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

A systematic chemical investigation of the deep-sea-derived fungus 170217 resulted in the isolation of six new (-) and 45 known (-) 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 () and B () feature a unique isoquinolinone-embedded citrinin scaffold, representing the first exemplars of a citrinin-isoquinolinone hybrid. Dicitrinones K-L (-) are two new dimeric citrinin analogues with a rare CH-CH bridge. Biologically, frangula-emodin () and diorcinol () displayed remarkable anti-food allergic activity with IC values of 7.9 ± 3.0 μM and 13.4 ± 1.2 μM, respectively, while diorcinol () and penicitrinol A () exhibited weak inhibitory activity against , with MIC values ranging from 128 to 256 μM.