Abstract

Background: Icariin (ICN) is the main bioactive natural flavonoid in plants of the Epimedium genus and is valued in traditional Chinese medicine owing to its beneficial effects, including enhancement of cardiovascular function and antitumorigenic activity. Current methods for detecting ICN employ expensive instruments that require a high level of skill for operation. As such, a more simple and rapid assay is desired.

Methods: A colloidal gold-conjugated anti-ICN monoclonal antibody was prepared and an Immunochromatographic Strip (ICS) test was developed for detecting ICN in plant preparations.

Results: The prepared anti-ICN MAbs show weak reactivity with compounds that are structurally related to ICN. Using anti-ICN MAbs, a specific and reliable ELISA was developed to detect ICN. The system shows a full measurement range from 10 ng/mL to 1280 ng/ml with regression equation is y = -0.158ln(x) + 1.3336 (R2 = 0.9924). Moreover, the usefulness of the ICS assay using anti-ICN mAb as a qualitative method was confirmed for the analysis of ICN in different samples by comparing to indirect competitive enzyme-linked immunosorbent assay. This ICS assay based on the competitive immunoassay system showed high specificity for ICN and had a detection limit of 500 ng/ml.

Conclusion: Our results indicate that the ICS assay can be a powerful tool for rapid screening of plant materials used in traditional Chinese medicine owing to its ease of manipulation and low cost. In addition, it can potentially be used for the detection of ICN in other types of biological sample.

Keywords: Icariin, monoclonal antibody, immunochromatographic strip, colloidal gold, traditional Chinese medicine, enzymelinked immunosorbent assay.

Graphical Abstract