Mansouramycins A-D, cytotoxic isoquinolinequinones from a marine streptomycete.
Hawas UW, Shaaban M, Shaaban KA, Speitling M, Maier A, Kelter G, Fiebig HH, Meiners M, Helmke E, Laatsch H.
Chemical screening of the ethyl acetate extract from the marine-derived Streptomyces sp. isolate Mei37 resulted in five isoquinolinequinones, four new derivatives, mansouramycin A-D (1, 3-5), and the known 3-methyl-7-(methylamino)-5,8-isoquinolinedione (2). Their structures were elucidated by NMR and MS techniques and by comparison with related compounds. Cytotoxicity profiling of the mansouramycins in a panel of up to 36 tumor cell lines indicated significant cytotoxicity of several derivatives, with pronounced selectivity for non-small cell lung cancer, breast cancer, melanoma, and prostate cancer cells.