Basic physicochemical properties of extract from Dracocephalum moldavica / 中草药

ABSTRACT

Objective: Taking luteolin-7-O-β-D-glucuronide, rosmarinic acid, and tilianin as indexes, the concentration of extracts from Dracocephalum moldavica (EDM) and their index components in various media, surfactant solution, and apparent oil/water partition coefficient (P) was detected in different pH values, then the stability of EDM in artificial gastrointestinal fluid was investigated. This research would give the reference for the selection and preparation of further novel formulation. Methods: Apparent solubility of EDM in various media and surfactant solution was determined by precipitation method and a shake flask method was used to determine the P of octanol-water/phosphate buffer salt, the stability of EDM in artificial gastrointestinal fluid was investigated. HPLC was adopted to determine the concentration of the index components with Shim-pack ODS column (250 mm×4.6 mm, 5 μm), mobile phase of acetonitrile (A)-0.5% formic acid aqueous solution (B) for gradient elution (0-30 min, 15% A; 30-55 min, 15%→25% A; 55-80 min, 25%→35% A) as the mobile phase at a flow rate of 1.0 mL/min. The detection wavelength was set at 324 nm and the column temperature was maintained at 35℃. Results: At 37℃, the equilibrium solubility of the three index components in acid buffer solution increased obviously in water, but in alkaline the buffer solution of the equilibrium solubility decreased with pH increasing. In 32 g/L sodium dodecyl sulfate solution, the equilibrium solubility of luteolin, rosmarinic acid, and tilianin increased to 1679.61, 1249.2, and 2765.27 μg/mL. The P of luteolin-7-O-β-D-glucuronide, rosmarinic acid, and tilianin were 0.1731 (lgP=-0.7618), 0.068 4 (lgP=-1.1650), and 1.0829 (lgP=0.0346), and increased as pH rising. EDM in artificial gastrointestinal fluid was stable (except luteolin). Conclusion: The methods can be used to determine the apparent solubility, the P value of the extracts and their index components; The EDM in artificial gastrointestinal fluid is stable. The research would give the reference for the selection and preparation of the further novel formulation.