Mansouramycins E-G, Cytotoxic Isoquinolinequinones from Marine Streptomycetes

Chemical investigation of the ethyl acetate extract from the marine-derived sp. isolate B1848 resulted in three new isoquinolinequinone derivatives, the mansouramycins E-G ( - ), in addition to the previously reported mansouramycins A ( ) and D ( ). Their structures were elucidated by computer-assisted interpretation of 1D and 2D NMR spectra, high-resolution mass spectrometry, and by comparison with related compounds. Cytotoxicity profiling of the mansouramycins in a panel of up to 36 tumor cell lines indicated a significant cytotoxicity and good tumor selectivity for mansouramycin F ( ), while the activity profile of E ( ) was less attractive.