Monoclonal antibody-based enzyme-linked immunosorbent assay for quantification of majonoside R2 as an authentication marker for Nngoc Linh and Lai Chau ginsengs

Abstract

Background: Recent years have witnessed increasing interest in the high amount of ocotillol-type saponin in Panax vietnamensis, particularly in relation to majonoside R2 (MR2). This unique 3%-5% MR2 content impart Ngoc Linh and Lai Chau ginsengs with unique pharmacological activities. However, in the commercial domain, unauthentic species have infiltrated and significantly hindered access to the authentic, efficacious variety. Thus, suitable analytical techniques for distinguishing authentic Vietnamese ginseng species from others is becoming increasingly crucial. Therefore, MR2 is attracting considerable attention as a target requiring effective management measures.

Methods: An enzyme-linked immunosorbent assay (ELISA) was developed by producing monoclonal antibodies against MR2 (mAb 16E11). The method was thoroughly validated, and the potential of the immunoassay was confirmed by high-performance liquid chromatography with ultraviolet spectroscopy. Furthermore, ELISA was applied to the assessment of the MR2 concentrations of various Panax spp., including Korean, American, and Japanese ginsengs.

Results and conclusions: An icELISA using mAb 16E11 exhibited linearity between 3.91 and 250 ng/mL of MR2, with detection and quantification limits of 1.53 and 2.50 $-$ 46.6 ng/mL, respectively. Based on this study, the developed icELISA using mAb 16E11 could be a valuable tool for analyzing MR2 level to distinguish authentic Ngoc Linh and Lai Chau ginsengs from unauthentic ones. Furthermore, the analysis of the samples demonstrated that Ngoc Linh and Lai Chau ginsengs exhibit a notably higher MR2 value than all other Panax spp. Thus, MR2 might be their ideal marker compound, and various bioactivities of this species should be explored.

Keywords: Enzyme-linked immunosorbent assay; Majonoside R2; Monoclonal antibody; Ngoc Linh ginseng; Vietnamese ginseng.

A workflow on the production and development of anti-MR2 monoclonal antibody for the determination of MR2 compounds and the application on the distinguishing of authentic Vietnamese ginseng.

Fig. 1

Chemical structure of MR2.

Fig. 2

Reactivity of mAb 16E11 in ELISA. A: The reactivity of mAb 16E11 against MR-2 OVA (4 μg/mL) determined by iELISA. B: The reactivity of mAb 16E11 (6.25 μg/mL) against free MR2 (0.39–250 μg/mL) determined by icELISA. A: the absorbance at 405 nm from the well with free MR2 A₀: the absorbance at 405 nm from the control well where control was 5 % (v/v) methanol.