Available online 6 January 2026, 100974

Majonoside R2 (MR2) is an ocotillol-type saponin found at 3 %–5 % (w/w) in Panax vietnamensis that serves as a critical biomarker for authenticating sought-after Vietnamese ginseng varieties, such as Ngoc Linh and Lai Chau. However, widespread adulteration with morphologically similar species has created an urgent need for high-throughput, cost-effective authentication methods beyond chromatographic or deoxyribonucleic acid-based techniques.

A single-chain variable fragment (scFv) antibody against MR2 was recombinantly expressed in Escherichia coli, purified, and functionally validated. Using this antibody, an indirect competitive enzyme-linked immunosorbent assays (icELISA) approach was optimized for MR2 quantification in complex herbal matrices. The performance of this novel assay was benchmarked against that of a previously validated method using monoclonal antibody (mAb)-based ELISA and verified using authentic Panax spp. and Randia siamensis samples.

The scFv-based icELISA demonstrated a detection range of 31.25–1000 ng/mL for MR2, with high reproducibility and accuracy (CV <12.4 %, recovery 90.6 %–116.7 %). The assay was found to reliably distinguish authentic Ngoc Linh and Lai Chau ginsengs from other Panax species with high specificity. Recombinant expression in E. coli enables scalable, animal-free production, facilitating the broader adoption of this icELISA across laboratories equipped with standard molecular biology infrastructure. These findings support the integration of scFv-based assays into regulatory frameworks for authenticating Vietnamese ginseng.

Ginseng authentication

Enzyme-linked immunosorbent assay

Majonoside R2

Panax vietnamensis

scFv antibody

© 2026 The Korean Society of Ginseng. Publishing services by Elsevier B.V.