Development of ultrasound-assisted centrifugal extraction and online solvent concentration coupled with parallel countercurrent chromatography for the preparation of purified phytochemicals: Application to Lycium ruthenicum

摘要

To improve the preparation efficiency of natural products, new techniques for extraction and concentration of natural products have been established. Based on this, an on-line technology to improve the yield and preparation efficiency of natural products have been established. In this study, a novel method to extract natural products from crops and plants, termed ultrasound-assisted centrifugal extraction (UACE), was developed as a supplement to a new online solvent concentration (OSC) technique. These techniques were coupled with parallel countercurrent chromatography (PCCC) and evaluated in the automated preparation of phytochemicals from Lycium ruthenicum. The UACE device comprises an extraction chamber and a solution separation chamber and offers the advantages of higher extraction efficiency, fewer impurities, and conduciveness to sample processing. The OSC device comprises a spray nozzle, concentrating cylinder, and hot-blast air nozzle. The mechanical parameters of the UACE and OSC were optimized, and the operation mode of online UACE combined with OSC and PCCC was described. Raw plant materials were extracted with a two-phase extractant comprising petroleum ether-ethyl acetate-ethanol-water (2:2:1:6, v/v/v/v), and the aqueous and organic phases were then concentrated by OSC. After extraction and online concentration, the concentrate was separated. During PCCC separation, the on-line extraction, and concentration were still conducted. When the first cycle of the UACE/OSC/PCCC was completed, the second cycle was initiated, and so on. As a result, six target compounds with purities exceeding 97.03 % (high performance liquid chromatography detection at 250 nm) were successfully separated using the countercurrent chromatography solvent systems comprising n-heptane-ethyl acetate-acetonitrilewater (20:4:17:1, v/v/v/v) and n-butanol-ethyl acetate-water (55:21:70, v/v/v). Compared with conventional extraction methods, the proposed method offers the advantages of efficiency, automation, high-purity separation of the analytes, and systematic preparation of natural products from crops.