Citriquinolinones A and B: Rare Isoquinolinone-Embedded Citrinin Analogues and Related Metabolites from the Deep-Sea-Derived Aspergillus versicolor 170217.

A systematic chemical investigation of the deep-sea-derived fungus Aspergillus versicolor 170217 resulted in the isolation of six new ( 1 - 6 ) and 45 known ( 7 - 51 ) compounds. The structures of the new compounds were established on the basis of exhaustive analysis of their spectroscopic data and theoretical-statistical approaches including GIAO-NMR, TDDFT-ECD/ORD calculations, DP4+ probability analysis, and biogenetic consideration. Citriquinolinones A ( 1 ) and B ( 2 ) feature a unique isoquinolinone-embedded citrinin scaffold, representing the first exemplars of a citrinin-isoquinolinone hybrid. Dicitrinones K-L ( 3 - 4 ) are two new dimeric citrinin analogues with a rare CH-CH ₃ bridge. Biologically, frangula-emodin ( 32 ) and diorcinol ( 17 ) displayed remarkable anti-food allergic activity with IC ₅₀ values of 7.9 ± 3.0 μM and 13.4 ± 1.2 μM, respectively, while diorcinol ( 17 ) and penicitrinol A ( 20 ) exhibited weak inhibitory activity against Vibrio parahemolyticus , with MIC values ranging from 128 to 256 μM.