An integrated approach to reveal the chemical changes of Ligustri Lucidi Fructus during wine steaming processing

Ligustri Lucidi Fructus (LLF) is a traditional Chinese medicine to treat osteopathic and hepatic diseases. Wine steaming is the major processing method for LLF in Chinese Pharmacopoeia, but the chemical changes involved are still unclear. In this study, a research strategy was proposed to reveal the chemical changes during wine steaming processing of LLF. Firstly, in total 104 compounds were tentatively identified using UHPLC/Orbitrap-MS. Secondly, potential chemical changes were revealed by comparing the peak areas of the 104 compounds between LLF and the corresponding wine-steamed LLF (WLLF). The results indicated that iridoid and phenylethanoid esters were readily hydrolyzed during wine steaming processing, while organic acids, flavonoids, and triterpenes were stable. Finally, 7 selected compounds were simultaneously determined in 21 batches of LLF/WLLF samples using a 10-min UPLC/UV method. The contents of 4 esters decreased from 3.64% to 2.71%, and the contents of 3 potential hydrolysis products increased from 0.27% to 0.88% after processing. Our study indicated that hydrolysis of iridoid and phenylethanoid esters such as specneuzhenide was responsible for the chemical changes during the wine processing of LLF. The proposed strategy could be employed to investigate the chemical changes of other herbs during processing.