Discovery of new hazimycin congeners from Kitasatospora sp. P07101

In an analytical study of microbial broths, the actinomycete strain Kitasatospora sp. P07101 was found to produce three new congeners, which were designated hazimycins B (1), C (2), and D (3), together with the previously reported hazimycin (renamed hazimycin A (4)). The structures of these hazimycins were examined using various spectroscopic methods including nuclear magnetic resonance (NMR), and the results revealed that 1–3 were analogues of hazimycin with the replacement of one of the two isonitrile groups in 4 by an NH-formyl group in 1, the two isonitrile groups and an amide group by two NH-formyl groups and a nitrile group in 2, and the two isonitrile groups and two amide groups by two NH-formyl groups and two nitrile groups in 3. Only hazimycin A exhibited moderate antimicrobial activities against Gram-positive bacteria and Candida albicans. These results indicated that the presence of two isonitrile groups in the hazimycin structure is essential for antimicrobial activity.