HPLC–UV-Guided Discovery of Eurotamines A–F: Six Pairs of Isoquinoline Derivative Enantiomers from Marine-Derived Fungus Eurotium sp. SCSIO F452

Six pairs of unprecedented isoquinoline derivative enantiomers were obtained by HPLC-UV-guided isolation from the salicylaldehyde-producing marine fungus Eurotium sp. SCSIO F452. Their structures were characterized by spectroscopic analyses, X-ray diffraction, and electronic circular dichroism calculations. They represent unusual groups of oxidized, prenylated benzopyridines with a C₇ side chain cyclized in different patterns, generating 6/6/5/6 (1-3), 6/6 (4 and 5), and 6/6/6 (6) ring systems. Selected isomers exhibited weak cytotoxic activities against a panel of cancer cell lines.