Discovery and molecular elucidation of the anti-influenza material basis of Banlangen granules based on biological activities and ultra-high performance liquid chromatography coupled with quadrupole-orbitrap mass spectrometry

Traditional Chinese medicine (TCM) has a wide range of applications, including human healthcare-associated treatments and bioactive compound discovery. However, complex chemical systems present a significant challenge for chemical-material-based research and quality control. For instance, Banlangen (BLG) granules is a well-acknowledged TCM preparation widely used in clinical treatment of virus infection. However, its chemical basis of anti-influenza efficacy remains unclear.In the present study, a systematic discovery strategy for identifying anti-influenza molecules based on biological activities and chemical analysis was established to contribute to the molecular elucidation of the anti-influenza material basis of Banlangen granules.Hemagglutinase inhibition (HAI) and neuraminidase inhibition (NAI) assays were used to compare the anti-influenza activities of different fractions of BLG granules against H1N1, H5N1 and H7N9 viruses. A comparative qualitative analysis of the chemical constituents in BLG granules and their fractions was performed using ultra-high-performance liquid chromatography coupled with quadrupole orbitrap mass spectrometry (UHPLC-Q-Exactive Orbitrap MS), in which a multiple mass spectrometry database platform and three compound identification strategies were used. The association between anti-influenza activities and chemical constituent characteristics was analyzed using multiple stoichiometries and data comparison strategies.The results showed that the chromatography fractions F3 and F4 of the BLG granules had the highest anti-influenza activity. A total of 88 compounds were identified in the BLG granules, including 31 alkaloids, 16 organic acids, 10 nucleosides, 8 phenylpropanoids, 6 sulfur-containing compounds, 5 amino acids, 4 aromatic compounds, 3 aldehydes and ketones, 2 flavonoids, 1 alcohol, 1 carbohydrate, and 1 aliphatic compound. Out of these, 31 characteristic compounds were identified in fractions F3-F4 as candidate compounds with anti-influenza activity. Additionally, 6-methoxyquinoline and 4-guanidinobutanal were identified in BLG granules and its raw material (Isatidis Radix) for the first time.In this study, we proposed a systematic discovery strategy to thoroughly investigate the anti-influenza activity, chemical identification, and constituents-activity relationship of BLG granules. These data not only provided a deeper understanding of the molecular mechanism of the activity of BLG granules, but also presented a basis for the discovery of potential novel drug candidates and quality evaluation and control of BLG granules.