Purification and component identification of total proanthocyanidins in Choerospondias axillaris pericarp

The present study determined the quantitative markers of total proanthocyanidins in the purification of the industrial waste Choerospondias axillaris pericarp based on the comparison results of high-performance liquid chromatography(HPLC) and mass spectrometry(MS) and optimized the purification process with two stable procyanidins as markers. The adsorption and desorption of five different macroporous adsorption resins, the static adsorption kinetics curve of NKA-Ⅱ resin, the maximum sample load, and the gradient elution were investigated. The UPLC-Q-TOF-MS/MS was employed for qualitative analysis of the newly-prepared total proanthocyanidins of C. axillaris pericarp. As revealed by the results, NKA-Ⅱ resin displayed strong adsorption and desorption toward total proanthocyanidins. The sample solution(50 mg·mL~(-1)) was prepared from 70% ethanol crude extract of C. axillaris pericarp dissolved in water and 7-fold BV of the sample solution was loaded, followed by static adsorption for 12 h. After 8-fold BV of distilled water and 6-fold BV of 10% ethanol were employed to remove impurities, the solution was eluted with 8-fold BV of 50% ethanol, concentrated, and dried under reduced pressure, and purified total proanthocyanidin powder was therefore obtained. Measured by vanillin-hydrochloric acid method, the purity and transfer rate of total proanthocyanidins were 47.67% and 59.92%, respectively, indicating the feasibi-lity of the optimized process. UPLC-Q-TOF-MS/MS qualitative analysis identified 16 procyanidins in C. axillaris total proanthocyanidins. The optimized purification process is simple in operation and accurate in component identification, and it can be applied to the process investigation of a class of components that are difficult to be separated and purified. It can also provide technical support and research ideas for the comprehensive utilization of industrial waste.