Activated Carbon-Based Immunochromatographic Strip Test for the Rapid Qualitative Analysis of Swertiamarin and Sweroside.

Abstract

Swertia japonica (S. japonica) is a medicinal plant that belongs to the Gentianaceae family. Several reports confirm the biological effects of the S. japonica extract. This plant is used mainly as a digestive stimulant, appetite stimulant, and gastrointestinal disease remedy in Japan. Secoiridoid glycosides are a group of compounds related to the beneficial effects of this plant. We developed an immunochromatographic strip test for major secoiridoid glycosides, such as swertiamarin (SM) and sweroside (SS) detection. We fabricated an immunoprobe using activated carbon as a reporter molecule and a monoclonal antibody against SM and SS (MAb D2) as a detection molecule. The test and control zones of the strip test contained SM-cBSA and Goat pAb anti-mouse IgM HRP conjugate, respectively. The immunoprobe reacted competitively with free SM and/or SS and immobilized SM-cBSA. The results were read and interpreted by the black spot intensity in the test zone. We succeeded in developing a strip test system with a detection limit (LOD) of 12.5 µg/mL. The selectivity and reliability evaluation revealed that the strip test is suitable for detecting SM and SS in S. japonica. The result was ready to be read in 30 min. This method can be a useful tool for the screening of biologically active S. japonica samples for further preparation of traditional medicine. To the best of our knowledge, this is the first immunochromatographic strip test developed for the detection of SM and SS in S. japonica samples.