Correlation between the main alkaloid contents and the powder fractions of pulverized Ephedra sinica

Abstract

The alkaloids in Ephedra sinica are important active pharmaceutical ingredients. During the investigation of ephedrine alkaloids, the herbaceous stems of Ephedra sinica are usually pulverized into powder to prepare sample solutions or to satisfy other test requirements. If the selection of particle size ranges is necessary, the distribution of the alkaloids in various size ranges of pulverized Ephedra sinica should be taken into account. In this work, three batches of herbaceous stems of Ephedra sinica were pulverized into powder under the same conditions. Each batch of the Ephedra sinica powder was separated into fractions (Fr.) 1–7, with size ranges of ≤20, 20–40, 40–60, 60–80, 80–100, 100–200, and >200 mesh. Ephedrine, pseudoephedrine and methylephedrine in each powder fraction were determined by HPLC. Statistical analysis illustrates that the distribution of each alkaloid within the powder fractions of pulverized Ephedra sinica are non-uniform (p < 0.05) and that three alkaloids are concentrated in Fr. 6 and 7, in which the main tissue is pith parenchyma. The correlation between the content of each determined alkaloid and the powder fractions could be represented using a quadratic equation with one unknown (r2 ≥ 0.743, p < 0.001). This work will allow plant analysts to improve their experimental plans for obtaining representative samples and to obtain more accurate results.