and develop an indirect competitive enzyme-linked immunosorbent assay (icELISA) for standardisation and quality control of Swertia japonica. The developed icELISA was sensitive, with a quantitative range of 0.78 to 12.5 μg/mL, and showed good repeatability with coefficients of variation below 10%. The method was accurate, as confirmed by recoveries in a spike and recovery assay ranging from 91.84% to 115.50%, and the SM content measured using the icELISA was consistent with the results of a high-performance liquid chromatography-ultraviolet (HPLC-UV) assay.