Commonalities and characteristics of aqueous extracts from three Uighur medicines were analyzed by using three-stage infrared spectroscopy combined with ultra-performance liquid chromatography-time of flight-mass spectra

OBJECTIVE: To establish a method to analyze the commonalities and characteristics of the aqueous extracts from three Uighur medicines.METHODS: In this study, a combination method of three-stage infrared spectroscopy and ultra-performance liquid chromatography-time of flight-mass spectra(UPLC-TOF-MS) method was used to analyze the commonalities and characteristics of the aqueous extracts from Hezi(Fructus Chebulae),Maohezi(Terminalia Belliricae Fructus) and Xiqingguo(Chebulae Fructus Immaturus).RESULTS: In Fourier transform-infrared spectroscopy spectra, all three samples showed the characteristic absorption peaks of tannins similarly. According to UPLC-TOF-MS data analysis, the difference of the position and intensity of the peaks at 1713-1707 cm^(-1) in the three samples were related to the difference in the relative content of tannin and pentacyclic triterpenoids. In second derivative infrared spectroscopy spectra, further analysis of the differences in the infrared spectra of the three samples was performed by increasing the apparent resolution. In combination with UPLC-TOF-MS data, some features infrared absorption peaks were assigned.The absorption peaks at 1032-1030 cm^(-1) assigned to the stretching vibration of C-O-C(ether bond)groups of tannins; 1164-1163, 1063-1062, 1009-1005, 904 cm^(-1) attributed to the stretching vibration of C-O(ether bond) and C-O-C groups of glycosidic compounds. 1385-1383 cm^(-1) attributed to the bending vibration of C-H(alkyl hydrogen) of methoxyl group of pentacyclic triterpenoids. Peak 835 cm^(-1) was assigned to the characteristic absorption peak of bending vibration of = C-H groups of pentacyclic triterpenoids. The two dimensional correlation infrared spectroscopy could further quickly distinguish three samples through the dynamic structural information of their chemical components and discrepancy of auto-peaks and cross-peaks intuitively in the range of 1720-419 cm^(-1).CONCLUSION: By comparing the intensity of the infrared characteristic absorption peaks, the main chemical components were assigned, which significantly enriched and perfected the data analysis of the infrared spectra of three Uighur Medicines. It provided a rationale for the identification of medicinal materials with complex and similar chemical components using the three-stage infrared spectroscopy and UPLC-TOF-MS.