Heterocycles and a Sorbicillinoid from the Coral-Derived Fungus Penicillium chrysogenum

A detailed chemical study of the culture of a coral-derived fungus Penicillium chrysogenum resulted in the isolation and identification of four new aromatic heterocycles chrysoquinazolinones A-B (1-2) and chrysobenzothiazoles A-B (3-4), along with a new sorbicillinoid 4-carboxylsorbicillin (5). Chrysoquinazolinones A-B (1-2) combine a quinazolinone fragment with a bicyclo[2.2.2]octane or a pyrrolidone moiety, respectively, demonstrating the unexpected structures of marine natural products. Chrysobenzothiazoles A-B (3-4) possess a benzothiazole system and are the second isolation of this class of skeleton compounds from marine organisms. The existence of the pair of enantiomers (±3) was deduced by chiral HPLC analysis. Their structures and absolute configurations were elucidated by detailed spectroscopic analysis, comparison with the literature data, single-crystal X-ray crystallographic analysis and TDDFT-ECD calculations. Compound 5 exhibited moderate cytotoxicity against K562 and NCI-H446 cell lines, with IC₅₀ values of 15.00 μM and 16.87 μM, respectively.