Simultaneous quantification of sixteen bioactive constituents in Zhi-zi-chi decoction: Application to the optimization of Zhi-zi-chi decoction in ratio of dosage

Abstract

A simple and robust method of liquid chromatography-mass spectrometry coupled with an electrospray ionization interface was developed for the simultaneous determination of sixteen representative ingredients including seven iridoids, four soy isoflavones, two flavonoids, one gardenia yellow pigment, one monoterpene glycoside, and one organic acid in different composition of Gardenia jasminoides fruit (GJF) and Fermented Soybean (FS) (4 : 0, 2 : 1, 1 : 1, 1 : 2, 0 : 4), which are two component herbs of Zhi-zi-chi decoction. Chromatographic separation was accomplished on a Gemini C₁₈ reversed-phase column (250 mm × 4.6 mm, 5 μm) using gradient elution with the mobile phase consisting of methanol and 0.1% aqueous formic acid. The analytes were quantified without interference in the selected ion monitoring mode with positive electrospray ionization. All calibration curves show good linearity (r > 0.9994) within test ranges. The precisions and repeatability were evaluated and relative standard deviation values were less than 3.0%. The recoveries were between 96.5 and 103.7%. The validated method was successfully applied to a comparative analysis of sixteen constituents. The results demonstrate that there are significant differences in the contents of compounds in different proportions, and the combination of GJF and FS (2 : 1) was considered as the optimum ratio of dosage of Zhi-zi-chi decoction.