Chemical diversity of azaphilones from the marine-derived fungus Talaromyces sp. HK1-18

GNPS-based mass spectrum-molecular networks is an effective strategy for rapidly identifying known natural products and discovering novel structures. The chemical diversity of azaphilones from the fermentation extracts of Talaromyces sp. HK1-18 was studied by molecular network technique. Three linear tricyclic azaphilones, sequoiamonacins A-C (2a, 2b, 1), were isolated by silica gel column chromatography and high performance liquid chromatography from the extracts of the fungal strain of HK1-18, and their structures were identified by nuclear magnetic resonance and high-resolution mass spectrometry. Guided by the mass spectra of sequoiamonacins A-C (2a, 2b, 1), the cluster of sequoiamonacinoid analogues was discovered from the full molecular networking of HK1-18. By analyzing the MS/MS fragments of each parent ion in this cluster, 7 azaphilones (3-9) included 6 new ones (4-9) were predicted successfully. Then the MS/MS cracking regularity of this type of azaphilones was revealed. Compound 1 showed anti-inflammatory activity, which can inhibit the production of interleukin-1α (IL-1α) in lipopolysaccharide (LPS)-induced mouse macrophage RAW264.7, with an inhibitory rate of 29% at the concentration of 12.5 μg·mL^-1.