Isoquinoline Alkaloids as Protein Tyrosine Phosphatase Inhibitors from a Deep-Sea-Derived Fungus Aspergillus puniceus .

Puniceusines A-N ( 1 - 14 ), 14 new isoquinoline alkaloids, were isolated from the extracts of a deep-sea-derived fungus, Aspergillus puniceus SCSIO z021. Their structures were elucidated by spectroscopic analyses. The absolute configuration of 9 was determined by ECD calculations, and the structures of 6 and 12 were further confirmed by a single-crystal X-ray diffraction analysis. Compounds 3 - 5 and 8 - 13 unprecedentedly contained an isoquinolinyl, a polysubstituted benzyl or a pyronyl at position C-7 of isoquinoline nucleus. Compounds 3 and 4 showed selective inhibitory activity against protein tyrosine phosphatase CD45 with IC 50 values of 8.4 and 5.6 µM, respectively, 4 also had a moderate cytotoxicity towards human lung adenocarcinoma cell line H1975 with an IC 50 value of 11.0 µM, and 14 , which contained an active center, -C=N + , exhibited antibacterial activity. An analysis of the relationship between the structures, enzyme inhibitory activity and cytotoxicity of 1 - 14 revealed that the substituents at C-7 of the isoquinoline nucleus could greatly affect their bioactivity.