Nonocarbolines A-E, -Carboline Antibiotics Produced by the Rare Actinobacterium sp. from Indonesia.

During the course of our ongoing screening for novel biologically active secondary metabolites, the rare Actinobacterium, sp. 1808210CR was found to produce five unprecedented -carboline derivatives, nonocarbolines A-E (). Their structures were elucidated from high-resolution mass spectrometry, 1D and 2D nuclear magnetic resonance spectroscopy, and the absolute configuration of was determined by using the modified Mosher method. Nonocarboline B () displayed moderate antifungal activity against , while nonocarboline D () exhibited significant cytotoxic activity against the human lung carcinoma cell line A-549 with the IC value of 1.7 µM.