Integrated liquid chromatography-mass spectrometry and nuclear magnetic resonance spectra for the comprehensive characterization of various components in the Shuxuening injection

Shuxuening injection (SXNI) is made from the extract of Ginkgo biloba, and used for curing coronary heart disease, stenocardia and cerebral vasospasm. However, the flavonoids and terpene trilactones (TTLs) only account for about 30% of the dry weight of SXNI according to the current quality control standard. Thus, systematic investigation of the chemical composition of SXNI is needed to guarantee the drug safety. In this study, the integral approach of ultra high performance liquid chromatography-Q Exactive hybrid quadrupole-orbitrap high resolution accurate mass spectrometry (UHPLC-Q-Orbitrap HRMS) and nuclear magnetic resonance (NMR) techniques, combining with the solvent partition, were used for identifying the phytochemical compounds in SXNI. The NMR analysis revealed the possible structure types based on the characteristic chemical shifts, coupling constants, and peak shape, which gave the clues for the further UHPLC-Q-Orbitrap HRMS analysis of previously unknown or uncatalogued compounds. The characteristic ions and structural network of flavonoids and TTLs were generated and used in the UHPLC-Q-Orbitrap HRMS based structure identification. Only 72 compounds could be identified by the direct UHPLC-Q-Orbitrap HRMS analysis of SXNI, while this systematic strategy led to the identification of 133 compounds, which included 73 flavonoids, 5 biflavone, 6 proanthocyanidin, 14 TTLs, 6 fatty acids, 5 fatty amides, 12 organic acids, 1 amino acid, 3 excipients, 2 saccharides and 6 other components. In addition, the presence of steroids and triglycerides were also suggested by NMR. The absence of toxic components in SXNI was also confirmed. In addition, the NMR spectrum also revealed some unknown signals, which need to be further identified. This approach was proved to be useful for the rapid and effective identification of various compounds in the TCM preparations.